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   6313篇
  免费   464篇
  国内免费   730篇
化学   515篇
晶体学   3篇
力学   191篇
综合类   113篇
数学   5620篇
物理学   1065篇
  2024年   11篇
  2023年   70篇
  2022年   115篇
  2021年   135篇
  2020年   155篇
  2019年   189篇
  2018年   198篇
  2017年   214篇
  2016年   194篇
  2015年   155篇
  2014年   213篇
  2013年   988篇
  2012年   216篇
  2011年   284篇
  2010年   250篇
  2009年   308篇
  2008年   410篇
  2007年   397篇
  2006年   357篇
  2005年   316篇
  2004年   311篇
  2003年   283篇
  2002年   297篇
  2001年   207篇
  2000年   223篇
  1999年   184篇
  1998年   165篇
  1997年   185篇
  1996年   109篇
  1995年   68篇
  1994年   44篇
  1993年   46篇
  1992年   25篇
  1991年   26篇
  1990年   15篇
  1989年   22篇
  1988年   19篇
  1987年   14篇
  1986年   16篇
  1985年   9篇
  1984年   16篇
  1983年   4篇
  1982年   9篇
  1981年   4篇
  1980年   3篇
  1979年   5篇
  1978年   4篇
  1977年   5篇
  1974年   3篇
  1936年   6篇
排序方式: 共有7507条查询结果,搜索用时 15 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.
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   
8.
The affine-scaling modification of Karmarkar's algorithm is extended to solve problems with free variables. This extended primal algorithm is used to prove two important results. First the geometrically elegant feasibility algorithm proposed by Chandru and Kochar is the same algorithm as the one obtained by appending a single column of residuals to the constraint matrix. Second the dual algorithm as first described by Adler et al., is the same as the extended primal algorithm applied to the dual.  相似文献   
9.
通过分析计算,设计了一种大口径宽视场折射式红外相机光学系统。该系统设计用于超长线阵扫描红外相机的地面演示成像,它能同时对短波2μm—3μm、中波3μm—4.5μm双波段成像,且同时具有24°的大视场和150mm的宽口径,成像质量接近衍射极限。该系统在航天遥感领域应用广泛。  相似文献   
10.
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   
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