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   6363篇
  免费   1064篇
  国内免费   1095篇
化学   5351篇
晶体学   60篇
力学   271篇
综合类   81篇
数学   771篇
物理学   1988篇
  2024年   24篇
  2023年   107篇
  2022年   138篇
  2021年   160篇
  2020年   234篇
  2019年   273篇
  2018年   234篇
  2017年   175篇
  2016年   289篇
  2015年   334篇
  2014年   362篇
  2013年   487篇
  2012年   532篇
  2011年   506篇
  2010年   421篇
  2009年   415篇
  2008年   435篇
  2007年   399篇
  2006年   376篇
  2005年   336篇
  2004年   320篇
  2003年   300篇
  2002年   355篇
  2001年   229篇
  2000年   192篇
  1999年   192篇
  1998年   124篇
  1997年   103篇
  1996年   72篇
  1995年   59篇
  1994年   59篇
  1993年   33篇
  1992年   37篇
  1991年   43篇
  1990年   30篇
  1989年   22篇
  1988年   17篇
  1987年   11篇
  1986年   18篇
  1985年   20篇
  1984年   9篇
  1983年   8篇
  1982年   7篇
  1981年   4篇
  1979年   4篇
  1977年   2篇
  1975年   2篇
  1974年   2篇
  1968年   3篇
  1936年   2篇
排序方式: 共有8522条查询结果,搜索用时 15 毫秒
871.
We study the Abreu?s equation in n-dimensional polytopes and derive interior estimates of solutions under the assumption of the uniform K-stability.  相似文献   
872.
We present a new approach to calculate analytic approximations of blow‐up solutions and their critical blow‐up times. Our approach applies the Adomian decomposition–Padé method to quickly and easily compute the critical blow‐up times, which comprises the Adomian decomposition method combined with the Padé approximants technique. We validate our new approach with a variety of numerical examples, including nonlinear ODEs, systems of nonlinear ODEs, and nonlinear PDEs. Furthermore, our new method is shown to be more convenient than prior art that relies on compound discretized algorithms. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
873.
In this paper we consider the problem of finding closed hypersurfaces with prescribed Weingarten curvature in a large class of Riemannian manifolds. Under some sufficient conditions, we obtain an existence result by establishing a priori estimates and standard degree theory for the admissible solutions to the prescribed curvature equation. We mainly show that the primary technique developed in Urbas, Wang and the second author’s work in 2004 is flexible enough to be used in more general ambient geometry.  相似文献   
874.
Difference systems of sets (DSS) are combinatorial configurations that arise in connection with code synchronization. This paper proposes a new method to construct DSSs, which uses known DSSs to partition some of the cosets of Zv relative to subgroup of order k, where v = km is a composite number. As applications, we obtain some new optimal DSSs.  相似文献   
875.
876.
具有交易成本的证券投资组合选择:一种求解方法   总被引:3,自引:0,他引:3  
本研究一类带交易成本证券投资组合选择的求解,在风险不超过某个阈值的假设下,我们给出一种求解方法,最后本通过实例计算表明该方法是有效的。  相似文献   
877.
In this paper, we propose new methods for solving variational inequalities. The proposed methods can be viewed as a refinement and improvement of the method of He et al. [B.S. He, X.M. Yuan, J.J. Zhang, Comparison of two kinds of prediction–correction methods for monotone variational inequalities, Comp. Opt. Appl. 27 (2004) 247–267] by performing an additional projection step at each iteration and another optimal step length is employed to reach substantial progress in each iteration. Under certain conditions, the global convergence of the both methods is proved. Preliminary numerical experiments are included to illustrate the efficiency of the proposed methods.  相似文献   
878.
879.
Evaluation for the performance of learning algorithm has been the main thread of theoretical research of machine learning. The performance of the regularized regression algorithm based on independent and identically distributed(i.i.d.) samples has been researched by a large number of references. In the present paper we provide the convergence rates for the performance of regularized regression based on the inputs of p-order Markov chains.  相似文献   
880.
In this paper, well-posedness and asymptotic behaviors for a predator-prey system with Lévy noise are studied by using stochastic analytical techniques. Firstly, the existence and uniqueness of positive global solution with positive initial value is proved. Then, stochastic permanence for the system is investigated. Finally, persistence in mean and extinction for the system are discussed and some numerical simulations are provided to support our results.  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