全文获取类型
收费全文 | 639篇 |
免费 | 70篇 |
国内免费 | 157篇 |
专业分类
航空 | 317篇 |
航天技术 | 306篇 |
综合类 | 47篇 |
航天 | 196篇 |
出版年
2023年 | 6篇 |
2022年 | 16篇 |
2021年 | 29篇 |
2020年 | 20篇 |
2019年 | 25篇 |
2018年 | 23篇 |
2017年 | 29篇 |
2016年 | 29篇 |
2015年 | 34篇 |
2014年 | 55篇 |
2013年 | 51篇 |
2012年 | 47篇 |
2011年 | 49篇 |
2010年 | 55篇 |
2009年 | 73篇 |
2008年 | 49篇 |
2007年 | 34篇 |
2006年 | 32篇 |
2005年 | 23篇 |
2004年 | 14篇 |
2003年 | 16篇 |
2002年 | 22篇 |
2001年 | 20篇 |
2000年 | 13篇 |
1999年 | 11篇 |
1998年 | 9篇 |
1997年 | 5篇 |
1996年 | 13篇 |
1995年 | 12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866条查询结果,搜索用时 352 毫秒
761.
飞行体的海空背景反射与辐射计算 总被引:2,自引:0,他引:2
徐南荣 《北京航空航天大学学报》1998,24(2):237-240
研究了对近海飞行体的红外特性有重要影响的海空背景辐射的反射特性.讨论了波浪面起伏随机规律,随机起伏对海面自身辐射及对阳光反射的影响,推演了此种随机起伏波浪面的自身辐射及反射的阳光在观测点形成的辐照度的计算方法.给出的算例结果表明,海空背景对飞行体的红外特性尤其对其前半球的红外特性有重要的意义. 相似文献
762.
用不同年代的国际地磁参考场(IGR)模式及最新的辐射带粒子通量模式,计算了低高度上空间某点的辐射带质子通量随时间的变化,讨论了地磁场的长期变化对L-B坐标及辐射带带电粒子通量计算的影响,对正确使用地磁场模式计算磁壳参量L及辐射带粒子通量模式给予了说明和建议. 相似文献
763.
电子束固化技术及在复合材料制造领域的应用 总被引:4,自引:0,他引:4
对辐射固化与光固化进行了比较,阐述了电子束辐射固化的基本过程,并对电子束固化复合材料的技术特点进行了概述.此外,还详细总结了电子束固化复合材料技术的发展状况,包括可电子束固化的树脂体系,辐敏剂以及活性稀释剂的选择和应用,固化机理的研究等.最后,还对复合材料的低能电子束固化技术以及新型树脂体系的探索进行了总结. 相似文献
764.
765.
766.
767.
彭桂荣%甄良%杨德庄%何世禹 《宇航材料工艺》2001,31(5):12-18
针对空间环境条件综述了真空紫外线辐射对材料物理、化学等性能的影响及机理。聚合物材料在真空紫外线作用下,表面粗糙度上升,结构发生明显变化,拉伸强度下降。同时透光率、耐热性等均发生变化。真空紫外线与原子氧等其它空间环境因素有一定程度的协同效应。不同材料对各因素的敏感程度稍有差异。 相似文献
768.
769.
M. Puchalska L. Sihver T. Sato T. Berger G. Reitz 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The radiation environment at the altitude of the International Space Station (ISS) is substantially different than anything typically encountered on Earth in both the character of the radiation field and the significantly higher dose rates. Concerns about the biological effects on humans of this highly complex natural radiation field are increasing due to higher amount of astronauts performing long-duration missions onboard the ISS and especially if looking into planned future manned missions to Mars. In order to begin the process of predicting the dose levels seen by the organs of an astronaut, being the prerequisite for radiation risk calculations, it is necessary to understand the character of the radiation environment both in- and outside of the ISS as well as the relevant contributions from the radiation field to the organ doses. 相似文献
770.
T.P. Dachev 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Space weather and related ionizing radiation has been recognized as one of the main health concerns for the International Space Station (ISS) crew. The estimation of the radiation effect on humans outside the ISS requires at first order accurate knowledge of their accumulated absorbed dose rates, which depend on the global space radiation distribution, solar cycle and local variations generated by the 3D mass distribution surrounding the ISS. The R3DE (Radiation Risks Radiometer-Dosimeter for the EXPOSE-E platform) on the European Technological Exposure Facility (EuTEF) worked successfully outside of the European Columbus module between February 2008 and September 2009. A very similar instrument named R3DR for the EXPOSE-R platform worked outside the Russian Zvezda module of the ISS between March 2009 and August 2010. Both are Liulin-type detectors, Bulgarian-built miniature spectrometer-dosimeters. The acquired approximately 5 million deposited energy spectra from which the flux and absorbed dose rate were calculated with 10 s resolution behind less than 0.41 g cm−2 shielding. This paper analyses the spectra collected in 2009 by the R3DE/R instruments and the long-term variations in the different radiation environments of Galactic Cosmic Rays (GCR), inner radiation belt trapped protons in the region of the South Atlantic Anomaly (SAA) and relativistic electrons from the Outer Radiation Belt (ORB). The R3DE instrument, heavily shielded by the surrounding structures, measured smaller primary fluxes and dose rates from energetic protons from the SAA and relativistic electrons from the ORB but higher values from GCRs because of the contribution from secondary particles. The main conclusion from this investigation is that the dose rates from different radiation sources around the International Space Station (ISS) have a large special and temporal dynamic range. The collected data can be interpreted as possible doses obtained by the cosmonauts and astronauts during Extra Vehicular Activities (EVA) because the R3DE/R instruments shielding is very similar to the Russian and American space suits average shielding (, and ). Fast, active measurements are required to assess accurately the dose accumulated by astronauts during EVA. 相似文献