全文获取类型
收费全文 | 2025篇 |
免费 | 277篇 |
国内免费 | 222篇 |
专业分类
航空 | 930篇 |
航天技术 | 610篇 |
综合类 | 144篇 |
航天 | 840篇 |
出版年
2024年 | 11篇 |
2023年 | 43篇 |
2022年 | 67篇 |
2021年 | 63篇 |
2020年 | 79篇 |
2019年 | 69篇 |
2018年 | 66篇 |
2017年 | 85篇 |
2016年 | 78篇 |
2015年 | 86篇 |
2014年 | 115篇 |
2013年 | 80篇 |
2012年 | 156篇 |
2011年 | 148篇 |
2010年 | 114篇 |
2009年 | 105篇 |
2008年 | 100篇 |
2007年 | 128篇 |
2006年 | 140篇 |
2005年 | 88篇 |
2004年 | 87篇 |
2003年 | 86篇 |
2002年 | 59篇 |
2001年 | 69篇 |
2000年 | 61篇 |
1999年 | 58篇 |
1998年 | 44篇 |
1997年 | 35篇 |
1996年 | 26篇 |
1995年 | 36篇 |
1994年 | 24篇 |
1993年 | 21篇 |
1992年 | 27篇 |
1991年 | 21篇 |
1990年 | 21篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 10篇 |
排序方式: 共有2524条查询结果,搜索用时 15 毫秒
1.
《中国航空学报》2020,33(3):749-770
Angle of Attack (AOA) is a crucial parameter which directly affects the aerodynamic forces of an aircraft. The measurement of AOA is required to ensure a safe flight within its designed flight envelop. This paper intends to summarise a comprehensive survey on the measurement techniques and estimation methods for AOA, specifically in Unmanned Aerial Vehicle (UAV) applications. In the case of UAVs, weight constraint plays a major role as far as sensor suites are concerned. This results in selecting a suitable estimation method to extract AOA using the available data from the autopilot. The most feasible and widely employed AOA measurement technique is by using the Multi-Hole Probes (MHPs). The MHP measures the AOA regarding the pressure variations between the ports. Due to the importance of MHP in AOA measurement, the calibration methods for the MHP are also included in this paper. This paper discusses the AOA measurement using virtual AOA sensors, their importance and the operation. 相似文献
2.
《中国航空学报》2020,33(10):2716-2727
In this paper, an Unmanned Aerial Vehicle (UAV) enabled Mobile Edge Computing (MEC) system is studied, in which UAV acts as server to offer computing offloading service to the Mobile Users (MUs) with limited computing capability and energy budget. We aim to minimize the total energy consumption of MUs by jointly optimizing the bit allocation for uplink, computing at the UAV and downlink, along with the UAV trajectory in a unified framework. To this end, a trajectory constraint model is employed to avoid sudden changes of velocity and acceleration during flying. Due to high-order information in use, we lead to a more reasonable nonconvex optimization problem than prior arts. An Alternating Direction Method of Multipliers (ADMM) method is introduced to solve the optimization problem, which is decomposed into a set of easy sub-problems, to meet the requirement on the efficiency in edge computing. Numerical results demonstrate that our approach leads a smoother UAV trajectory, significantly save the energy consumption for UAV during flying. 相似文献
3.
4.
5.
介绍了光敏元件与光传感器技术的发展及在国民经济和军事领域中的重要怍用;分析了国内外光电子产业的市场动态与发展趋势;论述了我国光电子产业面临的机遇和挑战。 相似文献
6.
航天遥感仪器的反射镜轻量化的研究 总被引:6,自引:0,他引:6
反射镜轻量化是航天遥感仪器轻型化的重要技术途径之一。阐述了反射镜轻量化的意义,反射镜材料的选择,玻璃反射镜轻量化的结构型式和设计要求、设计方案和计算以及温度试验结果。 相似文献
7.
我省高职高专院校图书馆现代技术应用情况调查 总被引:2,自引:0,他引:2
目的比较与探讨不同类型高职高专图书馆现代化技术应用情况方法采用自编问卷对部分高职高专图书馆进行调查结果高职高专图书馆情况差异较大二级学院、民办学院处于前列,新高职、高专、职工大学紧随其后,挂靠学院与普通中专正在崛起。 相似文献
8.
The architecture of digital sheet metal manufacturing system is proposed based on the classification of sheet metal manufacturing information.The essence of digital manufacturing is the definition,management and transfer of information,and the key technologies are brought forward and described.It is pointed out that knowledge-based manufacturing elements design is necessary to make digital technology efficient.The management of all kinds of sheet metal manufacturing element information is to build single source of manufacturing data.Multi-state model-based digital transfer and coordination method is designed to provide a foundation for digital manufacturing of aircraft sheet metal part.The application of digital sheet metal manufacturing is exemplified with an aircraft sheet metal part.The application result is compared to that of the traditional analog transfer technology.It is shown that the developed technology can improve part quality,shorten manufacturing time and lower manufacturing cost. 相似文献
9.
文章简述了星载遥感器辐射定标设备的研制过程及其在模拟空间环境中的调试过程,试验证明了该设备设计的合理性。 相似文献
10.