全文获取类型
收费全文 | 762篇 |
免费 | 117篇 |
国内免费 | 52篇 |
专业分类
航空 | 321篇 |
航天技术 | 360篇 |
综合类 | 66篇 |
航天 | 184篇 |
出版年
2024年 | 3篇 |
2023年 | 15篇 |
2022年 | 18篇 |
2021年 | 14篇 |
2020年 | 28篇 |
2019年 | 37篇 |
2018年 | 30篇 |
2017年 | 30篇 |
2016年 | 22篇 |
2015年 | 30篇 |
2014年 | 44篇 |
2013年 | 37篇 |
2012年 | 54篇 |
2011年 | 74篇 |
2010年 | 40篇 |
2009年 | 48篇 |
2008年 | 50篇 |
2007年 | 35篇 |
2006年 | 36篇 |
2005年 | 34篇 |
2004年 | 35篇 |
2003年 | 19篇 |
2002年 | 25篇 |
2001年 | 32篇 |
2000年 | 25篇 |
1999年 | 14篇 |
1998年 | 17篇 |
1997年 | 6篇 |
1996年 | 9篇 |
1995年 | 16篇 |
1994年 | 12篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 1篇 |
排序方式: 共有931条查询结果,搜索用时 15 毫秒
761.
在航空发动机控制系统中,存在着大量直流驱动负载,如力矩马达、电液伺服阀等。高精度,高稳定性的直流驱动电路对发动机控制系统的性能有着至关重要的影响。针对以往采用分立元器件设计的电路,精度较低,电路设计复杂,采用集成元器件设计直流驱动电路,提高了系统精度,简化了电路设计,同时降低了设备的重量和体积。 相似文献
762.
Yuanyong Deng Jingxiu WangGuoxiang Ai 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
The nature of a magnetic element, the elemental structure of the solar magnetic field, is one of the most important mysteries in solar physics. In this paper, we will discuss the requirements of magnetic element detection, such as spatial resolution and magnetic sensitivity. By these discussions, we conclude that it is almost impossible to detect magnetic element with currently used ground-based telescopes and techniques. The proposed Space Solar Telescope, a one-meter Chinese space project, can match these requirements. 相似文献
763.
C. Rioux R.J. Slobodrian 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The aggregates formed in low gravity are generally fractals. The fractal dimensions and the site growth probability measures of the resulting fractal structures strongly depend on the properties of the forces that cause the aggregation. Using some approximations, we solved the equation of motion and obtained the relation giving the particles separation as a function of time. The electric force between two charged particles and the magnetic force between two particles with a magnetic moment were considered. The two relations are different and it is shown that one can identify and separate these two interactions by analysing the recording of the aggregation. The apparatus used to record the aggregation has a resolution in the order of one micrometer per pixel and has the possibility of recording simultaneously two views at right angles. From a three dimensional recording of an aggregation, it will be possible to obtain the product of the two charges or magnetic moments causing the aggregation. 相似文献
764.
邓瑶 《西安航空技术高等专科学校学报》2012,(5):76-79
在介绍布鲁姆目标教学方法的基础上,提出目标教学方法在教学实践中的运行模式,并将其应用于《电路分析》教学实践中。多年来的教学实践证明,基于目标教学的方法对于全面培养学生的学习技能,充分激发学生的学习兴趣,提高教学效果具有显著成效。 相似文献
765.
L.L. Lazutin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
Temporal variations of the radiation belt particle during the magnetic storms are investigated using measurements by the low altitude satellite spectrometer. Along with several known effects, such as the outer radiation belt intensity decrease at the main phase, the radial diffusion with the particle acceleration and the recovery of the radiation belt during the recovery phase, some less known features were investigated, such as the dawn–dusk asymmetry of the radiation belt. 相似文献
766.
767.
768.
769.
利用CFX软件对某航空发动机应急油路内部流动进行模拟,通过计算得到该航空发动机应急油路喷嘴出口压力随引射角度、引射距离、引射压力及喷嘴安装孔直径的变化规律。 相似文献
770.