首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   4157篇
  免费   1458篇
  国内免费   1701篇
化学   813篇
晶体学   72篇
力学   203篇
综合类   204篇
数学   3574篇
物理学   2450篇
  2024年   14篇
  2023年   62篇
  2022年   76篇
  2021年   95篇
  2020年   62篇
  2019年   68篇
  2018年   60篇
  2017年   85篇
  2016年   87篇
  2015年   140篇
  2014年   357篇
  2013年   309篇
  2012年   336篇
  2011年   315篇
  2010年   517篇
  2009年   433篇
  2008年   570篇
  2007年   456篇
  2006年   299篇
  2005年   270篇
  2004年   216篇
  2003年   271篇
  2002年   208篇
  2001年   298篇
  2000年   305篇
  1999年   215篇
  1998年   170篇
  1997年   128篇
  1996年   129篇
  1995年   159篇
  1994年   145篇
  1993年   125篇
  1992年   81篇
  1991年   64篇
  1990年   83篇
  1989年   54篇
  1988年   10篇
  1987年   15篇
  1986年   8篇
  1985年   9篇
  1984年   3篇
  1983年   5篇
  1982年   1篇
  1959年   3篇
排序方式: 共有7316条查询结果,搜索用时 62 毫秒
91.
本文提出了模为合数的多模数线性同余方程组求解问题,研究了该类同余方程组的数值解法,得到了解的表达式,给出了算例,算例验证了解表达式的正确性。  相似文献   
92.
For an inhomogeneous quasilinear hyperbolic system of diagonal form, under the assumptions that the system is linearly degenerate and the C^1 norm of the boundary data is bounded, we show that the mechanism of the formation of singularities of C^1 classical solution to the Goursat problem with C^1 compatibility conditions at the origin must be an ODE type. The similar result is also obtained for the weakly discontinuous solution with C^0 compatibility conditions at the origin.  相似文献   
93.
A novel option pricing method based on Fourier-cosine series expansion was proposed by Fang and Oosterlee. Developing their idea, three new option pricing methods based on Fourier, Fourier-cosine and Fourier-sine series expansions are presented in this paper, which are more efficient when the option prices are calculated with many strike prices. A series of numerical experiments under different exp-L~vy models are also given to compare these new methods with the Fang and Oosterlee's method and other methods.  相似文献   
94.
By employing the fixed point theorem of cone expansion and compression of norm type, we investigate the existence of positive solutions of generalized Sturm-Liouville boundary value problems for a nonlinear singular differential equation with a parameter. Some sufficient conditions for the existence of positive solutions are established. In the last section, an example is presented to illustrate the applications of our main results.  相似文献   
95.
Let R be a commutative ring with identity, Nn(R) the matrix algebra consisting of all n × n strictly upper triangular matrices over R. Several types of proper local derivations of Nn(R) (n ≤ 4) are constructed, based on which all local derivations of Nn(R) (n ≤ 4) are characterized when R is a domain.  相似文献   
96.
This paper is devoted to studying the relationship between meromorphic functions f(z) and g(z) when their differential polynomials satisfy sharing condition weaker than sharing one value IM.  相似文献   
97.
In this paper, we show that the hyponormal Toeplitz operator Tφ with trigonometric polynomial symbol φ is either normal or completely non-normal. Moreover, if Tφ is non-normal, then Tφ has a dense set of cyclic vectors. Some general conditions are also considered.  相似文献   
98.
Let M and N be nonzero subspaces of a Hilbert space H, and PM and PN denote the orthogonal projections on M and N, respectively. In this note, an exact representation of the angle and the minimum gap of M and N is obtained. In addition, we study relations between the angle, the minimum gap of two subspaces M and N, and the reduced minimum modulus of (I - PN)PM,  相似文献   
99.
In this paper, an equivalent relation among the reflexivity, weak sequential completeness and bounded completeness in full function space is given. Some results on weakly sequential compactness of subset and the property (u) in substitution spaces are obtained.  相似文献   
100.
Under the non-Lipschitzian condition, a small time large deviation principle of diffusion processes on Hilbert spaces is established. The operator theory and Gronwall inequality play an important role.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号