全文获取类型
收费全文 | 255篇 |
免费 | 88篇 |
国内免费 | 9篇 |
专业分类
352篇 |
出版年
2022年 | 4篇 |
2021年 | 17篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 8篇 |
2012年 | 5篇 |
2011年 | 12篇 |
2010年 | 19篇 |
2009年 | 26篇 |
2008年 | 10篇 |
2007年 | 14篇 |
2006年 | 13篇 |
2005年 | 15篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 5篇 |
2000年 | 4篇 |
1999年 | 31篇 |
1998年 | 26篇 |
1997年 | 13篇 |
1996年 | 21篇 |
1995年 | 13篇 |
1994年 | 10篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1982年 | 2篇 |
排序方式: 共有352条查询结果,搜索用时 0 毫秒
301.
To deal with the radio frequency threat posed by modern complex radar networks to aircraft, we researched the unmanned aerial vehicle (UAV) formations radar countermeasures, aiming at the solution of radar jamming resource allocation under system countermeasures. A jamming resource allocation method based on an improved firefly algorithm (FA) is proposed. Firstly, the comprehensive factors affecting the level of threat and interference efficiency of radiation source are quantified by a fuzzy comprehensive evaluation. Besides, the interference efficiency matrix and the objective function of the allocation model are determined to establish the interference resource allocation model. Finally, A mutation operator and an adaptive heuristic are integtated into the FA algorithm, which searches an interference resource allocation scheme. The simulation results show that the improved FA algorithm can compensate for the deficiencies of the FA algorithm. The improved FA algorithm provides a more sci-entific and reasonable decision-making plan for aircraft mission allocation and can effectively deal with the battlefield threats of the enemy radar network. Moreover, in terms of convergence accuracy and speed as well as algorithm stability, the improved FA algorithm is superior to the simulated annealing algorithm (SA), the niche genetic algorithm (NGA), the improved discrete cuckoo algorithm (IDCS), the mutant firefly algorithm (MFA), the cuckoo search and fireflies algorithm (CSFA), and the best neighbor firefly algorithm (BNFA). 相似文献
302.
303.
采用流动注射分析技术建立了Zn^2+的FIA分析方法.谊分析方法可行、简便。其数据可靠,具有较好的选择性和重现性.样品测定频率大于30个/h;在1.0~5.0mg/L范围内呈良好的线性关系,γ=0.9999;回收率大于98%.实现了烟幕剂成烟产物中Zn^2+的快速定量测定. 相似文献
304.
Approximation schemes for single‐machine scheduling with a fixed maintenance activity to minimize the total amount of late work 下载免费PDF全文
We consider the problem of scheduling n independent and simultaneously available jobs without preemption on a single machine, where the machine has a fixed maintenance activity. The objective is to find the optimal job sequence to minimize the total amount of late work, where the late work of a job is the amount of processing of the job that is performed after its due date. We first discuss the approximability of the problem. We then develop two pseudo‐polynomial dynamic programming algorithms and a fully polynomial‐time approximation scheme for the problem. Finally, we conduct extensive numerical studies to evaluate the performance of the proposed algorithms. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 172–183, 2016 相似文献
305.
The paper analyzes the effects of military spending on economic growth in a small open stochastic endogenous growth model involving the supply-side and demand-side effects produced by military spending. We show that a rise in the military spending affects economic growth through four channels, including the crowding-out effect, the spin-off effect, the resource mobilization effect, and the portfolio effect. The net effect which depends on these four channels is ambiguous. Hence, we demonstrate that there exists an optimal defense burden that maximizes the economic growth rate. 相似文献
306.
研制了一种测量脉冲高电压的电容分压器,从理论和实验两个方面分析了高电压脉冲的频率对电容分压器分压比的影响。并用此电容分压器测量了Tesla变压器型强流电子束加速器的谐振特性波形,测量结果与理论分析一致。 相似文献
307.
Shang-su Wu 《Defence Studies》2018,18(1):76-94
As fixed facilities, naval fortresses seem unlikely to be important in a sea denial strategy which is usually about mobility, but new defence technologies and the changing geostrategic environment may revive the concept of the fortress. Extended ranges of anti-ship means allow onshore firepower to engage enemies over distance, even beyond the economic exclusive zones where most maritime territorial disputes occur. In the face of size limits on missile warheads that constrain their destruction of hardened targets, various active and passive defence technologies against missiles can enhance the survivability of onshore fortresses. Furthermore, onshore locations give fortresses the advantage of being unsinkable and able to accommodate greater energy and firepower capacity in contrast to vessels, as well as other mobile platforms. The onshore nature of fortresses also gives a different political meaning to being attacked, for the clear violation of sovereignty, as opposed to vessels and aircraft in a disputed space. However, the fact those fortresses are not invincible means cooperation with other existing capabilities still necessary. The case of Vietnam demonstrates how fortresses could strengthen the inferior defence capability of a coastal state vis-à-vis. a stronger sea power. 相似文献
308.
引战一体化设计是一个先进的设计理念,分析了引战一体化设计的内涵,它应包括:引战功能一体化和引战结构设计一体化两部分,详细阐述了引战结构一体化的设计设想和引战功能一体化中各设计变量及数学模型,并给出了“最佳有效毁伤效果”的概念。 相似文献
309.
吴志忠 《军队政工理论研究》2007,8(3):7-9
军队要为构建社会主义和谐社会作贡献,必须紧紧围绕履行我军历史使命,着眼于维护党的执政地位,进一步筑牢军魂,把听党指挥作为人民军队的最高政治要求;着眼于维护国家发展,以提高打赢能力为核心,提高应对多样化威胁、完成多样化任务的能力;着眼于维护世界和平,增强我军“软实力”,为建设和谐世界作出积极贡献。 相似文献
310.
本文介绍了一种新型多功能地面战场侦察雷达系统设计思路,阐述了利用相控阵技术实现雷达系统的战术多功能,综合其他类型传感器的使用进行数据融合,可对目标类型进行自动分类和识别。另外对实现该雷达系统的关键技术可行性和方法进行了简单的讨论和分析。 相似文献