全文获取类型
收费全文 | 442556篇 |
免费 | 5993篇 |
国内免费 | 1434篇 |
专业分类
化学 | 244892篇 |
晶体学 | 6358篇 |
力学 | 18092篇 |
综合类 | 10篇 |
数学 | 51188篇 |
物理学 | 129443篇 |
出版年
2020年 | 3242篇 |
2019年 | 3291篇 |
2018年 | 3793篇 |
2017年 | 3688篇 |
2016年 | 6598篇 |
2015年 | 4977篇 |
2014年 | 6853篇 |
2013年 | 19799篇 |
2012年 | 15420篇 |
2011年 | 18737篇 |
2010年 | 12081篇 |
2009年 | 12104篇 |
2008年 | 17421篇 |
2007年 | 17493篇 |
2006年 | 16927篇 |
2005年 | 15438篇 |
2004年 | 13931篇 |
2003年 | 12386篇 |
2002年 | 12116篇 |
2001年 | 14240篇 |
2000年 | 10838篇 |
1999年 | 8561篇 |
1998年 | 6574篇 |
1997年 | 6508篇 |
1996年 | 6525篇 |
1995年 | 5947篇 |
1994年 | 5716篇 |
1993年 | 5437篇 |
1992年 | 6281篇 |
1991年 | 6202篇 |
1990年 | 5852篇 |
1989年 | 5622篇 |
1988年 | 5833篇 |
1987年 | 5558篇 |
1986年 | 5267篇 |
1985年 | 7311篇 |
1984年 | 7412篇 |
1983年 | 6000篇 |
1982年 | 6337篇 |
1981年 | 6229篇 |
1980年 | 5993篇 |
1979年 | 6353篇 |
1978年 | 6416篇 |
1977年 | 6388篇 |
1976年 | 6261篇 |
1975年 | 6051篇 |
1974年 | 5887篇 |
1973年 | 6071篇 |
1972年 | 3669篇 |
1971年 | 2761篇 |
排序方式: 共有10000条查询结果,搜索用时 171 毫秒
931.
932.
933.
Recently extremal double circulant self-dual codes have been classified for lengths n ≤ 62. In this paper, a complete classification
of extremal double circulant self-dual codes of lengths 64 to 72 is presented. Almost all of the extremal double circulant
singly-even codes given have weight enumerators for which extremal codes were not previously known to exist. 相似文献
934.
935.
Coulomb systems in which the particles interact through thed-dimensional Coulomb potential but are confined in a flat manifold of dimensiond–1 are considered. The actual Coulomb potential acting is defined by particular boundary conditions involving a characteristic macroscopic distanceW in the direction perpendicular to the manifold: either it is periodic of periodW in that direction, or it vanishes on one ideal conductor wall parallel to the manifold at a distanceW from it, or it vanishes on two parallel walls at a distanceW from each other with the manifold equidistant from them. Under the assumptions that classical equilibrium statistical mechanics is applicable and that the system has the macroscopic properties of a conductor, it is shown that the suitably smoothed charge correlation function is universal, and that the free energy and the grand potential have universal dependences onW (universal means independent of the microscopic detail). The casesd=2 are discussed in detail, and the generic results are checked on an exactly solvable model. The cased=3 of a plane parallel to an ideal conductor is also explicitly worked out.Laboratoire associé au Centre National de la Recherche Scientifique-URA D0063. 相似文献
936.
937.
938.
939.
We show that Abelian gauge theories in 2+1 space-time dimensions with the introduction of a topological Chern-Simons term can be quantized with the use of the symplectic formalism. The consistency of our results are verified by the agreement with the ones from the Dirac case. 相似文献
940.
The application of some recently proposed algebraic multilevel methods for the solution of two-dimensional finite element problems on nonuniform meshes is studied. The locally refined meshes are created by the newest vertex mesh refinement method. After the introduction of this refinement technique it is shown that, by combining levels of refinement, a preconditioner of optimal order can be constructed for the case of local refinement along a line. Its relative condition number is accurately estimated. Numerical tests demonstrating the performance of the proposed preconditioners will be reported in a forthcoming paper. 相似文献