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   5321篇
  免费   343篇
  国内免费   504篇
化学   492篇
晶体学   4篇
力学   280篇
综合类   120篇
数学   4946篇
物理学   326篇
  2024年   5篇
  2023年   61篇
  2022年   86篇
  2021年   99篇
  2020年   111篇
  2019年   122篇
  2018年   134篇
  2017年   131篇
  2016年   134篇
  2015年   103篇
  2014年   209篇
  2013年   375篇
  2012年   232篇
  2011年   300篇
  2010年   270篇
  2009年   366篇
  2008年   355篇
  2007年   337篇
  2006年   336篇
  2005年   261篇
  2004年   230篇
  2003年   262篇
  2002年   226篇
  2001年   206篇
  2000年   175篇
  1999年   173篇
  1998年   177篇
  1997年   154篇
  1996年   91篇
  1995年   72篇
  1994年   56篇
  1993年   49篇
  1992年   37篇
  1991年   26篇
  1990年   20篇
  1989年   14篇
  1988年   13篇
  1987年   11篇
  1986年   10篇
  1985年   26篇
  1984年   20篇
  1983年   12篇
  1982年   22篇
  1981年   17篇
  1980年   18篇
  1979年   5篇
  1978年   7篇
  1977年   3篇
  1976年   4篇
  1974年   3篇
排序方式: 共有6168条查询结果,搜索用时 15 毫秒
101.
By using cone-directed contingent derivatives, the unified necessary and suffi-cient optimality conditions are given for weakly and strongly minimal elements respectively in generalized preinvex set valued optimization.  相似文献   
102.
We construct a family of partially ordered sets (posets) that are q-analogs of the set partition lattice. They are different from the q-analogs proposed by Dowling [5]. One of the important features of these posets is that their Whitney numbers of the first and second kind are just the q-Stirling numbers of the first and second kind, respectively. One member of this family [4] can be constructed using an interpretation of Milne [9] for S[n, k] as sequences of lines in a vector space over the Galois field F q. Another member is constructed so as to mirror the partial order in the subspace lattice.  相似文献   
103.
The solvability of a class of forward-backward stochastic differential equations (SDEs for short) over an arbitrarily prescribed time duration is studied. The authors design a stochastic relaxed control problem, with both drift and difftusion all being controlled, so that the solvability problem is converted to a problem of finding the nodal set of the viscosity solution to a certain Hamilton-Jacobi-Bellman equation. This method overcomes the fatal difficulty encountered in the traditional contraction mapping approach to the existence theorem of such SDEs.  相似文献   
104.
将分段函数划分为连结型分段函数 ,分离型分段函数和它们的组合形式三种类型 ,得到了分离型分段函数是初等函数的充分必要条件 ,完整地解决了分离型分段函数与初等函数之间的关系 ,并且给出了初等函数在其任一截取集上的限制函数 (截取函数 )仍然是初等函数的结果  相似文献   
105.
An interval-parameter fuzzy linear programming method (IFMOLP) is proposed in this study for multiple objective decision-making under uncertainty. As a hybrid of interval-parameter and fuzzy methodologies, the IFMOLP incorporates interval-parameter linear programming and fuzzy multiobjective programming approaches to form an integrated optimization system. The method inherits advantages of interval-parameter programming, and allows uncertainties and decision-makers’ aspirations to be effectively communicated into its programming processes and resulting solutions. Membership functions for both objectives and constraints are formulated to reflect uncertainties in different system components and their interrelationships. An interactive solution procedure has been developed based on solution approaches of the interval-parameter and fuzzy programming techniques, plus necessary measures for handling the multiobjective feature. A didactic example is provided in the paper to illustrate the detailed solution process. Possibilities of further improvements by seeking Pareto optimum and incorporating flexible preference within constraints are also discussed.  相似文献   
106.
借助于文(1)中的结论研究了仿紧集上的拟-似变分不等式,统一和发展了文(2-6)中的相应结果。  相似文献   
107.
We show that the problem of deciding whether anN-free ordered set has dimension at most 3 is NP-complete.Both authors supported by Office of Naval Research contract N00014-85K-0494.  相似文献   
108.
Let f and g be two permutable transcendental holomorphic maps in the plane. We shall discuss the dynamical properties of f, g and f o g and prove, among other things, that if either f has no wandering domains or f is of bounded type, then the Julia sets of f and f(g) coincide. Dedicated to Professor Sheng GONG on the occasion of his 75th birthday  相似文献   
109.
Alternatives based on polynomial expansions of gaussian basis set exponents are introduced and evaluated. The formulas presented here outperform methods based upon the even-tempered formula or combinations of it. They closely match the performance of other methods based upon larger polynomial expansions of the logarithm of the exponents using the same or one less parameter per orbital angular symmetry.  相似文献   
110.
本文推广了古典的Garisti不动点定理,作为应用,古典的Ekeland变分原理得到了推广,并且证明了推广的Garisti不动点定理和推广的Ekeland变分原理是等价的.  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