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   563篇
  免费   18篇
  2021年   11篇
  2019年   10篇
  2018年   7篇
  2017年   16篇
  2016年   10篇
  2015年   16篇
  2014年   13篇
  2013年   136篇
  2011年   7篇
  2009年   4篇
  2008年   8篇
  2007年   6篇
  2006年   8篇
  2005年   11篇
  2004年   4篇
  2003年   4篇
  2002年   7篇
  2001年   6篇
  2000年   6篇
  1999年   7篇
  1998年   10篇
  1997年   10篇
  1996年   8篇
  1995年   10篇
  1994年   12篇
  1993年   11篇
  1992年   12篇
  1991年   12篇
  1990年   4篇
  1989年   10篇
  1988年   18篇
  1987年   10篇
  1986年   16篇
  1985年   11篇
  1984年   6篇
  1983年   7篇
  1982年   4篇
  1981年   11篇
  1980年   6篇
  1979年   12篇
  1978年   7篇
  1977年   7篇
  1975年   12篇
  1974年   7篇
  1973年   6篇
  1972年   7篇
  1971年   5篇
  1970年   6篇
  1969年   6篇
  1966年   4篇
排序方式: 共有581条查询结果,搜索用时 15 毫秒
111.
112.
This article examines Edward Lansdale's return to South Vietnam during the Johnson administration. Lansdale offered a persuasive critique of the mistakes the American policy in Vietnam, but his potential influence was severely limited by a combination of bureaucratic infighting in Saigon and a general indifference to the political aspects of the conflict in Washington. While Lansdale was unable to signiflcantly influence the policies of the Johnson administration, his experience in Saigon during 1965–68 offers historians a unique perspective on many facets of American and South Vietnamese policymaking during a crucial period of the Vietnam War.  相似文献   
113.
114.

The article takes the cases of Peru's Tupac Amaru Revolutionary Movement (MRTA) as the pont of departure to discuss how a insurgent political movement uses the Internet and World Wide Web (WWW). During the 1996–97 Japanese Embassy hostage incident in Lima, Peru, MRTA supporters in Japan, Europe and North America used online technology to relay the group's message to a global public. The resulting direct media access provided the MRTA with an unprecendented level of global publicity. Through referring to the ‘MRTA Solidarity Page’, the types of message transmitted, the forms of transmission (text, video, audio, e‐mail or other), and target publics (national, global, political elites, media), the article outlines the issues and theoretical challenges raised by electronic anti‐government information provision. The Internet and WWW do not alone constitute the threat to state power as some analysts suggest but does in some sense dramatically alter political communication. New media will probably co‐exist with other forms of political communication for some time.  相似文献   
115.
The number of bilateral nuclear cooperation agreements surged during the “nuclear renaissance” of the past decade. This proliferation is only partially explained by the prevailing approaches that focus on strategic imperatives. To supplement these explanations, this study draws on neoliberal models of economic competition to posit that bilateral agreement negotiations also exhibit conditions of “uncoordinated interdependence” and maneuvering to gain market share. Case evidence suggests the contours of supplier state bids for civilian assistance are determined at least as much by considerations about economic competition as they are by positive strategic goals. In addition, this study identifies several cases of cooperation where there appears to be little or no strategic motive for export agreements. The study concludes that patterns of economic competition and the influence of peers in defined competitive spaces alter material payoffs and impact policies. It also identifies a surprising role for principled restraint in dampening strategic and economic competition in some dyads.  相似文献   
116.
Building on prior work on optimal replacement of aging aircraft, this paper presents three methodologies to evaluate prospective aviation Service Life Extension Programs (SLEPs) and applies these methodologies to US Navy F/A-18E/F data. While considerable uncertainty remains as to the values of key parameters (e.g. the cost of F/A-18E/F SLEPs), the preponderance of the evidence available at this juncture favors undertaking SLEPs on F/A-18E/Fs rather than replacing them with new Joint Strike Fighters.  相似文献   
117.
Egypt plays a pivotal role in the security of the Middle East as the doorway to Europe and its military expenditure reflects its involvement in the machinations of such an unstable region, showing considerable variation over the last 40?years. These characteristics make it a particularly interesting case study of the determinants of military spending. This paper specifies and estimates an econometric model of the Egyptian demand for military spending, taking into account important strategic and political factors. Both economic and strategic factors are found to play a role in determining military burden/spending, with clear positive effects of lagged military burden, suggesting some sort of institutional inertia, plus negative output and net exports effects. The strategic effect as a result of the impact of Israel’s military burden is mostly positive and significant, though its impact is reduced when the impact of important strategic events are taken into account. The military spending of Egypt’s allies Jordan and Syria generally seems to have had no effect on Egypt’s spending. These results are consistent over a range of econometric techniques.  相似文献   
118.
This article presents a branch and bound method for solving the problem of minimizing a separable concave function over a convex polyhedral set where the variables are restricted to be integer valued. Computational results are reported.  相似文献   
119.
This paper provides a framework in which warranty policies for non-repairable items can be evaluated according to risk preferences of both buyers and sellers. In particular, a warranty price schedule is established such that sellers are indifferent among the policies. Given this schedule, a buyer's response is expressed by selecting the price-warranty combination that minimizes disutility. Within this framework, a warranty can be viewed as an instrumet of risk management that can induce more sales and greater profitability. For given utility functions, analytical results for the development of a price schedule are developed. Numerical results illustrate the substitution effects between warranty terms, prices, and risk parameters.  相似文献   
120.
We implement a solution procedure for general convex separable programs where a series of relatively small piecewise linear programs are solved as opposed to a single large one, and where, based on bound calculations developed in [13] and [14], the ranges of linearization are systematically reduced for successive programs. The procedure inherits ε-convergence to the global optimum in a finite number of steps, but perhaps its most distinct feature is the rigorous way in which ranges containing an optimal solution are reduced from iteration to iteration. This paper describes the procedure, called successive approximation, discusses its convergence, tightness of the bounds, bound-calculation overhead, and its robustness. It presents a computer implementation to demonstrate its effectiveness for general problems and compares it (1) with the more standard separable programming approach and (2) with one of the recent augmented Lagrangian methods [10] included in a comprehensive study of nonlinear programming codes [12]. It seems clear from over 130 cases resulting from 80 distinct problems studied here that significant savings in terms of computational effort can be realized by a judicious use of the procedure, and the ease with which it can be used is appreciably increased by the robustness it shows. Moreover, for most of these problems, the advantage increases as the size, nonlinearity, and the degree of desired accuracy increase. Other important benefits include significantly smaller storage requirements, the ability to estimate the error in the current solution, and to terminate the algorithm as soon as the acceptable level of accuracy has been achieved. Problems requiring up to about 10,000 nonzero elements in their specification and about 45,000 nonzero elements in the generated separable programs resulting from up to 70 original nonlinear variables and 70 nonlinear constraints are included in the computations.  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