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   2488篇
  免费   368篇
  国内免费   129篇
  2024年   2篇
  2023年   7篇
  2022年   22篇
  2021年   34篇
  2020年   26篇
  2019年   61篇
  2018年   50篇
  2017年   92篇
  2016年   90篇
  2015年   67篇
  2014年   205篇
  2013年   264篇
  2012年   152篇
  2011年   207篇
  2010年   172篇
  2009年   194篇
  2008年   147篇
  2007年   175篇
  2006年   152篇
  2005年   146篇
  2004年   131篇
  2003年   108篇
  2002年   70篇
  2001年   77篇
  2000年   42篇
  1999年   40篇
  1998年   29篇
  1997年   31篇
  1996年   29篇
  1995年   23篇
  1994年   32篇
  1993年   18篇
  1992年   21篇
  1991年   18篇
  1990年   25篇
  1989年   12篇
  1988年   10篇
  1987年   3篇
  1975年   1篇
排序方式: 共有2985条查询结果,搜索用时 15 毫秒
971.
This paper investigates the multivariate Polya distribution (MPD) for application in combat models for which enemy targets must be randomly assigned to fighting units. Six sets of actual combat data motivate the allocation model. Scenarios include air‐to‐air combat, tank, and submarine warfare. Goodness of fit tests are derived which verify the validity of the MPD, and reinforce the notion that multinomial allocation is too simplistic for such combat models. Simulations to determine optimal allocations for minimal combat cost are applied in order to illustrate the role of the MPD in combat modeling. © 2001 John Wiley & Sons,Inc. Naval Research Logistics 48: 1–17, 2001  相似文献   
972.
相对论带电粒子与电磁波包之间的相互作用   总被引:1,自引:0,他引:1       下载免费PDF全文
研究了相对论带电粒子与电磁波包之间的相互作用,给出了带电粒子运动方程的严格解,得出了粒子的位置、速度和能量的显示表达式。本文结果对基础等离子体物理、自由电子激光、高功率微波和粒子加速器等领域具有一定的参考意义。  相似文献   
973.
We consider the parallel replacement problem in which machine investment costs exhibit economy of scale which is modeled through associating both fixed and variable costs with machine investment costs. Both finite- and infinite-horizon cases are investigated. Under the three assumptions made in the literature on the problem parameters, we show that the finite-horizon problem with time-varying parameters is equivalent to a shortest path problem and hence can be solved very efficiently, and give a very simple and fast algorithm for the infinite-horizon problem with time-invariant parameters. For the general finite-horizon problem without any assumption on the problem parameters, we formulate it as a zero-one integer program and propose an algorithm for solving it exactly based on Benders' decomposition. Computational results show that this solution algorithm is efficient, i.e., it is capable of solving large scale problems within a reasonable cpu time, and robust, i.e., the number of iterations needed to solve a problem does not increase quickly with the problem size. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 279–295, 1998  相似文献   
974.
The paper deals with a problem of scheduling a set of jobs on a single machine. Before a job is released for processing, it must undergo some preprocessing treatment that consumes resources. It is assumed that the release date of a job is a linear decreasing continuous function of the amount of a locally and globally constrained, continuously divisible resource (e.g., energy, catalyzer, financial outlay, gas). The problem is to find a sequence of jobs and a resource allocation that will minimize the maximum job completion time. Such a problem appears, for example, in the ingot preheating and hot-rolling process in steel mills. It is shown that the problem is strongly NP-hard. Some polynomially solvable cases of the problem and approximate algorithms with both experimental and worst-case analysis are presented. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 99–113, 1998  相似文献   
975.
This paper revisits the modeling by Bracken [3] of the Ardennes campaign of World War II using the Lanchester equations. It revises and extends that analysis in a number of ways: (1) It more accurately fits the model parameters using linear regression; (2) it considers the data from the entire campaign; and (3) it adds in air sortie data. In contrast to previous results, it concludes by showing that neither the Lanchester linear or Lanchester square laws fit the data. A new form of the Lanchester equations emerges with a physical interpretation. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 1–22, 1998  相似文献   
976.
经典的侦察与监测(S&R)系统效能分析方法存在模型难以建立、结果不准确等问题。考虑到S&R系统的目的是提供情报支持,提出一种基于信息需求的S&R系统情报支持效能分析方法。该方法以用户的信息需求为度量基准量,比较S&R系统性能对信息需求的满足度,并以此满足度作为S&R系统效能度量的指标。仿真实例表明了新方法的有用性。  相似文献   
977.
车辆位置信息是许多智能交通应用的基础,如车辆导航、路径规划和车辆编队等.现有研究中融合单车车载多源传感器的定位方法无法有效解决城市峡谷、隧道和立交桥等卫星信号不可用条件下的车辆定位问题.围绕车辆高精度定位进行了综合评述,主要深入研究分析了车辆协同定位技术.首先分析了单车自主定位的关键技术及其主要应用场景;然后对车辆协同...  相似文献   
978.
论高校学分制改革   总被引:2,自引:0,他引:2  
学分制改革是高校教学管理体制改革的主题 ,本文从学分制的特征、优点及存在问题 ,结合高校学分制改革的实践经验 ,对高校学分制改革作尝试性探讨  相似文献   
979.
部队院校学报同地方高等院校学报一样,是教学和科研的理论园地,是展示该校教学和科研水平的窗口。其质量高低,直接关系到该校的学术和科研工作水平。因此,部队院校的编辑工作者,在政治修养、理论知识、专业水平、语言文字等方面要具有较深的造诣,以强烈的责任感和高度的精品意识完成编辑工作。  相似文献   
980.
ABSTRACT

The India–Pakistan War of September 1965 has attracted little attention in the larger body of work on South Asia. Further, almost nothing has been written on the earlier skirmish, in April 1965, between Indian and Pakistani security forces in the Rann-of-Kutch, an uninhabited salt marsh. This article argues that the limited conflict in the Rann, its immediate consequences, and its impact on Pakistani military and civilian leaders were central to Pakistan’s consideration of a military solution to the ongoing dispute in Kashmir, which then led to Indian retaliation and the outbreak of war.  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