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   507篇
  免费   17篇
  国内免费   1篇
  525篇
  2021年   5篇
  2020年   5篇
  2019年   12篇
  2018年   7篇
  2017年   14篇
  2016年   11篇
  2015年   7篇
  2014年   10篇
  2013年   123篇
  2012年   5篇
  2011年   6篇
  2010年   7篇
  2009年   6篇
  2008年   5篇
  2007年   6篇
  2006年   8篇
  2005年   6篇
  2003年   5篇
  2002年   5篇
  2001年   5篇
  2000年   5篇
  1998年   5篇
  1997年   7篇
  1996年   9篇
  1995年   8篇
  1994年   9篇
  1993年   11篇
  1992年   12篇
  1991年   15篇
  1989年   10篇
  1988年   7篇
  1987年   10篇
  1986年   10篇
  1985年   14篇
  1984年   7篇
  1982年   5篇
  1981年   5篇
  1980年   11篇
  1979年   7篇
  1978年   9篇
  1976年   8篇
  1975年   10篇
  1974年   10篇
  1973年   10篇
  1972年   5篇
  1971年   5篇
  1970年   8篇
  1969年   5篇
  1968年   7篇
  1967年   5篇
排序方式: 共有525条查询结果,搜索用时 0 毫秒
241.
Boko Haram (BH) is an insurgent group that operates mainly in northeastern Nigeria. Its stated aim is to establish an Islamic state, and it employs terrorism as its strategy. Earlier interests of security analysts centred on the drivers of BH uprising and the possibility of its internationalisation. Today's concerns relate more to why the rebellion has lasted this long. In toeing the same line, this article demonstrates that BH is a purposive terror group against which the government has evolved no viable strategy. It examines some gains of BH over the past six years and how it benefitted from the government's underestimation of its capacity and determination. It concludes that to effectively engage BH, the Nigerian government must revaluate its threat and sincerely pursue an expanded strategy beyond the current military-centric approach. To be effective, government's response must be packaged in such a way as to enhance human security in the region.  相似文献   
242.
Scholars and policymakers argue that violent actors – termed ‘spoilers’ – pose a significant threat to civil war peace agreements. Yet existing research, which is overly reliant on single-case studies, has not effectively determined how prevalent spoiling is, or thoroughly examined what its ultimate effects are on peace agreements. This article draws on a newly constructed cross-national dataset of spoiling following 241 civil war peace agreements in the post-Cold War era to analyze spoiling. It finds that spoiling intended to terminate an agreement is not as common as typically assumed, but still plagues a sizeable number of peace agreements. Moreover, most actors who resort to this strategy typically fail in their goals and the agreement is not at risk, despite the high publicity and attention given to these threats. Yet particular types of actors, most notably paramilitaries and state security forces excluded from the agreement, can pose a significant threat to peace.  相似文献   
243.
This article examines the role of the Macedonian Question in the 1944 December Uprising (Dekemvriana) in Greece. While the Dekemvriana is commonly portrayed in right–left terminology in the historiography, this article argues that part of the reason for the left’s failure was their inability to manage the Macedonian ethnic component of the struggle, either within their armed forces or in their relationship with Yugoslavia. As such, this article integrates the early phases of the Greek Civil War into the broader literature on minorities in civil conflict, while simultaneously exposing some of the myths about Macedonian involvement that result from its contemporary political ramifications.  相似文献   
244.
245.
The theory of majorization is used to develop measures of information in the randomly right-censored model when the lifetime and censoring variables are discrete. Majorization also enables us to prove some basic theorems about the measures in a simple and unified fashion. These measures include Shannon's information as a special case. The measures are inadequate in the continuous case and some alternative measures, based on the variance of the lifetime random variable, are proposed.  相似文献   
246.
In teletraffic applications of retrial queues only the service zone is observable. Another part of a retrial queue, the orbit, which represents the delay before repeated attempts to get service, cannot be observed. Thus, it is very important to get general results about behavior of the orbit. We investigate two characteristics of the orbit, namely, the orbit busy period and the orbit idle period, which seem to be very useful from this point of view. © 1996 John Wiley & Sons, Inc.  相似文献   
247.
248.
Least squares fitting of regression models is a widely used technique. The presence of outliers in the data can have an adverse effect on the method of least squares, resulting in a model that does not adequately fit to the bulk of the data. For this situation, robust regression techniques have been proposed as an improvement to the method of least squares. We propose a robust regression procedure that performs well relative to the current robust methods against a variety of dataset types. Evaluations are performed using datasets without outliers (testing efficiency), with a large percentage of outliers (testing breakdown), and with high leverage outliers (testing bounded influence). The datasets are based on 2-level factorial designs that include axial points to evaluate leverage effects. A Monte Carlo simulation approach is used to evaluate the estimating capability of the proposed procedure relative to several competing methods. We also provide an application to estimating costs for government satellites. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 125–139, 1998  相似文献   
249.
This paper deals with the problem of makespan minimization in a flow shop with two machines when the input buffer of the second machine can only host a limited number of parts. Here we analyze the problem in the context of batch processing, i.e., when identical parts must be processed consecutively. We propose an exact branch-and-bound algorithm, in which the bounds exploit the batching nature of the problem. Extensive computational results show the effectiveness of the approach, and allow us to compare it with a previous heuristic approach. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 141–164, 1998  相似文献   
250.
Rearming Germany was a long and complicated process. It was especially difficult to create a new German air force. The army generals who dominated the Bundeswehr cadre did not even want an air force but rather a small arm air corps. Moreover, Adenauer's defense staff failed to adequately budget or plan for a new air force. As rearmament began, US Air Force leaders, working closely with the small Luftwaffe staff in West Germany's shadow Defense Ministry, basically took charge of the process to ensure that the Germans built a new Luftwaffe on the American model – a large, multipurpose force organized as an independent service and fully integrated into NATO. The first Bundesluftwaffe commanders allied themselves to the Americans, often in opposition to their army comrades, to overcome the political problems caused by Adenauer's poor defense planning and create a modern air force on American lines.  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