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   4146篇
  免费   580篇
  国内免费   429篇
  2024年   5篇
  2023年   7篇
  2022年   25篇
  2021年   91篇
  2020年   88篇
  2019年   68篇
  2018年   77篇
  2017年   189篇
  2016年   204篇
  2015年   108篇
  2014年   330篇
  2013年   252篇
  2012年   291篇
  2011年   304篇
  2010年   223篇
  2009年   330篇
  2008年   293篇
  2007年   257篇
  2006年   305篇
  2005年   293篇
  2004年   244篇
  2003年   174篇
  2002年   144篇
  2001年   141篇
  2000年   103篇
  1999年   109篇
  1998年   87篇
  1997年   71篇
  1996年   57篇
  1995年   56篇
  1994年   56篇
  1993年   43篇
  1992年   46篇
  1991年   38篇
  1990年   29篇
  1989年   14篇
  1988年   2篇
  1987年   1篇
排序方式: 共有5155条查询结果,搜索用时 15 毫秒
961.
弹载惯性测量系统抗高过载技术   总被引:2,自引:0,他引:2  
在现代高技术条件下的局部战争中,为了提高火炮的射程、打击精度和反应速度,发展制导炮弹系统就成为必然的选择.弹体姿态测量系统是制导系统的重要组成部分,解决其在炮弹发射高过载恶劣环境下的生存问题就成为研究的关键之一.提出了主要抗高过载手段,并对弹体姿态测量系统的抗高过载性能进行了Ansys软件仿真、马歇特试验以及实弹飞行试验.最后得到结论,所给出的抗高过载方案在降低高过载对弹体姿态测量系统的影响方面,可以发挥良好的作用.  相似文献   
962.
重点分析了比幅测向系统的原理,在此基础上提出对其进行"主动反侦察"干扰的方法,推导了受到干扰下比幅测向系统的测量结果公式,讨论了不同条件下的干扰效果,并通过仿真进行验证。  相似文献   
963.
During the Nigerian Civil War (1967–1970), France chose to support Biafra, but only on a limited scale, providing mercenaries and obsolete weaponry to Ojukwu's regime. General Charles de Gaulle's assistance to Ojukwu was conditioned by the French military drawdown after 1961, the increased power of French secret services on the continent, and the interventions in Katanga (1960–1963), Gabon (1964) and Chad (1968–1972). France supported Biafra primarily to protect its former colonies from Nigeria, stop Soviet subversion and acquire an economic foothold in the oil-rich Niger Delta. De Gaulle chose a limited strategy for two reasons. If Biafra won the war, France would be Biafra's greatest ally. If Nigeria won the war, France could extricate itself from the situation relatively easily and re-establish relations with the Nigerian government, which is what ultimately occurred.  相似文献   
964.
Measuring the relative importance of components in a mechanical system is useful for various purposes. In this article, we study Birnbaum and Barlow‐Proschan importance measures for two frequently studied system designs: linear consecutive k ‐out‐of‐ n and m ‐consecutive‐ k ‐out‐of‐ n systems. We obtain explicit expressions for the component importance measures for systems consisting of exchangeable components. We illustrate the results for a system whose components have a Lomax type lifetime distribution. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013  相似文献   
965.
Under what conditions can leaders achieve wartime political–military integration? In the Vietnam War, political–military integration exhibited dramatic variation: in the air war, the US was able to tightly integrate its political objectives and military conduct, but in the ground war, the American military prosecuted a strategy that was both divorced from broader political objectives and was immune from Washington's influence. I argue that the nature of information management between the military and civilian leadership explains the pattern of political–military integration in the Vietnam War more completely than do explanations that focus on the organizational cultures of professional militaries.  相似文献   
966.
ABSTRACT

This paper evaluates Boko Haram’s military capabilities and details the process of how its standing army, driven by these capabilities, came to pose a phased threat between 2013 and 2015 in particular. This was a period when military fighting dominated the insurgency in north-east Nigeria. Whereas there is an abundance of literature on Boko Haram’s histories and the impact of its insurgency on north-east Nigeria, analysis of Boko Haram’s military campaigning is still deficient. Attempting to fill this gap, this paper uses field findings and battlefield case studies from north-east Nigeria to highlight how Boko Haram’s overt front – its standing army – came to supplant its guerrilla operations as the main security threat to the frontier area.

This pivot towards military fighting, for a group initially composed of a few ragtag combatants, on the surface might seem surprising. Yet, whereas Boko Haram may lack the popular support required for ‘people’s war’, classic insurgency theories nevertheless hold some explanatory power for this deliberate shift: away from guerrilla warfare as the expedient of the weaker side, and towards the use of a large standing army of locals to swarm, and sometimes successfully overrun, state forces.  相似文献   
967.
ABSTRACT

The complicated problematic of Imperial Policing in many respects still comes down to the principle of minimum force, and much of what we consider an integral part of the modern doctrine of counterinsurgency, is perceived as by-product of post-1945 colonial experience. Charles Gwynn wrote about it in his still underestimated text-book on internal security, ‘Imperial Policing’. As a result, there is a lack of clear understanding how colonial (based on local experience) knowledge was transformed into the expert (universal, transferable) knowledge in confronting rebellions at the doctrinal level. This article examines the work of Gwynn as part of a transitional stage from the age of global empires to the age of nuclear superpowers within the context of internal security doctrine. Adaptation to the new realities during the interwar period and after the World War II – reconfiguration of the British army epistemological system in confronting insurgencies – was a hard process. In this sense, the question about transformation of colonial knowledge into expert knowledge onto the field of internal security is a part of a more general and sensitive question about transition from colonialism to the post-colonial age.  相似文献   
968.
针对当前在装备保障需求分析过程中缺乏合适的方法和工具的问题,提出一种基于能力与面向需求分析相结合的装备保障需求分析方法,并通过运用解释结构模型法,对分析结果的结构及相互关系进行科学构建.力求通过该方法的应用,能够辅助论证人员深刻理解和合理判断各种因素之间的相互影响关系,通过结构化和对比化的装备保障需求分析过程得到能正确反映保障需求的关系结构.从而为装备保障发展内容的分析打下良好的理论基础.  相似文献   
969.
部队指控系统的广泛应用对指控训练提出更高要求.仿真系统开始越来越多地应用于训练中,为之提供真实的指控训练环境.部队模拟训练系统中实装指控系统与基于仿真的训练支撑环境的互操作性问题是一个急待解决的问题.互操作性概念参考模型用于确认两者间交互的信息类型,是互操作性研究的基础.模拟训练系统中互操作性研究的重点集中在指控与仿真系统互操作性语言的研究上,主要体现在公共数据模型、形式化语法和形式化语义3个方面.  相似文献   
970.
针对坦克炮控系统未知齿隙及摩擦,设计了基于性能的新型控制器.提出了基于侵入和不变流型(I&I)的未知参数估计率的构造方法,使调节函数的选取及I&I估计率的设计变得直接简便.由于未知齿隙及摩擦被充分的描述成有界扰动与非线性动态项的组合,从而避免了将其简单的考虑成“总扰动”所造成的被控系统性能的损失.该控制器可有效抑制负载扰动及参数变化所带来的影响.同时通过快速准确的估计系统参数实现了对指令信号快速精确的跟踪.  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