全文获取类型
收费全文 | 223篇 |
免费 | 24篇 |
国内免费 | 34篇 |
专业分类
航空 | 131篇 |
航天技术 | 62篇 |
综合类 | 24篇 |
航天 | 64篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 12篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 10篇 |
2015年 | 14篇 |
2014年 | 19篇 |
2013年 | 11篇 |
2012年 | 11篇 |
2011年 | 25篇 |
2010年 | 14篇 |
2009年 | 14篇 |
2008年 | 9篇 |
2007年 | 15篇 |
2006年 | 15篇 |
2005年 | 12篇 |
2004年 | 10篇 |
2003年 | 9篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 2篇 |
1998年 | 6篇 |
1996年 | 1篇 |
1995年 | 5篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
排序方式: 共有281条查询结果,搜索用时 93 毫秒
71.
应用巡游载流子与负U中心局域化载流子混杂相互作用的高T_c氧化物超导体理论模型,对Bi系超导体2212相和2223相的主要特征量——超导转变温度、穿透深度、相干长度、热力学临界场和T_c处比热跳跃进行了数值计算,并将计算结果与实验值比较。根据计算结果,对高T_c氧化物超导体的一些特性进行了分析讨论。 相似文献
72.
73.
Spaceborne GPS receiver antenna phase center offset and variation estimation for the Shiyan 3 satellite 总被引:3,自引:2,他引:1
《中国航空学报》2016,(5):1335-1344
In determining the orbits of low Earth orbit (LEO) satellites using spaceborne GPS, the errors caused by receiver antenna phase center offset (PCO) and phase center variations (PCVs) are gradually becoming a major limiting factor for continued improvements to accuracy. Shiyan 3, a small satellite mission for space technology experimentation and climate exploration, was developed by China and launched on November 5, 2008. The dual-frequency GPS receiver payload delivers 1 Hz data and provides the basis for precise orbit determination within the range of a few centime-ters. The antenna PCO and PCV error characteristics and the principles influencing orbit determi-nation are analyzed. The feasibility of PCO and PCV estimation and compensation in different directions is demonstrated through simulation and in-flight tests. The values of receiver antenna PCO and PCVs for Gravity Recovery and Climate Experiment (GRACE) and Shiyan 3 satellites are estimated from one month of data. A large and stable antenna PCO error, reaching up to 10.34 cm in the z-direction, is found with the Shiyan 3 satellite. The PCVs on the Shiyan 3 satellite are estimated and reach up to 3.0 cm, which is slightly larger than that of GRACE satellites. Orbit validation clearly improved with independent k-band ranging (KBR) and satellite laser ranging (SLR) measurements. For GRACE satellites, the average root mean square (RMS) of KBR resid-uals improved from 1.01 cm to 0.88 cm. For the Shiyan 3 satellite, the average RMS of SLR resid-uals improved from 4.95 cm to 4.06 cm. 相似文献
74.
简要介绍了“风云二号”静止气象卫星的地面应用系统、主要包括指令控制与数据接收站、数据处理中心、卫星运行控制中心三大组成部分以及三者之间的信息流程,最后介绍了由该系统输出的气象产品。 相似文献
75.
L. Prange A. Jäggi R. Dach H. Bock G. Beutler L. Mervart 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
The gravity field model AIUB-CHAMP02S, which is based on six years of CHAMP GPS data, is presented here. The gravity field parameters were derived using a two step procedure: In a first step a kinematic trajectory of a low Earth orbiting (LEO) satellite is computed using the GPS data from the on-board receiver. In this step the orbits and clock corrections of the GPS satellites as well as the Earth rotation parameters (ERPs) are introduced as known. In the second step this kinematic orbit is represented by a gravitational force model and orbit parameters. 相似文献
76.
The African Regional Centre for Space Science and Technology Education in English (ARCSSTE-E) was inaugurated in November 1998, with a mandate for the development of indigenous skills, knowledge and capacity, through rigorous theory, research, applications, field exercises and pilot projects that can enhance socioeconomic development. The institution runs a nine-month Postgraduate Diploma (PGD) programme in the areas of Remote Sensing and Geographic Information Systems (RS/GIS); Satellite Communications; Satellite Meteorology and Global Climate; and Basic Space Science and Atmospheric Physics (BSS), as well as short courses and outreach programmes. This paper describes the impact of the space postgraduate diploma programmes in the African region, highlighting the capabilities of the centre. Using a survey of participants in its courses, it notes where changes are needed and makes recommendations to this end. 相似文献
77.
Abhishek Pandey R. Prasad V.P. Singh S.K. Jha K.K. Shukla 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
Learning fuzzy rule based systems with microwave remote sensing can lead to very useful applications in solving several problems in the field of agriculture. Fuzzy logic provides a simple way to arrive at a definite conclusion based upon imprecise, ambiguous, vague, noisy or missing input information. In the present paper, a subtractive based fuzzy inference system is introduced to estimate the potato crop parameters like biomass, leaf area index, plant height and soil moisture. Scattering coefficient for HH- and VV-polarizations were used as an input in the Fuzzy network. The plant height, biomass, and leaf area index of potato crop and soil moisture measured at its various growth stages were used as the target variables during the training and validation of the network. The estimated values of crop/soil parameters by this methodology are much closer to the experimental values. The present work confirms the estimation abilities of fuzzy subtractive clustering in potato crop parameters estimation. This technique may be useful for the other crops cultivated over regional or continental level. 相似文献
78.
星载光学遥感器消杂光技术现状与发展 总被引:9,自引:1,他引:9
通过对国内外杂散辐射理论发展状况的研究和消杂光技术的探讨,归纳出杂光技术领域目前的国际水平以及该项技术的发展趋势;分别从散射理论、分析软件、测试途径以及杂光抑制措施等7个方面,力图全面系统地阐述该项技术的诸方面内容。文章从国情出发,根据当前中国消杂光技术现状和未来高水平空间遥感器的要求,提出下一步中国消杂光技术发展的建议。 相似文献
79.
80.