全文获取类型
收费全文 | 2382篇 |
免费 | 324篇 |
国内免费 | 162篇 |
出版年
2024年 | 8篇 |
2023年 | 9篇 |
2022年 | 14篇 |
2021年 | 21篇 |
2020年 | 19篇 |
2019年 | 26篇 |
2018年 | 24篇 |
2017年 | 72篇 |
2016年 | 88篇 |
2015年 | 52篇 |
2014年 | 203篇 |
2013年 | 123篇 |
2012年 | 144篇 |
2011年 | 246篇 |
2010年 | 193篇 |
2009年 | 233篇 |
2008年 | 201篇 |
2007年 | 191篇 |
2006年 | 115篇 |
2005年 | 126篇 |
2004年 | 128篇 |
2003年 | 104篇 |
2002年 | 80篇 |
2001年 | 70篇 |
2000年 | 63篇 |
1999年 | 45篇 |
1998年 | 38篇 |
1997年 | 40篇 |
1996年 | 35篇 |
1995年 | 26篇 |
1994年 | 33篇 |
1993年 | 30篇 |
1992年 | 23篇 |
1991年 | 27篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 2篇 |
排序方式: 共有2868条查询结果,搜索用时 15 毫秒
821.
针对舰炮火控雷达高精度实时仿真建模的问题,运用高斯分布和正态平稳过程的两种误差序列生成方法,建立火控雷达简化仿真模型。通过对某火控雷达实测数据误差的统计及时序相关性分析,完成误差序列仿真生成与验证,给出了实现舰炮火控雷达探测误差仿真的优选方法。实践证明,正态平稳模型的误差生成方法可以有效满足新型舰炮仿真试验火控雷达建模要求。 相似文献
822.
以周向常值连续小推力作用下的绳系拖曳离轨为背景,针对离轨过程中的系绳摆动抑制问题,建立了系统质心轨道动力学方程及系绳摆动动力学方程,分析了无系绳收放控制时的系绳摆动特性以及系绳收放对系绳摆动的作用效果,构造了使系绳摆动衰减的期望绳长收放速率并设计了系绳张力控制律。仿真结果表明:无系绳收放控制时,系绳摆动表现为平衡位置附近的周期性往复运动;张力控制连续平滑,很好地实现了系绳实际长度对期望长度的跟踪,同时有效地抑制了离轨过程中的系绳摆动。 相似文献
823.
824.
825.
脉冲力的瞬间作用会引起攻角和侧滑角的急剧变化,对末修弹飞行稳定性产生较大的影响.以线性化运动微分方程组为数学解析手段,对末修弹脉冲作用稳定性进行深入分析研究.数值仿真表明,采用小扰动法分析弹丸脉冲控制弹丸飞行稳定性是可行的. 相似文献
826.
Todd Sandler 《Defence and Peace Economics》2013,24(3):533-548
This article puts forth collection action as a unifying theme for the conference essays on arms trade, control, and production. For each of these topics, collective action failures are related to group size and group composition considerations. Other issues are also examined including the manner in which individual contributions determine the overall level of the associated collective good ‐ the so‐called aggregation technology of public supply. Based on alternative aggregation technologies, the game‐theoretic underpinnings of these arms issues are explored. 相似文献
827.
J. M. Quinn 《Defence and Peace Economics》2013,24(5):536-554
This study models the structural sources of variation in the use of selective (discriminate) repression within 89 civil wars fought between 1981 and 2005. The severity of repressive violence is modeled as a function of the amount of territory being contested by the insurgents. This idea is operationalized using measures of the location, size, and density of insurgency violence. The analysis finds evidence that the repressive behavior of both governments and rebel groups is linked to conflict geography. Governments violate physical integrity rights more frequently and kill more civilians the greater the overall amount of territory under contestation. Rebels kill more civilians in highly dispersed insurgencies that lack a clear epicenter. 相似文献
828.
Sumit Ganguly 《The Nonproliferation Review》2013,20(3):577-581
South Asian Security and International Nuclear Order: Creating a Robust Indo-Pakistani Nuclear Arms Control Regime, by Mario Esteban Carranza. Ashgate, 2009. 208 pages, $99.95. 相似文献
829.
For many years, non-nuclear weapons states have sought binding commitments from nuclear armed states that they would not be the victim of either the threat or use of nuclear weapons—so-called negative security assurances (NSAs). The nuclear weapon states have traditionally resisted granting such unconditional NSAs. Recent U.S. efforts to use nuclear deterrence against the acquisition and use by other states of chemical, biological and radiological weapons, however, have further exacerbated this divide. This article analyzes the historical development of NSAs and contrasts U.S. commitments not to use nuclear weapons with the empirical realities of current U.S. nuclear weapons employment doctrines. The authors conclude that NSAs are most likely to be issued as unilateral declarations and that such pledges are the worst possible manner in which to handle the issue of security assurance. 相似文献
830.
Sarah Bidgood 《The Nonproliferation Review》2013,20(3-4):307-318
ABSTRACTRelations between the United States and Russia are in a prolonged downward spiral. Under these circumstances, cooperation on nuclear issues—once a reliable area of engagement even in difficult political environments—has all but completely halted. There are urgent reasons to find a way out of this situation, particularly the expiration of the New Strategic Arms Reduction Treaty in 2021. However, seemingly intractable disagreements about noncompliance with the Intermediate-range Nuclear Forces Treaty and US ballistic-missile defense, compounded by the Ukraine crisis, the conflict in Syria, and the accusations of Russian interference in the US election of 2016, threaten the future of arms control. Against this backdrop, policy makers and practitioners should identify ways to re-engage on nuclear issues now so they can be ready to implement them as soon as feasible. This article considers how the Comprehensive Nuclear-Test-Ban Treaty (CTBT) could serve as a platform for US–Russia cooperation on nuclear issues when circumstances permit. Taking into account the challenges posed by ongoing US non-ratification, it identifies a menu of CTBT-related activities short of ratification that the two countries could undertake together. It explores how joint work on this issue would advance shared US and Russian interests while helping to create the circumstances necessary for further arms-control work. 相似文献