全文获取类型
收费全文 | 64301篇 |
免费 | 2187篇 |
国内免费 | 169篇 |
专业分类
化学 | 38294篇 |
晶体学 | 377篇 |
力学 | 1277篇 |
综合类 | 4篇 |
数学 | 10715篇 |
物理学 | 15990篇 |
出版年
2022年 | 487篇 |
2021年 | 803篇 |
2020年 | 920篇 |
2019年 | 785篇 |
2018年 | 887篇 |
2017年 | 845篇 |
2016年 | 1848篇 |
2015年 | 1561篇 |
2014年 | 1742篇 |
2013年 | 3543篇 |
2012年 | 3152篇 |
2011年 | 3778篇 |
2010年 | 2143篇 |
2009年 | 1896篇 |
2008年 | 3428篇 |
2007年 | 3317篇 |
2006年 | 2976篇 |
2005年 | 2697篇 |
2004年 | 2145篇 |
2003年 | 1827篇 |
2002年 | 1625篇 |
2001年 | 1298篇 |
2000年 | 1140篇 |
1999年 | 853篇 |
1998年 | 706篇 |
1997年 | 718篇 |
1996年 | 875篇 |
1995年 | 722篇 |
1994年 | 753篇 |
1993年 | 827篇 |
1992年 | 720篇 |
1991年 | 557篇 |
1990年 | 593篇 |
1989年 | 477篇 |
1988年 | 492篇 |
1987年 | 508篇 |
1986年 | 462篇 |
1985年 | 655篇 |
1984年 | 656篇 |
1983年 | 573篇 |
1982年 | 590篇 |
1981年 | 586篇 |
1980年 | 537篇 |
1979年 | 480篇 |
1978年 | 511篇 |
1977年 | 484篇 |
1976年 | 431篇 |
1975年 | 404篇 |
1974年 | 371篇 |
1973年 | 395篇 |
排序方式: 共有10000条查询结果,搜索用时 359 毫秒
101.
102.
The control of piecewise-deterministic processes is studied where only local boundedness of the data is assumed. Moreover the discount rate may be zero. The value function is shown to be solution to the Bellman equation in a weak sense; however the solution concept is strong enough to generate optimal policies. Continuity and compactness conditions are given for the existence of nonrelaxed optimal feedback controls. 相似文献
103.
Paramagnetic pyrroline and 1,2,3,6-tetrahydropyridine derivatives of BODIPY and their diamagnetic analogs have been synthesized and characterized as novel redox double sensor and cation sensitive reagents. 相似文献
104.
I. P. Kuranova K. M. Polyakov E. A. Smirnova W. E. Höhne V. S. Lamzin R. Meijer 《Crystallography Reports》2003,48(6):953-958
Crystals of Saccharomyces cerevisiae inorganic pyrophosphatase suitable for X-ray diffraction study were grown by cocrystallization of the enzyme with cobalt chloride and imidodiphosphate. Saccharomyces cerevisiae is a metal-dependent enzyme which catalyzes hydrolysis of inorganic pyrophosphate to orthophosphate. The three-dimensional structure of this enzyme was solved by the molecular-replacement method and refined at 1.8 Å resolution to an R factor of 19.5%. Cobalt and phosphate ions were revealed in the active centers of both identical subunits (A and B) of the pyrophosphatase molecule. In subunit B, a water molecule was found between two cobalt ions. It is believed that this water molecule acts as an attacking nucleophile in the enzymatic cleavage of the pyrophosphate bond. It was demonstrated that cobalt ions and a phosphate group occupy only part of the potential binding sites (two chemically identical and crystallographically independent subunits have different binding sites). The arrangement of ligands and the structure of the nucleophile-binding site are discussed in relation to the mechanism of action of the enzyme and the nature of the metal activator. 相似文献
105.
106.
107.
108.
L. Bugliaro J. Fröhlich G.M. Graf J. Stubbe C. Fefferman 《Communications in Mathematical Physics》1997,187(3):567-582
A Lieb-Thirring-Sobolev type inequality for Pauli Hamiltonians with magnetic fields is derived. The bound is in terms of an
effective field, whose energy is comparable to that of the magnetic field itself. An application to the stability of matter
in magnetic fields is given.
Received: 19 September 1996 / Accepted: 3 January 1997 相似文献
109.
S. Pumplün 《manuscripta mathematica》1998,97(1):93-108
For a Brauer–Severi variety X over a field k of characteristic not two, every symmetric bilinear space over X up to Witt equivalence is defined over k.
Received: 2 February 1998 相似文献
110.
Periodica Mathematica Hungarica - 相似文献