全文获取类型
收费全文 | 397篇 |
免费 | 1篇 |
专业分类
化学 | 321篇 |
力学 | 5篇 |
数学 | 8篇 |
物理学 | 64篇 |
出版年
2022年 | 4篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 9篇 |
2014年 | 7篇 |
2013年 | 5篇 |
2012年 | 11篇 |
2011年 | 9篇 |
2010年 | 11篇 |
2009年 | 6篇 |
2007年 | 10篇 |
2006年 | 8篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2002年 | 3篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 3篇 |
1993年 | 7篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 12篇 |
1984年 | 3篇 |
1983年 | 8篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1979年 | 14篇 |
1978年 | 17篇 |
1977年 | 18篇 |
1976年 | 8篇 |
1975年 | 20篇 |
1974年 | 8篇 |
1973年 | 15篇 |
1972年 | 10篇 |
1971年 | 13篇 |
1970年 | 8篇 |
1969年 | 6篇 |
1967年 | 4篇 |
1966年 | 3篇 |
排序方式: 共有398条查询结果,搜索用时 15 毫秒
1.
2.
3.
A.Kh. Khusid G.V. Kryshtal V.A. Dombrovsky V.F. Kucherov L.A. Yanovskaya V.I. Kadentsev O.S. Chizhov 《Tetrahedron》1977,33(1):77-84
α,β-Unsaturated aldehyde acetals add :CCl2 (obtained in accordance with Makosza procedure) to form gem-dichlorocyclopropanecarboxaldehyde acetals (1) in high yields when the ratio of reactants is no less than 1:4. The addition of :CCl2 to polyunsaturated aldehyde acetals in the above conditions proceeds regioselectively at double bonds enriched by electrons. Compounds 1 are reduced by sodium in liquid ammonia to give cyclopropanecarboxaldehyde acetals (2). Both 1 and 2 are hydrolized by dilute H3P04 to the corresponding aldehydes and are added to vinyl ethers in the presence of BF3·Et2O to produce only 1:1 adducts which are hydrolyzed by a mixture of AcOH-AcONa-H2O to give β-formylcyclopropanes which were previously unknown. 相似文献
4.
A. G. Yurchenko N. L. Dovgan O. S. Chizhov N. F. Karpenko A. Ya. Podel'ko 《Journal of mass spectrometry : JMS》1977,12(2):98-99
The mass spectra of 1-adamantyl substituted carboxylic acids and alcohols with and without deuterated hydroxyl groups were studied. Deuterium exchange between functional group and adamantane nucleus was observed and a possible explantation of the phenomenon is given. 相似文献
5.
The corresponding 6- and 3-formyl derivatives were obtained by formylation of 2-methyl-3-carbethoxy-5-methoxy- and 2-methyl-5-methoxyindole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 339–341, March, 1971. 相似文献
6.
7.
O. S. Chizhov V. I. Kadentsev Yu. S. Dol'skaya N. I. Golovina 《Russian Chemical Bulletin》1975,24(11):2351-2356
8.
A. I. Kalinovsky E. P. Serebryakov B. M. Zolotarev A. V. Simolin V. F. Kucherov O. S. Chizhov 《Journal of mass spectrometry : JMS》1970,3(11):1393-1400
The mass spectra of nine compounds belonging to the group of (?)-kauran-16-ols are reported. These compounds differ either by stereochemistry at C16 (I, II) or by the nature of the substituent at C4 (III to VIII). In all cases the most characteristic ions correspond to a process in which ring D is split off and lost as a C3H6O fragment. The nature of the substituent R1 at C4 can be deduced from such typical ions as [M ? R1]+ or [M ? R1 ? H2O]+. Kauranols epimeric at C16 show little difference in their mass spectra; the assignment of configuration at this centre may be reliable only when the spectra of both epimers are compared. 相似文献
9.
O. S. Chizhov B. A. Dmitriev B. M. Zolotarev A. Ya. Chernyak N. K. Kochetov 《Journal of mass spectrometry : JMS》1969,2(10):947-952
The trifluoroacetyl derivatives of alditols are convenient compounds for mass spectrometric investigation as they are easily obtainable and highly volatile. They show simple fragmentation patterns with intensive peaks in the high mass range. Trifluoroacetates of alditols may be used for detection and location of deoxy groups in the molecule. 相似文献
10.
Vasily A. Kezin Elena S. Matyugina Mikhail S. Novikov Alexander O. Chizhov Robert Snoeck Graciela Andrei Sergei N. Kochetkov Anastasia L. Khandazhinskaya 《Molecules (Basel, Switzerland)》2022,27(9)
Pyrimidine nucleoside analogues are widely used to treat infections caused by the human immunodeficiency virus (HIV) and DNA viruses from the herpes family. It has been shown that 5-substituted uracil derivatives can inhibit HIV-1, herpes family viruses, mycobacteria and other pathogens through various mechanisms. Among the 5-substituted pyrimidine nucleosides, there are not only the classical nucleoside inhibitors of the herpes family viruses, 2′-deoxy-5-iodocytidine and 5-bromovinyl-2′-deoxyuridine, but also derivatives of 1-(benzyl)-5-(phenylamino)uracil, which proved to be non-nucleoside inhibitors of HIV-1 and EBV. It made this modification of nucleoside analogues very promising in connection with the emergence of new viruses and the crisis of drug resistance when the task of creating effective antiviral agents of new types that act on other targets or exhibit activity by other mechanisms is very urgent. In this paper, we present the design, synthesis and primary screening of the biological activity of new nucleoside analogues, namely, 5′-norcarbocyclic derivatives of substituted 5-arylamino- and 5-aryloxyuracils, against RNA viruses. 相似文献