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   196篇
  免费   9篇
  205篇
  2021年   1篇
  2019年   4篇
  2018年   5篇
  2017年   8篇
  2016年   5篇
  2015年   5篇
  2014年   5篇
  2013年   68篇
  2012年   2篇
  2011年   5篇
  2010年   3篇
  2009年   4篇
  2008年   4篇
  2007年   2篇
  2006年   5篇
  2005年   7篇
  2004年   4篇
  2003年   2篇
  2002年   3篇
  2000年   2篇
  1999年   2篇
  1998年   2篇
  1997年   2篇
  1996年   3篇
  1995年   4篇
  1994年   4篇
  1993年   4篇
  1992年   6篇
  1991年   3篇
  1990年   2篇
  1989年   3篇
  1988年   4篇
  1987年   4篇
  1986年   1篇
  1985年   2篇
  1983年   2篇
  1981年   3篇
  1980年   1篇
  1979年   1篇
  1975年   3篇
  1973年   1篇
  1971年   1篇
  1970年   1篇
  1967年   1篇
  1966年   1篇
排序方式: 共有205条查询结果,搜索用时 7 毫秒
141.
This article aims to review some of the key lessons learnt by the Royal Ulster Constabulary's (RUC) Special Branch in the 37 years of the troubles in Northern Ireland. Above all counter-terrorism is an intelligence led operation and Special Branch are the key agency for this in all UK police forces, who have now benefited enormously from the expertise that the RUC's Special Branch built up over the years and have passed on to their colleagues throughout the UK. Intelligence is more often than not a human role and relies on human agencies, which was the case in Northern Ireland. The bulk of intelligence gathering was carried out at quite low levels although the sifting and analysing of it became a more specialist skill. Electronic intelligence and computerised systems were often quite low down in the order of priorities and uses, which tends to confound popular impressions. Agents, informers and good old fashioned ‘coppers’ who knew their patch were much more important both in terms of gathering information and in terms of undermining the terrorists morale from within and it was these factors that fundamentally defeated the IRA in Northern Ireland.  相似文献   
142.
Tactical learning is critical to battlefield success, especially in a counterinsurgency. This article tests the existing model of military adaption against a ‘most-likely’ case: the British Army’s counterinsurgency in the Southern Cameroons (1960–61). Despite meeting all preconditions thought to enable adaptation – decentralization, leadership turnover, supportive leadership, poor organizational memory, feedback loops, and a clear threat – the British still failed to adapt. Archival evidence suggests politicians subverted bottom-up adaptation, because winning came at too high a price in terms of Britain’s broader strategic imperatives. Our finding identifies an important gap in the extant adaptation literature: it ignores politics.  相似文献   
143.
144.
145.
This article considers the dynamic lot-size problem under discounting, allowing a speculative motive for holding inventory. A forward procedure is developed that determines the first lot-size decision in a rolling horizon environment by using forecast data of the minimum possible number of future periods. © 1992 John Wiley & Sons, Inc.  相似文献   
146.
Consider two machines, labeled 1 and 2. A set of tasks has to be processed first on machine 1 and after that on machine 2. A second set of tasks has to be processed first on machine 2 and after that on machine 1. All the processing times are exponentially distributed. We present a policy which minimizes the expected completion time of all tasks.  相似文献   
147.
148.
This article considers two related questions of tactics in the context of the salvo model for naval missile combat. For a given set of targets, how many missiles should be fired to produce an effective attack? For a given available salvo size, how many enemy targets should be fired at? In the deterministic version of the model I derive a simple optimality relationship between the number of missiles to fire and the number of targets to engage. In the stochastic model I employ the expected loss inflicted and the probability of enemy elimination as the main performance measures and use these to derive salvo sizes that are in some sense “optimal.” I find that the offensive firepower needed for an effective attack depends not only on a target's total strength but also on the relative balance between its active defensive power and passive staying power. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007  相似文献   
149.
We study joint preventive maintenance (PM) and production policies for an unreliable production‐inventory system in which maintenance/repair times are non‐negligible and stochastic. A joint policy decides (a) whether or not to perform PM and (b) if PM is not performed, then how much to produce. We consider a discrete‐time system, formulating the problem as a Markov decision process (MDP) model. The focus of the work is on the structural properties of optimal joint policies, given the system state comprised of the system's age and the inventory level. Although our analysis indicates that the structure of optimal joint policies is very complex in general, we are able to characterize several properties regarding PM and production, including optimal production/maintenance actions under backlogging and high inventory levels, and conditions under which the PM portion of the joint policy has a control‐limit structure. In further special cases, such as when PM set‐up costs are negligible compared to PM times, we are able to establish some additional structural properties. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.  相似文献   
150.
We develop a heuristic procedure for partitioning graphs into clusters of nodes such that each cluster of nodes induces a connected subgraph with the objective of minimizing the differences within clusters as measured by the total differences between all pairs of nodes of a cluster. We apply our procedure to determine optimal delivery zones for community sections of a major newspaper while including a number of operational constraints. Our results demonstrate a 18–56% improvement in the total differences within the zones designed over the usual intuitive heuristics. Given the magnitude of the revenue generated by larger local newspapers through zoning, our method demonstrates how better zoning can significantly enhance the value of segmentation. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2005.  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