全文获取类型
收费全文 | 212964篇 |
免费 | 23574篇 |
国内免费 | 16960篇 |
专业分类
化学 | 118704篇 |
晶体学 | 2500篇 |
力学 | 15256篇 |
综合类 | 1018篇 |
数学 | 47089篇 |
物理学 | 68931篇 |
出版年
2024年 | 436篇 |
2023年 | 2610篇 |
2022年 | 4715篇 |
2021年 | 5142篇 |
2020年 | 5402篇 |
2019年 | 5439篇 |
2018年 | 13943篇 |
2017年 | 13717篇 |
2016年 | 12185篇 |
2015年 | 7533篇 |
2014年 | 8505篇 |
2013年 | 10912篇 |
2012年 | 16183篇 |
2011年 | 22748篇 |
2010年 | 14164篇 |
2009年 | 14380篇 |
2008年 | 15539篇 |
2007年 | 16622篇 |
2006年 | 7968篇 |
2005年 | 7818篇 |
2004年 | 6413篇 |
2003年 | 5786篇 |
2002年 | 4748篇 |
2001年 | 3340篇 |
2000年 | 2948篇 |
1999年 | 2910篇 |
1998年 | 2518篇 |
1997年 | 2279篇 |
1996年 | 2444篇 |
1995年 | 1918篇 |
1994年 | 1848篇 |
1993年 | 1502篇 |
1992年 | 1324篇 |
1991年 | 1196篇 |
1990年 | 1001篇 |
1989年 | 722篇 |
1988年 | 624篇 |
1987年 | 510篇 |
1986年 | 510篇 |
1985年 | 415篇 |
1984年 | 308篇 |
1983年 | 224篇 |
1982年 | 197篇 |
1981年 | 160篇 |
1980年 | 133篇 |
1979年 | 106篇 |
1978年 | 75篇 |
1977年 | 60篇 |
1974年 | 60篇 |
1973年 | 61篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
从点电荷的电势计算公式出发推导出了瓣形均匀带电面在其直径处的电势分布.进一步讨论了均匀带电半球面在其底面以及均匀带电球面内部和外部的电势分布. 相似文献
22.
Q. Sun Q. Wang X.G. Gong V. Kumar Y. Kawazoe 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):77-81
We report results of the atomic and electronic structures of Al7C cluster using ab initio molecular dynamics with ultrasoft pseudopotentials and generalized gradient approximation. The lowest energy structure is
found to be the one in which carbon atom occupies an interstitial position in Al7 cluster. The electronic structure shows that the recent observation [Chem. Phys. Lett. 316, 31 (2000)] of magic behavior of Al7C- cluster is due to a large highest occupied and lowest unoccupied molecular orbital (HOMO-LUMO) gap which makes Al7C- chemically inert. These results have further led us to the finding of a new neutral magic cluster Al7N which has the same number of valence electrons as in Al7C- and a large HOMO-LUMO gap of 1.99 eV. Further, calculations have been carried out on (Al7N)2 to study interaction between magic clusters.
Received 28 July 2001 相似文献
23.
24.
In this paper, the dimension of the spaces of bivariate spline with degree less that 2r and smoothness order r on the Morgan-Scott triangulation is considered. The concept of the instability degree in the dimension of spaces of bivariate spline is presented. The results in the paper make us conjecture the instability degree in the dimension of spaces of bivariate spline is infinity. 相似文献
25.
26.
Julio Castellanos 《Mathematische Zeitschrift》2002,239(4):777-802
We consider complete ideals supported on finite sequences of infinitely near points, in regular local rings with dimensions
greater than two. We study properties of factorizations in Lipman special *-simple complete ideals. We relate it to a type
of proximity, linear proximity, of the points, and give conditions in order to have unique factorization. Several examples
are presented.
Received: 2 February 2000 / in final form: 14 March 2001 / Published online: 18 January 2002 相似文献
27.
28.
Claudia-Elisabeth Wulz 《Czechoslovak Journal of Physics》2002,52(3):C155-C170
The principal physics goals of the Compact Muon Solenoid experiment under construction at the Large Hadron Collider at CERN in Geneva are reviewed. Procedures to search for the Standard Model Higgs boson, supersymmetric Higgses and other supersymmetric particles are described. 相似文献
29.
Solitary waves and their bifurcations of KdV like equation with higher order nonlinearity 总被引:3,自引:1,他引:2
We investigate the KdV like equation with higher order nonlinearity ut + a(1 +bun)unux + uxxx = 0with n ≥ 1, a, b ∈ R and α≠ 0. The bifurcations and explicit expressions of solitary wave solutions for theequation are discussed by using the bifurcation method and qualitative theory of dynamical systems. Thebifurcation diagrams, existence and number of the solitary waves are given. 相似文献
30.
Guofen Yu Yuanci Gao Shenggang Liu Wenxiang Wang Jin Wu 《International Journal of Infrared and Millimeter Waves》2002,23(8):1261-1269
Analysis of the field distributions in a single biological cell under electromagnetic wave is given. With Debye approximation, the dielectric relaxation of each part of the cell, including the extracellular and cellular media, the cell membrane and the nuclear membrane, was taken into account. Making use of some typical parameters for a cell, the voltage across nuclear and cytoplasma membranes under electromagnetic waves are calculated up to millimeter wave frequency range. The calculated result indicates that it is unlikely to generate electroporation by present available millimeter wave sources. 相似文献