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   691篇
  免费   19篇
  710篇
  2019年   26篇
  2018年   17篇
  2017年   15篇
  2016年   17篇
  2015年   16篇
  2014年   9篇
  2013年   145篇
  2011年   13篇
  2010年   8篇
  2009年   7篇
  2008年   7篇
  2007年   13篇
  2006年   8篇
  2005年   16篇
  2004年   8篇
  2003年   8篇
  2001年   7篇
  2000年   10篇
  1999年   10篇
  1998年   6篇
  1997年   12篇
  1996年   15篇
  1995年   7篇
  1994年   16篇
  1993年   9篇
  1992年   10篇
  1991年   17篇
  1990年   11篇
  1989年   16篇
  1988年   10篇
  1987年   15篇
  1986年   10篇
  1985年   13篇
  1984年   10篇
  1983年   9篇
  1982年   6篇
  1981年   8篇
  1980年   10篇
  1979年   8篇
  1978年   8篇
  1977年   8篇
  1976年   10篇
  1975年   8篇
  1974年   12篇
  1973年   11篇
  1972年   13篇
  1971年   15篇
  1970年   6篇
  1969年   7篇
  1968年   7篇
排序方式: 共有710条查询结果,搜索用时 0 毫秒
121.
This paper examines the rationale and centrality of private military and security companies (PMSCs) in humanitarian assistance operations in Sudan, asking why PMSCs are involved in humanitarian assistance operations in Sudan and what the principles underlying their activities are. To answer this question, the paper draws attention to the link between humanitarian crises and PMSC interventions. Where there is no meaningful alternative intervention, undergirded by humanitarian concerns that are also profit driven, PMSCs come in to provide the needed services. The protracted and complicated internal armed conflicts in Sudan, which have lasted for over two decades, have produced as many as 4,8 million internally displaced persons (IDPs) – the single largest number in the world. The kind of humanitarian assistance operations provided by PMSCs in Sudan have become critical to the provision of much-needed services which were inadequately provided by governmental authorities at both unilateral and multilateral levels. This paper argues that the humanitarian crises in Sudan created a regime that permits humanitarian assistance operations by both state and non-state actors.  相似文献   
122.

The US Air Force is asking when to replace its aging aircraft. We develop a framework to identify economically optimal replacement strategies that recognizes cost trade-offs and incorporates age effects. We also preview a stochastic methodology. We use the framework to identify an optimal strategy, defined by the replacement age, for a generic fleet and conduct a sensitivity analysis. Quantitative illustrations show that the range of strategies that provides close-to-optimal outcomes widens as the operating and support (O&S) cost growth rate decreases and the ratio of the acquisition price to the initial O&S cost increases. A wider range implies more decision-making leeway.  相似文献   
123.
124.
125.
The Royal Air Force was successful in the Battle of Britain because of the elaborate and sophisticated air defence system of Fighter Command. This system had its foundations in the early warnings which radar provided. The process of collecting a huge amount of often inaccurate and contradictory data from radar stations, and then turning it into useful information which could direct fighters to their targets was a remarkable accomplishment. Information was the key to this revolution in military organisation, command and control procedures, and tactics. The origins of this information revolution predate radar, and can be traced back to World War I.  相似文献   
126.
127.
Those leading the war on terrorism have emphasized from the beginning that this war would be unlike other wars. Special Operations Forces (SOF) are military forces unlike other military forces. The implication is that SOF and the war on terrorism are thus made for each other. This contribution examines this assumption, the war on terrorism and SOF in greater detail.  相似文献   
128.
129.
130.
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