全文获取类型
收费全文 | 346篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 285篇 |
晶体学 | 1篇 |
力学 | 3篇 |
数学 | 24篇 |
物理学 | 36篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 5篇 |
2016年 | 11篇 |
2015年 | 8篇 |
2014年 | 9篇 |
2013年 | 15篇 |
2012年 | 19篇 |
2011年 | 27篇 |
2010年 | 15篇 |
2009年 | 8篇 |
2008年 | 9篇 |
2007年 | 8篇 |
2006年 | 15篇 |
2005年 | 17篇 |
2004年 | 12篇 |
2003年 | 12篇 |
2002年 | 9篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 13篇 |
1998年 | 6篇 |
1997年 | 16篇 |
1996年 | 15篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1984年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1972年 | 2篇 |
1968年 | 1篇 |
排序方式: 共有349条查询结果,搜索用时 15 毫秒
81.
V. D. Dyachenko S. G. Krivokolysko V. P. Litvinov 《Chemistry of Heterocyclic Compounds》1996,32(9):1055-1057
By condensation of the anilide of acetoacetic acid, propionaldehyde, and cyanothioacetamide, 6-methyl-5-phenylcarbamoyl-3-cyano-4-ethylpyridine-2(IH)thione has been obtained. In an alkaline medium, this compound is alkylated, forming the corresponding substituted 2-pyridyl sulfides. From these pyridines, substituted thienoj2,3-blpyridines have been synthesized through the Thorpe-Ziegler reaction.T. G. Shevchenko Lugansk Pedagogical Institute, Lugansk 348011. N. D. Zelinskii Institute of Organic Chemistry, Moscow 117913. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1232–1234, September, 1996. Original article submitted May 13, 1996. 相似文献
82.
V. D. Dyachenko A. A. Nikishin A. N. Chernega 《Chemistry of Heterocyclic Compounds》2003,39(9):1153-1160
4,4-Dialkyl-substituted N-methylmorpholinium 3,5-dicyano-6-oxo-1,4,5,6-tetrahydropyridine-2-thiolates were synthesized by the condensation of 2-alkyl-2-cyanoethyl crotonates with cyanothioacetamide and N-methylmorpholine. They were used for the production of substituted 2-alkylthio-1,4,5,6-tetrahydropyridines, 2-acetylthio-1,4,5,6,-tetrahydropyridine, 6-hydrazino-1,4,5,6-tetrahydropyridine, and 2,3,4,5,6,7-hexahydrothiazolo[3,2-a]pyridine. The structure of 6-bromo-3-bromomethyl-6,8-dicyano-7,7-dimethyl-2,3,4,5,6,7-hexahydrothiazolo[3,2-a]pyridine was proved by X-ray crystallographic analysis. 相似文献
83.
Gritsenko V. V. Fujiwara E. Fujiwara H. Tanaka H. Tamura I. Kobayashi H. Dyachenko O. A. 《Russian Journal of Coordination Chemistry》2003,29(11):773-779
Molecular conductors on the basis of bis(ethylenedithio)tetraselenafulvalene (BETS) with tetrahedral anions TlCl4
–, MnBr4
2–, and CoCl4
2– were synthesized and studied by X-ray diffraction analysis. The salts under study exhibit various conducting properties: -(BETS)2TlCl4 (I) is a superconductor with T
c = 2.5 K, -(BETS)4MnBr4 · 2C2H5OH (II) is a metal up to 30 K, while (BETS)2CoCl4 (III) is a dielectric. Salt I has -packing of the donor molecules, salt II has -packing, whereas salt III has no conducting layers. These structural differences are mainly the reasons for different conducting properties of compounds I–III. 相似文献
84.
85.
3-(4-Chlorophenyl)-1-phenylprop-2-en-1-one reacted with 3-amino-N-phenyl-3-thioxopropanamide under basic conditions in ethanol to give a mixture of 3-(4-chlorophenyl)-2-cyano-5-oxo-N,5-diphenylpentanamide and 3-(4-chlorophenyl)-1,5-diphenylpentane-1,5-dione. The structure of the former was determined by X-ray analysis. The reaction of the same compounds in DMSO in the presence of sodium hydroxide produced 4-(4-chlorophenyl)-N,6-diphenyl-2-thioxo-1,2,3,4-tetrahydropyridine-3-carboxamide. 相似文献
86.
By condensation of 2-acyl-1-(morpholin-4-yl)cycloalkenes with CH-acids new 3-functuinally substituted carbo[c]fused pyridin-2-ones(thiones) were synthesized. N, 1-Diphenyl-5, 6, 7, 8-tetrahydroisoquinoline-3-thione under the action of acrylonitrile and alkyl halides suffered a selective S-alkylation. 相似文献
87.
4-Carbamoyl(thiocarbamoyl)-3-thioxo-2,3,5,6,7,8-hexahydroisoquinolines were synthesized by the SNVin reaction of 2-acetyl-1-(N-morpholinyl)acetylcyclohexene with malonothio(dithio)amides. The cyclocondensation direction was confirmed with the X-ray
diffraction analysis of 1-methyl-3-methylthio-5,6,7,8-tetrahydroisoquinoline-4-carboxamide. 相似文献
88.
S. G. Krivokolysko V. D. Dyachenko A. N. Chernega V. P Litvinov 《Chemistry of Heterocyclic Compounds》2001,37(6):727-732
The reaction of 2-chlorobenzaldehyde with cyanothioacetamide and dibenzoylmethane in the presence of piperidine or N-methylmorpholine gave the corresponding 5-benzoyl-4-(2-chlorophenyl)-3-cyano-6-hydroxy-6-phenyl-1,4,5,6-tetrahydropyridine-2-thiolates, used in the synthesis of 1-alkylthio-4-benzoyl-1-benzoylamino-3-(2-chlorophenyl)-2-cyanobut-1-enes. 相似文献
89.
E. V. Ishchenko V. K. Yatsimirskii A. G. Dyachenko I. V. Kongurova É. V. Prilutskii 《Theoretical and Experimental Chemistry》2006,42(4):229-233
The catalytic activity and adsorption characteristics of the surface of catalysts in the form of carbon nanotubes produced
on nickel and cobalt oxides with the Cu-Co-Fe oxide system as supported active phase were studied. At carbon nanotubes produced
on nickel oxide with (10 + 10) wt.% of the catalytically active phase total conversion of CO to CO2 is realized at 47 °C. This sample has high specific surface area and a large volume of mesopores. It was shown that the increase
in catalytic activity correlates with the increase in the amount of the α2 form of CO2.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 4, pp. 222–226, July–August, 2006. 相似文献
90.
Synthesis and alkylation of 1-substituted 3-thioxo-2,3,5,6,7,8-hexahydroisoquinoline-4-carbonitriles
The condensation of cyclohexylidene(cyano)thioacetamides with aldehydes or of 2-acyl-1-(morpholin-4-yl)cycloalkenes with dithiomalonamide gave 1-alkyl(aryl)-3-thioxo-2,3,5,6,7,8-hexahydroisoquinoline-4-carbonitriles. Reactions of the latter with various alkylating agents selectively produced the corresponding isoquinolin-3-yl sulfides or products of their subsequent Thorpe cyclization, thieno[2,3-c]isoquinolines. 相似文献