首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   511篇
  免费   112篇
  国内免费   5篇
  2024年   2篇
  2023年   9篇
  2022年   5篇
  2021年   6篇
  2020年   8篇
  2019年   16篇
  2018年   15篇
  2017年   24篇
  2016年   31篇
  2015年   29篇
  2014年   35篇
  2013年   140篇
  2012年   25篇
  2011年   24篇
  2010年   24篇
  2009年   24篇
  2008年   16篇
  2007年   11篇
  2006年   18篇
  2005年   21篇
  2004年   24篇
  2003年   16篇
  2002年   18篇
  2001年   22篇
  2000年   12篇
  1999年   8篇
  1998年   14篇
  1997年   5篇
  1996年   4篇
  1995年   6篇
  1994年   4篇
  1993年   2篇
  1992年   5篇
  1991年   3篇
  1990年   1篇
  1988年   1篇
排序方式: 共有628条查询结果,搜索用时 15 毫秒
621.
军用电站谐波测量方法研究   总被引:1,自引:0,他引:1  
详细地介绍了基于离散傅里叶变换(DFT)的谐波测量方法,分析了不同窗函数的特征及其对谐波测量精度的影响,并依据军用电站谐波测量特点采用布莱克曼窗提高测量精度。针对所述测量方法,利用软件进行了仿真计算,利用实用电站装备进行了对比测量实验,根据仿真和实测数据的误差分析,指出了造成测量误差的原因。  相似文献   
622.
为了有效地从风浪背景下检测舰船水压场信号,鉴于舰船水压场信号与海浪水压信号在频谱上的差异,采用求卓越频率下的功率谱的方法对信号进行检测,取窗宽20s,每次计算21个采样点,分别求取海浪水压场的仿真信号及不同波浪级别下海上某目标的水压场实测数据的功率谱进行信号检测,验证了方法的有效性。  相似文献   
623.
分析了MIMO OFDM的系统模型,研究了MIMO OFDM系统的自适应调制技术,给出了完整的自适应算法,探讨了自适应MIMO OFDM系统的频谱效率。仿真结果表明,自适应调制提高了MIMO OFDM的误比特率性能。  相似文献   
624.
ABSTRACT

The making of the Treaty on the Prohibition of Nuclear Weapons (TPNW) has put Austria and its involvement in nuclear disarmament in the spotlight. This study highlights several factors that led Austria to become a prominent voice in nuclear-disarmament debates. First, its involvement dovetails with the emphasis on humanitarian disarmament it has promoted since the 1990s. Second, a strong antinuclear identity pervades Austrian society. This “nuclear allergy” combines antimilitarism inherited from the Cold War and, more broadly, an aversion to nuclear power, including for energy purposes. These two considerations form the background to the increased activism of the Austrian Foreign Ministry on nuclear disarmament in international fora. But, equally, Austria’s crusade for the TPNW can be attributed to the engagement of a small team of diplomats implementing personal as well as national preferences in favor of disarmament.  相似文献   
625.
在基于导频的信道估计方法中,伪导频的功率决定了该信道估计方法的性能.为了提高OFDM/OQAM系统的信道估计精度,提高频谱效率,提出一种基于改进导频结构的信道估计方法.在原有导频结构的基础上,对其中功率最高的导频结构进行改进,并给出对应的信道估计方法.由于缺乏足够的接收信号先验知识,无法直接对信道进行估计.为了解决这一...  相似文献   
626.
ABSTRACT

Under what conditions are cyber-weapons effective in nuclear counter-proliferation? With continued interest in nuclear proliferation professed by Iran, North Korea, and Saudi Arabia, a discussion of the effectiveness of counter-proliferation measures remains relevant. Cyber-attacks as military option in a state-on-state conflict still requires additional corroborating evidence to make conclusions about its long-term effectiveness. This work analyses the general applicability of cyber-weapons and their usefulness in nuclear counter-proliferation. Through a comparative case study of Operation Orchard, Stuxnet, and recent “Left-of-Launch” operations against North Korea, the essay finds that cyber-operations are not particularly effective against nuclear programmes that are in the later stages of their development. They can disrupt and delay a nuclear programme temporarily, if the attack remains clandestine, but cannot halt nuclear proliferation all together. However, effectiveness increases if they are used in combination with conventional weapons. The article addresses a topic of interest to national-level decision-makers: whether cyber-operations can and should play a role in nuclear counter-proliferation.  相似文献   
627.
ABSTRACT

This article focuses on the final years of South Africa’s nuclear-weapon program, particularly on the decision-making process leading up to the signature of the 1968 Treaty on the Non-Proliferation of Nuclear Weapons (NPT) by the South African government in 1991. In August 1988, after two decades of defiance, negotiations between the apartheid government and the NPT depository powers (the United Kingdom, the United States, and the Soviet Union) ensued at the International Atomic Energy Agency (IAEA) in Vienna. Despite South Africa being the only state to give up its indigenously developed nuclear weapons and subsequently join the nonproliferation regime, little is known about how the national position on NPT accession and IAEA safeguards evolved. Research carried out in multiple archives using hitherto untapped primary sources and interviews with key actors from several countries show how domestic and regional political dynamics influenced Pretoria’s position on entering the nonproliferation regime. In the process, the F.W. de Klerk government managed to skillfully exploit international proliferation fears to advance its own agenda, thereby connecting South African NPT accession with that of the neighboring Frontline States coalition of Angola, Mozambique, Tanzania, Zambia, and Zimbabwe.  相似文献   
628.
ABSTRACT

For the first time in a generation, the US Navy finds itself in an era of great power competition. As US naval strategists and defense planners begin to organise materially and conceptually to confront the strategic and operational-level challenges posed by China and Russia, what should they keep in mind? What should frame their thinking? Absorbed with the day-to-day tasks associated with managing how the fleet is being built, operated, and rationalised, these busy officers and civilians seldom can step back and gain some perspective on fundamental aspects of the security environment and relate those to naval purpose. To that end, this article provides a primer on what to keep in mind and how to think in an era of maritime great power competition.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号