全文获取类型
收费全文 | 382篇 |
免费 | 72篇 |
国内免费 | 12篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 11篇 |
2020年 | 8篇 |
2019年 | 18篇 |
2018年 | 8篇 |
2017年 | 15篇 |
2016年 | 17篇 |
2015年 | 14篇 |
2014年 | 30篇 |
2013年 | 143篇 |
2012年 | 20篇 |
2011年 | 15篇 |
2010年 | 15篇 |
2009年 | 14篇 |
2008年 | 10篇 |
2007年 | 18篇 |
2006年 | 17篇 |
2005年 | 11篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 10篇 |
2001年 | 6篇 |
2000年 | 11篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
排序方式: 共有466条查询结果,搜索用时 62 毫秒
451.
基于图像序列分析的图像制导极大地提高了成像武器的跟踪精度。给出了一种基于可变模板技术和遗传退火算法的图像序列目标跟踪算法。根据目标的物理特征构造出可变模板,定义合适的能量函数,采用遗传退火算法进行优化搜索。实验结果表明,该算法能够精确检测并跟踪目标,具有很快的收敛性和较高的抗噪声性。 相似文献
452.
453.
多目标数据关联的神经网络方法 总被引:1,自引:0,他引:1
数据关联是多目标跟踪的关键问题。基于 Hopfield神经网络的 JPDA是解决这一关键问题的有效方法之一 ,但此方法的难点在于优化系数的整定。提出一种改进算法 ,用于解决优化系数在线自适应整定问题。首先重新构造了李雅普诺夫能量函数 ,接着引入变化的优化系数因子 ,并给出了优化系数求解的迭代公式 ;最后对已有和改进的算法进行了仿真研究。结果表明改进的方法和原有的方法相比 ,一方面具有在线整定优化系数的功能 ,另一方面可以获得和原有算法非常接近的估计误差。 相似文献
454.
针对海洋工程平台的防护吸能和浮力储备需求,设计一种纤维缠绕复合材料约束球形浮力芯材吸能结构。为分析其变形损伤特征和能量耗散机理,通过ABAQUS有限元软件和万能材料试验机开展数值模拟分析和试验验证研究。通过力学响应特征和损伤破坏模式分析可知,结构吸能设计的关键在于表层和芯材的泊松比匹配。芯材主要通过塑性压缩损伤和剪切断裂破坏吸收能量,而表层吸能则主要通过环向的花瓣形拉伸断裂破坏。研究表明,该型结构单元压缩吸能特性优异,可实现海洋工程结构平台的防护吸能和浮力储备要求。 相似文献
455.
登陆破障行动是联合登陆战斗中各军兵种破障力量在敌预先设置和临机设置的各种障碍物中开辟通路的行动,也是确保登陆兵突击上陆和向纵深发展进攻的前提和关键。进入21世纪,随着高新技术的不断发展,传统的破障装备和手段已经不能适应新的战场,各种新式障碍相继出现,对登陆部队的破障能力提出更高要求,破障装备体系化、破障手段精确化以及破障过程无人化成为未来破障技术的重要发展方向。本文首先简要介绍了当前世界主流的破障装备和手段,并论述了其局限性,如破障效率低、人员和弹药消耗量大以及容易形成二次障碍等,然后从破障装备体系化、破障手段精确化和破障过程无人能化三个方面对未来破障装备技术发展趋势进行了展望。 相似文献
456.
The aim of this article is to evaluate how French Major Conventional Weapons (MCW) exports impact on the conflict intensity of recipient countries. The recent increase in French arms exports seems to contradict the French political discourse on the promotion of regional stability. We run zero-inflated ordered probit model in order to analyze the role of the arms trade on the intensity of civil conflicts in 144 countries from 1992 to 2014, using SIPRI and UCDP/PRIO data. Our results suggest that French MCW exports tended not to exacerbate intrastate conflicts during this period. This finding is robust to changes in the empirical framework. We propose two lines of explanations: France seems to be prone to choosing partners that respect human rights and selling more ‘defense-oriented’ MCW than the rest of the world. 相似文献
457.
Albert Mauroni 《The Nonproliferation Review》2019,26(1-2):127-141
The US government initiated a Defense Counterproliferation Initiative to address the concern that, in the post-Cold War years, the proliferation of nuclear, biological, and chemical weapons would be widespread and create a significant challenge to the US military’s combat operations. In particular, non-nuclear states might use chemical or biological warfare agents against US forces with the belief that nuclear weapons would not be used against them in retaliation. Following the events of September 11, 2001, defense strategy and policy shifted to a wider view of the threat of adversarial use of “weapons of mass destruction” (WMD) and the term “counterproliferation” was replaced by “combating” or “countering WMD.” Over time, the Defense Department increasingly moved away from counterproliferation principles with the detrimental effect of losing capabilities that US forces still need for contemporary adversaries. This shift has been aggravated by other US government agencies’ use of “counterproliferation” in lieu of what would have been termed “nonproliferation” activities in the 1990s. The loss of clarity within the US government on these terms has led to the inability to focus the “whole of government” on this significant national security challenge. To alleviate this challenge, the US government needs a top-down initiative to refocus policy on the distinctly different aspects of WMD with respect to military combat operations, combating terrorism, and homeland security. 相似文献
458.
ABSTRACT The growing area of military bio-technologies, especially the use of cogniceuticals, raises several ethical concerns for military physicians. These include the role of military physicians in prescribing amphetamines whose long-term effects are largely unknown, and the possible undermining of the ethic of “do no harm,” since amphetamines may diminish a soldier’s moral responsibility. Below, we outline some important questions relating to the ethics of amphetamines and medical military physicians. 相似文献
459.
Gregory D. Koblentz 《The Nonproliferation Review》2019,26(5-6):575-598
ABSTRACTInternational efforts to hold the government of President Bashar al-Assad accountable for the use of chemical weapons in the Syrian Civil War have entered a new phase. For the first time, the Organisation for the Prohibition of Chemical Weapons (OPCW), the international organization responsible for implementing the 1993 Chemical Weapons Convention, has been empowered to identify the perpetrators of chemical attacks in Syria. The Investigation and Identification Team (IIT), which was formed to conduct the OPCW’s new attribution mission, has announced its intention to investigate and identify the perpetrators of nine chemical attacks in Syria, including the April 7, 2018, attack in Douma. This article reviews recent efforts to attribute chemical attacks in Syria, describes what we know about the nine incidents to be investigated, summarizes what is known about the Syrian government officials, military commanders, and chemical-warfare scientists suspected of being responsible for these attacks, discusses what to expect during the next phase of the attribution process, and offers insights into how the international community can move beyond attribution to accountability. Accountability is necessary to provide justice for victims and to prevent future incidents by demonstrating that perpetrators of chemical attacks will be identified and punished. 相似文献
460.
Robert Brathwaite 《Defence Studies》2016,16(4):327-345
The utilization of chemical weapons to quash domestic rebellion is a drastic action for a regime facing domestic challengers to take, especially given the reputation costs and risk of international intervention. However, recent developments have illustrated that some regimes have contemplated and implemented extraordinary measures (including the use of chemical munitions) to quash rebellion. This study addresses the question of why some states utilize chemical weapons against domestic challengers while others refrain from this level of state repression. I argue that the utilization of chemical weapons has both domestic and international elements. Specifically, that ethnic cleavages that lead to secessionist challenges and factors associated with inter-state rivalry impact the likelihood that a state utilizes the employment of chemical munitions. I test my argument and other explanations regarding repression with a casestudy approach utilizing captured Iraqi Government documents comparing Iraq’s Al-Anfal campaigns with developments during the recent Syrian Civil War. 相似文献