全文获取类型
收费全文 | 505586篇 |
免费 | 4116篇 |
国内免费 | 1132篇 |
专业分类
化学 | 247653篇 |
晶体学 | 7761篇 |
力学 | 25601篇 |
综合类 | 13篇 |
数学 | 70684篇 |
物理学 | 159122篇 |
出版年
2020年 | 3513篇 |
2019年 | 3889篇 |
2018年 | 12024篇 |
2017年 | 12669篇 |
2016年 | 10711篇 |
2015年 | 5183篇 |
2014年 | 7334篇 |
2013年 | 18183篇 |
2012年 | 17392篇 |
2011年 | 26542篇 |
2010年 | 17604篇 |
2009年 | 17382篇 |
2008年 | 23882篇 |
2007年 | 26838篇 |
2006年 | 15159篇 |
2005年 | 18608篇 |
2004年 | 15061篇 |
2003年 | 13951篇 |
2002年 | 12137篇 |
2001年 | 12382篇 |
2000年 | 9751篇 |
1999年 | 7369篇 |
1998年 | 6307篇 |
1997年 | 6239篇 |
1996年 | 5956篇 |
1995年 | 5509篇 |
1994年 | 5519篇 |
1993年 | 5150篇 |
1992年 | 5812篇 |
1991年 | 5883篇 |
1990年 | 5701篇 |
1989年 | 5400篇 |
1988年 | 5533篇 |
1987年 | 5468篇 |
1986年 | 5153篇 |
1985年 | 6840篇 |
1984年 | 7240篇 |
1983年 | 6017篇 |
1982年 | 6321篇 |
1981年 | 6220篇 |
1980年 | 6065篇 |
1979年 | 6134篇 |
1978年 | 6489篇 |
1977年 | 6375篇 |
1976年 | 6486篇 |
1975年 | 5979篇 |
1974年 | 6042篇 |
1973年 | 6311篇 |
1972年 | 4304篇 |
1971年 | 3521篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
D. P. Zhelobenko 《Acta Appl Math》2004,81(1):347-354
A special class of associative algebras is introduced and studied. A criteria of semisimplicity for suitable category of modules is obtained. 相似文献
992.
D. P. Zhelobenko 《Acta Appl Math》2004,81(1):355-383
An algebraic approach to harmonic analysis on reductive Lie groups is proposed. The case of complex semisimple Lie groups is considered in details. Some problems for real reductive Lie groups are discussed. 相似文献
993.
In this note we show how 1-factors in the middle two layers of the discrete cube can be used to construct 2-factors in the
Odd graph (the Kneser graph of (k − 1)-sets from a (2k − 1)-set). In particular, we use the lexical matchings of Kierstead and Trotter, and the modular matchings of Duffus, Kierstead
and Snevily, to give explicit constructions of two different 2-factorisations of the Odd graph.
This revised version was published online in September 2006 with corrections to the Cover Date. 相似文献
994.
995.
996.
997.
Petro P Onys'ko Olena A SuvalovaYuliya V Rassukana Tetyana I ChudakovaAnatolii D Sinitsa 《Tetrahedron letters》2003,44(9):1855-1857
The reaction of alkyl trifluoro(organylsulfonylimino)propionates with phosphites occurs with NC transfer of the RSO2 group and leads to sulfonyl-substituted trifluoroalanine derivatives. The novel rearrangement is interpreted as cheletropic 1,4-cycloaddition of the phosphite and subsequent 1,2-shift of the sulfonyl group in the intermediate cyclic phosphorane. 相似文献
998.
Matveeva E. D. Podrugina T. A. Grishin Yu. K. Tkachev V. V. Zhdankin V. V. Aldoshin S. M. Zefirov N. S. 《Russian Journal of Organic Chemistry》2003,39(4):536-541
A mixed phosphonium-iodonium ylide, phenyliodoniumethoxycarbonylmethylenetriphenylphosphorane borofluoride, was synthesized. Its structure was established by means of X-ray diffraction analysis. Temperature dependence of 1H, 13C, and 31P spectra of the ylide synthesized was investigated. A dynamic equilibrium between Z and E-isomers was observed. 相似文献
999.
Curtis T. Mcmullen 《Acta Mathematica》2003,191(2):191-223
1000.
We investigate the effects of adding uniformity requirements to concepts in computable structure theory such as computable categoricity (of a structure) and intrinsic computability (of a relation on a computable structure). We consider and compare two different notions of uniformity, previously studied by Kudinov and by Ventsov. We discuss some of their results and establish new ones, while also exploring the connections with the relative computable structure theory of Ash, Knight, Manasse, and Slaman and Chisholm and with previous work of Ash, Knight, and Slaman on uniformity in a general computable structure-theoretical setting. 相似文献