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   2471篇
  免费   345篇
  国内免费   153篇
  2024年   3篇
  2023年   8篇
  2022年   22篇
  2021年   36篇
  2020年   27篇
  2019年   59篇
  2018年   50篇
  2017年   86篇
  2016年   90篇
  2015年   62篇
  2014年   209篇
  2013年   258篇
  2012年   154篇
  2011年   204篇
  2010年   179篇
  2009年   192篇
  2008年   147篇
  2007年   175篇
  2006年   151篇
  2005年   146篇
  2004年   135篇
  2003年   108篇
  2002年   74篇
  2001年   77篇
  2000年   40篇
  1999年   38篇
  1998年   27篇
  1997年   28篇
  1996年   29篇
  1995年   23篇
  1994年   29篇
  1993年   17篇
  1992年   19篇
  1991年   17篇
  1990年   24篇
  1989年   13篇
  1988年   10篇
  1987年   2篇
  1975年   1篇
排序方式: 共有2969条查询结果,搜索用时 15 毫秒
791.
针对装备技术发展管理的重用度和冗余度问题,研究了体系网络建模与结构优化方法。将装备技术抽象为节点,技术关系抽象为边,提出了基于装备技术描述属性框架和技术关系分析的体系网络建模方法;将3种经典的网络社团探测方法应用于装备技术聚类,通过比较评估指标,生成了技术聚类优化方案;基于加权网络中心度算法,识别了对体系冗余影响最大的装备技术。以包含235项激光武器装备技术的技术体系为例,验证了方法的有效性,总结了体系结构的优化结论。  相似文献   
792.
提出了一种恒星角距不变的星敏感器内部参数的地面标定方法。较常见的星角距的标定方法不同的是,该方法利用对在0°附近的角度变化较敏感的恒星角距的正弦值建立观测方程;采用两步法分别估计焦距、主点和高阶畸变系数,并采用迭代优化的方法,获得最优估计值。为了确保标定精度,对观测时刻的导航星进行了视位置的修正。实验结果表明,采用星角距的正弦值建立观测方程,估计精度较高,采用考虑高阶畸变的改进正弦法标定后的星角距误差的均方根值为2.2×10-5rad。  相似文献   
793.
The authors propose five principles for addressing the major deficiencies of the current treaty-based approach to nonproliferation. These involve: effectively closing the door to withdrawals from the Treaty on the Non-Proliferation of Nuclear Weapons (NPT); defining which nuclear technologies fall within the NPT's “inalienable right” provision, so as to maintain a reasonable safety margin against possible military application; expansion of International Atomic Energy Agency inspections to include greater readiness to use its “special” inspection authority; creation of an NPT enforcement regime, to include a secretariat; and universalizing the NPT so as to apply to all states, while creating a path for current non-parties to come into compliance. There is no illusion here about the prospects for the adoption of this approach. At a minimum, the world needs to be frank about the gap between nuclear programs and current nonproliferation protection. Encouragement of greater use of nuclear power should be predicated on closing that gap.  相似文献   
794.
Separatist terrorism has been a severe problem for Turkey since the mid-1980s. The conventional wisdom contends that economic deprivation in southeastern Turkey is the fundamental reason for the long-running battle against the Kurdish rebels. Considering that there is limited empirical literature on the roots of terrorism in Turkey, yielding conflicting results about the claim that the main cause of terrorism is deprived economic conditions, this study aims to answer whether there is a causal relationship between income inequality and separatist terrorism in Turkey. To this end, the Global Terrorism Data Base for the period of 1973–2006, two Theil indices of pay inequality as proxy for income inequality, and the vector autoregression and Autoregressive Moving Average (ARMA) methods are utilized. The results support the early findings that income inequality, a particular focus in this paper and an essential indicator of economic deprivation, is not a main cause of escalation of separatist terrorism in Turkey.  相似文献   
795.
In most western countries, there is a strong incentive for defence department budget-holders to expend all of the funds they are authorized to spend in a fiscal year. In this paper, we question whether this emphasis makes sense. We develop a model of a defence department’s operating expenditure assuming a fixed level of funding for a year and uncertain costs. The results of the model suggest that the incentive for departmental managers to expend all authorized funds is inefficient. We explore the implications of the model for the Department of National Defence (DND) in Canada in light of the recent criticism of DND lapsed funding by the Auditor-General of Canada.  相似文献   
796.
基于数形结合方法以及变量代换方法发现计算卷积公式存在某些不足之处,研究卷积公式的计算方法,给出一种新的确定积分限的方法.该方法直观明了、容易理解和掌握并且可操作性强,有效避免作图和分析图形的繁琐,并举例说明了该应用方法.  相似文献   
797.
Some of the most active arms races are taking place between developed and less developed countries. The inability of less developed countries to compete financially, as well as technologically, with developed countries may be forcing the former to acquire terror weapons (TWP). The Iran–Iraq war in the 1980s and the events of 9/11 proved that the use of TWP is no longer a mere threat; there are several organizations and countries that will not hesitate to use them. This study develops a model of resource allocation in an arms race between a developed country that is characterized by state‐of‐the‐art technology and high GDP, and a less developed country whose technological capability and GDP are much lower. The model is used to predict the optimal mix of weapons of the two countries that are engaged in the arms race. Applying the model to the arms race between Israel and Syria demonstrates its use.  相似文献   
798.
We explore the impact of strategic assessment efforts on military organizations at war. To do so, we construct a model to explore the impact of a principal’s choice among imperfect performance metrics for a military operation. In doing so, the principal must consider both the incentivizing and informational properties of the metric. We show the conditions under which uncertainty regarding the nature of the agent, as well as uncertainty regarding the operational environment, drives a metric choice that induces pathological behavior from the agent. More specifically, a poor metric choice can create an overly optimistic assessment and end up prolonging the conflict. We illustrate the model’s insights in the cases of World War II and the Vietnam War.  相似文献   
799.
Abstract

This paper examines the nexus between the Japanese strategy and economic–industrial mobilization during the period 1937–1945. From 1937 to December 1941, the country was engaged in a land war of attrition in China. This war requested an immense amount of resources and was associated with armaments procurement strategy with emphasis in the army. However, the Japanese strategic vision assumed that the state was strong enough to engage in one land war against China and in a naval war in the Pacific simultaneously. The basis of Japanese strategy was a utopia. Making things worse, the naval war in the Pacific was conducted against the most industrialized powers in the world [the US and the British Empire (Britain, Australia, India, etc.)]. Finally, the internal Japanese industrial mobilization was associated with immense errors in armaments production (absence of economies of scale and scope, limited raw materials, etc.). Under these circumstances, the defeat was an expected outcome.  相似文献   
800.
In the ten years since the establishment of South Africa's first inclusive democratic government, an ambitious, extensive and systematic process of reform has been carried out in the governance of security. The process is widely regarded as having been successful and a model for other processes of ‘security sector reform’ in the context of transitions from authoritarian forms of governance to democratic ones.

That this been achieved with hardly a shot fired in anger is a remarkable achievement and a credit to visionary political leadership as well as organisational capacity, in other words to effective security governance.

At the same time, progress has been uneven and sometimes fragmentary, policy intentions and commitments have not always been translated into practice, the end results have not been to everyone's liking, and transformation has engendered its own pathologies. Thus several challenges remain in improving security governance.

This article provides a broad overview of the roles played by the various actors in the governance of the security sector, including the executive, parliament and civil society. It examines the main policy frameworks and touches on organisational transformation, because it is impossible to deal with governance in isolation from these issues. Policy processes and the frameworks they give rise to—in particular—are critical for effective governance. This article deals with the defence, safety and security and intelligence fields. A comprehensive overview would need to include the governance of criminal justice and foreign policy. The article does not seek to make an overall evaluation of governance, but to identify achievements, shortfalls and challenges.  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