全文获取类型
收费全文 | 2533篇 |
免费 | 252篇 |
国内免费 | 386篇 |
专业分类
航空 | 768篇 |
航天技术 | 1269篇 |
综合类 | 258篇 |
航天 | 876篇 |
出版年
2024年 | 4篇 |
2023年 | 44篇 |
2022年 | 49篇 |
2021年 | 101篇 |
2020年 | 79篇 |
2019年 | 63篇 |
2018年 | 72篇 |
2017年 | 35篇 |
2016年 | 64篇 |
2015年 | 67篇 |
2014年 | 206篇 |
2013年 | 132篇 |
2012年 | 100篇 |
2011年 | 215篇 |
2010年 | 168篇 |
2009年 | 172篇 |
2008年 | 133篇 |
2007年 | 101篇 |
2006年 | 106篇 |
2005年 | 132篇 |
2004年 | 78篇 |
2003年 | 71篇 |
2002年 | 84篇 |
2001年 | 82篇 |
2000年 | 104篇 |
1999年 | 119篇 |
1998年 | 95篇 |
1997年 | 73篇 |
1996年 | 69篇 |
1995年 | 60篇 |
1994年 | 65篇 |
1993年 | 43篇 |
1992年 | 28篇 |
1991年 | 28篇 |
1990年 | 29篇 |
1989年 | 27篇 |
1988年 | 36篇 |
1987年 | 16篇 |
1986年 | 17篇 |
1984年 | 4篇 |
排序方式: 共有3171条查询结果,搜索用时 343 毫秒
961.
Survey of orbital dynamics and control of space rendezvous 总被引:2,自引:1,他引:1
Rendezvous orbital dynamics and control (RODC) is a key technology for operating space rendezvous and docking missions. This paper surveys the studies on RODC. Firstly, the basic relative dynamics equation set is introduced and its improved versions are evaluated. Secondly, studies on rendezvous trajectory optimization are commented from three aspects: the linear rendez- vous, the nonlinear two-body rendezvous, and the perturbed and constrained rendezvous. Thirdly, studies on relative navigation are briefly reviewed, and then close-range control methods including automated control, manual control, and telecontrol are analyzed. Fourthly, advances in rendezvous trajectory safety and robust analysis are surveyed, and their applications in trajectory optimization are discussed. Finally, conclusions are drawn and prospects of studies on RODC are presented. 相似文献
962.
The application of high-performance imaging sensors in space-based space surveillance systems makes it possible to recognize space objects and estimate their poses using vision-based methods. In this paper, we proposed a kernel regression-based method for joint multi-view space object recognition and pose estimation. We built a new simulated satellite image dataset named BUAA-SID 1.5 to test our method using different image representations. We evaluated our method for recognition-only tasks, pose estimation-only tasks, and joint recognition and pose estimation tasks. Experimental results show that our method outperforms the state-of-the-arts in space object recognition, and can recognize space objects and estimate their poses effectively and robustly against noise and lighting conditions. 相似文献
963.
Based on the uncertainty theory, this paper is devoted to the redundancy allocation problem in repairable parallel-series systems with uncertain factors, where the failure rate, repair rate and other relative coefficients involved are considered as uncertain variables. The availability of the system and the corresponding designing cost are considered as two optimization objectives. A crisp multiobjective optimization formulation is presented on the basis of uncertainty theory to solve this resultant problem. For solving this problem efficiently, a new multiobjective artificial bee colony algorithm is proposed to search the Pareto efficient set, which introduces rank value and crowding distance in the greedy selection strategy, applies fast non-dominated sort procedure in the exploitation search and inserts tournament selection in the onlooker bee phase. It shows that the proposed algorithm outperforms NSGA-II greatly and can solve multiobjective redundancy allocation problem efficiently. Finally, a numerical example is provided to illustrate this approach. 相似文献
964.
965.
966.
967.
迎接航空工业新一轮技术革命 总被引:1,自引:0,他引:1
以波音787和F-35为代表的高复杂性与高风险并存的大型飞机项目,虽然严格按照系统工程进行管理,却屡屡出现延迟交付和成本超支等问题,由此引发了业界的深刻反思.传统的系统工程方法只适用于过去各个组成部分可分解的结构性复杂项目,而今天的大型项目由于大量采用了软件、供应链发生了重大改变,使得由此形成的整体复杂性用传统的系统工... 相似文献
968.
969.
目前基于模型的控制方法是空间机器人遥操作控制的主流方法,但该方法不可避免地会引入运动的累积误差,甚至造成控制失稳。针对这一问题,基于自抗扰控制方法为空间机器人主从遥操作设计了一类单关节控制器,并采用计算机仿真方法研究了其基本性能,结果表明所设计的自抗扰控制器能够实现稳定的遥操作控制,且具有良好的抗扰性和鲁棒性。特别是由于自抗扰控制方法不依赖于机器人的数学模型,因此十分适合作为现行基于模型控制的有益补充。 相似文献
970.