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   2057篇
  免费   204篇
  国内免费   39篇
化学   57篇
力学   17篇
综合类   40篇
数学   2052篇
物理学   134篇
  2023年   5篇
  2022年   58篇
  2021年   84篇
  2020年   49篇
  2019年   47篇
  2018年   46篇
  2017年   48篇
  2016年   61篇
  2015年   53篇
  2014年   138篇
  2013年   117篇
  2012年   121篇
  2011年   102篇
  2010年   103篇
  2009年   144篇
  2008年   112篇
  2007年   151篇
  2006年   88篇
  2005年   75篇
  2004年   71篇
  2003年   63篇
  2002年   59篇
  2001年   58篇
  2000年   40篇
  1999年   38篇
  1998年   31篇
  1997年   27篇
  1996年   45篇
  1995年   29篇
  1994年   33篇
  1993年   10篇
  1992年   14篇
  1991年   21篇
  1990年   8篇
  1989年   10篇
  1988年   17篇
  1987年   7篇
  1986年   8篇
  1985年   26篇
  1984年   19篇
  1983年   7篇
  1982年   13篇
  1981年   7篇
  1980年   13篇
  1979年   4篇
  1978年   5篇
  1977年   8篇
  1976年   3篇
  1968年   1篇
  1959年   1篇
排序方式: 共有2300条查询结果,搜索用时 15 毫秒
11.
One of the most ignored, but urgent and vital challenges confronting society today is the vulnerability of urban areas to extreme events. Current organization of response systems, predominantly based on a command and control model, limits their effectiveness and efficiency. Particularly, in decision‐making processes where a large number of actors may be involved. In this article, a new distributed collaborative decision‐making model is proposed to overcome command and control limitations encountered in stressful, hostile, chaotic, and large‐scale settings. This model was derived by borrowing concepts from the collective decision making of honeybees foraging, a successful process in solving complex tasks within complex settings. The model introduced in this article was evaluated through differential equations, i.e., continuous analysis, and difference equations, i.e., discrete analysis. The most important result found is that the best available option in any large‐scale decision‐making problem can be configured as an attractor, in a distributed and timely manner. We suggest that the proposed model has the potential to facilitate decision‐making processes in large‐scale settings. © 2005 Wiley Periodicals, Inc. Complexity 11:28–38, 2005  相似文献   
12.
The control of piecewise-deterministic processes is studied where only local boundedness of the data is assumed. Moreover the discount rate may be zero. The value function is shown to be solution to the Bellman equation in a weak sense; however the solution concept is strong enough to generate optimal policies. Continuity and compactness conditions are given for the existence of nonrelaxed optimal feedback controls.  相似文献   
13.
14.
15.
本文根据国家关键技术管理工作的特点,本着提高决策质量,满足用户要求的原则,分析和设计国家关键技术管理计算机系统,为高层次宏观决策提供丰富的信息支持。  相似文献   
16.
一类经典”秘书问题”的推广   总被引:2,自引:0,他引:2  
”秘书问题”在最优停时理论的发展中曾起过重要作用 ,实际中的一类问题与”秘书问题”有类似之处 ,但比”秘书问题”更复杂 .本文将经典”秘书问题”进行推广 ,建立了一类比经典”秘书问题”更有实际意义的模型 ,并给出了该类模型的解 .  相似文献   
17.
In this paper we propose a general integration scheme for a Multi-Criteria Decision Making model of the Multi-Attribute Utility Theory in Constraint Programming. We introduce the Choquet integral as a general aggregation function for multi-criteria optimization problems and define the Choquet global constraint that propagates this function during the Branch-and-Bound search. Finally the benefits of the propagation of the Choquet constraint are evaluated on the examination timetabling problem.  相似文献   
18.
In this paper, nonconvex multiobjective optimization problems are studied. New characterizations of a properly efficient solution in the sense of Geoffrion's are established in terms of the stability of one scalar optimization problem and the existence of an exact penalty function of a scalar constrained program, respectively. One of the characterizations is applied to derive necessary conditions for a properly efficient control-parameter pair of a nonconvex multiobjective discrete optimal control problem with linear constraints.  相似文献   
19.
We introduce the time-consistency concept that is inspired by the so-called “principle of optimality” of dynamic programming and demonstrate – via an example – that the conditional value-at-risk (CVaR) need not be time-consistent in a multi-stage case. Then, we give the formulation of the target-percentile risk measure which is time-consistent and hence more suitable in the multi-stage investment context. Finally, we also generalize the value-at-risk and CVaR to multi-stage risk measures based on the theory and structure of the target-percentile risk measure.  相似文献   
20.
In this paper the problem of verifying the Pareto-optimality of a given solution to a dynamic multiple-criterion decision (DMCD) problem is investigated. For this purpose, some new conditions are derived for Pareto-optimality of DMCD problems. In the literature, Pareto-optimality is characterized by means of Euler-Lagrangian differential equations. There exist problems in production and inventory control to which these conditions cannot be applied directly (Song 1997). Thus, it is necessary to explore new conditions for Pareto-optimality of DMCD problems. With some mild assumptions on the objective functionals, we develop necessary and/or sufficient conditions for Pareto-optimality in the sprit of optimization theory. Both linear and non-linear cases are considered.  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