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   264篇
  免费   55篇
  国内免费   8篇
  2022年   1篇
  2021年   5篇
  2020年   3篇
  2019年   7篇
  2018年   2篇
  2017年   6篇
  2016年   11篇
  2015年   15篇
  2014年   15篇
  2013年   61篇
  2012年   10篇
  2011年   11篇
  2010年   8篇
  2009年   13篇
  2008年   13篇
  2007年   16篇
  2006年   7篇
  2005年   18篇
  2004年   10篇
  2003年   12篇
  2002年   10篇
  2001年   9篇
  2000年   6篇
  1999年   9篇
  1998年   5篇
  1997年   12篇
  1996年   7篇
  1995年   2篇
  1994年   4篇
  1993年   6篇
  1992年   1篇
  1991年   6篇
  1990年   2篇
  1988年   2篇
  1986年   1篇
  1983年   1篇
排序方式: 共有327条查询结果,搜索用时 640 毫秒
141.

As we enter the 21st Century, technologies originally developed for defense purposes such as computers and satellite communications appear to have become a driving force behind economic growth in the United States. Paradoxically, almost all previous econometric models suggest that the largely defense‐oriented federal industrial R&;D funding that helped create these technologies had no discernible effect on U.S. industrial productivity growth. This paper addresses this paradox by stressing that defense procurement as well as federal R&;D expenditures were targeted to a few narrowly defined manufacturing sub‐sectors that produced high tech weaponry. Analysis employing data from the NBER Manufacturing Productivity Database and the BEA’ s Input Output tables then demonstrates that defense procurement policies did have significant effects on the productivity performance of disaggregated manufacturing industries because of a process of procurement‐driven technological change.  相似文献   
142.
We study the determinants of social preferences for national defence and for police and law enforcement. For this task, we estimate a bivariate ordered probit model for a set of European countries (France, Finland, Norway, Portugal, Spain and Sweden) in 2006. Determinants of spending decisions for defence and police are found to be linked but are of significantly different magnitudes. Besides, measures against terrorist threats are positively linked to police and defence spending increases, while the subjective perception of fiscal pressure has no influence. Finally, no significant differences are found between Northern and Southern Europe.  相似文献   
143.
144.
145.
改革开放以来,我军战略理论的创新境界从立足生存到谋求发展,从"以敌为敌"到"以敌为师",从面对现实到系统前瞻,从突出对抗到追求超越,不断跃升。抓住战略机遇期,使我们摆脱倾力临战的生存型国防,建设长久巩固的发展型国防。以对世界军事形势的前瞻性预测为依据,我军实行军队建设指导思想的战略性转变。虽然几经调整变迁,我军战略理论的发展始终凝聚着"合理内核"。我军战略理论的创新境界,体现着中国特色的当代马克思主义认识论原则。  相似文献   
146.
烟火药剂的热值计算在烟火研究领域有着重要的作用.本文根据最小自由能原理,通过一系列基本假设计算出了体系燃烧爆炸反应后的热值,计算结果与实验衡量数据相吻合,并且程序可通过进一步完善,扩展应用于非理想气体,提高计算精度.  相似文献   
147.
We consider an M/G/1 retrial queue with finite capacity of the retrial group. First, we obtain equations governing the dynamic of the waiting time. Then, we focus on the numerical inversion of the density function and the computation of moments. These results are used to approximate the waiting time of the M/G/1 queue with infinite retrial group for which direct analysis seems intractable. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007  相似文献   
148.
This paper finds the optimal integrated production schedule and preventive maintenance plan for a single machine exposed under a cumulative damage process, and investigates how the optimal preventive maintenance plan interacts with the optimal production schedule. The goal is to minimize the total tardiness. The optimal policy possesses the following properties: Under arbitrary maintenance plan when jobs have common processing time, and different due dates, the optimal production schedule is to order the jobs by earliest due date first rule; and when jobs have common due date and different processing times, the optimal production schedule is shortest processing time first. The optimal maintenance plan is of control limit type under any arbitrary production schedule when machine is exposed under a cumulative damage failure process. Numerical studies on the optimal maintenance control limit of the maintenance plan indicate that as the number of jobs to be scheduled increases, the effect of jobs due dates on the optimal maintenance control limit diminishes. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007  相似文献   
149.
The existing product line design literature devotes little attention to the effect of demand uncertainty. Due to demand uncertainty, the supply‐demand mismatch is inevitable which leads to different degrees of lost sales depending on the configuration of product lines. In this article, we adopt a stylized two‐segment setup with uncertain market sizes and illustrate the interplay between two effects: risk pooling that mitigates the impact of demand uncertainty and market segmentation that facilitates consumer differentiation. Compared to downward substitution, inducing bidirectional substitution through product line decisions including quality levels and prices can yield greater risk pooling effects. However, we show that the additional benefit from the risk pooling effect cannot compensate for the reduced market segmentation effect. We demonstrate that the presence of demand uncertainty can reduce the benefit of market segmentation and therefore the length of product lines in terms of the difference between products. We also propose three heuristics that separate product line and production decisions; each of these heuristics corresponds to one particular form of demand substitution. Our numerical studies indicate that the best of the three heuristics yields performance that is close to optimality. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 143–157, 2015  相似文献   
150.
Consider a repeated newsvendor problem for managing the inventory of perishable products. When the parameter of the demand distribution is unknown, it has been shown that the traditional separated estimation and optimization (SEO) approach could lead to suboptimality. To address this issue, an integrated approach called operational statistics (OS) was developed by Chu et al., Oper Res Lett 36 (2008) 110–116. In this note, we first study the properties of this approach and compare its performance with that of the traditional SEO approach. It is shown that OS is consistent and superior to SEO. The benefit of using OS is larger when the demand variability is higher. We then generalize OS to the risk‐averse case under the conditional value‐at‐risk (CVaR) criterion. To model risk from both demand sampling and future demand uncertainty, we introduce a new criterion, called the total CVaR, and find the optimal OS under this new criterion. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 206–214, 2015  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