全文获取类型
收费全文 | 94篇 |
免费 | 152篇 |
国内免费 | 15篇 |
专业分类
航空 | 212篇 |
航天技术 | 16篇 |
综合类 | 6篇 |
航天 | 27篇 |
出版年
2023年 | 2篇 |
2022年 | 12篇 |
2021年 | 16篇 |
2020年 | 7篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2013年 | 25篇 |
2012年 | 10篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 5篇 |
2006年 | 10篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 10篇 |
2001年 | 13篇 |
2000年 | 15篇 |
1999年 | 12篇 |
1998年 | 11篇 |
1997年 | 16篇 |
1996年 | 14篇 |
1995年 | 6篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 7篇 |
1987年 | 3篇 |
排序方式: 共有261条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
95.
96.
伴随着高速、高效、高精加工技术的飞速发展,电主轴产品得到了极为广泛的应用,课题分别以转速和转矩为核心要素对电机与驱动相关技术进行了分析,为不同应用场合电主轴产品的电机与驱动设计方案给予较为准确的评价和指导。 相似文献
97.
98.
《中国航空学报》2020,33(2):520-528
The tire spray produced by aircraft running on wet runways may enter the intake of engines, which may lead to the compressor stall, surge, or even combustion flameout. Therefore, it is necessary to do some research work on the tire spray to help to solve this problem. Firstly, the mechanism of tire spray is analyzed, and some parameters are defined to describe the spray pattern. Secondly, the numerical model of tire spray is established by coupled Smoothed Particle Hydrodynamics (SPH) and Finite Element Method (FEM) in LS-DYNA software, and the model is validated by a simplified water spray experiment. Then some influence factors on the spray pattern are studied by numerical simulation. Finally, some suggestions are proposed on different types of aircraft to avoid too much tire spray being ingested into the engine intakes. 相似文献
99.
《中国航空学报》2020,33(12):3112-3124
This paper presents a method to predict the pilot workload in helicopter landing after one engine failure. The landing procedure is simulated numerically via applying nonlinear optimal control method in the form of performance index, path constraints and boundary conditions based on an augmented six-degree-of-freedom rigid-body flight dynamics model, solved by collocation and numerical optimization method. UH-60A helicopter is taken as the sample for the demonstration of landing after one engine failure. The numerical simulation was conducted to find the trajectory of helicopter and the controls from pilot for landing after one engine failure with different performance index considering the factor of pilot workload. The reasonable performance index and corresponding landing trajectory and controls are obtained by making a comparison with those from the flight test data. Furthermore, the pilot workload is evaluated based on wavelet transform analysis of the pilot control activities. The workloads of pilot control activities for collective control, longitudinal and lateral cyclic controls and pedal control during the helicopter landing after one engine failure are examined and compared with those of flight test. The results show that when the performance index considers the factor of pilot workload properly, the characteristics of amplitudes and constituent frequencies of pilot control inputs in the optimal solution are consistent with those of the pilot control inputs in the flight test. Therefore, the proposed method provides a tool of predicting the pilot workload in helicopter landing after one engine failure. 相似文献
100.