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   331篇
  免费   4篇
  2023年   2篇
  2021年   2篇
  2019年   7篇
  2018年   11篇
  2017年   9篇
  2016年   7篇
  2015年   5篇
  2014年   6篇
  2013年   94篇
  2011年   2篇
  2009年   4篇
  2008年   6篇
  2007年   4篇
  2006年   4篇
  2005年   5篇
  2004年   7篇
  2003年   5篇
  2002年   7篇
  2001年   3篇
  2000年   2篇
  1999年   3篇
  1998年   5篇
  1997年   5篇
  1996年   4篇
  1995年   9篇
  1994年   7篇
  1993年   6篇
  1992年   7篇
  1991年   7篇
  1990年   5篇
  1989年   5篇
  1988年   5篇
  1987年   9篇
  1986年   5篇
  1985年   7篇
  1984年   3篇
  1983年   3篇
  1982年   5篇
  1981年   3篇
  1980年   4篇
  1977年   2篇
  1976年   3篇
  1975年   2篇
  1974年   6篇
  1973年   5篇
  1972年   3篇
  1970年   2篇
  1969年   4篇
  1967年   2篇
  1966年   1篇
排序方式: 共有335条查询结果,搜索用时 15 毫秒
201.
The assessment of a Bernoulli utility function is often accomplished by an approximation process which makes use of ever more information on the preference as it is elicited from a decision maker. Simultaneous approximations of the utility function and the underlying distributions are generally not sufficient for the expectations to converge to the expected value of the respective limits. We give various sufficient stability conditions for the expected utility. All these conditions contain some “uniformness”. © 1995 John Wiley & Sons, Inc.  相似文献   
202.
203.
This article gives an overall assessment of ISIS’s conventional conduct of combat operations by examining their warfighting functions patterns. In sum, the approach of ISIS comprised fundamental principles: their weapons can be organized into categories, purposeful combination of these forces in keeping with the concept of combined arms combat, and hierarchical command and control executed by experienced commanders. ISIS combat groups combined the elements of formation and firepower as well as movement and mobility. The paper concludes that ISIS obviously had a vast range of conventional capabilities at its disposal and was thus able to conduct major operations.  相似文献   
204.
The security sector reform (SSR) programme in the Democratic Republic of the Congo (DRC) has failed, according to a former high-level member of the United Nations (UN) mission in the DRC, as a large section of the country remains outside government control, and the security institutions of the state continue to constitute one of the predominant sources of insecurity for the local population in a number of ways. Based on several field studies, this article critically scrutinises the SSR of the Congolese National Police (Police nationale congolaise; PNC) and the efforts to reform it between 2004 and 2016. It further attempts to explain why so little progress was made in the SSR of the PNC, despite extensive involvement from donors. The article shows that the instrumental and traditional approach to SSR is partly to blame, because in this case it failed to address the root problems and initiate the needed fundamental reform and reconstruction of the police force. It also shows that reforming local security institutions becomes even more difficult when the local authorities do not support the effort.  相似文献   
205.
The malaise that the United States, and the West, have experienced in recent campaigns stems in large part from unclear thinking about war, its political essence, and the strategies needed to join the two. Instead, analysis and response are predicated on entrenched theoretical concepts with limited practical utility. The inadequacy of understanding has spawned new, and not so new, terms to capture unanticipated trends, starting with the re-discovery of “insurgency” and “counterinsurgency” and leading to discussion of “hybrid threats” and “gray-zone” operations. New terminology can help, but the change must go deeper. Challenging analytical orthodoxy, this article sets out a unifying approach for the study of political violence, or more accurately: violent politics. It provides a conceptual foundation that helps to make sense of recent shifts in warfare. In effect, it offers sorely needed theoretical insights into the nature of strategy and guides the process of responding to nontraditional threats.  相似文献   
206.
The estimation of optimal solution values for large-scale optimization problems is studied. Optimal solution value estimators provide information about the deviation between the optimal solution and the heuristic solution. Some estimation techniques combine heuristic solutions with randomly generated solutions. In particular, we examine a class of jacknife-based estimators which incorporate any heuristic solution value with the two best randomly generated solution values. The primary contribution of this article is that we provide a framework to analytically evaluate a class of optimal solution value estimators. We present closed-form results on the relationship of heuristic performance, sample size, and the estimation errors for the case where the feasible solutions are uniformly distributed. In addition, we show how to compute the estimation errors for distributions other than uniform given a specific sample size. We use a triangular and an exponential distribution as examples of other distributions. A second major contribution of this article is that, to a large extent, our analytical results confirm previous computational results. In particular, the best estimator depends on how good the heuristic is, but seems to be independent of the underlying distribution of solution values. Furthermore, there is essentially an inverse relationship between the heuristic performance and the performance of any estimator. © 1994 John Wiley & Sons, Inc.  相似文献   
207.
The gas turbine engine is used to power many different types of commercial and military aircraft. During the scheduled maintenance of these engines, many of the turbine components are replaced. Of particular importance to us is the replacement of nozzle guide vanes in the nozzle assembly section of the engine. Individual vanes are selected from inventory to make up sets, and each set must meet certain characteristics in order to be feasible. The vanes in each set must then be sequenced in order to meet additional criteria. In this article, we give heuristics for the above partitioning and sequencing problems. Empirical analyses, using actual data from a branch of the armed services and a major engine manufacturer, are used to evaluate the proposed heuristics. The results of these analyses indicate that the heuristics are effective.  相似文献   
208.
Customers served by an M/M/1 queueing system each receive a reward R but pay a holding cost of C per unit time (including service time) spent in the system. The decision of whether or not a customer joins the queue can be made on an individual basis or a social basis. The effect of increasing the arrival rate on the optimal policy parameters is examined. Some limiting results are also derived.  相似文献   
209.
210.
Postmodern terrorism presents a significant challenge to global security and law enforcement institutions. Non-state actors operating across international borders, engaged in an apparent global insurgency of extremism that transects the traditional boundaries of crime and war, pose significant challenges to both intelligence and law enforcement agencies. These networked global insurgents blend political and religious fanaticism with criminal enterprises to challenge the rule of law and pose an epochal shift in the structures and relations among states. Negotiating this epochal shift requires traditional organs of national security (the diplomatic, military and intelligence services) to forge new partnerships with police and public safety organizations at the state and local (sub-national), as well as transnational levels. Significant operational, policy and cultural challenges must be overcome to forge an effective multi-lateral global network to counter global terrorism and insurgency.  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