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   5182篇
  免费   206篇
  国内免费   615篇
化学   150篇
力学   103篇
综合类   96篇
数学   4825篇
物理学   829篇
  2024年   6篇
  2023年   47篇
  2022年   63篇
  2021年   96篇
  2020年   86篇
  2019年   146篇
  2018年   149篇
  2017年   156篇
  2016年   119篇
  2015年   104篇
  2014年   147篇
  2013年   889篇
  2012年   144篇
  2011年   235篇
  2010年   202篇
  2009年   270篇
  2008年   352篇
  2007年   337篇
  2006年   302篇
  2005年   247篇
  2004年   261篇
  2003年   244篇
  2002年   252篇
  2001年   176篇
  2000年   178篇
  1999年   149篇
  1998年   147篇
  1997年   163篇
  1996年   88篇
  1995年   53篇
  1994年   34篇
  1993年   28篇
  1992年   20篇
  1991年   19篇
  1990年   13篇
  1989年   16篇
  1988年   9篇
  1987年   5篇
  1986年   7篇
  1985年   6篇
  1984年   11篇
  1983年   5篇
  1982年   4篇
  1981年   2篇
  1979年   3篇
  1977年   2篇
  1975年   1篇
  1974年   1篇
  1968年   1篇
  1936年   5篇
排序方式: 共有6003条查询结果,搜索用时 15 毫秒
1.
2.
In the periodic table the position of each atom follows the ‘aufbau’ principle of the individual electron shells. The resulting intrinsic periodicity of atomic properties determines the overall behavior of atoms in two-dimensional (2D) bonding and structure formation. Insight into the type and strength of bonding is the key in the discovery of innovative 2D materials. The primary features of 2D bonding and the ensuing monolayer structures of the main-group II–VI elements result from the number of valence electrons and the change of atom size, which determine the type of hybridization. The results reveal the tight connection between strength of bonding and bond length in 2D networks. The predictive power of the periodic table reveals general rules of bonding, the bonding-structure relationship, and allows an assessment of published data of 2D materials.  相似文献   
3.
4.
5.
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   
6.
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   
7.
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   
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