全文获取类型
收费全文 | 11926篇 |
免费 | 1217篇 |
国内免费 | 938篇 |
专业分类
化学 | 2198篇 |
晶体学 | 28篇 |
力学 | 877篇 |
综合类 | 294篇 |
数学 | 7757篇 |
物理学 | 2927篇 |
出版年
2024年 | 26篇 |
2023年 | 120篇 |
2022年 | 188篇 |
2021年 | 251篇 |
2020年 | 315篇 |
2019年 | 332篇 |
2018年 | 322篇 |
2017年 | 349篇 |
2016年 | 453篇 |
2015年 | 301篇 |
2014年 | 553篇 |
2013年 | 1028篇 |
2012年 | 488篇 |
2011年 | 686篇 |
2010年 | 638篇 |
2009年 | 709篇 |
2008年 | 741篇 |
2007年 | 777篇 |
2006年 | 689篇 |
2005年 | 649篇 |
2004年 | 557篇 |
2003年 | 544篇 |
2002年 | 515篇 |
2001年 | 398篇 |
2000年 | 379篇 |
1999年 | 329篇 |
1998年 | 308篇 |
1997年 | 239篇 |
1996年 | 201篇 |
1995年 | 160篇 |
1994年 | 118篇 |
1993年 | 109篇 |
1992年 | 93篇 |
1991年 | 84篇 |
1990年 | 47篇 |
1989年 | 55篇 |
1988年 | 40篇 |
1987年 | 26篇 |
1986年 | 35篇 |
1985年 | 39篇 |
1984年 | 30篇 |
1983年 | 16篇 |
1982年 | 19篇 |
1981年 | 22篇 |
1980年 | 16篇 |
1979年 | 25篇 |
1978年 | 14篇 |
1977年 | 16篇 |
1976年 | 9篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
In this paper we extend a result of Semrl stating that every 2-local automorphism of the full operator algebra on a separable infinite dimensional Hilbert space is an automorphism. In fact, besides separable Hilbert spaces, we obtain the same conclusion for the much larger class of Banach spaces with Schauder bases. The proof rests on an analogous statement concerning the 2-local automorphisms of matrix algebras for which we present a short proof. The need to get such a proof was formulated in Semrl's paper.
74.
The problem of generating a matrix A with specified eigen‐pair, where A is a symmetric and anti‐persymmetric matrix, is presented. An existence theorem is given and proved. A general expression of such a matrix is provided. We denote the set of such matrices by ??????En. The optimal approximation problem associated with ??????En is discussed, that is: to find the nearest matrix to a given matrix A* by A∈??????En. The existence and uniqueness of the optimal approximation problem is proved and the expression is provided for this nearest matrix. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
75.
This paper considers a new approach to a priori sparsification of the sparsity pattern of the factorized approximate inverses (FSAI) preconditioner using the so‐called vector aggregation technique. The suggested approach consists in construction of the FSAI preconditioner to the aggregated matrix with a prescribed sparsity pattern. Then small entries of the computed ‘aggregated’ FSAI preconditioning matrix are dropped, and the resulting pointwise sparsity pattern is used to construct the low‐density block sparsity pattern of the FSAI preconditioning matrix to the original matrix. This approach allows to minimize (sometimes significantly) the construction costs of low‐density high‐quality FSAI preconditioners. Numerical results with sample matrices from structural mechanics and thin shell problems are presented. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
76.
Ren-Cang Li. 《Mathematics of Computation》2003,72(242):715-728
This paper continues earlier studies by Bhatia and Li on eigenvalue perturbation theory for diagonalizable matrix pencils having real spectra. A unifying framework for creating crucial perturbation equations is developed. With the help of a recent result on generalized commutators involving unitary matrices, new and much sharper bounds are obtained.
77.
78.
Yong Lee Kazuhiko Hosomi Hiroyuki Uchiyama Toshio Katsuyama Shinya Kominami Tomoyoshi Mishima 《Optical Review》2003,10(1):38-42
An InGaAsP slab-type asymmetric-coupled-waveguide-based dispersion compensator with a mode selector has been designed and fabricated. The mode selector is necessary to select either a symmetric [with a positive group-velocity dispersion (GVD)] or antisymmetric (with a negative GVD) supermode. These supermodes exist simultaneously in the dispersion-compensation region of the device. Pulse-compression experiments were used to test the dispersion compensator, evaluating the function of the mode selector. A theoretical study of the experimental results shows that the mode selector obtains a very strong selectivity (nearly 100%) for the antisymmetric supermode. 相似文献
79.
Xuyang Lou 《Journal of Mathematical Analysis and Applications》2007,328(1):316-326
In this paper, the problem of stochastic stability for a class of time-delay Hopfield neural networks with Markovian jump parameters is investigated. The jumping parameters are modeled as a continuous-time, discrete-state Markov process. Without assuming the boundedness, monotonicity and differentiability of the activation functions, some results for delay-dependent stochastic stability criteria for the Markovian jumping Hopfield neural networks (MJDHNNs) with time-delay are developed. We establish that the sufficient conditions can be essentially solved in terms of linear matrix inequalities. 相似文献
80.
Dmitry Tamarkin 《Geometric And Functional Analysis》2007,17(2):537-604
We give a proof of the Etingof–Kazhdan theorem on quantization of Lie bialgebras based on the formality of the chain operad
of little disks and show that the Grothendieck–Teichmüller group acts non-trivially on the corresponding quantization functors.
Partially supported by an NSF Grant and A. Sloan Research Fellowship
Received: November 2004 Revision: April 2006 Accepted: May 2006 相似文献