全文获取类型
收费全文 | 199篇 |
免费 | 8篇 |
国内免费 | 75篇 |
出版年
2023年 | 15篇 |
2021年 | 12篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2014年 | 6篇 |
2013年 | 9篇 |
2011年 | 1篇 |
2010年 | 2篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 7篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 9篇 |
1997年 | 25篇 |
1996年 | 15篇 |
1995年 | 16篇 |
1994年 | 18篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 18篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1984年 | 5篇 |
1983年 | 1篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 14篇 |
1979年 | 4篇 |
1977年 | 10篇 |
1976年 | 6篇 |
1973年 | 7篇 |
排序方式: 共有282条查询结果,搜索用时 609 毫秒
231.
Unexploded ordnance(UXO) poses a threat to soldiers operating in mission areas, but current UXO detection systems do not necessarily provide the required safety and efficiency to protect soldiers from this hazard. Recent technological advancements in artificial intelligence(AI) and small unmanned aerial systems(sUAS) present an opportunity to explore a novel concept for UXO detection. The new UXO detection system proposed in this study takes advantage of employing an AI-trained multi-spectral(MS... 相似文献
232.
In this study, high velocity impact behaviour of friction stir welded AA7075-T651 25 mm thick plates were investigated using a 7.62 mm × 51 mm lead core and 7.62 mm × 39 mm steel core projectiles. Prior to ballistic trails, mechanical and metallurgical properties of friction stir welded AA 7075-T651 25 mm thick plates were studied. Microstructural and hardness studies revealed that friction stir welds constituted three distinct regions namely Weld Nugget(WN), Thermo-Mechanically Affected Zone(TM... 相似文献
233.
As an innovative propulsion technique, laser augmented chemical propulsion(LACP) seems superior to the traditional ones. However, the corresponding combustion theories have still to be ascertained for LACP. Burning rate of 5-aminotetrazole(5-ATZ) propellant has been studied by testing pressed samples under different combustor pressures and laser powers. Based on micro computed tomography(Micro CT),an advanced thickness-over-time(TOT) method to characterize the regression of the produced nonplana... 相似文献
234.
Wojciech Przyby? Adam Januszko Norbert Radek Marcin Szczepaniak Krzysztof A.Bogdanowicz Ireneusz Plebankiewicz Bogus?awa Szczodrowska Robert Mazurczuk 《防务技术》2023,(4):1-9
The paper explores the possibilities of using carbonyl iron in the form of a powder for the manufacture of radar-absorbing paints-reducing the radar signature of the objects that they cover. The attenuation values in the range of 4-18 GHz for various coating thicknesses, ranging from 0.5 to 2.00 mm with 0.5 mm increment, and for different absorber content-75% and 80%, as well as the use of two different binders in the form of epoxy resins with hardeners, were investigated. For the frequency of 1... 相似文献
235.
236.
237.
238.
239.
如果莫迪政策得以贯彻,那么实施了约25年的“向东看”政策将升级为“向东行动”政策。莫迪印太政策包括三个方面:一、精心构织印度洋一太平洋地区的战略伙伴关系;二、加强海上安全能力建设;三、积极参与地区事务。莫迪欲通过以上三个方面来实现在印太地区的战略影响。 相似文献
240.