全文获取类型
收费全文 | 622篇 |
免费 | 114篇 |
国内免费 | 29篇 |
专业分类
765篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 15篇 |
2020年 | 13篇 |
2019年 | 11篇 |
2018年 | 26篇 |
2017年 | 33篇 |
2016年 | 28篇 |
2015年 | 23篇 |
2014年 | 57篇 |
2013年 | 50篇 |
2012年 | 40篇 |
2011年 | 60篇 |
2010年 | 37篇 |
2009年 | 50篇 |
2008年 | 46篇 |
2007年 | 35篇 |
2006年 | 37篇 |
2005年 | 28篇 |
2004年 | 33篇 |
2003年 | 18篇 |
2002年 | 25篇 |
2001年 | 26篇 |
2000年 | 14篇 |
1999年 | 9篇 |
1998年 | 2篇 |
1997年 | 10篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 2篇 |
排序方式: 共有765条查询结果,搜索用时 0 毫秒
541.
探讨了装备设计研制阶段面向再制造的装备材料设计概念,提出了面向再制造的装备材料设计的5个影响因素,即材料服役寿命、材料可恢复性、材料经济性、材料环保性、材料可分离性,并对每个因素进行了分析。在此基础上,建立了基于专家评价法的材料再制造性评价模型,并进行了案例验证,为面向装备再制造的材料设计及选择提供了一种选择思路及评价手段。 相似文献
542.
赵志浩 《兵团教育学院学报》2010,20(5):21-23,36
马克思在研究亚洲或东方社会的状况时,提到亚细亚生产方式的概念,对此概念的严格定义则不是马克思关注的焦点,他的关注点集中在东西生产方式的区别上,以及当时东方社会为何遭受到西方社会的打击,并在此基础上为包括东方国家在内的落后国家寻找一条出路。然而,后人却对亚细亚生产方式概念进行了各种各样的论争,这虽有时代背景上的原因,也有诸多理论上的原因,无疑也背离了马克思探讨亚细亚生产方式的原意。可是另一方面,通过对亚细亚生产方式的研究和争论,有助于了解包括中国在内的亚洲国家的历史和现状。了解自身历史的生产方式,以及和西欧生产方式进行对比,对于现代化进程中的中国有着很大的借鉴和启发意义。 相似文献
543.
郭三学 《武警工程学院学报》2010,(4):70-73
结合我院任职教育实际,分析了任职教育出现的新情况、新问题,从整合专业内容、创新教学方法、构建教学体系、规范教学管理、建设教员队伍、优化教学环境等方面提出了深化任职教育的途径及对策。 相似文献
544.
火控计算机的软件支持 总被引:1,自引:0,他引:1
针对机载、舰用以及地面火控计算机,阐述软件和软件支持的概念,强调软件支持应该遵守的前提原则,讨论软件支持的发展替续,并例举软件支持的实现过程。给出的结论和模式,对于火控软件的低成本获取具有参考价值,对于火控任务的高效率完成具有重要意义。 相似文献
545.
546.
547.
《防务技术》2020,16(6):1130-1141
Based on fuzzy adaptive and dynamic surface (FADS), an integrated guidance and control (IGC) approach was proposed for large caliber naval gun guided projectile, which was robust to target maneuver, canard dynamic characteristics, and multiple constraints, such as impact angle, limited measurement of line of sight (LOS) angle rate and nonlinear saturation of canard deflection. Initially, a strict feedback cascade model of IGC in longitudinal plane was established, and extended state observer (ESO) was designed to estimate LOS angle rate and uncertain disturbances with unknown boundary inside and outside of system, including aerodynamic parameters perturbation, target maneuver and model errors. Secondly, aiming at zeroing LOS angle tracking error and LOS angle rate in finite time, a nonsingular terminal sliding mode (NTSM) was designed with adaptive exponential reaching law. Furthermore, combining with dynamic surface, which prevented the complex differential of virtual control laws, the fuzzy adaptive systems were designed to approximate observation errors of uncertain disturbances and to reduce chatter of control law. Finally, the adaptive Nussbaum gain function was introduced to compensate nonlinear saturation of canard deflection. The LOS angle tracking error and LOS angle rate were convergent in finite time and whole system states were uniform ultimately bounded, rigorously proven by Lyapunov stability theory. Hardware-in-the-loop simulation (HILS) and digital simulation experiments both showed FADS provided guided projectile with good guidance performance while striking targets with different maneuvering forms. 相似文献
548.
549.
JAKKIE CILLIERS 《African Security Review》2013,22(3):123-126
Africa has emerged as a strategic location for transcontinental narcotics trade. Particularly the West African subcontinent has turned into a cocaine warehousing and trans-shipment hub along the way to the European underground markets. At this juncture, African drug networks (ADNs) began to play a momentous role in global drug trade, and pose a considerable threat to international security, as they operate in more than 80 countries. The United Nations Office on Drugs and Crime, Interpol, and Europol perceive ADNs as one of the primary issues in international counter-narcotics policy. These agencies have launched several multilateral initiatives to contain the West African threat. None of these initiatives, however, retarded the expansion of the problem. Indeed, the containment efforts turned out to be quite embryonic. The ADNs eventually entered the Turkish market by the early 2000s. West African drug networks (WADNs) in particular have begun to operate within Turkey extensively, often supplying and distributing drugs. The gravity of the threat became ever more serious by 2012. The upsurge of the new threat has compelled the Turkish drug-law enforcement agencies to adopt new policies and counter-strategies. These policies have to be based upon proper strategic analysis of the threat. This paper seeks to address the need for a threat assessment of ADNs. It investigates the dimensions of the problem, profiles the members of WADNs, their modes of operation, and the factors that compelled them to exploit the illicit Turkish drug markets. The analyses are based upon the scrutiny of 227 narcotic interdictions files and statements from the African individuals in these case files. The paper concludes by presenting policy implications and recommendations for the Turkish security and foreign-policy institutions to cope with this impending threat. 相似文献
550.
Mariam Jooma 《African Security Review》2013,22(1):55-60
Using crime review figures for four randomly selected states in Nigeria, this study examines cases of kidnapping and its implications for the national economy. The findings reveal that kidnapping is consistently on the increase in Nigeria and is not evenly spread across regions. It is shown that 15 cases were recorded in 2005 and 43 cases in 2008. In 2009, 138 cases were officially recorded, of which 22% and 76% occurred in Rivers and Edo states respectively. Findings further showed that modern kidnapping in Nigeria is triggered by resource control disputes directed both at oil expatriate workers and at prominent citizens, politicians and members of their families. The crisis, which came to the fore in 2005, has forced oil production shutdowns of up to 800 000 barrels per day. The study concludes that kidnapping is becoming a serious crime in Nigeria with significant negative implications for foreign investment, national foreign exchange earnings, and revenue generation. 相似文献