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   1468篇
  免费   59篇
  国内免费   246篇
化学   415篇
晶体学   4篇
力学   33篇
综合类   9篇
数学   1136篇
物理学   176篇
  2024年   2篇
  2023年   29篇
  2022年   29篇
  2021年   25篇
  2020年   26篇
  2019年   45篇
  2018年   37篇
  2017年   40篇
  2016年   23篇
  2015年   32篇
  2014年   73篇
  2013年   134篇
  2012年   77篇
  2011年   62篇
  2010年   67篇
  2009年   103篇
  2008年   111篇
  2007年   112篇
  2006年   92篇
  2005年   68篇
  2004年   83篇
  2003年   65篇
  2002年   49篇
  2001年   41篇
  2000年   45篇
  1999年   37篇
  1998年   45篇
  1997年   31篇
  1996年   33篇
  1995年   22篇
  1994年   20篇
  1993年   15篇
  1992年   14篇
  1991年   8篇
  1990年   7篇
  1989年   3篇
  1988年   9篇
  1987年   4篇
  1986年   8篇
  1985年   7篇
  1984年   7篇
  1983年   4篇
  1982年   5篇
  1981年   4篇
  1980年   2篇
  1979年   2篇
  1978年   8篇
  1977年   3篇
  1976年   3篇
  1973年   1篇
排序方式: 共有1773条查询结果,搜索用时 0 毫秒
131.
A nonnegative 1-periodic multifractal measure on is obtained as infinite random product of harmonics of a 1-periodic function W(t). Such infinite products are statistically self-affine and generalize certain Riesz products with random phases. They are martingale structures, therefore converge. The criterion on W for nondegeneracy is provided. It differs completely from those for other known random measures constructed as martingale limits of multiplicative processes. In particular, it is very sensitive to small changes in W(t). When these infinite products are interpreted in the framework of thermodynamic formalism for random transformations, logW is a potential function when W>0. For regular enough potentials, in case of degeneracy, the natural normalization makes the sequence of measures converge. Moreover, this normalization is neutral for nondegenerate martingales. The multifractal analysis of the limit martingale measure is performed for a class of potential functions having a dense countable set of jump points.  相似文献   
132.
In this paper a comparison is made between two decomposition techniques to solve a staff scheduling problem with column generation. In the first approach, decomposition takes place on the staff members, whereas in the second approach decomposition takes place on the activities that have to be performed by the staff members. The resulting master LP is respectively a set partitioning problem and a capacitated multi-commodity flow problem. Both approaches have been implemented in a branch-and-price algorithm. We show a trade-off between modeling power and computation times of both techniques.  相似文献   
133.
We show that the problem of searching for v-structures in a directed acyclic graph can be decomposed into searches in its decomposed subgraphs. This result simplifies the search for v-structures and the recovery of local causal relationships.  相似文献   
134.
We give new characterizations of Lorentz spaces by means of certain quasi-norms which are shown to be equivalent to the classical ones.

  相似文献   

135.
The analytic continuation of the exponential transform of a domain in Rn is proved under some global geometric assumptions on the boundary. Two approximation schemes of the continued transform (one based on a Taylor series truncation, the other on a global eigenfunction expansion) are also discussed.  相似文献   
136.
ONTHEEXISTENCEOFGLOBALGENERALSOLUTIONSOF POLYNOMIALSYSTEMSZHAOXIAOQIANG(赵晓强)(InstituteofAppliedMathematics,theChineseAcademyo...  相似文献   
137.
Robinson has proposed the bundle-based decomposition algorithm to solve a class of structured large-scale convex optimization problems. In this method, the original problem is transformed (by dualization) to an unconstrained nonsmooth concave optimization problem which is in turn solved by using a modified bundle method. In this paper, we give a posteriori error estimates on the approximate primal optimal solution and on the duality gap. We describe implementation and present computational experience with a special case of this class of problems, namely, block-angular linear programming problems. We observe that the method is efficient in obtaining the approximate optimal solution and compares favorably with MINOS and an advanced implementation of the Dantzig—Wolfe decomposition method.  相似文献   
138.
AVERAGE σ-K WIDTH OF CLASS OF L_p(R~n)IN L_q(R~n)AVERAGEσ-KWIDTHOFCLASSOFL_p(R~n)INL_q(R~n)¥LIUYONGPINGAbstract:Theaverageσ-Kwidt...  相似文献   
139.
In this paper, the space-time Riesz fractional partial differential equations with periodic conditions are considered. The equations are obtained from the integral partial differential equation by replacing the time derivative with a Caputo fractional derivative and the space derivative with Riesz potential. The fundamental solutions of the space Riesz fractional partial differential equation (SRFPDE) and the space-time Riesz fractional partial differential equation (STRFPDE) are discussed, respectively. Using methods of Fourier series expansion and Laplace transform, we derive the explicit expressions of the fundamental solutions for the SRFPDE and the STRFPDE, respectively.  相似文献   
140.
张鸿亮 《应用数学》1994,7(2):131-136
对于带调速器的多台电机组,本文引入关联矩阵E=(e_(ij))_(n×n),应用李雅普诺夫函数分解法,研究了此电力大系统的暂态关联稳定性,得到了系统的分解系数与稳定区域的估计公式。  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