全文获取类型
收费全文 | 1501篇 |
免费 | 198篇 |
国内免费 | 101篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 14篇 |
2021年 | 18篇 |
2020年 | 16篇 |
2019年 | 23篇 |
2018年 | 21篇 |
2017年 | 51篇 |
2016年 | 61篇 |
2015年 | 28篇 |
2014年 | 134篇 |
2013年 | 134篇 |
2012年 | 87篇 |
2011年 | 141篇 |
2010年 | 120篇 |
2009年 | 124篇 |
2008年 | 102篇 |
2007年 | 127篇 |
2006年 | 106篇 |
2005年 | 100篇 |
2004年 | 85篇 |
2003年 | 89篇 |
2002年 | 46篇 |
2001年 | 35篇 |
2000年 | 29篇 |
1999年 | 15篇 |
1998年 | 14篇 |
1997年 | 10篇 |
1996年 | 5篇 |
1995年 | 8篇 |
1994年 | 17篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 1篇 |
排序方式: 共有1800条查询结果,搜索用时 15 毫秒
321.
Governments are increasingly recognizing the problem posed by internally weak nuclear-capable states. The problem, however, is under-theorized. This article brings together literature on sovereignty and international order, the nonproliferation regime, and weak states, and introduces new concepts to provide a more structured understanding of this problem. Insight comes from focusing attention on the function and governance of two nuclear estates (termed the production and operational estates), and on their resilience to decay and disorder occurring within the state and society. Drawing on empirical observation, the authors suggest a typology of weakness in nuclear states, involving state fragmentation typified by the former Soviet Union, the “hard weak state” typified by North Korea, and the internally conflicted state typified by Pakistan. Although these types give rise to distinctive difficulties, their alleviation depends heavily on the maintenance of internal authority within the state and estates, the presence or absence of cooperative relations, and the international regulatory framework's vitality. 相似文献
322.
International safeguards is the system of measures put in place by the International Atomic Energy Agency and states to ensure nuclear programs remain dedicated to peaceful purposes. This international safeguards system consists of agreements, inspections, and evaluations that have never considered the safeguards culture of a state or facility. Neither a common definition nor an understanding of safeguards culture is internationally recognized. This article provides an analysis of the concept of safeguards culture and gauges its value to the international safeguards community. The authors explore distinctions among safeguards culture, safeguards compliance, and safeguards performance, and suggest possible indicators of safeguards culture and methods to promote a strong, positive safeguards culture. 相似文献
323.
Leonard Weiss 《The Nonproliferation Review》2013,20(2):269-284
The phenomenon of global warming has led to a revival of the prospects for increased nuclear energy production worldwide, yet such increased production carries with it the increased risk of proliferation. To mitigate this risk, various multinational arrangements have been proposed to provide reliable supply of nuclear fuel while at the same time discouraging the construction of national plants for nuclear enrichment and reprocessing. This article provides a brief history of some of these proposals and concludes that the likelihood of success for such schemes as effective tools for nonproliferation is not high at this time. A proposal from the World Council on Renewable Energy to expand the understanding of supplier obligations under Article IV of the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) to include the development of non-nuclear energy technologies for NPT parties in good standing is potentially a much better nonproliferation tool. Such an approach tracks the ideas contained in Title V of the Nuclear Non-Proliferation Act of 1978, which has recently received revived congressional interest. 相似文献
324.
Paul Meyer 《The Nonproliferation Review》2013,20(3):463-472
For more than forty years, the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) has provided major security benefits to the international community; however, the treaty is suffering from internal and external pressures, and benign neglect on the part of its members is undermining its authority. To ensure the treaty's continued viability, it is time for member states to start showing the NPT the respect it deserves and to renew their commitments to its fundamental purposes. Achieving this requires remedial action in at least four areas of vulnerability: reinvigorating nuclear disarmament; strengthening nonproliferation; overcoming the NPT's institutional deficit; and fostering a rapprochement between NPT and non-NPT states that does not abandon the goal of treaty universalization. There is still time before the 2010 NPT Review Conference for concerted action to restore the NPT's vitality and for the United States to resume its leadership role on behalf of the treaty and its membership. 相似文献
325.
Nina Wilén 《Defense & Security Analysis》2013,29(2):117-127
The Congolese security sector reform – disarmament demobilisation and reintegration (SSR-DDR) process has suffered from setbacks in its military sector during the last 10 years, such as insufficient funding, lack of coordination and domestic reluctance to major changes, with as a result, a very fragile and disjointed Army. These problems have deepened as officers have defected from the Army and caused new instability in the East of the Congo. This article aims to analyse the recent mutinies and the reaction by the Congolese government by applying a capabilities-based approach in combination with a typology of spoilers. The objective is to identify and classify the spoilers and answer the questions of why they emerge now and how they are dealt with on a national level. From the analysis, the author suggests that there are several spoilers involved in the current situation – the most powerful being the Congolese and the Rwandan governments, prompting the question of whether an international involvement is necessary to solve the problem. 相似文献
326.
通过设置弹丸初速并研究其对单级磁阻型线圈发射器发射性能的影响,模拟分析前一级线圈弹丸出口速度对后一级线圈发射性能影响的规律;利用Ansoft有限元仿真软件进行了动态仿真,得到弹丸初速对单级磁阻型线圈发射器驱动电流、驱动线圈感应电压、电磁力、弹丸出VI速度、弹丸位移及能量转换效率等影响的规律.研究表明:弹丸初速越大,经过单级线圈加速后弹丸出口速度也越大,但弹丸出口速度增量减小;随着弹丸初速增大,能量转换效率呈现先增大后减小的趋势. 相似文献
327.
328.
设计了新型半圆管形式的不锈钢板式换热器,对其作为太阳能光电热综合利用一体化系统集热组件的性能进行实验研究。通过新型集热光电热组件及光电组件系统的对比实验,研究该光电热组件在重庆地区夏季应用情况,分析其光电和光热特性。结果表明:在以晴朗为主的天气,半圆管形式的不锈钢板式光电热组件电热系统的电热性能与光电组件系统的相比较,前者的太阳能电池输出功率提高约26.48%,热利用效率提高23.70%以上,新型半圆管形式的光电热组件整体光电热(光电+光热)综合效率可达到25.70%,有效提高了光电热系统的综合效率。新型半圆管形式不锈钢板式换热器的换热面积增大,提高了换热效率,为太阳能光电热综合利用一体化系统在重庆等太阳辐射强度较小地区的应用提供了参考。 相似文献
329.
介绍了北斗、短波授时技术;对高稳恒温晶振及其频率特性进行分析的基础上,设计了一种基于北斗卫星、短波无线电授时的高精度时钟系统;该系统通过利用北斗接收处理模块、短波授时接收模块得到的秒脉冲信号、时间信息,经过延迟修正处理、脉冲滤波、脉冲补偿、脉冲统计得到标准的秒脉冲信号,实现对恒温晶振频率的校准,获得一个短期及长期频率稳定度都比较优良的时间频率标准,同时利用校频后恒温晶振分频出的1pps信号对时间芯片进行校准,对外输出高精度时间信息;对恒温晶振校频系统的基本工作原理及部分模块电路图进行了说明,试验结果表明,在时间不长于1h内,频率准确度优于1×10-10;该系统实用方便的方法达到了将晶体振荡器校准到较高指标的目的。 相似文献
330.
针对海洋环境对鱼雷等武器装备战术效能影响的试验数据和案例样本匮乏等普遍性问题,引入信息扩和模糊映射思想,并基于遗传算法改进和发展了最优窗宽扩散模型。该方法可从有限的试验样本中客观拟合出数据结构信息,进而实现有限数据样本信息的合理扩散。利用该方法进行了基于小样本案例的潜射鱼雷战术效能的海洋环境影响评估的信息扩散建模和仿真实验和对比分析。结果表明,窗宽优化的信息扩散模型可有效改进常规信息扩散模型的评估效果,对武器装备环境影响评估中普遍存在的小样本或信息不完备困难有一定参考应用意义。 相似文献