全文获取类型
收费全文 | 2178篇 |
免费 | 332篇 |
国内免费 | 213篇 |
专业分类
航空 | 620篇 |
航天技术 | 1085篇 |
综合类 | 134篇 |
航天 | 884篇 |
出版年
2024年 | 2篇 |
2023年 | 41篇 |
2022年 | 48篇 |
2021年 | 89篇 |
2020年 | 90篇 |
2019年 | 66篇 |
2018年 | 86篇 |
2017年 | 37篇 |
2016年 | 73篇 |
2015年 | 73篇 |
2014年 | 203篇 |
2013年 | 124篇 |
2012年 | 112篇 |
2011年 | 184篇 |
2010年 | 129篇 |
2009年 | 141篇 |
2008年 | 123篇 |
2007年 | 105篇 |
2006年 | 112篇 |
2005年 | 120篇 |
2004年 | 87篇 |
2003年 | 58篇 |
2002年 | 70篇 |
2001年 | 69篇 |
2000年 | 64篇 |
1999年 | 72篇 |
1998年 | 59篇 |
1997年 | 45篇 |
1996年 | 35篇 |
1995年 | 46篇 |
1994年 | 20篇 |
1993年 | 25篇 |
1992年 | 18篇 |
1991年 | 22篇 |
1990年 | 17篇 |
1989年 | 17篇 |
1988年 | 27篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1984年 | 2篇 |
排序方式: 共有2723条查询结果,搜索用时 0 毫秒
1.
More and more proposals, or potential projects have been proposed in recent two years. We try to briefly outline these new proposals, although most of them are in fact only in their conception studies. The progress of previously mentioned projects, like Space Solar Telescope (SST), the Hard X-ray Modulation Telescope (HXMT), as well as newly initiated LUnar Resource Explorer (LUREX), will be introduced elsewhere. 相似文献
2.
A numerical procedure for the calculation of the transonic dip of airfoils in the time domain is presented. A viscous-inviscid aerodynamic interaction method is taken to calculate the unsteady aerodynamic loads. In the present case the integral boundary layer equations are coupled with the Transonic Small Disturbance (TSD) Potential Equation. The coupling between structural motion and aerodynamic loads is carried out using State Space equation. It is solved by State Transition Matrix technique. Results are presented for NACA 64A010 and NLR 7301 airfoils with structural data from Isogai and DLR, respectively. Comparisons show good agreement with other numerical results. Certain deviations of experimental data taken from literature need more insight in the detailed test conditions. 相似文献
3.
The Cluster mission of the European Space Agency (ESA) will allow, for the first time three-dimensional measurements in key regions of the Earth's magnetosphere to be carried out. The European Numerical Simulation Network (ENSN) aims at providing a theoretical support to the mission. We describe the achievements of the ENSN during its first period of activity 1991–1994, during which the network was funded by the European Union. In particular, the ENSN has set up (i) thematic Working Groups on the prime scientific goals of the mission, (ii) a code development Working Group to develop numerical simulation codes specifically adapted to studying magnetospheric boundaries and the corresponding scale mixing, and (iii) software models of Cluster instruments to test in a numerical simulation what the set of four instruments will measure. 相似文献
4.
通过分析对比,详细介绍了南飞公司应用工业工程重新规划和改进钣金车间生产现场的作法,以及所取得的技术经济效果。 相似文献
5.
H. Lundstedt 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,36(12):2516-2523
The methods of today’s predictions of space weather and effects are so much more advanced and yesterday’s statistical methods are now replaced by integrated knowledge-based neuro-computing models and MHD methods. Within the ESA Space Weather Programme Study a real-time forecast service has been developed for space weather and effects. This prototype is now being implemented for specific users. Today’s applications are not only so many more but also so much more advanced and user-oriented. A scientist needs real-time predictions of a global index as input for an MHD model calculating the radiation dose for EVAs. A power company system operator needs a prediction of the local value of a geomagnetically induced current. A science tourist needs to know whether or not aurora will occur. Soon we might even be able to predict the tropospheric climate changes and weather caused by the space weather. 相似文献
6.
航天火工装置种类很多,性能各异。文章仅对广泛使用的弹射器和解锁器类火工装置的推力测量系统进行论述,分析测量过程中的干扰环节,说明不同干扰类型对测量结果的影响。并提出测试改进建议。 相似文献
7.
航天火工装置种类很多,性能各异。文章仅对广泛使用的弹射器和解锁器类火工装置的推力测量系统进行论述,分析测量过程中的干扰环节,说明不同干扰类型对测量结果的影响。并提出测试改进建议。 相似文献
8.
本文提出了故障检测与分离的广义一致性算子法的一般形式。得出了两个故障可分离的充要条件和多个故障可分离的充要条件。最后给出了检测和分离故障的过程。 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.
针对电子商务网站建设过程中存在的问题,从软件工程基本原理出发,分析结合软件生存周期瀑布模型提出电子商务网站的建设过程,对克服当前主要不足有一定的帮助作用。 相似文献