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   2015篇
  免费   175篇
  国内免费   177篇
化学   38篇
力学   172篇
综合类   25篇
数学   1964篇
物理学   168篇
  2024年   5篇
  2023年   27篇
  2022年   21篇
  2021年   41篇
  2020年   71篇
  2019年   75篇
  2018年   67篇
  2017年   76篇
  2016年   70篇
  2015年   61篇
  2014年   103篇
  2013年   186篇
  2012年   105篇
  2011年   82篇
  2010年   84篇
  2009年   115篇
  2008年   141篇
  2007年   132篇
  2006年   100篇
  2005年   101篇
  2004年   72篇
  2003年   80篇
  2002年   75篇
  2001年   51篇
  2000年   56篇
  1999年   61篇
  1998年   42篇
  1997年   54篇
  1996年   25篇
  1995年   27篇
  1994年   23篇
  1993年   18篇
  1992年   9篇
  1991年   11篇
  1990年   12篇
  1989年   5篇
  1988年   3篇
  1987年   5篇
  1986年   2篇
  1985年   17篇
  1984年   8篇
  1983年   4篇
  1982年   5篇
  1981年   7篇
  1980年   4篇
  1979年   7篇
  1978年   9篇
  1977年   6篇
  1976年   3篇
  1957年   1篇
排序方式: 共有2367条查询结果,搜索用时 15 毫秒
121.
稀缺资源的节省利用研究   总被引:1,自引:0,他引:1  
本在建立模型的基础上,对稀缺资源的节省利用问题进行了研究,给出了稀缺资源能否节省的判别条件和具体作法。  相似文献   
122.
A kind of generalization of the Curve Type Node Configuration is given in this paper,and it is called the generalized node configuration CTNCB in RS(S>2).The related multivariate polynomial interpolation problem is discussed.It is proved that the CTNCB is an appropriate node configuration for the polynomial space PSn (S>2).And the expressions of the multivariate Vandermonde determinants that are related to the Odd Curve Type Node Configuration in R2 are also obtained.  相似文献   
123.
We revise the notion of von Neumann regularity in JB^*-triples by finding a new characterisation in terms of the range of the quadratic operator Q(a). We introduce the quadratic conorm of an element a in a JB^*-triple as the minimum reduced modulus of the mapping Q(a). It is shown that the quadratic conorm of a coincides with the infimum of the squares of the points in the triple spectrum of a. It is established that a contractive bijection between JBW^*-triples is a triple isomorphism if, and only if, it preserves quadratic conorms. The continuity of the quadratic conorm and the generalized inverse are discussed. Some applications to C^*-algebras and von Neumann algebras are also studied.  相似文献   
124.
We give some necessary and sufficient conditions which completely characterize the strong and total Lagrange duality, respectively, for convex optimization problems in separated locally convex spaces. We also prove similar statements for the problems obtained by perturbing the objective functions of the primal problems by arbitrary linear functionals. In the particular case when we deal with convex optimization problems having infinitely many convex inequalities as constraints the conditions we work with turn into the so-called Farkas-Minkowski and locally Farkas-Minkowski conditions for systems of convex inequalities, recently used in the literature. Moreover, we show that our new results extend some existing ones in the literature.  相似文献   
125.
In this article, we implement relatively new analytical techniques, the variational iteration method and the Adomian decomposition method, for solving nonlinear partial differential equations of fractional order. The fractional derivatives are described in the Caputo sense. The two methods in applied mathematics can be used as alternative methods for obtaining analytic and approximate solutions for different types of fractional differential equations. In these schemes, the solution takes the form of a convergent series with easily computable components. Numerical results show that the two approaches are easy to implement and accurate when applied to partial differential equations of fractional order.  相似文献   
126.
In the framework of the theory of normal coderivative for multifunctions, new implicit function theorems are obtained. The main tools of the proofs are the Ekeland variational principle, a nonsmooth version of Fermat's rule, a sum rule, and the differential estimate for marginal functions established by B.S. Mordukhovich and Y. Shao [B.S. Mordukhovich, Y. Shao, Nonsmooth sequential analysis in Asplund spaces, Trans. Amer. Math. Soc. 348 (1996) 1235-1280].  相似文献   
127.
The maximum entropy principle consists of two steps: The first step is to find the distribution which maximizes entropy under given constraints. The second step is to calculate the corresponding thermodynamic quantities. The second part is determined by Lagrange multipliers’ relation to the measurable physical quantities as temperature or Helmholtz free energy/free entropy. We show that for a given MaxEnt distribution, the whole class of entropies and constraints leads to the same distribution but generally different thermodynamics. Two simple classes of transformations that preserve the MaxEnt distributions are studied: The first case is a transform of the entropy to an arbitrary increasing function of that entropy. The second case is the transform of the energetic constraint to a combination of the normalization and energetic constraints. We derive group transformations of the Lagrange multipliers corresponding to these transformations and determine their connections to thermodynamic quantities. For each case, we provide a simple example of this transformation.  相似文献   
128.
129.
综述了国内和国外学者研究连续介质分析动力学问题的进展,阐明了本文主要论述将Lagrange方程应用于连续介质动力学的问题.论文采用Lagrange-Hamilton体系,分别论述了非保守非线性弹性动力学、不可压缩黏性流体动力学、黏弹性动力学、热弹性动力学、刚--弹耦合动力学和刚--液耦合动力学的Lagrange方程及其应用.论述了应用Lagrange方程建立有限元计算模型的问题. 最后,展望了将Lagrange方程应用于连续介质动力学问题的研究前景.  相似文献   
130.
FuBaolian(付宝连)(ReceivedNov.22,1993;CommunicatedbyChienWeizang)COUPLEDVARIATIONALPRINCIPLESANDGENERALIZEDCOUPLEDVARIATIONALPRI...  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