全文获取类型
收费全文 | 284篇 |
免费 | 61篇 |
国内免费 | 45篇 |
出版年
2024年 | 5篇 |
2023年 | 3篇 |
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 3篇 |
2017年 | 29篇 |
2016年 | 32篇 |
2015年 | 16篇 |
2014年 | 28篇 |
2013年 | 27篇 |
2012年 | 35篇 |
2011年 | 29篇 |
2010年 | 15篇 |
2009年 | 23篇 |
2008年 | 15篇 |
2007年 | 14篇 |
2006年 | 23篇 |
2005年 | 20篇 |
2004年 | 15篇 |
2003年 | 12篇 |
2002年 | 4篇 |
2001年 | 7篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1993年 | 3篇 |
1990年 | 2篇 |
排序方式: 共有390条查询结果,搜索用时 15 毫秒
251.
252.
President Barack Obama and an array of other Western leaders continue to assert that the spread of weapons of mass destruction (WMD) to non-state actors is one of most pressing challenges to global security today. Yet, Western efforts to engage governments—particularly governments across the global South—in a practical nonproliferation dialogue have largely yielded disappointing results. This viewpoint examines the need for a new strategy to engage the developing world in nonproliferation programs. It argues that strategies focused strictly on WMD nonproliferation are unsustainable, and ultimately are destined for failure. An alternative “dual-benefit” nonproliferation engagement strategy utilizes the enlightened self-interest of partner governments needed to achieve broad-based buy-in among all partners. In a concluding section, we recommend that the “Group of 8” Global Partnership Against the Spread of Weapons and Materials of Mass Destruction standardize this model of nonproliferation engagement as it sets out to identify and fund WMD nonproliferation capacity-building initiatives beyond the states of the former Soviet Union. 相似文献
253.
Anders Corr 《The Nonproliferation Review》2013,20(1):127-147
Nuclear proliferation, lax security standards in the storage of fissile materials, and international apathy in the prosecution of terrorists make nuclear terror a serious threat to the United States and its allies, yet no doctrine of retaliation has been established. To decrease the probability of terrorist use of nuclear weapons, a doctrine of retaliation—a negligence doctrine—should be considered. If the United States can distinguish whose fissile material was used for a nuclear terror event, a negligence doctrine would prescribe retaliation against that state. Where the proximate cause—terrorists—is unavailable for deterrent retaliation, deterring an accessible mediate cause—a state that has failed to adequately secure its fissile material—is one of a few effective alternatives. In the absence of such a negligence doctrine, the United States and its allies are increasingly vulnerable to a nuclear terror attack and the ensuing negative consequences. 相似文献
254.
In 2007, 334 nuclear reactors (including for naval propulsion) and isotope production facilities employed highly enriched uranium (HEU) fuel or target material. One year of operations at these reactors and facilities required more than 3,100 kilograms (kg) of HEU for naval propulsion, more than 750 kg for research reactors, and 40?–50 kg for isotope production in civilian facilities—in addition to several tons used in other types of reactors. Material with high enrichment levels and low radiation barriers stored or handled in large batches, such as HEU target waste and certain types of fuel from isotope production, research reactors/critical assemblies, and naval fuel, presents serious safety and security concerns. Forty-eight civilian research reactors have converted to low-enriched uranium as a result of a three-decade international effort to minimize HEU use, resulting in a decrease in HEU consumption of 278 kg per year. This article's establishment of baseline measurements for assessing the results of HEU minimization efforts calls for additional focus on the scope and methodology of HEU minimization. Facility decommissioning and dismantling should play a larger role in the future HEU minimization effort, materials with specific weapons-relevant properties should be given higher priority compared to bulk HEU material, and the use of large quantities of weapon-grade HEU fuel for naval propulsion should be reconsidered. 相似文献
255.
通过对空中兵力的合理编组,实现作战资源的优化配置是提升兵力作战效能的有效途径。针对现代空战编队对抗过程的特点,从战术企图和信息优势角度提出了编队目标威胁评估方法。以编队目标为研究对象从宏观上调配己方作战资源,提出了作战资源成本和兵力调度成本2种兵力编组成本,在此基础上建立了资源约束条件下的兵力编组优化模型,并采用改进PSO算法对模型进行求解。作战想定仿真结果表明兵力编组模型能够有效解决空战兵力分配问题。 相似文献
256.
研究了多机器人观测到同一目标时的协同定位问题。建立了各个机器人相对观测一致程度的数学描述模型,进而提出用基于极大熵准则的最大熵博弈获取使相对观测一致程度最优的协同定位方式。针对博弈结果的多样性,相应地改变观测方程的雅克比矩阵,推导了可适应多机器人各种博弈结果的扩展Kalman滤波协同定位算法。仿真实验表明,方法可实现机器人团队在协同定位时有选择、更高效地共享相互间的观测信息;在保证协同定位精度提高的同时有效地消除了多机器人相对观测信息间的冲突。 相似文献
257.
258.
为降低轿车主减速器噪声测试试验台本底噪声,其传动系统采用了四对三角胶带传动。本文论述的三角胶带轮必须满足:传动比要求、重量最轻、转动惯量最小、制造成本最低,故对三角胶带轮采用了多目标优化设计,其优化结果用于试验台的效果令人满意。 相似文献
259.
基于对策论的威胁评估模型 总被引:4,自引:2,他引:2
数据融合模型一般包括多个层次,威胁评估是其中之一。威胁评估根据态势情况,推测威胁程度及可能的行动方案。在分析对策论和威胁评估的基础上,提出基于矩阵对策的威胁评估模型及分析方法。 相似文献
260.
本文利用LDV—02型激光测速仪,在循环水槽里测量了加热和非加热流线型细长旋成体尾流的速度分布和湍流度,并把Hama&Peterson的半经验理论(它适用于非加热体的类似尾流)修正为本文的半经验分析,较好地描述了尾流温度场对其速度场的影响,还从测得的尾流速度数据推断出加热对水下运动物体阻力系数的影响。 相似文献