全文获取类型
收费全文 | 1068篇 |
免费 | 228篇 |
国内免费 | 215篇 |
专业分类
航空 | 1080篇 |
航天技术 | 131篇 |
综合类 | 122篇 |
航天 | 178篇 |
出版年
2024年 | 1篇 |
2023年 | 15篇 |
2022年 | 27篇 |
2021年 | 54篇 |
2020年 | 52篇 |
2019年 | 45篇 |
2018年 | 44篇 |
2017年 | 56篇 |
2016年 | 73篇 |
2015年 | 64篇 |
2014年 | 82篇 |
2013年 | 75篇 |
2012年 | 106篇 |
2011年 | 93篇 |
2010年 | 75篇 |
2009年 | 70篇 |
2008年 | 75篇 |
2007年 | 51篇 |
2006年 | 43篇 |
2005年 | 53篇 |
2004年 | 40篇 |
2003年 | 34篇 |
2002年 | 35篇 |
2001年 | 24篇 |
2000年 | 30篇 |
1999年 | 25篇 |
1998年 | 23篇 |
1997年 | 35篇 |
1996年 | 20篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 18篇 |
1992年 | 9篇 |
1991年 | 20篇 |
1990年 | 10篇 |
1989年 | 9篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 2篇 |
排序方式: 共有1511条查询结果,搜索用时 156 毫秒
811.
HUANG Xu-dong CHEN Hai-xin FU Song David Wisler Aspi Wadi G. Scott McNulty 《航空动力学报》2007,22(9):1455-1460
IntroductionVortex is often the essential element re-sponsible for triggering stall and surge in com-pressors.So the identification and the analysisof the vortices in compressor are usually quitehelpful for the understanding of the compressorbehavior.Howe… 相似文献
812.
813.
814.
815.
The fine space-time structure of a vortex generator (VG) in supersonic flow is studied with the nanoparticle-based planar laser scattering (NPLS) method in a quiet supersonic wind tunnel. The fine coherent structure at the symmetrical plane of the flow field around the VG is imaged with NPLS. The spatial structure and temporal evolution characteristics of the vortical structure are analyzed, which demonstrate periodic evolution and similar geometry, and the characteristics of rapid movement and slow change. Because the NPLS system yields the flow images at high temporal and spatial resolutions, from these images the position of a large scale structure can be extracted precisely. The position and velocity of the large scale structures can be evaluated with edge detection and correlation algorithms. The shocklet structures induced by vortices are imaged, from which the generation and development of shocklets are discussed in this paper. 相似文献
816.
817.
燃油泵调节器供油特性的优劣,直接关系到航空发动机能否可靠工作和充分发挥性能。某燃气涡轮起动机燃油泵调节器,为满足用户使用要求,需改变其起动加速供油特性。主要通过增加数控模块,利用其控制器和传感器来实现信号的反馈与匹配,再通过放油实现脉宽调制电磁阀对流量的修正,从而实现对燃油泵调节器起动加速供油特性的修正。最后通过试验验证了改进方法的可行性。 相似文献
818.
Generally, casing treatment(CT) is a passivity method to enhance the stall margin of fan/compressor. A novel casing treatment based on the small disturbance theory and vortex and wave interaction suggestion is a method combining passive control and active control, which has been proved effective at enhancing the stall margin of fan/compressor in experiment. In order to investigate the mechanism of this kind of casing treatment, an experimental investigation of a stall precursor-suppressed(SPS) casing treatment with air suction or blowing air is conducted in the present paper. The SPS casing treatment is designed to suppressing stall precursors to realize stall margin enhancement in turbomachinery. The experimental results show that the casing treatment with blowing air of small quantity can improve the stall margin by about 8% with about 1% efficiency loss. By contrast, the SPS casing treatment with micro-bias flow does not improve the stall margin much more than that without bias flow, even worse. Meanwhile, the present investigation has also attempted to reveal the mechanism of stall margin improvement with the casing treatment.It is found that the stall margin improvements vary with the modification of the unsteady shedding flow and the unsteady wall boundary impedance. The experimental results agree fairly well with the theoretical prediction using a flow stability model of rotating stall. 相似文献
819.
820.