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   867篇
  免费   21篇
  888篇
  2021年   13篇
  2019年   28篇
  2018年   22篇
  2017年   20篇
  2016年   21篇
  2015年   19篇
  2014年   14篇
  2013年   190篇
  2011年   8篇
  2009年   12篇
  2008年   11篇
  2007年   9篇
  2006年   10篇
  2005年   19篇
  2004年   17篇
  2003年   12篇
  2002年   9篇
  2000年   9篇
  1999年   8篇
  1998年   11篇
  1997年   18篇
  1996年   16篇
  1995年   9篇
  1994年   19篇
  1993年   7篇
  1992年   11篇
  1991年   26篇
  1989年   15篇
  1988年   12篇
  1987年   23篇
  1986年   15篇
  1985年   19篇
  1984年   11篇
  1983年   10篇
  1982年   10篇
  1980年   11篇
  1979年   14篇
  1978年   10篇
  1977年   14篇
  1976年   12篇
  1975年   8篇
  1974年   13篇
  1973年   15篇
  1972年   15篇
  1971年   11篇
  1970年   14篇
  1969年   11篇
  1968年   9篇
  1967年   10篇
  1966年   7篇
排序方式: 共有888条查询结果,搜索用时 0 毫秒
641.
Liquid-filled compartment structure consists of a bulk steel plate with matrix blind holes which are filled with liquid and a steel front plate to seal up the liquid with rings and bolts.The liquid-filled compart-ment structure can resist the shaped charge warhead effectively.This paper presents experimental and theoretical investigations of the penetration ability of the residual shaped charge jet emerging from the liquid-filled compartment structure after the penetration process at different impact angles.On the basis of shock wave propagation theory,the influence of the liquid-filled compartment structure on jet sta-bility is analysed.The interferences of the liquid backflow caused by a reflected shock wave and a back plate on jet stability under different impact angles are also examined.In addition,the range of the disturbed velocity segments of the jet at different impact angles and the penetration ability of the re-sidual jet are obtained.A theoretical model is validated against the experimental penetration depths.  相似文献   
642.
The structural changes inside the French innovation system have impacted the role of defense firms since the late 1980s. Major changes have affected the defense budget and public R&D funding system in particular. The aim of this article is to understand French defense firms’ repositioning within the National Innovation System (NIS) based on an analysis of their R&D behavior over a long period of time (1987–2010). We show that French defense firms remain major players in the NIS and faced up to these major changes by adapting the funding of their R&D and their research priorities and rolling out new innovation capabilities. Additionally, they developed new innovation models to take advantage of new collaborative partnerships developed for civil and military markets.  相似文献   
643.
Most counterinsurgency campaigns have featured the use of some form of local defense forces. Such forces have had a somewhat mixed record, both in their usefulness in actually countering insurgents and in their longer-term impact on internal security. This article focuses on historical cases that provide lessons for the best operational and strategic uses of local defense forces and measures to control their activities.  相似文献   
644.
ABSTRACT

This article aims to identify and elaborate the causes and ramifications of applying transitional justice, in particular accountability measures, to situations of war. It focuses on the correlations between peace and justice – and hence an important perspective on the question ‘how do wars end’. The article seeks to understand some of the main challenges associated with pursuing accountability for crimes committed in contemporary forms of conflict, including civil wars and abuses committed by major powers in armed conflict.  相似文献   
645.
Why does terrorist violence escalate from some ethnic groups but not others? According to theoretical insights, many groups endure conditions that should spur on terrorist campaigns, but in reality only some carry them out. In contrast to studies emphasising motivations, this article constructs a framework centred on opportunity structures that contributes to our understanding of the rise of terrorism waged along ethnic lines. It argues that beyond grievances or other motivations, terrorist campaigns develop from communities when moderate political leaders depart from their positions in nationalist movements, causing terrorists to fill the subsequent power vacuum, while little terrorism occurs when leaders do not relinquish the nationalist agenda. This argument is evaluated with evidence from the Tamil and Muslim cases in the context of the Sri Lankan Civil War. Tamil United Liberation Front leaders left the Tamil nationalist movement in the early 1980s, enabling the Liberation Tigers of Tamil Eelam’s rise to dominate the nationalist agenda for three decades, while the Sri Lanka Muslim Congress did not relinquish the Muslim cause, which in part precluded the normalisation of violence in the community.  相似文献   
646.

This paper employs public choice analysis to explain certain kinds of military decision‐making during the Civil War. Specifically, the political costs and benefits which may have influenced policy with respect to casualty rates in the Union army are considered. A primary empirical finding is that electoral votes per capita are a strong explainer of casualties across Union states, all else equal.  相似文献   
647.
ALL TOGETHER NOW     
Banning Weapons of Mass Destruction, by Frederick N. Mattis. Praeger Security International, 2009. 129 pages, $39.95.  相似文献   
648.
NUCLEAR ISLANDS     
Current International Atomic Energy Agency safeguards do not provide adequate protection against the diversion to military use of materials or technology from certain types of sensitive nuclear fuel cycle facilities. In view of highly enriched uranium's relatively greater ease of use as a nuclear explosive material than plutonium and the significant diseconomies of commercial spent fuel reprocessing, this article focuses on the need for improved international controls over uranium enrichment facilities as the proximate justification for creation of an International Nuclear Fuel Cycle Association (INFCA). In principle, the proposal is equally applicable to alleviating the proliferation concerns provoked by nuclear fuel reprocessing plants and other sensitive nuclear fuel cycle facilities. The INFCA would provide significantly increased nonproliferation assurance to its member states and the wider international community by holding long-term leasehold contracts to operate secure restricted zones containing such sensitive nuclear facilities.  相似文献   
649.
650.
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