全文获取类型
收费全文 | 1426471篇 |
免费 | 29960篇 |
国内免费 | 12269篇 |
专业分类
化学 | 719544篇 |
晶体学 | 21342篇 |
力学 | 78040篇 |
综合类 | 431篇 |
数学 | 249999篇 |
物理学 | 399344篇 |
出版年
2021年 | 14675篇 |
2020年 | 17046篇 |
2019年 | 17280篇 |
2018年 | 17111篇 |
2017年 | 15773篇 |
2016年 | 30439篇 |
2015年 | 22337篇 |
2014年 | 31926篇 |
2013年 | 76410篇 |
2012年 | 43553篇 |
2011年 | 43945篇 |
2010年 | 41754篇 |
2009年 | 43645篇 |
2008年 | 41664篇 |
2007年 | 38290篇 |
2006年 | 39907篇 |
2005年 | 35004篇 |
2004年 | 34366篇 |
2003年 | 31507篇 |
2002年 | 31842篇 |
2001年 | 30584篇 |
2000年 | 26181篇 |
1999年 | 23514篇 |
1998年 | 21726篇 |
1997年 | 21464篇 |
1996年 | 21620篇 |
1995年 | 19565篇 |
1994年 | 19025篇 |
1993年 | 18518篇 |
1992年 | 18527篇 |
1991年 | 18753篇 |
1990年 | 17935篇 |
1989年 | 17935篇 |
1988年 | 17524篇 |
1987年 | 17420篇 |
1986年 | 16323篇 |
1985年 | 22698篇 |
1984年 | 23915篇 |
1983年 | 20105篇 |
1982年 | 21686篇 |
1981年 | 20906篇 |
1980年 | 20241篇 |
1979年 | 20475篇 |
1978年 | 21762篇 |
1977年 | 21368篇 |
1976年 | 21062篇 |
1975年 | 19772篇 |
1974年 | 19437篇 |
1973年 | 19911篇 |
1972年 | 14397篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
A. A. Nazarov 《Physics of the Solid State》2003,45(6):1166-1169
A solution to the equation of grain-boundary diffusion is obtained under conditions where migration of the diffusant from the boundaries into the grains is absent and the diffusion coefficient decreases with time from an increased value to a value characteristic of equilibrium grain boundaries. The specific features of the grain-boundary diffusion in nanocrystals are qualitatively analyzed in terms of this solution. 相似文献
992.
V. Bradnova M. M. Chernyavsky L. Just S. P. Kharlamov A. D. Kovalenko M. Haiduc K. A. Kotel’nikov V. A. Krasnov V. G. Larionova F. G. Lepekhin A. I. Malakhov G. I. Orlova N. G. Peresadko N. G. Polukhina P. A. Rukoyatkin V. V. Rusakova N. A. Salmanova B. B. Simonov S. Vokal P. I. Zarubin 《Physics of Atomic Nuclei》2003,66(9):1646-1650
A physical program of irradiation of emulsions in beams of relativistic nuclei named the BECQUEREL Project is reviewed. It is destined to study in detail the processes of relativistic fragmentation of light radioactive and stable nuclei. The expected results would make it possible to answer some topical questions concerning the cluster structure of light nuclei. Owing to the best spatial resolution, the nuclear emulsions would enable one to obtain unique and evident results. The most important irradiations will be performed in the secondary beams of He, Be, B, C, and N radioactive nuclei formed on the basis of JINR Nuclotron beams of stable nuclei. We present results on the charged state topology of relativistic fragmentation of the 10B nucleus at low energy-momentum transfers as the first step of the research. 相似文献
993.
994.
995.
In previous papers by the present author, a machinery for calculating automorphisms, constructing invariants, and classifying real submanifolds of a complex manifold was developed. The main step in this machinery is the construction of a “nice” model surface. The nice model surface can be treated as an analog of the osculating paraboloid in classical differential geometry. Model surfaces suggested earlier possess a complete list of the desired properties only if some upper estimate for the codimension of the submanifold is satisfied. If this estimate fails, then the surfaces lose the universality property (that is, the ability to touch any germ in an appropriate way), which restricts their applicability. In the present paper, we get rid of this restriction: for an arbitrary type (n,K) (where n is the dimension of the complex tangent plane, and K is the real codimension), we construct a nice model surface. In particular, we solve the problem of constructing a nondegenerate germ of a real analytic submanifold of a complex manifold of arbitrary given type (n,K) with the richest possible group of holomorphic automorphisms in the given class. 相似文献
996.
997.
The title compound is a centrosymmetric dimer with each cadmium in a distorted CdS5 square pyramidal geometry. The Cd–S bond distances range from 2.5626(11) to 2.8459(11) Å. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
998.
A lithium(I) coordination polymer has been formed from LiClO4 and the 2,2′‐bipyrimidine (bpym) ligand in which each square pyramidal lithium(I) atom is coordinated in the basal plane by four nitrogen donor atoms derived from two bpym ligands and one water molecule at the apical position. These are connected into a layer structure via hydrogen‐bonding interactions involving the perchlorate anions. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
999.
1000.