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   880篇
  免费   16篇
  国内免费   51篇
化学   49篇
晶体学   1篇
力学   17篇
综合类   4篇
数学   819篇
物理学   57篇
  2023年   11篇
  2022年   19篇
  2021年   20篇
  2020年   14篇
  2019年   16篇
  2018年   25篇
  2017年   18篇
  2016年   11篇
  2015年   17篇
  2014年   34篇
  2013年   129篇
  2012年   21篇
  2011年   50篇
  2010年   40篇
  2009年   72篇
  2008年   77篇
  2007年   85篇
  2006年   55篇
  2005年   34篇
  2004年   30篇
  2003年   28篇
  2002年   24篇
  2001年   16篇
  2000年   15篇
  1999年   10篇
  1998年   11篇
  1997年   14篇
  1996年   5篇
  1995年   5篇
  1994年   10篇
  1993年   4篇
  1992年   3篇
  1991年   1篇
  1990年   4篇
  1989年   5篇
  1987年   1篇
  1986年   2篇
  1984年   1篇
  1983年   3篇
  1982年   2篇
  1980年   2篇
  1979年   1篇
  1977年   1篇
  1975年   1篇
排序方式: 共有947条查询结果,搜索用时 156 毫秒
1.
作为移位平面分拆的自然拓广,本文引入了梯形平面分拆的概念.应用矢量控制技巧,建立了给定形状和行(列)分部约束的列严格梯形平面分拆集合之枚举函数的初等对称函数行列式表达式.其中之一的重要特例构成了关于循环对称平面分拆的Macdonald猜想的证明基础.  相似文献   
2.
Let Ω be a symmetric cone. In this note, we introduce Hilbert's projective metric on Ω in terms of Jordan algebras and we apply it to prove that, given a linear invertible transformation g such that g(Ω) = Ω and a real number p, |p| 〉 1, there exists a unique element x ∈ Ω satisfying g(x) = x^p.  相似文献   
3.
New compactifications of symmetric spaces of noncompact type X are constructed using the asymptotic geometry of the Borel–Serre enlargement. The controlled K-theory associated to these compactifications is used to prove the integral Novikov conjecture for arithmetic groups.  相似文献   
4.
A special family of partitions occurs in two apparently unrelated contexts: the evaluation of one-dimensional configuration sums of certain RSOS models, and the modular representation theory of symmetric groups or their Hecke algebras Hm. We provide an explanation of this coincidence by showing how the irreducible Hm-modules which remain irreducible under restriction to Hm_1 (Jantzen–Seitz modules) can be determined from the decomposition of a tensor product of representations sln.  相似文献   
5.
Mass distributions of fragments in the low-energy fission of nuclei from 187Ir to 213At have been analysed. This analysis has shown that shell effects in symmetric-mode fragment mass yields from the fission of pre-actinide nuclei could be described if one assumes the existence of two strongly deformed neutron shells in the arising fragments with neutron numbers N1 ≈ 52 and N2 ≈ 68. A new method has been proposed for quantitatively describing the mass distributions of the symmetric fission mode for pre-actinides with A ≈ 180–220.  相似文献   
6.
The paper contains proofs of the following results. For all sufficiently large odd integers n, there exists a set of 2n−1 permutations that pairwise generate the symmetric group Sn. There is no set of 2n−1+1 permutations having this property. For all sufficiently large integers n with n≡2mod4, there exists a set of 2n−2 even permutations that pairwise generate the alternating group An. There is no set of 2n−2+1 permutations having this property.  相似文献   
7.
Covering numbers of precompact symmetric convex subsets of Hilbert spaces are investigated. Lower bounds are derived for sets containing orthogonal subsets with norms of their elements converging to zero sufficiently slowly. When these sets are convex hulls of sets with power-type covering numbers, the bounds are tight. The arguments exploit properties of generalized Hadamard matrices. The results are illustrated by examples from machine learning, neurocomputing, and nonlinear approximation.  相似文献   
8.
In this paper we obtain some formulas for totally umbilical hypersurfaces in a locally symmetric manifold, and derive some local results on the hypersurfaces from these formulas.  相似文献   
9.
We give combinatorial proofs that certain families of differences of products of Schur functions are monomial-positive. We show in addition that such monomial-positivity is to be expected of a large class of generating functions with combinatorial definitions similar to Schur functions. These generating functions are defined on posets with labelled Hasse diagrams and include for example generating functions of Stanley's (P,ω)-partitions. T.L. was supported in part by NSF DMS-0600677.  相似文献   
10.
An energy-dependent partitioning scheme is explored for extracting a small number of eigenvalues of a real symmetric matrix with the help of genetic algorithm. The proposed method is tested with matrices of different sizes (30 × 30 to 1000 × 1000). Comparison is made with Löwdin’s strategy for solving the problem. The relative advantages and disadvantages of the GA-based method are analyzed  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