全文获取类型
收费全文 | 356篇 |
免费 | 76篇 |
国内免费 | 55篇 |
出版年
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 17篇 |
2020年 | 9篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 18篇 |
2016年 | 24篇 |
2015年 | 15篇 |
2014年 | 33篇 |
2013年 | 23篇 |
2012年 | 37篇 |
2011年 | 26篇 |
2010年 | 19篇 |
2009年 | 44篇 |
2008年 | 20篇 |
2007年 | 27篇 |
2006年 | 20篇 |
2005年 | 19篇 |
2004年 | 15篇 |
2003年 | 12篇 |
2002年 | 12篇 |
2001年 | 17篇 |
2000年 | 13篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 8篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 6篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
排序方式: 共有487条查询结果,搜索用时 15 毫秒
141.
142.
针对典型舰船的系统组成,进行了全舰任务成功性指标的示例计算,给出了总体指标的层次化表达方式。以舰船任务过程和典型任务剖面为依据,分析了任务可靠性和任务成功性之间的区别与联系,建立了舰船总体任务成功性指标的多阶段整体模型,并对航渡、待机、交战、撤离、返航阶段分别进行了仿真和解析建模。在建模与计算的基础上,通过敏感性分析计算了任务阶段持续时间的单位降低率等指标,为舰船任务成功性问题及其相关研究,提供了一个系统性的分析框架和方法。 相似文献
143.
威布尔分布的战术导弹可靠性试验信息融合方法 总被引:1,自引:0,他引:1
针对战术导弹可靠性试验小子样问题,提出了基于威布尔分布,利用小概率原理,针对不同试验环境下试验数据的融合方法。该方法扩大了战术导弹可靠性试验的统计子样,提高了可靠性评定的可信度。 相似文献
144.
The drivers of HIV/AIDS in the South African Police Service (SAPS) and impact of the disease on this workforce are neglected areas of research. Existing evidence suggests that while the occupational risk for contracting HIV is low, there are factors associated with the profession that, if left unmanaged, place police officers at risk of contracting HIV. This study's two aims are to identify the potential pathways of HIV infection within policing services and determine the probable impact of HIV/AIDS on SAPS. Through a systematic literature review on HIV/AIDS within police services, and by analysing selected SAPS human resource data, the causal pathways and impact of HIV/AIDS on police services are explored. The study finds that police officers (particularly male officers) are likely to be highly susceptible to HIV infection as a result of risky sexual behaviours born out of occupational characteristics such as high levels of stress, difficult working conditions, living away from home and interactions with sex workers. The problem is exacerbated by the ‘macho’ culture that often prevails among police officers. HIV/AIDS interventions within SAPS must focus on sustained behaviour change. Further, HIV programmes must equip officers with the knowledge and awareness to avoid engaging in high-risk sexual practices that may compromise their health and the effectiveness of the policing service. 相似文献
145.
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
146.
Max Abrahms 《Defence and Peace Economics》2013,24(6):583-594
The basic narrative of bargaining theory predicts that, all else equal, anarchy favors concessions to challengers who demonstrate the will and ability to escalate against defenders. For this reason, post-9/11 political science research explained terrorism as rational strategic behavior for non-state challengers to induce government compliance given their constraints. Over the past decade, however, empirical research has consistently found that neither escalating to terrorism nor with terrorism helps non-state actors to achieve their demands. In fact, escalating to terrorism or with terrorism increases the odds that target countries will dig in their political heels, depriving the non-state challengers of their given preferences. These empirical findings across disciplines, methodologies, as well as salient global events raise important research questions, with implications for counterterrorism strategy. 相似文献
147.
Full‐system testing for large‐scale systems is often infeasible or very costly. Thus, when estimating system reliability, it is desirable to use a method that uses subsystem tests, which are often less expensive and more feasible. This article presents a method for bounding full‐system reliabilities based on subsystem tests and, if available, full‐system tests. The method does not require that subsystems be independent. It accounts for dependencies through the use of certain probability inequalities. The inequalities provide the basis for valid reliability calculations while not requiring independent subsystems or full‐system tests. The inequalities allow for test information on pairwise subsystem failure modes to be incorporated, thereby improving the bound on system reliability. We illustrate some of the properties of the estimates via an example application. © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013 相似文献
148.
目前,对导弹抗干扰能力的要求越来越高,干扰条件下的导弹单发命中概率已成为评定导弹性能的重要指标.针对箔条干扰条件下舰空导弹单发杀伤概率评定,建立了雷达导引头接收端信干比模型、舰空导弹圆目标落入概率模型以及抗干扰改善因子模型,从而构建了箔条干扰条件下舰空导弹单发命中概率模型,计算出真实有效的单发命中概率. 相似文献
149.
150.
高速/超高速碰撞会产生大量破片,并伴随闪光、等离子体等现象.高速碰撞材料受冲击产生射流及破片高温会引起碰撞闪光现象,获得了碰撞等离子体电磁场强度的变化规律.采用数值仿真与理论分析相结合的方法,获得了高速碰撞破片云团分布规律. 相似文献