全文获取类型
收费全文 | 1793篇 |
免费 | 213篇 |
国内免费 | 94篇 |
专业分类
航空 | 302篇 |
航天技术 | 864篇 |
综合类 | 30篇 |
航天 | 904篇 |
出版年
2024年 | 1篇 |
2023年 | 33篇 |
2022年 | 36篇 |
2021年 | 63篇 |
2020年 | 58篇 |
2019年 | 44篇 |
2018年 | 57篇 |
2017年 | 17篇 |
2016年 | 31篇 |
2015年 | 47篇 |
2014年 | 174篇 |
2013年 | 100篇 |
2012年 | 66篇 |
2011年 | 166篇 |
2010年 | 116篇 |
2009年 | 114篇 |
2008年 | 105篇 |
2007年 | 89篇 |
2006年 | 81篇 |
2005年 | 109篇 |
2004年 | 70篇 |
2003年 | 41篇 |
2002年 | 56篇 |
2001年 | 46篇 |
2000年 | 55篇 |
1999年 | 61篇 |
1998年 | 38篇 |
1997年 | 31篇 |
1996年 | 31篇 |
1995年 | 29篇 |
1994年 | 14篇 |
1993年 | 19篇 |
1992年 | 12篇 |
1991年 | 17篇 |
1990年 | 17篇 |
1989年 | 18篇 |
1988年 | 24篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1984年 | 2篇 |
排序方式: 共有2100条查询结果,搜索用时 0 毫秒
901.
文章介绍了北京空间机电研究所50年来在回收与着陆技术、航天光学遥感技术和复合材料成型技术领域所取得的成就,并对三大技术领域的后续发展进行了展望. 相似文献
902.
T. Flohrer T. SchildknechtR. Musci 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(7):1010-1021
Two ESA-funded feasibility studies that aimed to develop observation strategies, to propose suitable sensor architectures, and to assess the expected performance of an independent European Space Surveillance System were carried out during the last years. The French company ONERA led two study teams comprising a number of European companies. 相似文献
903.
Redundant space manipulators, including Space Station Remote Manipulator System (SSRMS), Special Purpose Dexterous Manipulator (SPDM) and European Robotic Arm (ERA), have been playing important roles in the construction and maintenance of International Space Station (ISS). They all have 7 revolute joints arranged in similar configurations, and are referred to as SSRMS-type manipulators. 相似文献
904.
空间光学系统技术发展探讨 总被引:1,自引:0,他引:1
文章总览国际典型大科学工程和计划,对空间光学系统技术在过去20年的发展做出了简要的归纳和总结。同时通过跟踪一些领域前沿和技术生长点,指出了一些可能对未来空间光学系统带来重大改变的方向。 相似文献
905.
P. Papushev Yu. KaravaevM. Mishina 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
On the base of the photometrical data an analysis of the periods and light curves of the uncontrolled artificial satellites was performed. 相似文献
906.
Werner R. Balogh Hans J. Haubold 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009,43(12):1847-1853
The United Nations Programme on Space Applications, implemented by the United Nations Office for Outer Space Affairs, promotes the benefits of space-based solutions for sustainable economic and social development. The Programme assists Member States of the United Nations to establish indigenous capacities for the use of space technology and its applications. In the past the Programme has primarily been focusing on the use of space applications and on basic space science activities. However, in recent years there has been a strong interest in a growing number of space-using countries to build space technology capacities, for example, the ability to develop and operate small satellites. In reaction to this development, the United Nations in cooperation with the International Academy of Astronautics has been organizing annual workshops on small satellites in the service of developing countries. Space technology related issues have also been addressed as part of various other activities of the Programme on Space Applications. Building on these experiences, the Office for Outer Space Affairs is now considering the launch of a new initiative, preliminarily titled the United Nations Basic Space Technology Initiative (UNBSTI), to promote basic space technology development. The initiative would be implemented in the framework of the Programme on Space Applications and its aim would be to help building sustainable capacities for basic space technology education and development, thereby advancing the operational use of space technology and its applications. 相似文献
907.
R.T. James McAteer Peter T. GallagherPaul A. Conlon 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
The issue of predicting solar flares is one of the most fundamental in physics, addressing issues of plasma physics, high-energy physics, and modelling of complex systems. It also poses societal consequences, with our ever-increasing need for accurate space weather forecasts. Solar flares arise naturally as a competition between an input (flux emergence and rearrangement) in the photosphere and an output (electrical current build up and resistive dissipation) in the corona. Although initially localised, this redistribution affects neighbouring regions and an avalanche occurs resulting in large scale eruptions of plasma, particles, and magnetic field. As flares are powered from the stressed field rooted in the photosphere, a study of the photospheric magnetic complexity can be used to both predict activity and understand the physics of the magnetic field. The magnetic energy spectrum and multifractal spectrum are highlighted as two possible approaches to this. 相似文献
908.
This viewpoint examines the likely reasons behind the renewed focus on international cooperation in the new US National Space Policy, noting that the rise of various Asian space powers is one factor. It demonstrates the increase in US-Asian space cooperation that is already underway, arguing that such cooperation can only be to the good in providing Asian countries with a greater degree of cutting-edge technology and know-how, as well as contributing to the overall safety and security of outer space. Nevertheless, there will doubtless be problems such as cost overruns and delays and effort will have to be applied if cooperation is to work. 相似文献
909.
Whipple shield is widely used on manned spacecraft, numerical simulation is an important way for obtaining the ballistic limit. The large population of particles and the large space span of Whipple shield simulation model restrict the computational efficiency. A fast numerical approach is presented for Whipple shield ballistic limit analysis. First, the critical penetration analysis of the rear walls is converted into specific impulse analysis delivered by the secondary debris cloud, because the maximum of specific impulse is the main determinant of the penetration. The dual plate simulation model is then converted into single plate model and the population of particles is reduced. Second, based on the isotropic expansion theory of secondary debris cloud, the specific impulse analysis is further converted into particle position and velocity analysis when the stable secondary debris formed. The space span of the simulation model is reduced. An example of Whipple shield ballistic limit analysis is provided for the verification of the fast numerical approach, it shows that this approach can significantly increase the computation efficiency with acceptable accuracy. 相似文献
910.