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   2956篇
  免费   30篇
  国内免费   53篇
化学   106篇
力学   87篇
综合类   28篇
数学   2572篇
物理学   246篇
  2024年   3篇
  2023年   6篇
  2022年   17篇
  2021年   15篇
  2020年   38篇
  2019年   17篇
  2018年   18篇
  2017年   32篇
  2016年   51篇
  2015年   52篇
  2014年   124篇
  2013年   187篇
  2012年   151篇
  2011年   200篇
  2010年   132篇
  2009年   237篇
  2008年   167篇
  2007年   214篇
  2006年   172篇
  2005年   114篇
  2004年   99篇
  2003年   84篇
  2002年   89篇
  2001年   118篇
  2000年   84篇
  1999年   69篇
  1998年   70篇
  1997年   57篇
  1996年   55篇
  1995年   40篇
  1994年   13篇
  1993年   16篇
  1992年   15篇
  1991年   12篇
  1990年   9篇
  1989年   12篇
  1988年   10篇
  1987年   3篇
  1986年   6篇
  1985年   50篇
  1984年   48篇
  1983年   19篇
  1982年   38篇
  1981年   33篇
  1980年   24篇
  1979年   15篇
  1978年   4篇
排序方式: 共有3039条查询结果,搜索用时 15 毫秒
91.
一种完备完全分配格上矩阵方程的求解方法   总被引:2,自引:0,他引:2  
模糊理论已经在决策、模式识别、故障诊断、过程控制等许多方面得到了广泛应用,在这些应用问题求解中往往要遇到求解模糊关系方程。本文从完备完全分配格的角度给出了一种求解模糊关系方程极小解的完备解法,并用计算机实现了提出的算法,为实际问题求解计算机化打下了基础。  相似文献   
92.
本文讨论了F数的扩张加法和扩张数乘运算的性质;并举反例说明这样的扩张运.算不能使F数全体F*构成线性空间;最后对可列个F数的运算进行了讨论.  相似文献   
93.
In pattern recognition one often wants to measure geometric properties of imprecisely defined subsets of an image. This paper proposes definitions of intrinsic and extrinsic diameter for fuzzy subsets which reduce to the ordinary definitions when the subsets are crisp. We also define height and width for a fuzzy subset and show how they relate to the area (i.e., integral of membership). For convex fuzzy subsets the intrinsic diameter cannot exceed the extrinsic diameter, but it can be smaller. Finally, for piecewise constant convex fuzzy subsets the intrinsic diameter cannot exceed half the fuzzy perimeter, but this need not be true in the nonconvex case.  相似文献   
94.
Ideas are presented to show how fuzzy mathematics can be applied in macro-economics in combination with the systems approach in order to bridge the gap between mathematical and language-oriented economists.Two reasons are given.From a mathematical point of view, fuzzy sets, fuzzy relations and fuzzy logic are not fuzzy at all. They are all well defined, but tend to be more complicated than traditional, mathematical concepts used in economics.From a language-oriented economist's point of view, fuzzy sets, etc. are used to express mathematically the type of concepts which are typical in language and most valuable in dealing with complex systems like an economy.The paper deals with economics in general terms, but examples are provided to illustrate the ideas.  相似文献   
95.
We apply the theory of fuzzy subsets to the multiple objective decision problem of stock selection. We allow our objectives to have varying degrees of importance. We discuss various criteria used in selecting stocks. We indicate some procedures for subjectively evaluating the membership functions associated with these criteria.  相似文献   
96.
97.
A fuzzy dynamical system on an underlying complete, locally compact metric state space X is defined axiomatically in terms of a fuzzy attainability set mapping on X. This definition includes as special cases crisp single and multivalued dynamical systems on X. It is shown that the support of such a fuzzy dynamical system on X is a crisp multivalued dynamical system on X, and that such a fuzzy dynamical system can be considered as a crisp dynamical system on a state space of nonempty compact fuzzy subsets of X. In addition fuzzy trajectories are defined, their existence established and various properties investigated.  相似文献   
98.
The paper presents a formula for the γ-interior of a set under special conditions for , more general than those in the previous paper [Acta Math. Hungar. 80 (1998) 89-93]. There are also some applications.  相似文献   
99.
Non-dual fuzzy connections   总被引:1,自引:0,他引:1  
The lack of double negation and de Morgan properties makes fuzzy logic unsymmetrical. This is the reason why fuzzy versions of notions like closure operator or Galois connection deserve attention for both antiotone and isotone cases, these two cases not being dual. This paper offers them attention, comming to the following conclusions: – some kind of hardly describable local preduality still makes possible important parallel results; – interesting new concepts besides antitone and isotone ones (like, for instance, conjugated pair), that were classically reducible to the first, gain independency in fuzzy setting.  相似文献   
100.
In this paper, we introduce and study the signed fuzzy-valued measure and using the representation theorem of fuzzy numbers, we establish the Radon-Nikodym theorem for fuzzy-valued measurable functions with respect to fuzzy-valued measures.AMS Subject Classification (2000): 28E10, 04A72The research of this work is supposed by a grant of the education committee of Liaoning Province, China #20161049  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