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   7685篇
  免费   264篇
  国内免费   684篇
化学   2038篇
力学   119篇
综合类   85篇
数学   5462篇
物理学   929篇
  2023年   61篇
  2022年   74篇
  2021年   99篇
  2020年   98篇
  2019年   166篇
  2018年   190篇
  2017年   175篇
  2016年   147篇
  2015年   117篇
  2014年   166篇
  2013年   969篇
  2012年   172篇
  2011年   269篇
  2010年   230篇
  2009年   325篇
  2008年   404篇
  2007年   394篇
  2006年   327篇
  2005年   281篇
  2004年   288篇
  2003年   261篇
  2002年   278篇
  2001年   188篇
  2000年   195篇
  1999年   154篇
  1998年   152篇
  1997年   170篇
  1996年   88篇
  1995年   56篇
  1994年   37篇
  1993年   32篇
  1992年   26篇
  1991年   22篇
  1990年   11篇
  1989年   14篇
  1985年   13篇
  1984年   15篇
  1982年   43篇
  1981年   247篇
  1980年   253篇
  1979年   230篇
  1978年   281篇
  1977年   225篇
  1976年   242篇
  1975年   41篇
  1974年   60篇
  1973年   171篇
  1972年   105篇
  1969年   16篇
  1947年   14篇
排序方式: 共有8633条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
In this paper, the deformation of the Heisenberg algebra, consistent with both the generalized uncertainty principle and doubly special relativity, has been analyzed. It has been observed that, though this algebra can give rise to fractional derivative terms in the corresponding quantum mechanical Hamiltonian, a formal meaning can be given to them by using the theory of harmonic extensions of function. Depending on this argument, the expression of the propagator of the path integral corresponding to the deformed Heisenberg algebra, has been obtained. In particular, the consistent expression of the one dimensional free particle propagator has been evaluated explicitly. With this propagator in hand, it has been shown that, even in free particle case, normal generalized uncertainty principle and doubly special relativity show very much different result.  相似文献   
5.
Numerical integration of ordinary differential equations on manifolds   总被引:4,自引:0,他引:4  
Summary This paper is concerned with the problem of developing numerical integration algorithms for differential equations that, when viewed as equations in some Euclidean space, naturally evolve on some embedded submanifold. It is desired to construct algorithms whose iterates also evolve on the same manifold. These algorithms can therefore be viewed as integrating ordinary differential equations on manifolds. The basic method “decouples” the computation of flows on the submanifold from the numerical integration process. It is shown that two classes of single-step and multistep algorithms can be posed and analyzed theoretically, using the concept of “freezing” the coefficients of differential operators obtained from the defining vector field. Explicit third-order algorithms are derived, with additional equations augmenting those of their classical counterparts, obtained from “obstructions” defined by nonvanishing Lie brackets.  相似文献   
6.
Algebra matrix and similarity classification of operators   总被引:1,自引:0,他引:1  
In this paper, by the Gelfand representation theory and the Silov idempotents theorem, we first obtain a central decomposition theorem related to a unital semi-simple n-homogeneous Banach algebra, and then give a similarity classification of two strongly irreducible Cowen-Douglas operators using this theorem.  相似文献   
7.
In the paper we study the equation L u = f, where L is a degenerate elliptic operator, with Neumann boundary condition in a bounded open set μ. We prove existence and uniqueness of solutions in the space H(μ) for the Neumann problem.  相似文献   
8.
We give a coring version for the duality theorem for actions and coactions of a finitely generated projective Hopf algebra. We also provide a coring analogue for a theorem of H.-J. Schneider, which generalizes and unifies the duality theorem for finite Hopf algebras and its refinements. This paper was written while the first author visited the Mathematics Departments of Syracuse University and California State University Dominguez Hills. He would like to thank both departments for their hospitality.  相似文献   
9.
We construct the complex simple Lie algebras using elementary algebraic geometry. We use our construction to obtain a new proof of the classification of complex simple Lie algebras that does not appeal to the classification of root systems.  相似文献   
10.
本文给出了所有弱紧算子 ,强紧算子 ,Mackey紧算子 ,构成无穷矩阵拓扑下相同紧集的特征的刻画 .  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