全文获取类型
收费全文 | 14793篇 |
免费 | 1516篇 |
国内免费 | 1372篇 |
专业分类
化学 | 3516篇 |
晶体学 | 52篇 |
力学 | 991篇 |
综合类 | 352篇 |
数学 | 9642篇 |
物理学 | 3128篇 |
出版年
2024年 | 20篇 |
2023年 | 146篇 |
2022年 | 206篇 |
2021年 | 335篇 |
2020年 | 405篇 |
2019年 | 436篇 |
2018年 | 409篇 |
2017年 | 461篇 |
2016年 | 594篇 |
2015年 | 399篇 |
2014年 | 718篇 |
2013年 | 1264篇 |
2012年 | 651篇 |
2011年 | 893篇 |
2010年 | 793篇 |
2009年 | 930篇 |
2008年 | 963篇 |
2007年 | 948篇 |
2006年 | 877篇 |
2005年 | 757篇 |
2004年 | 675篇 |
2003年 | 686篇 |
2002年 | 634篇 |
2001年 | 473篇 |
2000年 | 486篇 |
1999年 | 391篇 |
1998年 | 339篇 |
1997年 | 314篇 |
1996年 | 265篇 |
1995年 | 201篇 |
1994年 | 153篇 |
1993年 | 135篇 |
1992年 | 111篇 |
1991年 | 110篇 |
1990年 | 57篇 |
1989年 | 55篇 |
1988年 | 56篇 |
1987年 | 30篇 |
1986年 | 37篇 |
1985年 | 34篇 |
1984年 | 40篇 |
1983年 | 20篇 |
1982年 | 26篇 |
1981年 | 31篇 |
1980年 | 26篇 |
1979年 | 20篇 |
1978年 | 18篇 |
1977年 | 17篇 |
1976年 | 10篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Let Um be an m×m Haar unitary matrix and U[m,n] be its n×n truncation. In this paper the large deviation is proven for the empirical eigenvalue density of U[m,n] as m/n→λ and n→∞. The rate function and the limit distribution are given explicitly. U[m,n] is the random matrix model of quq, where u is a Haar unitary in a finite von Neumann algebra, q is a certain projection and they are free. The limit distribution coincides with the Brown measure of the operator quq. 相似文献
82.
§ 1 IntroductionLetRn×mdenotetherealn×mmatrixspace ,Rn×mr itssubsetwhoseelementshaverankr ,ORn×nthesetofalln×northogonalmatrices,SRn×n(SRn×n≥ ,SRn×n>)thesetofalln×nrealsymmetric (symmetricpositivesemidefinite ,positivedefinite)matrices.ThenotationA>0 (≥ 0 ,<0 ,≤ 0 )m… 相似文献
83.
In this paper, we exhibit a unified treatment of the mixed initial boundary value problem for second order (in time) parabolic linear differential equations in Banach spaces, whose boundary conditions are of a dynamical nature. Results regarding existence, uniqueness, continuous dependence (on initial data) and regularity of classical and strict solutions are established. Moreover, several examples are given as samples for possible applications.
84.
85.
86.
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.
87.
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
88.
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.
89.
90.
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