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   757篇
  免费   11篇
  国内免费   8篇
  776篇
  2025年   2篇
  2024年   2篇
  2023年   4篇
  2022年   4篇
  2021年   15篇
  2020年   11篇
  2019年   39篇
  2018年   38篇
  2017年   49篇
  2016年   50篇
  2015年   28篇
  2014年   60篇
  2013年   115篇
  2012年   23篇
  2011年   38篇
  2010年   43篇
  2009年   41篇
  2008年   45篇
  2007年   24篇
  2006年   23篇
  2005年   24篇
  2004年   19篇
  2003年   18篇
  2002年   8篇
  2001年   6篇
  2000年   5篇
  1999年   6篇
  1998年   6篇
  1997年   7篇
  1996年   3篇
  1995年   3篇
  1994年   4篇
  1993年   2篇
  1992年   1篇
  1991年   5篇
  1990年   2篇
  1989年   3篇
排序方式: 共有776条查询结果,搜索用时 15 毫秒
571.
    
Cyberspace has emerged as a potentially new (and unconventional) domain for warfare. Much debate has focused on understanding cyber conflict. The ability to critically analyse this phenomenon is important; however, the nascent nature of cyberwarfare and the complexity of the systems involved create challenges not met by conventional approaches. As a first step, this requires an analytical construct to frame discussions in a way that highlights distinct characteristics of the cyber domain. An approach proposed is one of the postulating conjectures for debate as a way to achieve this and to demonstrate its use, both at the strategic and operational levels. It is suggested that such an approach provides one component of a mature analytical framework for the analysis of cyber across a range of warfare domains.  相似文献   
572.
    
This article investigates how US national security planners have envisioned the emerging strategic environment during the early twenty-first century and evaluates how their perceptions of this strategic environment have changed during these years. This conceptual evolution can be seen in how defense planners define threats, identify defense priorities, and design security strategies. Five key strategic planning documents serve as the basis for this analysis and illustrate significant shifts in how the US government has envisioned its own security requirements as well as the context within which its strategic vision will need to be realized. These planning documents are: (1) Joint Vision 2020, (2) the Bush Administration's 2002 National Security Strategy of the United States, (3) the Obama Administration's 2010 National Security Strategy, (4) US Strategic Defense Guidance entitled Sustaining US Global Leadership: Priorities for 21st Century Defense, and (5) the US Chairman of the Joint Chiefs of Staff's Capstone Concept for Joint Operations: Joint Force 2020.  相似文献   
573.
Following the 11 September 2001 attacks, the US government increased its counterterrorism (CT) funding and created several Federal Agencies such as the Department of Homeland Security; Transportation Security Administration; and National Counterterrorism Center. Similarly, the 7 July 2005, London bombings also compelled the British government to increase its CT funding. These examples illustrate a phenomenon that when states experience terrorism, they dramatically increase public safety spending in order to reduce or eliminate the incidents of and casualties resulting from acts of terror. Using statistical data collected from 34 countries covering nine years, this article examines recent CT spending increases. Critically, the authors explore whether recent public safety expenditures can measurably reduce the number of domestic and international terrorist attacks. The implications of their findings should be salient for policy-makers’ assessments of their countries’ current CT strategies and policies concerning their respective Intelligence and Security Communities.  相似文献   
574.
    
States confronting cross-border intrusions of terrorism, illegal immigration, and/or drug trafficking weigh the costs of such intrusions against the costs of imposing barriers to prevent or curb the intrusions. In such situations, the degree of national security afforded a state depends, in large measure, upon the degree of border openness the state chooses. Depending upon the intensity and frequency of the intrusions – expressed in terms of opportunity-cost functions – a state might have little choice but to pursue a border policy of zero openness. It is this relationship of border openness to national security that explains why many states choose to construct security fences. In the 49 cases of security fences examined, many – among them Israel vis-à-vis the West Bank, India vis-à-vis Pakistan, Turkey vis-à-vis Greece in Cyprus – the construction of security fences becomes more complicated by their placement on lands whose sovereignties are disputed.  相似文献   
575.
    
In the years since the 2003 Rose Revolution, the popularly elected leadership of the Republic of Georgia has responded to organized protests with a variety of repressive tactics. These reactions suggest that former challengers to authoritarian elites may utilize similar methods of retaining power during crisis periods. Yet, the alleged involvement of agencies of the Russian Federation in fomenting domestic instability has also occupied a central position in the national security policies of the outgoing Saakashvili government. These conditions both preceded and were reinforced by the South Ossetia War of August 2008. This article proposes a theoretical model that represents the intervening effect of interstate conflicts on state–society relations in Georgia from 2003 to present. It presents several hypotheses and possible indicators, data sources, and techniques for analyzing the interaction between characteristics of opposition groups, external threats, and the domestic security practices of contemporary Georgian political elites.  相似文献   
576.
    
  相似文献   
577.
    
This article identifies and evaluates likely challenges facing NATO today and into the next millennium. These contingencies include ethnic‐based civil wars in Europe, transnational terrorism, rogue states, increased world income inequality, out‐of‐area conflicts, and environmental and resource security. Using concepts and tools from collective action, I assess these challenges and suggest effective policies for addressing them. NATO still has a crucial role to play in maintaining world security in the post‐Cold War era.  相似文献   
578.
    
In July 2001, member states will gather in New York for the UN Conference on the Illicit Trade in Arms in All its Aspects. It represents part of the effort to establish controls on small arms and light weapons. This article argues that it is possible that nuclear and conventional arms control represent two ends of a continuum, with common goals and a common set of mechanisms and processes at work. A decade after the end of the Cold War, it is not surprising that the international community is working on mechanisms to deal with conventional arms. The existence of a continuum and connections between conventional and nuclear arms control is less evident. The two arms control communities appear to function in isolation of each other. The return to the debate on small arms and light weapons echoes post-World War I and II periods. The fact that small arms control is back on the agenda within the context of the UN may signify recognition that any kind of arms control serves the same purpose—preventing and mitigating the effects and duration of, and bringing an end to conflict.  相似文献   
579.
    
Since the terrorist attacks of 11 September 2001, the continent of Africa, particularly Greater East Africa, has played an increasingly signifi cant role in United States (US) national security strategy. Transnational security threats and political authoritarianism continue to plague the region, creating calls for greater US and international involvement. Before reacting to the situation, however, it is prudent to pause, reflect, and understand that the United States developed strategic relations with nation-states in the region well before contemporary concerns for international terrorism and ungoverned spaces entered the strategic lexicon. Toward a more comprehensive understanding of Greater East Africa's strategic history, this paper examines the core strategic relationship in the region, US-Kenya relations, its origins and implications, and offers policy recommendations that will affect future international security.  相似文献   
580.
    
《防务技术》2020,16(6):1130-1141
Based on fuzzy adaptive and dynamic surface (FADS), an integrated guidance and control (IGC) approach was proposed for large caliber naval gun guided projectile, which was robust to target maneuver, canard dynamic characteristics, and multiple constraints, such as impact angle, limited measurement of line of sight (LOS) angle rate and nonlinear saturation of canard deflection. Initially, a strict feedback cascade model of IGC in longitudinal plane was established, and extended state observer (ESO) was designed to estimate LOS angle rate and uncertain disturbances with unknown boundary inside and outside of system, including aerodynamic parameters perturbation, target maneuver and model errors. Secondly, aiming at zeroing LOS angle tracking error and LOS angle rate in finite time, a nonsingular terminal sliding mode (NTSM) was designed with adaptive exponential reaching law. Furthermore, combining with dynamic surface, which prevented the complex differential of virtual control laws, the fuzzy adaptive systems were designed to approximate observation errors of uncertain disturbances and to reduce chatter of control law. Finally, the adaptive Nussbaum gain function was introduced to compensate nonlinear saturation of canard deflection. The LOS angle tracking error and LOS angle rate were convergent in finite time and whole system states were uniform ultimately bounded, rigorously proven by Lyapunov stability theory. Hardware-in-the-loop simulation (HILS) and digital simulation experiments both showed FADS provided guided projectile with good guidance performance while striking targets with different maneuvering forms.  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