Обучение по природни науки и върхови технологии

2018/5, стр. 759 - 770

METHYL, THE SMALLEST ALKYL GROUP WITH STUNNING EFFECTS

Saâd Moulay
E-mail: polymchemlab@hotmail.com
Laboratoire de Chimie-Physique Moléculaire et Macromoléculaire
Département de Génie des Procédés, Faculté de Technologie
Université Saâd Dahlab de Blida
B. P. 270, Route de Soumâa, 09000, Blida, Algeria

Резюме: In several instances, methyl group was found to play a pivotal role when present in a molecule. Its hydrophobic character has been the key success factor for specific performances when lipophilicity is the basic requirement for a phenomenon to occur. In some cases, chemical reactivity and physical phenomena are specifically linked to the effects of methyl group.

Ключови думи: caffeine; chemiluminescence; chocolate; fragrance; methyl; NLAP; SOA

Introduction

Organic-related molecules (organic and organometallic ones) are often featured by the presence of groups that are actually assemblies of organic atoms. Of these are the functional groups, particularly the polyvalent ones, which peculiarly characterize the molecule and impart some of its characteristic chemical and physical properties. As the term ‘functional’ may suggest, the functional group would make the molecule chemically reactive and hence transformable. Functionalization of a molecule would bring about changes in its known properties which can be dependent on the intrinsic characteristics of the related functionalizing agent, such as polarity, spatial geometry and spatial volume.

Of particular interest, alkyl groups in an organic molecule present several effects, owing to their hydrocarbonaceous nature: electron induction, electron donation, hindrance, hyperconjugation, energy, hydrophobicity, polarizability…etc; moreover, these effects usually varied with the length of the alkyl chain, its linearity, and its degree of branching (Taft, 1981). The alkyl groups are known to lower the acidity of carboxylic acids and alcohols and the longer the alkyl chain, the higher the effect (Radom, 1975; Dewick, 2006). Besides, the polarity and the polarizability were demonstrated to explain the effects of the alkyl groups on the acidity and the basicity of alcohols, and the stability of cations and anions (Exner & Böhm, 2007). Another role of alkyl groups is their protection of some sensitive functional groups such as phenolics.

Methyl group, being the smallest alkyl group, has been the readily recourse when organophilic (lipophilic) character is sought for a water-borne molecule. The simplest example is the stunning alteration of properties when molecules of water are changed to molecules of methanol, by substituting a hydrogen atom of water molecule with a methyl group (Fig. 1). Less surprising, perhaps, is the readily miscibility of water and methanol. Yet, methanol has not been made out of water via a mechanism involving a hydrogen substitution. The unique facet of the methyl group is its impact and leading role when attached to biological molecules, particularly DNA. The methyl group is believed to have played a major role in the dynamics and evolution of biomolecules (Nickels, 2012).

OC108.9°HHH

H

H O H

104.45°

A B

Figure 1. A – Water; B – Methanol

Indeed, the literature survey reveals a trove of reports on methylation of such molecules and the effects of thus-tethered methyl groups were illustrated1) (Barreiro et al., 2011). An astounding fact is the link between the methyl group in methylated DNA and the cancer development (Newberne & Rogers, 1986; Wajed et al., 2001); methylation of biological molecules contributes to the regulation of gene expression and protein function, and RNA processing. However, methylated flavones such as 5,7-dimethoxyflavone exhibit potent antiproliferative activities and inhibit the carcinogenic activation of some enzymes such as cytochrome P450 (Murakami et al., 2002; Morley et al., 2007). On the other hand, the impact of the methyl group on the biological potency of a drug has been broadly elucidated (Schönherr & Cernak, 2013). Although methamphetamine and amphetamine (Fig. 2) were generally claimed to present about the same drug potency, the methyl group in the methamphetamine renders amphetamine more lipid soluble, that is, increases its lipophilicity. Yet, methamphetamine was found to last longer because the methyl group decreases the polarity of the molecule, making the latter penetration easily into the blood (MacKenzie & Heischoner, 1997). Methionine, a sulfur- and methyl-containing amino acid, has been claimed to potentially detoxify a body from toxic heavy metals such as lead through methyl donating phenomenon (Chaitow, 1988); for this reason and others, L-methionine is taken as a dietary supplement.

NH2

CH3
NCHCH3NH23H3COHO
SHH

A B C

Figure 2. A Amphetamine; B – Methamphetamine; C – L-Methionine

Because of its critical existence within some molecules, the term “methyl” usually preceded their common names, such as methyldopa (antihypertensive drug), methyl orange (acid-base titration indicator), methyl red (acid-base titration indicator), methyl yellow (acid-base titration indicator), methyl green (cationic dye), methyl violet (cationic dye), and methyl viologen; the methyl groups in these substances are attached to nitrogen atoms. In general, the incorporation of methyl group onto an organic molecule is commonly achieved via a methylation reaction using a methylating agent. As per the site reactivity, the methylation may take place on the main atoms of the organic molecules, and, therefore one speaks chiefly of C-, N-, S-, and O-methylations. Screened literature revealed several methylating agents and a variety of catalysts to promote the methylation reaction (Lamoutreux & Agüero, 2009). The methylation of biological molecules occurs in the presence of enzymes as catalysts. Methylcobalamin (the cyano group in vitamin B12 is substituted by methyl group) is one of the biomethylating agents; it methylates heavy metals such as mercury.

Special effects/roles of methyl group

Besides the few above-cited effects and roles of the methyl group when present in biological molecules, other significant effects are worth of mentioning. Methyl fixation in drugs imparts some benefits for the healthcare and this was therefore associated with the coined term “magic methyl effect” (Barreiro et al., 2011; Schönherr & Cernak, 2013). For example, the enzymatic inhibiting effect of p38α (Fig. 3A) increased by 208 fold when methylated (Fig. 3B); IC50 of the unmethylated p38α was greater than 2500 nM, and that for the methylated one was  12 nM (Angell et al., 2008). To one’s surprise, the molecular structure of caffeine (Fig. 3C) differs from that of theobromine (Fig. 3D) by only an extra methyl group. The former is the main component of coffee, and the latter is that of cacao and chocolate. It seems that the extra methyl group on the caffeine molecule (coffee) has an active effect on one’s central nervous systems, while theobromine (chocolate) smoothly affects one’s muscle functions.2)

HNONHO
HNONHOH3C

A B

CH CH3

H3 NNNNOCCH3 H3

NHNNNOCOD

Yu and his co-workers (Li et al., 2006) demonstrated spectroscopically the contribution of methyl group in the formation of hydrogen bonding in DMSO-MeOH mixture. By means of quantum chemical calculations, methyl groups were shown to affect the strength H2O---XF and H2S---XF halogen-bonds (X = Cl and Br) (Li et al., 2010); O---X in H2 O---XF complex is stronger than S---X one in H2 S---XF complex but the reverse is true when hydrogen atoms are replaced with methyl groups. The calculated interaction energies (∆E) suggest positive contribution of the methyl groups in the formation of halogen bonding: -16.5 kJ/mol for H2 O---ClF, -22.3 kJ/ mol for (CH3)2O---ClF; -10.9 kJ/mol for H2S---ClF, -27.2 kJ/mol for (CH3)2S---ClF. Based on theoretical calculations, Borden et al.(Zhang et al., 2011) advanced the effect of geminal methyl group on the rate of cyclopropylcarbinyl radical; the ring opening rate of B1 to 1,1-dimethyl-3-butenyl radical B2 should be 104 times faster than that of unsubstituted cyclopropylcarbinyl radical A1 to 3-butenyl radical (A2) and 106 times faster than that of B1 to 2,2-dimethyl-3-butenyl radical C2 (Scheme 1).

CHCH2H,CH

CH2 CH2

A2HCCRHCCR2222A1R =R =B2,B13 R = H2CCH3, C CR22

Scheme 1. Methyl effect on ring opening of cyclopropylcarbinyl radical

Valadbeigi & Gal (2016) disclosed the effect of the number of methyl groups on polarizabilities and dipole moments of oxygen-, nitrogen-, and phosphoruscontaining molecules. That is, the polarizabilities increase linearly with the number of methyl groups, and the dipole moments either decrease or increase. It was found that the polarizabilities of H 2O, CH2O, NH3 , and PH3 increase by nearly 1.89, 1.83, 1.76, and 2.00 Å 3 per methyl group, respectively, when hydrogen atoms are substituted by methyl groups. In 1979, Burkert (1979) certified by means of molecular mechanics calculations the effects of the number of methyl groups on the geometry and conformational equilibrium of 1,3-dioxanes. Rao (2002) reported the effect of methyl groups on the chemical reactivity of isoxazoles as per the calculated π-electron densities, π-bond energies, delocalizing energies, and ionization potentials, which revealed a substantial electron exchange between isoxazole ring and the methyl groups. Russian workers Vdovin et al. (1973) proved the effect of the number of methyl groups and their positions on pyridine molecule on the pK a and the nonlinear acoustic parameter (NLAP) as shown in Table 1.

Table 1. Effect of methyl groups on pyridine molecule

Pyridineα-Picolineβ-Picolineϒ-Picoline2,3-Lutidine2,4-Lutidine2,6-LutidinepKaNLAP5.221.0005.941.1355.651.0796.031.1496.581.2636.651.2706.751.281

The influence of methyl group on the fragrance of aliphatic nitriles (Fig. 4) was disclosed by Sell & Cairns (1982). The odor alteration was dependent not only on methyl substitution, but also on its position and on the length of the alkyl chains (Table 2).

CH3 CH3 R CH2 CH C2 N R CH2 CHNRCHC CH2 C N

A B C Figure 4. A Alkanonitrile; B – 2-Methyl alkanonitrile; C – 3-Methyl alkanonitrile

Table 2. Effect of methyl groups and the length of alkyl chain on the odor of alkanonitriles

OctanonitrileNonanonitrileDecanonitrileUndecanonitrileDodecanonitrileAPeach andcoconutnotesPeach notesstronger thanthose ofAetcoconut notesweaker thanthose ofAWaxy peachnotesOrange andmandarin notesOrangecharacterBFloral,jasminiccharacterFloral, jasminic,and peachycharacterFloral,jasminic,and peachycharacterFloral with lilaccharacterFloral withgreen jasminiccharacterCFloral,jasminiccharacterwithagrumenqualityFloral, andjasminic, withgreen qualityCitrus oralnotesGreen oralwith slight citrusnotesOrangecharacter, di󰀨useby green sea-fresh quality

Polo and his group (Müller et al., 2015) studied the influence of the methyl groups on phenanthroline ligands (Fig. 5) on the dye-sensitizing power of its ruthenium complex for solar cells. The incorporation of the ruthenium complex B in TiOled2 to the following solar cell parameters: open-circuit potential, J=11.9SC mA cm−2; short circuit current density, VOC = 0.627 V; overall performance, η = 5%; Fill factor, FF = 0.67. Those of unsubstituted ruthenium complex A were 13.25 mAcm−2 , 0.687 V, 6.1%, 0.67, respectively. The methyl groups were thus found to lower the sensitizer efficiency.

COOH

NNNNRuSCNNCSHOOCHOOC3COOH3CH3NNNNRuSCNNCSCHCH

A B

Figure 5. Acis-[Ru(phen)(dcbH2 )(NCS)2]; B cis-[Ru((CH3)4-phen)(dcbH2)(NCS)2] Theoretical and experimental works have been undertaken to elucidate the chemiluminescence property of 1,2-dioxetanes3) (O’Neal & Richardson, 1970; De Vico, 2007; da Silva & da Silva, 2014). Substitution by methyl groups in 1,2-dioxetane (Eq. 1) was shown to affect its thermal and chemiluminescent properties (Adam & Baader, 1985; Vacher, 2017); methylation promoted higher chemiluminescence yield. Higher number of methyl groups led to an increase in thermal stability; the tetramethyl-1,2-dioxetane was about 2.5 kcal/mol more thermally stable than the unsubstituted one. Also, the greater the number of methyl groups, the slower the dissociation of the dioxetane molecule, favoring higher population in triplet state from the ground one; the dissociation half-time t1/2 for tetramethylated 1,2-dioxetane was nearly twice that for unmethylated one, 116.9 against 58.6 fs.

O O

(1)O O (H3C)H CCH(CH3) (H 3C)H CH(CH3) + (H3C)H CH(CH3) + hγ

Removal of one of the methyl groups 7’, 8’, and 9’ in abscisic acid (ABA) (Fig. 6A) resulted in modification of its physiologic activity (Walker-Simmons et al., 1994; Wilmer et al., 1998). While ABA was observed to induce a growth inhibition of oilseed rape embryos (Brassica napus L.) and an increase in the quantity of erucic acid, ABA demethylated at 7’showed a significant decrease in activity (Wilmer et al., 1998); however, the activity of ABA demethylated at 8’ and 9’ was less decreased. About the same results were found towards wheat embryo (Triticumaestivum 1.) (Walker-Simmons et al., 1994).

Ohno and his collaborators (Mukai et al., 2004) reported the impact of the methyl substituent on the liquid crystallinity and the ionic conductivity of N, N-dim ethylimidazoliumdodecylsulfonate (Fig. 6B). By increasing the number of methyl groups, the liquid crystallinity has the tendency to be annihilated; indeed, the fully methylated imidazolium salt showed no liquid crystalline phase. Peculiarly, the substitution at position 2 led to an imidazolium salt with no liquid crystallinity. N, N-dimethylimidazolium dodecylsulfonate presented an enantiotropicsmectic A phase, while 1,3,4-trimethylimidazolium salt showed monotropic phase.

(H3C)HH(CH3)8' 9'

CH CH

H3CCOOHOH7'OCH3(CH)112SO3H3CCH333CH3(HC)H3ABA B

Figure 6. A Abscisic acid; B – Methylated/unmethylated N, N-dimethylimidazolium dodecylsulfonate

The substitution of different carbon atoms of polyene chain of the retinal Schiff base by methyl groups affected its proton affinity, charge distribution, pKa, and chromophore characteristic (Tajkhorshid & Suhai, 1999). Upon methylation, an increase in proton affinity of the Schiff base models could be ensued and the effect was more significant when substitution occurred at the evennumbered carbons atoms of the main chain, particularly at the terminal atom of the conjugated chain

Methyl groups on monocyclic aromatic hydrocarbons were demonstrated to reduce the formation of secondary organic aerosol (SOA), a particulate matter found in atmosphere and resulted from oxidation of organic molecules (Li et al., 2016); the SOA formation was in this order: benzene > toluene > m-xylene > 1,2,4-trimethylbenzene (pseudocumene) > pentamethylbenzene > hexamethylbenzene > 1,2,4,5-tetramethylbenzene. Methyl groups were believed to stabilize the ring-opening radical and to inhibit subsequently the formation of cyclic compounds and the oligomerization. The monocyclic aromatic hydrocarbon becomes less prone to oxidation as the number of methyl groups on the benzene ring increases.

Kim and his team (Park et al., 2013) studied the effect of the number of methyl groups in poly(styrene-co-sodium acrylate) ionomer (Fig. 7) on its mechanical properties and morphology. It was found that the matrix and cluster Tgs and ionic modulus Eionic of C (ionomer with two methyl groups) were lower than those of A and B (ionomer with one methyl group).

CH3 CH3CH3

CH2C2CHCCOO NaxyH H A
CHH2CH2CCCOO NaxyB
CHH2CCHCCOO NaxyC

Figure 7. A – Poly(styrene-co-sodium acrylate) ionomer; B – Poly(styrenecosodium methacrylate) ionomer; C – Poly(styrene-co-sodium tiglate) ionomer

Methyl groups are sought for in the protection of some sensitive functional groups such as the phenolics, radical scavengers. For example, the radical polymerization of vinylcatechol does not proceed unless the hydroxyl groups are masked as traced in equation below (Eq. 2) (Daly & Moulay, 1986). A large number of demethylation agents, each with its demethylation specificity, were used to deprotect the phenolic functionality, and they are: BCl3/DCM, Me3SiI, HBr/NaI, HCl/ pyridine, EtSNa, LiCl/DMF, Lil/collidine, lithium diphenyl phosphide, NiCl2/Zn, BeCl2/alumina or KF/alumina,…etc. (Kulkarni et al., 1999).

OCH3RadicalpolymerizationCHH2Cn

Deprotected
Methyl-protected

poly(vinylcatechol) vinylcatechol

NOTES

1. https://www.princeton.edu/chemistry/macmillan/group-meetings/PZ_MME.pdf

2. https://scienceandfooducla.wordpress.com/2015/09/29/caffeine-vs-chocolate-amighty-methyl-group/

3. http://uu.diva-portal.org/smash/get/diva2:1130597/FULLTEXT01.pdf

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АНАЛИЗ НА ПРИРОДНИ ВОДИ В ОБЩИНА СЛИВЕН

Никола Урумов, Анелия Иванова

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Виктория Дечкова, Никола Велчев, Нели Иванова

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MATHEMATICAL MODELLING OF THE TRANSMISSION DYNAMICS OF PNEUMONIA AND MENINGITIS COINFECTION WITH VACCINATION

Deborah O. Daniel, Sefiu A. Onitilo, Omolade B. Benjamin, Ayoola A. Olasunkanmi

2024 година
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2023 година
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ПОДКАСТ – КОГА, АКО НЕ СЕГА?

Христо Чукурлиев

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2022 година
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METEOROLOGICAL DETERMINANTS OF COVID-19 DISEASE: A LITERATURE REVIEW

Z. Mateeva, E. Batchvarova, Z. Spasova, I. Ivanov, B. Kazakov, S. Matev, A. Simidchiev, A. Kitev

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MATHEMATICAL MODELLING OF THE TRANSMISSION MECHANISM OF PLAMODIUM FALCIPARUM

Onitilo S. A, Usman M. A., Daniel D. O. Odetunde O. S., Ogunwobi Z. O., Hammed F. A., Olubanwo O. O., Ajani A. S., Sanusi A. S., Haruna A. H.

ПОСТАНОВКА ЗА ИЗМЕРВАНЕ СКОРОСТТА НА ЗВУКА ВЪВ ВЪЗДУХ

Станислав Сланев, Хафизе Шабан, Шебнем Шабан, Анета Маринова

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MAGNETIC PROPERTIES

Sofija Blagojević, Lana Vujanović, Andreana Kovačević Ćurić

„TAP, TAP WATER“ QUANTUM TUNNELING DEMONSTRATION

Katarina Borković, Andreana Kovačević Ćurić

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КОМЕТИТЕ – I ЧАСТ

Пенчо Маркишки

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DISTANCE LEARNING: HOMEMADE COLLOIDAL SILVER

Ana Sofía Covarrubias-Montero, Jorge G. Ibanez

2021 година
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STUDY OF COMPOSITIONS FOR SELECTIVE WATER ISOLATION IN GAS WELLS

Al-Obaidi S.H., Hofmann M., Smirnov V.I., Khalaf F.H., Alwan H.H.

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POTENTIAL APPLICATIONS OF ANTIBACTERIAL COMPOUNDS IN EDIBLE COATING AS FISH PRESERVATIVE

Maulidan Firdaus, Desy Nila Rahmana, Diah Fitri Carolina, Nisrina Rahma Firdausi, Zulfaa Afiifah, Berlian Ayu Rismawati Sugiarto

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INVESTIGATION OF 238U, 234U AND 210PO CONTENT IN SELECTED BULGARIAN DRINKING WATER

Bozhidar Slavchev, Elena Geleva, Blagorodka Veleva, Hristo Protohristov, Lyuben Dobrev, Desislava Dimitrova, Vladimir Bashev, Dimitar Tonev

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DEMONSTRATION OF DAMPED ELECTRICAL OSCILLATIONS

Elena Grebenakova, Stojan Manolev

2020 година
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ДОЦ. Д-Р МАРЧЕЛ КОСТОВ КОСТОВ ЖИВОТ И ТВОРЧЕСТВО

Здравка Костова, Елена Георгиева

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JACOB’S LADDER FOR THE PHYSICS CLASSROOM

Kristijan Shishkoski, Vera Zoroska

КАЛЦИЙ, ФОСФОР И ДРУГИ ФАКТОРИ ЗА КОСТНО ЗДРАВЕ

Радка Томова, Светла Асенова, Павлина Косева

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MATHEMATICAL MODELING OF 2019 NOVEL CORONAVIRUS (2019 – NCOV) PANDEMIC IN NIGERIA

Sefiu A. Onitilo, Mustapha A. Usman, Olutunde S. Odetunde, Fatai A. Hammed, Zacheous O. Ogunwobi, Hammed A. Haruna, Deborah O. Daniel

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WATER PURIFICATION WITH LASER RADIATION

Lyubomir Lazov, Hristina Deneva, Galina Gencheva

2019 година
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LASER MICRO-PERFORATION AND FIELDS OF APPLICATION

Hristina Deneva, Lyubomir Lazov, Edmunds Teirumnieks

ПРОЦЕСЪТ ДИФУЗИЯ – ОСНОВА НА ДИАЛИЗАТА

Берна Сабит, Джемиле Дервиш, Мая Никова, Йорданка Енева

IN VITRO EVALUATION OF THE ANTIOXIDANT PROPERTIES OF OLIVE LEAF EXTRACTS – CAPSULES VERSUS POWDER

Hugo Saint-James, Gergana Bekova, Zhanina Guberkova, Nadya Hristova-Avakumova, Liliya Atanasova, Svobodan Alexandrov, Trayko Traykov, Vera Hadjimitova

Бележки върху нормативното осигуряване на оценяването в процеса

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ТЕХНОЛОГИЯ

Б. В. Тошев

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ON THE GENETIC TIES BETWEEN EUROPEAN NATIONS

Jordan Tabov, Nevena Sabeva-Koleva, Georgi Gachev

Иван Странски – майсторът на кристалния растеж [Ivan Stranski

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CHEMOMETRIC ANALYSIS OF SCHOOL LIFE IN VARNA

Radka Tomova, Petinka Galcheva, Ivajlo Trajkov, Antoaneta Hineva, Stela Grigorova, Rumyana Slavova, Miglena Slavova

ЦИКЛИТЕ НА КРЕБС

Ивелин Кулев

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ПРИНЦИПИТЕ НА КАРИЕРНОТО РАЗВИТИЕ НА МЛАДИЯ УЧЕН

И. Панчева, М. Недялкова, С. Кирилова, П. Петков, В. Симеонов

UTILISATION OF THE STATIC EVANS METHOD TO MEASURE MAGNETIC SUSCEPTIBILITIES OF TRANSITION METAL ACETYLACETONATE COMPLEXES AS PART OF AN UNDERGRADUATE INORGANIC LABORATORY CLASS

Anton Dobzhenetskiy, Callum A. Gater, Alexander T. M. Wilcock, Stuart K. Langley, Rachel M. Brignall, David C. Williamson, Ryan E. Mewis

THE 100

Maria Atanassova, Radoslav Angelov

A TALE OF SEVEN SCIENTISTS

Scerri, E.R. (2016). A Tale of Seven Scientists and a New Philosophy of Science.

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DEVELOPMENT OF A LESSON PLAN ON THE TEACHING OF MODULE “WATER CONDUCTIVITY”

A. Thysiadou, S. Christoforidis, P. Giannakoudakis

AMPEROMETRIC NITRIC OXIDE SENSOR BASED ON MWCNT CHROMIUM(III) OXIDE NANOCOMPOSITE

Arsim Maloku, Epir Qeriqi, Liridon S. Berisha, Ilir Mazreku, Tahir Arbneshi, Kurt Kalcher

THE EFFECT OF AGING TIME ON Mg/Al HYDROTALCITES STRUCTURES

Eddy Heraldy, Triyono, Sri Juari Santosa, Karna Wijaya, Shogo Shimazu

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A CONTENT ANALYSIS OF THE RESULTS FROM THE STATE MATRICULATION EXAMINATION IN MATHEMATICS

Elena Karashtranova, Nikolay Karashtranov, Vladimir Vladimirov

SOME CONCEPTS FROM PROBABILITY AND STATISTICS AND OPPORTUNITIES TO INTEGRATE THEM IN TEACHING NATURAL SCIENCES

Elena Karashtranova, Nikolay Karashtranov, Nadezhda Borisova, Dafina Kostadinova

45. МЕЖДУНАРОДНА ОЛИМПИАДА ПО ХИМИЯ

Донка Ташева, Пенка Василева

2018 година
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ЗДРАВЕ И ОКОЛНА СРЕДА

Кадрие Шукри, Светлана Великова, Едис Мехмед

РОБОТИКА ЗА НАЧИНАЕЩИ ЕНТУСИАСТИ

Даниела Узунова, Борис Велковски, Илко Симеонов, Владислав Шабански, Димитър Колев

DESIGN AND DOCKING STUDIES OF HIS-LEU ANALOGUES AS POTENTIOAL ACE INHIBITORS

Rumen Georgiev, , Tatyana Dzimbova, Atanas Chapkanov

X-RAY DIFFRACTION STUDY OF M 2 Zn(TeО3)2 (M - Na, K) ТELLURIDE

Kenzhebek T. Rustembekov, Mitko Stoev, Aitolkyn A. Toibek

CALIBRATION OF GC/MS METHOD FOR DETERMINATION OF PHTHALATES

N. Dineva, I. Givechev, D. Tanev, D. Danalev

ELECTROSYNTHESIS OF CADMIUM SELENIDE NANOPARTICLES WITH SIMULTANEOUS EXTRACTION INTO P-XYLENE

S. S. Fomanyuk, V. O. Smilyk, G. Y. Kolbasov, I. A. Rusetskyi, T. A. Mirnaya

БИОЛОГИЧЕН АСПЕКТ НА РЕКАНАЛИЗАЦИЯ С ВЕНОЗНА ТРОМБОЛИЗА

Мариела Филипова, Даниела Попова, Стоян Везенков

CHEMISTRY: BULGARIAN JOURNAL OF SCIENCE EDUCATION ПРИРОДНИТЕ НАУКИ В ОБРАЗОВАНИЕТО VOLUME 27 / ГОДИНА XXVII, 2018 ГОДИШНО СЪДЪРЖАНИЕ СТРАНИЦИ / PAGES КНИЖКА 1 / NUMBER 1: 1 – 152 КНИЖКА 2 / NUMBER 2: 153 – 312 КНИЖКА 3 / NUMBER 3: 313 – 472 КНИЖКА 4 / NUMBER 4: 473 – 632 КНИЖКА 5 / NUMBER 5: 633 – 792 КНИЖКА 6 / NUMBER 6: 793 – 952 КНИЖКА 1 / NUMBER 1: 1 – 152 КНИЖКА 2 / NUMBER 2: 153 – 312 КНИЖКА

(South Africa), A. Ali, M. Bashir (Pakistan) 266 – 278: j-j Coupled Atomic Terms for Nonequivalent Electrons of (n-1)fx and nd1 Configurations and Correlation with L-S Terms / P. L. Meena (India) 760 – 770: Methyl, тhe Smallest Alkyl Group with Stunning Effects / S. Moulay 771 – 776: The Fourth State of Matter / R. Tsekov

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ИМОБИЛИЗИРАНЕНАФРУКТОЗИЛТРАНСФЕРАЗА ВЪРХУКОМПОЗИТНИФИЛМИОТПОЛИМЛЕЧНА КИСЕЛИНА, КСАНТАН И ХИТОЗАН

Илия Илиев, Тонка Василева, Веселин Биволарски, Ася Виранева, Иван Бодуров, Мария Марудова, Теменужка Йовчева

ELECTRICAL IMPEDANCE SPECTROSCOPY OF GRAPHENE-E7 LIQUID-CRYSTAL NANOCOMPOSITE

Todor Vlakhov, Yordan Marinov, Georgi. Hadjichristov, Alexander Petrov

ON THE POSSIBILITY TO ANALYZE AMBIENT NOISERECORDED BYAMOBILEDEVICETHROUGH THE H/V SPECTRAL RATIO TECHNIQUE

Dragomir Gospodinov, Delko Zlatanski, Boyko Ranguelov, Alexander Kandilarov

RHEOLOGICAL PROPERTIES OF BATTER FOR GLUTEN FREE BREAD

G. Zsivanovits, D. Iserliyska, M. Momchilova, M. Marudova

ПОЛУЧАВАНЕ НА ПОЛИЕЛЕКТРОЛИТНИ КОМПЛЕКСИ ОТ ХИТОЗАН И КАЗЕИН

Антоанета Маринова, Теменужка Йовчева, Ася Виранева, Иван Бодуров, Мария Марудова

CHEMILUMINESCENT AND PHOTOMETRIC DETERMINATION OF THE ANTIOXIDANT ACTIVITY OF COCOON EXTRACTS

Y. Evtimova, V. Mihailova, L. A. Atanasova, N. G. Hristova-Avakumova, M. V. Panayotov, V. A. Hadjimitova

ИЗСЛЕДОВАТЕЛСКИ ПРАКТИКУМ

Ивелина Димитрова, Гошо Гоев, Савина Георгиева, Цвета Цанова, Любомира Иванова, Борислав Георгиев

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PARAMETRIC INTERACTION OF OPTICAL PULSES IN NONLINEAR ISOTROPIC MEDIUM

A. Dakova, V. Slavchev, D. Dakova, L. Kovachev

ДЕЙСТВИЕ НА ГАМА-ЛЪЧИТЕ ВЪРХУ ДЕЗОКСИРИБОНУКЛЕИНОВАТА КИСЕЛИНА

Мирела Вачева, Хари Стефанов, Йоана Гвоздейкова, Йорданка Енева

RADIATION PROTECTION

Natasha Ivanova, Bistra Manusheva

СТАБИЛНОСТ НА ЕМУЛСИИ ОТ ТИПА МАСЛО/ ВОДА С КОНЮГИРАНА ЛИНОЛОВА КИСЕЛИНА

И. Милкова-Томова, Д. Бухалова, К. Николова, Й. Алексиева, И. Минчев, Г. Рунтолев

THE EFFECT OF EXTRA VIRGIN OLIVE OIL ON THE HUMAN BODY AND QUALITY CONTROL BY USING OPTICAL METHODS

Carsten Tottmann, Valentin Hedderich, Poli Radusheva, Krastena Nikolova

ИНФРАЧЕРВЕНА ТЕРМОГРАФИЯ ЗА ДИАГНОСТИКА НА ФОКАЛНА ИНФЕКЦИЯ

Рая Грозданова-Узунова, Тодор Узунов, Пепа Узунова

ЕЛЕКТРИЧНИ СВОЙСТВА НА КОМПОЗИТНИ ФИЛМИ ОТ ПОЛИМЛЕЧНА КИСЕЛИНА

Ася Виранева, Иван Бодуров, Теменужка Йовчева

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ТРИ ИДЕИ ЗА ЕФЕКТИВНО ОБУЧЕНИЕ

Гергана Карафезиева

МАГИЯТА НА ТВОРЧЕСТВОТО КАТО ПЪТ НА ЕСТЕСТВЕНО УЧЕНЕ В УЧЕБНИЯ ПРОЦЕС

Гергана Добрева, Жаклин Жекова, Михаела Чонос

ОБУЧЕНИЕ ПО ПРИРОДНИ НАУКИ ЧРЕЗ МИСЛОВНИ КАРТИ

Виолета Стоянова, Павлина Георгиева

ИГРА НА ДОМИНО В ЧАС ПО ФИЗИКА

Росица Кичукова, Ценка Маринова

ПРОБЛЕМИ ПРИ ОБУЧЕНИЕТО ПО ФИЗИКА ВЪВ ВВМУ „Н. Й. ВАПЦАРОВ“

А. Христова, Г. Вангелов, И. Ташев, М. Димидов

ИЗГРАЖДАНЕ НА СИСТЕМА ОТ УЧЕБНИ ИНТЕРНЕТ РЕСУРСИ ПО ФИЗИКА И ОЦЕНКА НА ДИДАКТИЧЕСКАТА ИМ СТОЙНОСТ

Желязка Райкова, Георги Вулджев, Наталия Монева, Нели Комсалова, Айше Наби

ИНОВАЦИИ В БОРБАТА С ТУМОРНИ ОБРАЗУВАНИЯ – ЛЕЧЕНИЕ ЧРЕЗ БРАХИТЕРАПИЯ

Георги Върбанов, Радостин Михайлов, Деница Симеонова, Йорданка Енева

NATURAL RADIONUCLIDES IN DRINKING WATER

Natasha Ivanova, Bistra Manusheva

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АДАПТИРАНЕ НА ОБРАЗОВАНИЕТО ДНЕС ЗА УТРЕШНИЯ ДЕН

И. Панчева, М. Недялкова, П. Петков, Х. Александров, В. Симеонов

STRUCTURAL ELUCIDATION OF UNKNOWNS: A SPECTROSCOPIC INVESTIGATION WITH AN EMPHASIS ON 1D AND 2D 1H NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

Vittorio Caprio, Andrew S. McLachlan, Oliver B. Sutcliffe, David C. Williamson, Ryan E. Mewis

j-j Coupled Atomic Terms for Nonequivalent Electrons of (n-1)f

j-jCOUPLEDATOMICTERMSFORNONEQUIVALENT, ELECTRONS OF (n-f X nd CONFIGURATIONS AND, CORRELATION WITH L-S TERMS

INTEGRATED ENGINEERING EDUCATION: THE ROLE OF ANALYSIS OF STUDENTS’ NEEDS

Veselina Kolarski, Dancho Danalev, Senia Terzieva

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ZAGREB CONNECTION INDICES OF TiO2 NANOTUBES

Sohaib Khalid, Johan Kok, Akbar Ali, Mohsin Bashir

SYNTHESIS OF NEW 3-[(CHROMEN-3-YL)ETHYLIDENEAMINO]-PHENYL]-THIAZOLIDIN-4ONES AND THEIR ANTIBACTERIAL ACTIVITY

Ramiz Hoti, Naser Troni, Hamit Ismaili, Malesore Pllana, Musaj Pacarizi, Veprim Thaçi, Gjyle Mulliqi-Osmani

2017 година
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GEOECOLOGICAL ANALYSIS OF INDUSTRIAL CITIES: ON THE EXAMPLE OF AKTOBE AGGLOMERATION

Zharas Berdenov, Erbolat Mendibaev, Talgat Salihov, Kazhmurat Akhmedenov, Gulshat Ataeva

TECHNOGENESIS OF GEOECOLOGICAL SYSTEMS OF NORTHEN KAZAKHSTAN: PROGRESS, DEVELOPMENT AND EVOLUTION

Kulchichan Dzhanaleyeva, Gulnur Mazhitova, Altyn Zhanguzhina, Zharas Berdenov, Tursynkul Bazarbayeva, Emin Atasoy

СПИСАНИЕ ПРОСВѢТА

Списание „Просвета“ е орган на Просветния съюз в България. Списанието е излизало всеки месец без юли и август. Годишният том съдържа 1280 стра- ници. Списанието се издава от комитет, а главен редактор от 1935 до 1943 г. е проф. Петър Мутафчиев, историк византолог и специалист по средновеков-

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47-А НАЦИОНАЛНА КОНФЕРЕНЦИЯ НА УЧИТЕЛИТЕ ПО ХИМИЯ

В последните години тези традиционни за българското учителство конфе- ренции се организират от Българското дружество по химическо образование и история и философия на химията. То е асоцииран член на Съюза на химици- те в България, който пък е член на Европейската асоциация на химическите и

JOURNALS OF INTEREST: A REVIEW (2016)

BULGARIAN JOURNAL OF SCIENCE AND EDUCATION POLICY ISSN 1313-1958 (print) ISSN 1313-9118 (online) http://bjsep.org

INVESTIGATING THE ABILITY OF 8

Marina Stojanovska, Vladimir M. Petruševski

SYNTHESIS OF TiO -M (Cd, Co, Mn)

Candra Purnawan, Sayekti Wahyuningsih, Dwita Nur Aisyah

EFFECT OF DIFFERENT CADMIUM CONCENTRATION ON SOME BIOCHEMICAL PARAMETERS IN ‘ISA BROWN’ HYBRID CHICKEN

Imer Haziri, Adem Rama, Fatgzim Latifi, Dorjana Beqiraj-Kalamishi, Ibrahim Mehmeti, Arben Haziri

PHYTOCHEMICAL AND IN VITRO ANTIOXIDANT STUDIES OF PRIMULA VERIS (L.) GROWING WILD IN KOSOVO

Ibrahim Rudhani, Florentina Raci, Hamide Ibrahimi, Arben Mehmeti, Ariana Kameri, Fatmir Faiku, Majlinda Daci, Sevdije Govori, Arben Haziri

ПЕДАГОГИЧЕСКА ПОЕМА

Преди година-две заедно с директора на Националното издателство „Аз- буки“ д-р Надя Кантарева-Барух посетихме няколко училища в Родопите. В едно от тях ни посрещнаха в голямата учителска стая. По стените ѝ имаше големи портрети на видни педагози, а под тях – художествено написани умни мисли, които те по някакъв повод са казали. На централно място бе портретът на Антон Семьонович Макаренко (1888 – 1939). Попитах учителките кой е Макаренко – те посрещнаха въпроса ми с мълчание. А някога, в г

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„СИМВОЛНИЯТ КАПИТАЛ“ НА БЪЛГАРСКОТО УЧИЛИЩЕ

Николай Цанков, Веска Гювийска

KINETICS OF PHOTO-ELECTRO-ASSISTED DEGRADATION OF REMAZOL RED 5B

Fitria Rahmawati, Tri Martini, Nina Iswati

ALLELOPATHIC AND IN VITRO ANTICANCER ACTIVITY OF STEVIA AND CHIA

Asya Dragoeva, Vanya Koleva, Zheni Stoyanova, Eli Zayova, Selime Ali

NOVEL HETEROARYLAMINO-CHROMEN-2-ONES AND THEIR ANTIBACTERIAL ACTIVITY

Ramiz Hoti, Naser Troni, Hamit Ismaili, Gjyle Mulliqi-Osmani, Veprim Thaçi

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Quantum Connement of Mobile Na+ Ions in Sodium Silicate Glassy

QUANTUM CONFINEMENT OF MOBILE Na + IONS, IN SODIUM SILICATE GLASSY NANOPARTICLES

OPTIMIZATION OF ENGINE OIL FORMULATION USING RESPONSE SURFACE METHODOLOGY AND GENETIC ALGORITHM: A COMPARATIVE STUDY

Behnaz Azmoon, Abolfazl Semnani, Ramin Jaberzadeh Ansari, Hamid Shakoori Langeroodi, Mahboube Shirani, Shima Ghanavati Nasab

EVALUATION OF ANTIBACTERIAL ACTIVITY OF DIFFERENT SOLVENT EXTRACTS OF TEUCRIUM CHAMAEDRYS (L.) GROWING WILD IN KOSOVO

Arben Haziri, Fatmir Faiku, Roze Berisha, Ibrahim Mehmeti, Sevdije Govori, Imer Haziri

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COMPUTER SIMULATORS: APPLICATION FOR GRADUATES’ADAPTATION AT OIL AND GAS REFINERIES

Irena O. Dolganova, Igor M. Dolganov, Kseniya A. Vasyuchka

SYNTHESIS OF NEW [(3-NITRO-2-OXO-2H-CHROMEN4-YLAMINO)-PHENYL]-PHENYL-TRIAZOLIDIN-4-ONES AND THEIR ANTIBACTERIAL ACTIVITY

Ramiz Hoti, Hamit Ismaili, Idriz Vehapi, Naser Troni, Gjyle Mulliqi-Osmani, Veprim Thaçi

STABILITY OF RJ-5 FUEL

Lemi Türker, Serhat Variş

A STUDY OF BEGLIKTASH MEGALITHIC COMPLEX

Diana Kjurkchieva, Evgeni Stoykov, Sabin Ivanov, Borislav Borisov, Hristo Hristov, Pencho Kyurkchiev, Dimitar Vladev, Irina Ivanova

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2016 година
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THE EFFECT OF KOH AND KCL ADDITION TO THE DESTILATION OF ETHANOL-WATER MIXTURE

Khoirina Dwi Nugrahaningtyas, Fitria Rahmawati, Avrina Kumalasari

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ОЦЕНЯВАНЕ ЛИЧНОСТТА НА УЧЕНИКА

Министерството на народното просвещение е направило допълне- ния към Правилника за гимназиите (ДВ, бр. 242 от 30 октомври 1941 г.), според които в бъдеще ще се оценяват следните прояви на учениците: (1) трудолюбие; (2) ред, точност и изпълнителност; (3) благовъзпитаност; (4) народностни прояви. Трудолюбието ще се оценява с бележките „образцово“, „добро“, „незадо- волително“. С „образцово“ ще се оценяват учениците, които с любов и по- стоянство извършват всяка възложена им ил

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VOLTAMMERIC SENSOR FOR NITROPHENOLS BASED ON SCREEN-PRINTED ELECTRODE MODIFIED WITH REDUCED GRAPHENE OXIDE

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ИЗСЛЕДВАНЕ НА ПРОФЕСИОНАЛНО-ПЕДАГОГИЧЕСКАТА РЕФЛЕКСИЯ НА УЧИТЕЛЯ ПО БИОЛОГИЯ (ЧАСТ ВТОРА)

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На 8 март 2016 г. в голямата зала на Националния политехнически музей в София фондация „Вигория“ връчи годишните си награди – почетен плакет „Златна детелина“. Тази награда се дава за цялостна професионална и творче- ска изява на личности с особени заслуги към обществото в трите направления на фондация „Вигория“ – образование, екология, култура. Наградата цели да се даде израз на признателност за високи постижения на личности, които на професионално равнище и на доброволни начала са рабо

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ПО ПЪТЯ

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TEACHER’S ACCEPTANCE OF STUDENTS WITH DISABILITY

Daniela Dimitrova-Radojchikj, Natasha Chichevska-Jovanova

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Книжка 4
БЛАГОДАРЯ ВИ!

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SYNTHESIS OF FLUORINATED HYDROXYCINNAMOYL DERIVATIVES OF ANTI-INFLUENZA DRUGS AND THEIR BIOLOGICAL ACTIVITY

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Книжка 2
TEACHING CHEMISTRY AT TECHNICAL UNIVERSITY

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РУМЕН ЛЮБОМИРОВ ДОЙЧЕВ (1938 – 1999)

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145 ГОДИНИ БЪЛГАРСКА АКАДЕМИЯ НА НАУКИТЕ

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V. Romanenko, G. Nikitina Academy of Information Technologies in Education, Russia

ALLELOPATHIC AND CYTOTOXIC ACTIVITY OF ORIGANUM VULGARE SSP. VULGARE GROWING WILD IN BULGARIA

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GENDER ISSUES OF UKRAINIAN HIGHER EDUCATION

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44

Донка Ташева, Пенка Василева

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SCIENTIX – OБЩНОСТ ЗА НАУЧНО ОБРАЗОВАНИЕ В ЕВРОПА

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Книжка 1
ОБРАЗОВАНИЕ ЗА ПРИРОДОНАУЧНА ГРАМОТНОСТ

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DIFFERENTIAL TEACHING IN SCHOOL SCIENCE EDUCATION: CONCEPTUAL PRINCIPLES

G. Yuzbasheva Kherson Academy of Continuing Education, Ukraine

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Книжка 5

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Книжка 4
RECASTING THE DERIVATION OF THE CLAPEYRON EQUATION INTO A CONCEPTUALLY SIMPLER FORM

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Книжка 3
SIMULATION OF THE FATTY ACID SYNTHASE COMPLEX MECHANISM OF ACTION

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Книжка 2
Книжка 1
COLORFUL EXPERIMENTS FOR STUDENTS: SYNTHESIS OF INDIGO AND DERIVATIVES

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Книжка 6
ADDRESING STUDENTS’ MISCONCEPTIONS CONCERNING CHEMICAL REACTIONS AND SYMBOLIC REPRESENTATIONS

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КОНЦЕПТУАЛНА СХЕМА НА УЧИЛИЩНИЯ КУРС П О ХИМИЯ – МАКР О СКОПСКИ ПОДХОД

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