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   2826篇
  免费   126篇
  国内免费   248篇
化学   220篇
晶体学   1篇
力学   50篇
综合类   30篇
数学   2671篇
物理学   228篇
  2024年   3篇
  2023年   21篇
  2022年   37篇
  2021年   32篇
  2020年   41篇
  2019年   61篇
  2018年   57篇
  2017年   53篇
  2016年   67篇
  2015年   58篇
  2014年   125篇
  2013年   182篇
  2012年   108篇
  2011年   149篇
  2010年   124篇
  2009年   201篇
  2008年   227篇
  2007年   177篇
  2006年   161篇
  2005年   151篇
  2004年   108篇
  2003年   112篇
  2002年   105篇
  2001年   97篇
  2000年   94篇
  1999年   91篇
  1998年   88篇
  1997年   77篇
  1996年   59篇
  1995年   36篇
  1994年   32篇
  1993年   28篇
  1992年   26篇
  1991年   16篇
  1990年   16篇
  1989年   16篇
  1988年   15篇
  1987年   7篇
  1986年   4篇
  1985年   27篇
  1984年   18篇
  1983年   5篇
  1982年   15篇
  1981年   15篇
  1980年   19篇
  1979年   15篇
  1978年   9篇
  1977年   5篇
  1976年   4篇
  1969年   2篇
排序方式: 共有3200条查询结果,搜索用时 15 毫秒
31.
本文讨论了笔者在[1]中提出的伪凸集,拟凸集的支撑函数与障碍锥的性质,并通过这些性质得出了二个闭性准则。  相似文献   
32.
设 G=(A,△)为紧矩阵量子群,G为A的所有有限维光滑的、不可约余表示等价类的集合.本文通过(A,△)的一个余表示Vo构造了两个相互配对的集合,利用Hilbert C*-模的理论证明它们分别为A和Baaj与Skandalis构造的量子群A,并且证明了对任意的α∈G,在A中都对应一个有限维投影算子Pα,满足 dim(α)=dim(pα).  相似文献   
33.
Fuzzy集的基数   总被引:6,自引:0,他引:6  
关于Fuzzy集的基数,[1]中曾对有限支集的Fuzzy集以及极苛刻条件下的无限Fuzzy集给出过一种定义。但是,正如本文将要指出的那样,该定义是不合理的。本文将从研究Fuzzy映射入手,给出Fuzzy集基数的一般性定义。基于这一定义,不但得到有关基数的大部分结论,而且有其自身的特殊性。  相似文献   
34.
We give an estimate for the number of elements in the intersection of topological Sidon sets inR n with compact convex subsets and deduce a necessary and sufficient conditions for an orbit of a linear transformation ofR n to be a topological Sidon set.  相似文献   
35.
Fixed Point Theorems on Product Topological Spaces and Applications   总被引:3,自引:0,他引:3  
A new collectively fixed point theorem for a family of set-valued mappings defined on product spaces of non-compact topological spaces without linear structure is proved and some special cases are also discussed. As applications, some non-empty intersection theorems of sets with convex sections and equilibrium existence theorem of abstract economies are obtained under much weaker assumptions. Our results includes a number of known results as many special cases.  相似文献   
36.
Goguadze  D. F. 《Mathematical Notes》2003,74(3-4):346-351
We introduce a generalized notion of semiring and prove that all known properties that semirings have according to the old definition are preserved.  相似文献   
37.
We developed a compact equipment working at 94 GHz to replace the commonly used network analyzer for nondestructive testing of materials. The compact equipment was designed to measure the variations in the amplitude and phase of the reflected signal from the material relative to a reference signal. A good accuracy of the amplitude and phase measurement of the equipment was obtained in the confirmative experiments. The distribution of a drop of water in a wood plate is clearly visible in the millimeter wave images obtained by the amplitude and phase measurement.  相似文献   
38.
In finite dimensional Euclidean space, we prove the contractibility of the efficient frontier of simply shaded sets. This work extends the result of Peleg [7], which confirms the contractibility of the efficient frontier in the convex case.  相似文献   
39.
Noninferior Nash Strategies for Multi-Team Systems   总被引:1,自引:0,他引:1  
This paper is concerned with the optimization of systems that are controlled by several teams of decision makers. The decision makers within each team cooperate for the benefit of their team. On the other hand, the teams compete among themselves in order to achieve an objective that relates to the overall performance of the system. An approach that merges concepts from team theory and game theory for dealing with such systems and a solution called the noninferior Nash strategy are introduced. This multi-team solution provides a new framework for analyzing hierarchically controlled systems so as to address complicated coordination problems among the decision makers. The properties of the noninferior Nash solution in static multi-team systems are investigated and necessary conditions for its existence are derived. Analytical expressions for the noninferior Nash strategies are derived for a class of linear-quadratic static multi-team games. In order to deal with the issue of nonuniqueness of the solution, the concept of a noninferior Nash strategy with a team leader is introduced. Several examples are presented to illustrate the results.  相似文献   
40.
For the Queens_n 2 graph coloring problems no chromatic numbers are available for n > 9 except where n is not a multiple of 2 or 3. In this paper we propose an exact algorithm that takes advantage of the particular structure of these graphs. The algorithm works on the independent sets of the graph rather than on the vertices to be colored. It combines branch and bound, for independent set assignment, with a clique based filtering procedure. A first experimentation of this approach provided the coloring number values ranging for n = 10 to n = 14.  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