全文获取类型
收费全文 | 149篇 |
免费 | 1篇 |
专业分类
化学 | 137篇 |
力学 | 1篇 |
数学 | 2篇 |
物理学 | 10篇 |
出版年
2019年 | 1篇 |
2018年 | 6篇 |
2017年 | 2篇 |
2016年 | 4篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 5篇 |
2011年 | 6篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 8篇 |
2006年 | 7篇 |
2005年 | 14篇 |
2004年 | 11篇 |
2003年 | 6篇 |
2002年 | 13篇 |
2001年 | 14篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 3篇 |
1987年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 2篇 |
排序方式: 共有150条查询结果,搜索用时 31 毫秒
1.
Molchanov A. P. Stepakov A. V. Boitsov V. M. Kostikov R. R. 《Russian Journal of Organic Chemistry》2002,38(11):1666-1670
Esters of 4-R-4,5-dihydro-1H-pyrazole-3,5,5-tricarboxylic acids with chlorine yield esters of 4-R-5-chloro-4,5-dihydro-3H-pyrazole-3,3,5-tricarboxylic acids that at thermolysis provide the esters of the corresponding 2-chlorocyclopropanetricarboxylic acid. The same esters react with bromine in dichloromethane at room temperature to give a mixture of esters of the corresponding 1H-pyrazole-3,5-dicarboxylic acids and 5-bromo-4,5-dihydro-3,3,5-tricarboxylic acids. From 5,5-diethyl 3-methyl 4,5-dihydro-1Hpyrazole-3,5,5-tricarboxylate and N-iodosuccinimide or a system iodine-silver trifluoroacetate we obtained 1,1-diethyl 2-methyl 2-iodocyclopropane-1,1,2-tricarboxylate. 相似文献
2.
Molchanov A. P. Diev V. V. Kopf J. Kostikov R. R. 《Russian Journal of Organic Chemistry》2004,40(3):431-433
Carbonyl ylide generated from 1-diazo-5-phenylpentane-2,5-dione in the presence of Rh2(OAc)4 reacts with 3-substituted cyclopropenes following the 1,3-dipolar cycloaddition pattern to afford substituted 9-oxatricyclo[3.3.1.02,4]nonan-6-ones. 相似文献
3.
Mikhail S. Novikov Alexander F. Khlebnikov Elena S. Sidorina Rafael R. Kostikov 《Journal of fluorine chemistry》1998,90(2):1553-119
2-Fluoropyrroles were synthesised via 1,3-dipolar cycloaddition of iminiodifluoromethanides derived from corresponding imines and difluorocarbene to dimethyl acetylenedicarboxylate. 相似文献
4.
D. V. Kuznetsov V. A. Raev G. L. Kuranov O. V. Arapov R. R. Kostikov 《Russian Journal of Organic Chemistry》2005,41(12):1719-1749
Data on the effect of microwave irradiation on organic reactions are reviewed. Possible mechanisms of microwave activation are discussed, and some examples of acceleration of organic reactions and change of their direction and selectivity as compared to traditional thermal activation are described. Specific aspects of the application of microwave activation to various fields of organic synthesis are considered. The review covers mainly the data published over the last 5 years. 相似文献
5.
Alexander V. Stepakov Jörg Magull Galina L. Starova Rafael R. Kostikov 《Tetrahedron》2006,62(15):3610-3618
Treatment of substituted 1,3-dithiolanes and 1,3-oxathiolanes with methyl diazoacetate in the presence of Rh2(OAc)4 effects ring expansion to the corresponding substituted 1,4-dithiane-2-carboxylates and 1,4-oxathiane-3-carboxylates. The sulfur ylides initially generated in these reactions undergo Stevens rearrangement in competition with both [2,3]-C-C-sigmatropic rearrangement and intramolecular fragmentation. In the case of 2-styryl-substituted 1,3-oxathiolane and 1,3-dithiolane, ring expansion on one-, three- and four-carbons subsequently takes place. 相似文献
6.
M. S. Novikov A. F. Khlebnikov M. A. Egarmin J. Kopf R. R. Kostikov 《Russian Journal of Organic Chemistry》2004,40(10):1493-1499
Azomethine ylides generated by reaction of difluorocarbene with N-alkyl- and N-arylimines derived from benzaldehyde and benzophenone react with N-benzylidenebenzenesulfonamide in a regioselective fashion, yielding the corresponding imidazolidin-4-ones via 1,3-dipolar cycloaddition at the C=N bond. Ylides generated from benzaldehyde imines give rise to mixtures of stereoisomeric 2,5-diphenyl-1-(phenylsulfonyl)-imidazolidin-4-ones, the cis isomer prevailing.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1542–1548.Original Russian Text Copyright © 2004 by Novikov, Khlebnikov, Egarmin, Kopf, Kostikov. 相似文献
7.
A. P. Molchanov V. S. Korotkov R. R. Kostikov 《Russian Journal of Organic Chemistry》2006,42(8):1146-1150
In reaction of 4′-arylspiro[1,2,3,4-tetrahydronaphthalene-2,3′-(1′-pyrazolin)]-1-ones with N-chlorosuccinimide formed spirocyclic substituted 3-chloro-1-pyrazolines that lost nitrogen at heating transforming into spirocyclic chlorocyclopropanes. The reaction of the same pyrazolines with chlorine led to the formation of spirocyclic gem-dichlorocyclopropanes. 相似文献
8.
Esters of substituted 2,3,7-triazabicyclo[3.3.0]oct-3-ene-4-carboxylic acids react with acetone in the presence of hydrogen chloride (bromide) affording esters of substituted 2-(1,1-dimethyl-3-oxobutyl)-2,3,7-triazabicyclo[3.3.0]oct-3-ene-4-carboxylic acids. Reactions of esters of substituted 2,3,7-triazabicyclo[3.3.0]octa-1(5),3-diene-4-carboxylic acids with 1-adamantanol in trifluoroacetic acid resulted in esters of substituted 2-(1-adamantyl)- 2,3,7-triazabicyclo[3.3.0]octa-1(5),3-diene-4-carboxylic acids.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 2, 2005, pp. 252–263.Original Russian Text Copyright © 2005 by Stepakov, Molchanov, Kostikov. 相似文献
9.
M. S. Novikov A. F. Khlebnikov M. V. Shevchenko R. R. Kostikov D. Vidovic 《Russian Journal of Organic Chemistry》2005,41(10):1496-1506
2-Fluoro-4,5-dihydropyrrole-3,4-dicarboxylic acid derivatives were obtained by reaction of difluorocarbene with N-substituted ketone imines in the presence of fumaronitrile, maleonitrile, or dimethyl maleate. The reaction involves intermediate formation of azomethine ylides and their subsequent cycloaddition at the double bond. 11H-Dibenz[b,e]azepine and 3,4-dihydroisoquinolines react with difluorocarbene in the presence of fumaronitrile to give fluoro-substituted dibenzo[c,f]pyrrolo[1,2-a]azepine and pyrrolo[2,1-a]-isoquinoline derivatives. Treatment of 2-fluoro-4,5-dihydropyrrole-3,4-dicarbonitrile with amines and alkoxides affords the corresponding 2-amino- and 2-alkoxy derivatives, while its reactions with hydrazine hydrate and benzimidamide lead to formation of substituted pyrrolo[2,3-c]pyrazole and pyrrolo[2,3-d]-pyrimidine derivatives. 相似文献
10.
de Meijere A Khlebnikov AF Kozhushkov SI Kostikov RR Schreiner PR Wittkopp A Rinderspacher C Menzel H Yufit DS Howard JA 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(4):828-842
(M)-(-)- and (P)-(+)-Trispiro[2.0.0.2.1.1]nonanes [(M)- and (P)-3] as well as (M)-(-)- and (P)-(+)-tetraspiro[2.0.0.0.2.1.1.1]undecanes [(M)- and (P)-4]-enantiomerically pure unbranched [4]- and [5]triangulanes-have been prepared starting from racemic bicyclopropylidenecarboxylic [(1RS)-12] and exo-dispiro[2.0.2.1]heptane-1-carboxylic [(1RS,3SR)-13] acids. The optical resolutions of rac-12 and rac-13 furnished enantiomerically pure acids (S)-(+)-12, (R)-(-)-12, (1R,3S)-(-)-13, and (1S,3R)-(+)-13. The ethyl ester (R)-25 of the acid (R)-(-)-12 was cyclopropanated to give carboxylates (1R,3R)-26 and (1R,3S)-26. The ester (1R,3S)-26 and acids (1R,3S)-13 and (1S,3R)-13 were converted into enantiomerically pure methylene[3]triangulanes (S)-(-)- and (R)-(+)-28. An alternative approach consisted of an enzymatic deracemization of endo-[(1SR,3SR)-dispiro[2.0.2.1]heptyl]methanol (rac-20) or anti-[(1SR,3RS)-4-methylenespiropentyl]methanol (rac-18). This afforded (S)-(-)- and (R)-(+)-28 (starting from rac-20), as well as enantiomerically pure (M)-(-)- and (P)-(+)-1,4-dimethylenespiropentanes [(M)- and (P)-23] starting from rac-18. The methylenetriangulanes (S)-(-)- and (R)-(+)-28 were cyclopropanated furnishing (M)- and (P)-3. The rhodium-catalyzed cycloaddition of ethyl diazoacetate onto (S)-(-)- and (R)-(+)-28 yielded four diastereomeric ethyl trispiro[2.0.0.2.1.1]nonane-1-carboxylates in approximately equal proportions. The enantiomerically pure esters (1R,3S,4S)- and (1S,3R,4R)-30 were isolated by careful distillation and then transformed into [5]triangulanes (M)- and (P)-4 using the same sequence of reactions as applied for (M)- and (P)-3. The structures of the key intermediates (R)-12 and rac-31 were confirmed by X-ray analyses. Although [4]- and [5]triangulanes have no chromophore which would lead to any significant absorption above 200 nm, they have remarkably high specific rotations even at 589 nm with [alpha](20)D=-192.7 [(M)-3, c=1.18, CHCl(3))] or +373.0 [(P)-4, c=1.18, CHCl(3))]. This remarkable optical rotatation is in line with their helical arrangement of sigma bonds, as confirmed by a full valence space single excitation configuration interaction treatment (SCI) in conjunction with DFT computations at the B3LYP/TZVP//B3LYP/6-31+G(d,p) level of theory which reproduce the ORD very well. Thus, it is appropriate to call the helically shaped unbranched [n]triangulanes the "sigma-[n]helicenes", representing the sigma-bond analogues of the aromatic [n]helicenes. 相似文献