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   10306篇
  免费   1104篇
  国内免费   884篇
化学   2009篇
晶体学   100篇
力学   823篇
综合类   223篇
数学   6740篇
物理学   2399篇
  2024年   14篇
  2023年   102篇
  2022年   171篇
  2021年   191篇
  2020年   292篇
  2019年   332篇
  2018年   284篇
  2017年   332篇
  2016年   371篇
  2015年   287篇
  2014年   494篇
  2013年   917篇
  2012年   508篇
  2011年   583篇
  2010年   496篇
  2009年   593篇
  2008年   641篇
  2007年   632篇
  2006年   550篇
  2005年   510篇
  2004年   411篇
  2003年   406篇
  2002年   456篇
  2001年   369篇
  2000年   364篇
  1999年   333篇
  1998年   278篇
  1997年   275篇
  1996年   176篇
  1995年   121篇
  1994年   96篇
  1993年   86篇
  1992年   58篇
  1991年   67篇
  1990年   47篇
  1989年   43篇
  1988年   41篇
  1987年   39篇
  1986年   25篇
  1985年   49篇
  1984年   46篇
  1983年   24篇
  1982年   29篇
  1981年   26篇
  1980年   24篇
  1979年   28篇
  1978年   20篇
  1977年   13篇
  1976年   14篇
  1974年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
A method using third order moments for estimating the regression coefficients as well as the latent state scores of the reduced-rank regression model when the latent variable(s) are non-normally distributed is presented in this paper. It is shown that the factor analysis type indeterminacy of the regression coefficient matrices is eliminated. A real life example of the proposed method is presented. Differences of this solution with the reduced-rank regression eigen solution are discussed.  相似文献   
5.
给出2005年全国部分高校研究生数学建模竞赛D题的研究背景,对参赛论文作了简要评注,并提供了一种参考解答.  相似文献   
6.
We consider immersions: and construct a subspace of which corresponds to a set of embedded manifolds which are either parallel to f, tubes around f or, in general, partial tubes around f. This space is invariant under the action of the normal holonomy group, We investigate the case where is non-trivial and obtain some results on the number of connected components of . Received 24 March 2000.  相似文献   
7.
The purpose of this paper is to give a proof of Kummer type congruence for the q-Bernoulli numbers of higher order, which is an answer to a part of the problem in a previous publication (see Indian J. Pure Appl. Math. 32 (2001) 1565-1570).  相似文献   
8.
We first discuss nonlinear aspects of phase transition theory applied to a particular liquid crystal phase transition. A simple derivation is given to show how two coupled Goldstone modes (one appearing as gauge fluctuations of the ordered phase) can force a phase transition, against all expectations, to take place discontinuously (theory of Halperin, Lubensky, and Ma)-but the discontinuity may be immeasurably small. Then, we describe a new dynamical test of phase transition order, developed by Cladiset al., that turns out to be more sensitive than x-ray diffraction and adiabatic calorimetry. Quantitative data found by this new method are in excellent agreement with the measurements of adiabatic calorimetry and x-ray diffraction as well as expectations implicit in the predictions of HLM.This is the text of an after-banquet talk given at the CNLS Workshop on the Dynamics of Concentrated Systems.  相似文献   
9.
This paper develops a modified quasi-Newton method for structured unconstrained optimization with partial information on the Hessian, based on a better approximation to the Hessian in current search direction. The new approximation is decided by both function values and gradients at the last two iterations unlike the original one which only uses the gradients at the last two iterations. The modified method owns local and superlinear convergence. Numerical experiments show that the proposed method is encouraging comparing with the methods proposed in [4] for structured unconstrained optimization Presented at the 6th International Conference on Optimization: Techniques and Applications, Ballarat, Australia, December 9–11, 2004  相似文献   
10.
Developement of numerical methods for obtaining approximate solutions to the three dimensional diffusion equation with an integral condition will be carried out. The numerical techniques discussed are based on the fully explicit (1,7) finite difference technique and the fully implicit (7,1) finite difference method and the (7,7) Crank‐Nicolson type finite difference formula. The new developed methods are tested on a problem. Truncation error analysis and numerical examples are used to illustrate the accuracy of the new algorithms. The results of numerical testing show that the numerical methods based on the finite difference techniques discussed in the present article produce good results. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 193–202, 2002; DOI 10.1002/num.1040  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