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   1121篇
  免费   15篇
  国内免费   30篇
化学   637篇
晶体学   1篇
力学   32篇
数学   370篇
物理学   126篇
  2020年   7篇
  2018年   7篇
  2016年   18篇
  2015年   9篇
  2014年   17篇
  2013年   71篇
  2012年   32篇
  2011年   39篇
  2010年   28篇
  2009年   33篇
  2008年   41篇
  2007年   38篇
  2006年   42篇
  2005年   35篇
  2004年   46篇
  2003年   43篇
  2002年   36篇
  2001年   21篇
  2000年   18篇
  1999年   9篇
  1998年   7篇
  1997年   19篇
  1996年   23篇
  1995年   24篇
  1993年   20篇
  1992年   8篇
  1991年   17篇
  1990年   12篇
  1989年   14篇
  1988年   18篇
  1987年   19篇
  1986年   10篇
  1985年   25篇
  1984年   17篇
  1983年   17篇
  1982年   25篇
  1981年   26篇
  1980年   29篇
  1979年   28篇
  1978年   19篇
  1977年   18篇
  1976年   19篇
  1975年   13篇
  1974年   14篇
  1973年   16篇
  1972年   11篇
  1971年   8篇
  1970年   7篇
  1967年   7篇
  1966年   7篇
排序方式: 共有1166条查询结果,搜索用时 31 毫秒
991.
992.
993.
This paper presents a hybrid metaheuristic approach (HMA) for solving the unconstrained binary quadratic programming (UBQP) problem. By incorporating a tabu search procedure into the framework of evolutionary algorithms, the proposed approach exhibits several distinguishing features, including a diversification-based combination operator and a distance-and-quality based replacement criterion for pool updating. The proposed algorithm is able to easily obtain the best known solutions for 31 large random instances up to 7000 variables (which no previous algorithm has done) and find new best solutions for three of nine instances derived from the set-partitioning problem, demonstrating the efficacy of our proposed algorithm in terms of both solution quality and computational efficiency. Furthermore, some key elements and properties of the HMA algorithm are also analyzed.  相似文献   
994.
995.
Nauenberg’s extended critique of Quantum Enigma rests on fundamental misunderstandings.  相似文献   
996.
Computer science and decision theory   总被引:1,自引:0,他引:1  
This paper reviews applications in computer science that decision theorists have addressed for years, discusses the requirements posed by these applications that place great strain on decision theory/social science methods, and explores applications in the social and decision sciences of newer decision-theoretic methods developed with computer science applications in mind. The paper deals with the relation between computer science and decision-theoretic methods of consensus, with the relation between computer science and game theory and decisions, and with “algorithmic decision theory.”  相似文献   
997.
In this paper, we prove sharp blow up and global existence results for a heat equation with nonlinear memory. It turns out that the Fujita critical exponent is not the one which would be predicted from the scaling properties of the equation.  相似文献   
998.
999.
The construction of new mediator-free and fully electroactive protein multilayer electrodes based on DNA and cyt c is demonstrated. The assembly is characterized by a rather high stability, effective electron transfer, and a tunability of the electroactive protein amount by the number of deposited cyt c layers.  相似文献   
1000.
This paper presents a statistic for testing the hypothesis of elliptical symmetry. The statistic also provides a specialized test of multivariate normality. We obtain the asymptotic distribution of this statistic under the null hypothesis of multivariate normality, and give a bootstrapping procedure for approximating the null distribution of the statistic under an arbitrary elliptically symmetric distribution. We present simulation results to examine the accuracy of the asymptotic distribution and the performance of the bootstrapping procedure. Finally, for selected alternatives, we compare the power of our test statistic with that of recently proposed tests for elliptical symmetry given by Manzotti et al. [A statistic for testing the null hypothesis of elliptical symmetry, J. Multivariate Anal. 81 (2002) 274-285] and Schott [Testing for elliptical symmetry in covariance-matrix-based analyses, Statist. Probab. Lett. 60 (2002) 395-404], and with that of the well known tests for multivariate normality of Mardia [Measures of multivariate skewness and kurtosis with applications, Biometrika 57 (1970) 519-530] and Baringhaus and Henze [A consistent test for multivariate normality based on the empirical characteristic function, Metrika 35 (1988) 339-348].  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