全文获取类型
收费全文 | 787篇 |
免费 | 161篇 |
国内免费 | 52篇 |
出版年
2024年 | 5篇 |
2023年 | 5篇 |
2022年 | 14篇 |
2021年 | 20篇 |
2020年 | 23篇 |
2019年 | 18篇 |
2018年 | 13篇 |
2017年 | 36篇 |
2016年 | 42篇 |
2015年 | 31篇 |
2014年 | 61篇 |
2013年 | 66篇 |
2012年 | 58篇 |
2011年 | 61篇 |
2010年 | 42篇 |
2009年 | 65篇 |
2008年 | 35篇 |
2007年 | 56篇 |
2006年 | 68篇 |
2005年 | 50篇 |
2004年 | 40篇 |
2003年 | 33篇 |
2002年 | 24篇 |
2001年 | 22篇 |
2000年 | 23篇 |
1999年 | 12篇 |
1998年 | 10篇 |
1997年 | 7篇 |
1996年 | 9篇 |
1995年 | 9篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 3篇 |
1991年 | 11篇 |
1990年 | 13篇 |
1989年 | 3篇 |
1987年 | 1篇 |
排序方式: 共有1000条查询结果,搜索用时 15 毫秒
161.
为解决小子样条件下进行产品固有可用度试验验证的问题,基于Bayes理论,提出了一种固有可用度定时截尾试验方案.该试验方案在假设故障间隔时间和修复时间均服从指数分布的前提下,将现场试验分为同时进行的可靠性和维修性定时截尾试验2个部分,要求在利用验前试验信息的基础上,使本次试验获得的验后分布还可以作为下一次现场试验的验前分布,提高了试验数据的利用率,具有较好的经济效益. 相似文献
162.
Michael Steinberg 《Defense & Security Analysis》2013,29(1):68-75
In principle, national sovereignty is the right of a nation to govern its internal affairs without foreign interference. In practice, it is defined by one's interpretation of international law, which may permit legal external intervention under some circumstances, ultimately removing a nation's sovereignty. This paper will examine the current system of international law outlined by the United Nations, analyse the ambiguities contained within its Charter and elaborate on how external intervention can be justified. The case-study of recent developments related to Libya will demonstrate that the manner in which international law is interpreted is changing the notion of principles of sovereignty. 相似文献
163.
164.
165.
为了研究土中爆炸作用下埋地管线的安全问题,利用AUTODYN-2D、AU?TODYN-3D程序,采用程序提供的流固耦合功能和网格映射功能,对爆炸地冲击作用下埋地管线的变形和破坏问题进行了数值模拟分析,得到不同爆心间距管线的应力峰值.将模拟计算结果和理论计算结果进行了对比分析,结果表明:模拟计算值与TM5-855-1手册理论计算值比较吻合,表明采用数值模拟方法分析爆炸地冲击对埋地管线的作用是可行的,计算结果对地下爆破的安全施工和埋地管线的安全运行具有参考价值. 相似文献
166.
167.
168.
A. Steven Dietz 《Small Wars & Insurgencies》2013,24(2):385-401
The current approach to countering the threat of improvised explosive devices (IEDs) in Afghanistan has met with limited success. The relative lack of success may be in part because the current approach is not holistic and discounts the social systems that foster the IEDs. Insurgents are using IEDs as a tool to further their strategic aims, but the coalition and to a lesser extent the Government of the Islamic Republic of Afghanistan (GIRoA) are attacking the IEDs as if they are an end in and of themselves. Combining network disruption with information change maximizes the opportunities for mitigating the IED threat. More specifically, to mitigate the IED threat requires disrupting the social and economic systems associated with IEDs, and at the same time providing alternative economic opportunities and improving rule of law and governance at the local level. In other words, counter-IED (C-IED) must be Counter-Insurgency (COIN) centric to be successful. This paper reviews the current state of C-IED efforts, identifies five main problems with the current approach, and suggests changes to reduce or mitigate the IED threat in Afghanistan. 相似文献
169.
Alok Bansal 《Small Wars & Insurgencies》2013,24(2):182-200
Balochistan has been in the midst of a full fledged insurgency for over five years now. Pakistani establishment has tried to project the current insurgency as a tribal mischief being perpetrated by a few feudal lords but the widespread support that the insurgents have been enjoying and the impunity with which they have been targeting symbols of government authority not only across the entire length and breadth of Balochistan but even outside, indicate that there are deep rooted, well defined causes that have led to this insurgency. The paper attempts to analyse the factors that have led to current round of insurgency in Balochistan. 相似文献
170.
建构主义学习理论在强化大学生信仰教育方面有着重要的指导作用。夺文简要分析了夫掌生信仰教育存在的问题,探讨了建构主义学习理论对于强化大学生信仰教育的重要意义,并以建构主义卷习理论隽指导,从“以学生为中心”、“情景创设”、“协作学习”、“利用各种资源”四个方面提出了强化对策,以期提高大学生信仰教育水平,实现大学思想政治教育的功能。 相似文献