全文获取类型
收费全文 | 616篇 |
免费 | 68篇 |
国内免费 | 148篇 |
专业分类
航空 | 310篇 |
航天技术 | 297篇 |
综合类 | 46篇 |
航天 | 179篇 |
出版年
2023年 | 6篇 |
2022年 | 15篇 |
2021年 | 29篇 |
2020年 | 18篇 |
2019年 | 24篇 |
2018年 | 23篇 |
2017年 | 29篇 |
2016年 | 28篇 |
2015年 | 32篇 |
2014年 | 56篇 |
2013年 | 50篇 |
2012年 | 49篇 |
2011年 | 47篇 |
2010年 | 52篇 |
2009年 | 68篇 |
2008年 | 44篇 |
2007年 | 30篇 |
2006年 | 29篇 |
2005年 | 21篇 |
2004年 | 13篇 |
2003年 | 15篇 |
2002年 | 21篇 |
2001年 | 19篇 |
2000年 | 13篇 |
1999年 | 10篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1996年 | 13篇 |
1995年 | 11篇 |
1994年 | 13篇 |
1993年 | 10篇 |
1992年 | 12篇 |
1991年 | 1篇 |
1989年 | 6篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1984年 | 7篇 |
排序方式: 共有832条查询结果,搜索用时 468 毫秒
381.
Huiya Zhang Xiaohui Zhang Junli Yang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
ChangE-1 (CE-1) will be the first satellite of China in lunar orbit. Its Microwave Detector makes real-time and periodical calibration at high and low temperature points. The low brightness temperature calibration source will be provided by calibration antenna which is pointing towards the cold space. 相似文献
382.
主要通过灯丝放电磁场约束型原子氧剥蚀效应地面模拟设备模拟空间环境,对空间常用材料Kapton进行了原子氧剥蚀效应、温度升高对材料原子氧效应的影响试验以及原子氧与紫外辐射复合效应试验,对试验前后试样的外观、质量及表面形貌进行了比较,得出了材料在设备中的反应特点以及温度变化、紫外辐射对材料的原子氧效应的影响规律.同时测量了原子氧暴露试验前后、原子氧与紫外辐射复合作用前后试样的反射率和透射率,并进行了比较. 相似文献
383.
飞机发动机冷气道与隔热层的耦合传热分析 总被引:2,自引:1,他引:1
数值研究了某飞机发动机外侧冷气道与隔热层的耦合传热过程。采用低雷诺数k-ε模型与SIMPLEC算法计算通道内可压缩变物性气流的湍流对流换热,采用蒙特卡罗法求解通道壁面间的辐射换热。通道内气流湍流对流换热、壁面间辐射换热与隔热层内导热耦合求解。通过模拟计算,分析了通道与隔热层的耦合传热机制,考察了相关参数的影响。结果表明,在所考虑的通道结构与空气流条件下,冷气道外环壁面的温度高于气流温度,气流对内外环壁面均起冷却作用;在隔热层参数不变条件下,壁面间的辐射换热与气流的对流冷却是该传热过程的控制机制,增大冷气流量、降低壁面发射率均可显著降低隔热层的外壁面温度。 相似文献
384.
385.
386.
387.
388.
389.
M.V. Sunil Krishna Vir Singh 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
A comprehensive model is developed to study the atomic oxygen OI 8446 Å dayglow emission. The emission rate profiles and intensities are obtained using the recently developed Solar2000 EUV (Extreme Ultra Violet) flux model. These emission profiles are used to construct the morphology of the 8446 Å emission between equator and 45°N in the northern hemisphere. The longitudinal variation of 8446 Å dayglow emission is found about 5% and is not included in the presentation of morphology. A span of five years is chosen to study the effect of varying solar activity on the morphology of the OI 8446 Å dayglow emission. The morphology is studied on April 3 which lies under the equinox conditions. In year 2001 the solar F10.7 index on the chosen date was as high as 223.1 which is the case of solar maximum. From the present calculations it is found that the intensity does not vary linearly with the F10.7 solar index. The morphology shows that the region of maximum emission rate expands towards the higher latitudes as F10.7 solar index increases. The similar effects have also been found in the morphology of 7320 Å dayglow emission (Sunil Krishna and Singh, 2009). The similarities in the morphology of 7320 Å and 8446 Å dayglow emissions further suggest that the photoelectron flux has strong bearing on the production of these emissions. 相似文献
390.
Francis F. Badavi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The completion of the international space station (ISS) in 2011 has provided the space research community an ideal proving ground for future long duration human activities in space. Ionizing radiation measurements in ISS form the ideal tool for the validation of radiation environmental models, nuclear transport codes and nuclear reaction cross sections. Indeed, prior measurements on the space transportation system (STS; shuttle) provided vital information impacting both the environmental models and the nuclear transport code developments by indicating the need for an improved dynamic model of the low Earth orbit (LEO) trapped environment. Additional studies using thermo-luminescent detector (TLD), tissue equivalent proportional counter (TEPC) area monitors, and computer aided design (CAD) model of earlier ISS configurations, confirmed STS observations that, as input, computational dosimetry requires an environmental model with dynamic and directional (anisotropic) behavior, as well as an accurate six degree of freedom (DOF) definition of the vehicle attitude and orientation along the orbit of ISS. 相似文献