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   1676篇
  免费   125篇
  国内免费   182篇
化学   85篇
晶体学   3篇
力学   145篇
综合类   40篇
数学   1489篇
物理学   221篇
  2023年   13篇
  2022年   14篇
  2021年   24篇
  2020年   18篇
  2019年   30篇
  2018年   41篇
  2017年   51篇
  2016年   48篇
  2015年   41篇
  2014年   72篇
  2013年   133篇
  2012年   106篇
  2011年   93篇
  2010年   92篇
  2009年   95篇
  2008年   111篇
  2007年   112篇
  2006年   115篇
  2005年   81篇
  2004年   73篇
  2003年   89篇
  2002年   71篇
  2001年   59篇
  2000年   55篇
  1999年   58篇
  1998年   54篇
  1997年   41篇
  1996年   36篇
  1995年   20篇
  1994年   19篇
  1993年   10篇
  1992年   15篇
  1991年   9篇
  1990年   11篇
  1989年   6篇
  1988年   6篇
  1987年   2篇
  1986年   7篇
  1985年   7篇
  1984年   4篇
  1983年   2篇
  1982年   13篇
  1981年   6篇
  1980年   4篇
  1979年   5篇
  1978年   5篇
  1977年   1篇
  1976年   1篇
  1974年   2篇
  1959年   1篇
排序方式: 共有1983条查询结果,搜索用时 15 毫秒
91.
The mutational equations of Aubin extend ordinary differential equations to metric spaces (with compact balls). In first-order geometric evolutions, however, the topological boundary need not be continuous in the sense of Painlevé–Kuratowski. So this paper suggests a generalization of Aubin’s mutational equations that extends classical notions of dynamical systems and functional analysis beyond the traditional border of vector spaces: Distribution-like solutions are introduced in a set just supplied with a countable family of (possibly non-symmetric) distance functions. Moreover their existence is proved by means of Euler approximations and a form of “weak” sequential compactness (although no continuous linear forms are available beyond topological vector spaces). This general framework is applied to a first-order geometric example, i.e. compact subsets of ℝ N evolving according to the nonlocal properties of both the current set and its proximal normal cones. Here neither regularity assumptions about the boundaries nor the inclusion principle are required. In particular, we specify sufficient conditions for the uniqueness of these solutions.   相似文献   
92.
In this paper, we present an existence result for weak efficient solution for the vector optimization problem. The result is stated for invex strongly compactly Lipschitz functions.  相似文献   
93.
Exploiting sparsity has been a key issue in solving large-scale optimization problems. The most time-consuming part of primal-dual interior-point methods for linear programs, second-order cone programs, and semidefinite programs is solving the Schur complement equation at each iteration, usually by the Cholesky factorization. The computational efficiency is greatly affected by the sparsity of the coefficient matrix of the equation which is determined by the sparsity of an optimization problem (linear program, semidefinite program or second-order cone program). We show if an optimization problem is correlatively sparse, then the coefficient matrix of the Schur complement equation inherits the sparsity, and a sparse Cholesky factorization applied to the matrix results in no fill-in. S. Kim’s research was supported by Kosef R01-2005-000-10271-0 and KRF-2006-312-C00062.  相似文献   
94.
The problem of the boundedness of the Riesz potential I α , 0 < α < n, in local Morrey-type spaces is reduced to the boundedness of the Hardy operator in weighted L p -spaces on the cone of non-negative non-increasing functions. This allows obtaining sufficient conditions for the boundedness in local Morrey-type spaces for all admissible values of the parameters. Moreover, for a certain range of the parameters, these sufficient conditions coincide with the necessary ones. V. Guliyev’s research was partially supported by the grant of the Azerbaijan-U. S. Bilateral Grants Program II (project ANSF Award / AZM1-3110-BA-08) and the Turkish Scientific and Technological Research Council (TUBITAK, programme 2221, no. 220.01-619-4889).  相似文献   
95.
利用不动点指数理论研究奇异二阶周期边值问题.在有关其线性算子方程对应的第一特征值的条件下得到边值问题正解的存在性,推广和改进了最近文献的结果.  相似文献   
96.
向量优化问题有效解的稳定性   总被引:1,自引:0,他引:1  
运用标量化的方法,通过锥正定真有效解的上半连续性讨论了无限维赋范空间中锥有效解的部分上半连续性,证明了锥有效解的通有稳定性.在此基础上,进一步证明,在Baire纲的意义下,绝大多数的向量优化问题至少存在一个锥正定真有效解是本质的有效解,换句话说,绝大多数的向量优化问题锥有效解是几乎下半连续的.  相似文献   
97.
A result on pure shear provides the motivation for the determination of some new general results relating real second order Cartesian tensors.   相似文献   
98.
In this paper, by the fixed point index theory, the number of fixed points for sublinear and asymptotically linear operators via two coupled parallel sub-super solutions is studied. Under suitable conditions, the existence of at least nine or seven distinct fixed points for sublinear and asymptotically linear operators is proved. Finally, the theoretical results are applied to a nonlinear system of Hammerstein integral equations.  相似文献   
99.
This paper shows that some characterizations of the harmonic majorization of the Martin function for domains having smooth boundaries also hold for cones.  相似文献   
100.
借助于与给定共振的非线性周期边值问题相关的非共振的线性边值问题来构造算子,利用范数形式的锥拉伸-压缩不动点定理,得到了非线性周期边值问题非负解的存在性定理.  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