全文获取类型
收费全文 | 400篇 |
免费 | 79篇 |
国内免费 | 78篇 |
专业分类
航空 | 259篇 |
航天技术 | 86篇 |
综合类 | 94篇 |
航天 | 118篇 |
出版年
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 10篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 9篇 |
2015年 | 14篇 |
2014年 | 26篇 |
2013年 | 22篇 |
2012年 | 12篇 |
2011年 | 26篇 |
2010年 | 24篇 |
2009年 | 27篇 |
2008年 | 31篇 |
2007年 | 28篇 |
2006年 | 33篇 |
2005年 | 17篇 |
2004年 | 13篇 |
2003年 | 21篇 |
2002年 | 18篇 |
2001年 | 19篇 |
2000年 | 27篇 |
1999年 | 33篇 |
1998年 | 22篇 |
1997年 | 14篇 |
1996年 | 8篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有557条查询结果,搜索用时 15 毫秒
121.
研究了模糊控制应用于多输入、多输出的空间智能桁架系统的振动控制.首先建立空间智能桁架的有限元方程,在此基础上,设计了一个标准的模糊控制器,并通过选择合适的量化因子将该标准模糊控制器应用于每一对同位布置的作动器/传感器,各个控制器之间独立工作.这样就避免了设计MIMO模糊控制器带来的复杂问题.最后针对空间智能桁架进行仿真,结果表明,设计的模糊控制器可以有效抑制桁架的振动,并且具有结构简单、鲁棒性强、抑制控制溢出的优点. 相似文献
122.
卫星定位和卫星通讯是正在寻求的空间飞行器高级自主交会系统的首选测控手段。本文概述了航天器的交会对接基本要求和过程以及美国全球定位系统(GPS)和组成、定位原理、精度和差分原理后,列出了两种形式的相对运动方程。利用运动方程求解、单纯GPS、差分GPS的结合,可以完成追踪航天器向目标航天器接近的整个导引过程,且可以省去庞大的地面遥控遥测、星上雷达等设备,减少误差源。仿真计算证实了这一设计思想的可行性和 相似文献
123.
124.
本文通过边界元数值法求解了部分充液自旋球腔内的液体晃动问题。以流体运动的基本方程和系统运动的Euler动力学方程为基础,考虑了贮箱偏置、涡旋、重力及Coriolis力等因素对流体晃动和系统运动状态的影响,求解出液体的速度场,并在此基础上估算液体的能量耗散率和系统的章动时间常数 相似文献
125.
126.
127.
128.
129.
Tao Yu Tian Mao Yungang Wang Zhongcao Zeng Chunliang Xia Fenglei Wu Le Wang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
With the rapid increase of GPS/GNSS receivers being deployed and operated in China, real-time GPS data from nearly a thousand sites are available at the National Center for Space Weather, China Meteorology Administration. However, it is challenging to generate a high-quality regional total electron content (TEC) map with the traditional two-dimensional (2-D) retrieval scheme because a large horizontal gradient has been reported over east–south Asia due to the northern equatorial ionization anomaly. We developed an Ionosphere Data Assimilation Analysis System (IDAAS), which is described in this study, using an International Reference Ionosphere (IRI) model as the background and applying a Kalman filter for updated observations. The IDAAS can reconstruct a three-dimensional ionosphere with the GPS slant TEC. The inverse slant TEC correlates well with observations both for GPS sites involved in the reconstruction and sites that are not involved. Based on the IDAAS, simulations were performed to investigate the deviation relative to the slant-to-vertical conversion (STV). The results indicate that the relative deviation induced by slant-to-vertical conversion may be significant in certain instances, and the deviation varies from 0% to 40% when the elevation decreases from 90° to 15°, while the relative IDAAS deviation is much smaller and varies from −5% to 15% without an elevation dependence. Compared with ‘true TEC’ map derived from the model, there is large difference in STV TEC map but no obvious discrepancy in IDAAS map. Generally, the IDAAS TEC map is much closer to the “true TEC” than is STV TEC map is. 相似文献
130.
Andrea DAmbrosio Christian Circi Xiangyuan Zeng 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(11):3691-3705
Solar-photon sails can be useful for missions towards and about asteroids. Indeed, for the interplanetary transfer phase, missions to asteroids often require a large variation in inclination and solar-photon sails perform very well for such high energy missions. In the same way, solar-photon sails are also expected to perform well in the phase about the asteroid. This paper studies single and binary asteroids’ hovering regions by using a sailcraft. In order to consider a sailcraft with its own mass and shape, the mutual polyhedral method (usually used to study asteroid dynamics) is used; therefore, the sailcraft is designed by means of tetrahedra. The procedure to obtain the hovering regions about a single asteroid is presented and an accurate analysis of the control variables is carried out. Moreover, control torques required to maintain hovering orbits are obtained by considering the gravitational torques acting on the sailcraft due to the asteroid. In the end, the theory for hovering orbits is extended to binary-asteroid systems and applied to the binary system 1999 KW4. 相似文献