全文获取类型
收费全文 | 6603篇 |
免费 | 38篇 |
国内免费 | 18篇 |
专业分类
航空 | 3097篇 |
航天技术 | 2139篇 |
综合类 | 24篇 |
航天 | 1399篇 |
出版年
2021年 | 62篇 |
2019年 | 41篇 |
2018年 | 230篇 |
2017年 | 176篇 |
2016年 | 117篇 |
2015年 | 59篇 |
2014年 | 171篇 |
2013年 | 180篇 |
2012年 | 204篇 |
2011年 | 355篇 |
2010年 | 254篇 |
2009年 | 391篇 |
2008年 | 424篇 |
2007年 | 264篇 |
2006年 | 145篇 |
2005年 | 206篇 |
2004年 | 170篇 |
2003年 | 203篇 |
2002年 | 132篇 |
2001年 | 197篇 |
2000年 | 96篇 |
1999年 | 125篇 |
1998年 | 155篇 |
1997年 | 121篇 |
1996年 | 115篇 |
1995年 | 157篇 |
1994年 | 145篇 |
1993年 | 98篇 |
1992年 | 126篇 |
1991年 | 63篇 |
1990年 | 50篇 |
1989年 | 114篇 |
1988年 | 51篇 |
1987年 | 52篇 |
1986年 | 45篇 |
1985年 | 142篇 |
1984年 | 126篇 |
1983年 | 104篇 |
1982年 | 115篇 |
1981年 | 155篇 |
1980年 | 65篇 |
1979年 | 45篇 |
1978年 | 47篇 |
1977年 | 33篇 |
1976年 | 42篇 |
1975年 | 36篇 |
1974年 | 30篇 |
1973年 | 29篇 |
1972年 | 28篇 |
1971年 | 28篇 |
排序方式: 共有6659条查询结果,搜索用时 15 毫秒
301.
P. V. Bulat M. P. Bulat I. A. Volobuev A. A. Levikhin 《Russian Aeronautics (Iz VUZ)》2018,61(3):420-424
The bearing capacity of hybrid segmented bearings with different groove systems is compared. The research establishes that the system with a crescent groove has the best characteristics. 相似文献
302.
S. Sadeghi M.R. Emami 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(8):2050-2056
This paper studies an auroral event using data from three spacecraft of the Cluster mission, one inside and two at the poleward edge of the bottom of the Auroral Acceleration Region (AAR). The study reveals the three-dimensional profile of the region’s poleward boundary, showing spatial segmentation of the electric potential structures and their decay in time. It also depicts localized magnetic field variations and field-aligned currents that appear to have remained stable for at least 80?s. Such observations became possible due to the fortuitous motion of the three spacecraft nearly parallel to each other and tangential to the AAR edge, so that the differences and variations can be seen when the spacecraft enter and exit the segmentations, hence revealing their position with respect to the AAR. 相似文献
303.
The DB-8 detectors of the ISS radiation monitoring system (RMS) have operated almost continuously onboard the ISS service module since August 2001 till December 2014. The RMS data obtained were used for the daily monitoring of the radiation environment aboard the station. This paper considers the technique of RMS data analysis that allows one to distinguish the contributions of galactic cosmic rays and the Earth’s inner radiation belt to the daily dose based on the dosimetry data obtained as a result of the station’s passage in areas of the highest geomagnetic latitudes. The paper presents the results of an analysis of the dosimetry data based on this technique for 2005–2011, as well as a comparison with similar results the authors obtained previously using the technique based on an analysis of the dosimetry data obtained during station passages in the area of the South Atlantic Anomaly. 相似文献
304.
305.
306.
307.
López-Valverde Miguel A. Gerard Jean-Claude González-Galindo Francisco Vandaele Ann-Carine Thomas Ian Korablev Oleg Ignatiev Nikolai Fedorova Anna Montmessin Franck Määttänen Anni Guilbon Sabrina Lefevre Franck Patel Manish R. Jiménez-Monferrer Sergio García-Comas Maya Cardesin Alejandro Wilson Colin F. Clancy R. T. Kleinböhl Armin McCleese Daniel J. Kass David M. Schneider Nick M. Chaffin Michael S. López-Moreno José Juan Rodríguez Julio 《Space Science Reviews》2018,214(1):1-31
Space Science Reviews - Time measured by an ideal clock crucially depends on the gravitational potential and velocity of the clock according to general relativity. Technological advances in... 相似文献
308.
D. V. Nedel’ko 《Russian Aeronautics (Iz VUZ)》2016,59(3):297-302
A method of determining the maximum permissible values for diagnostic signs, being an integral part of health and usage monitoring systems (HUMS) of the helicopter transmission units, has been developed based on a probabilistic approach. 相似文献
309.
R.V. Semenyshyn A.N. VeklichI.L. Babich V.F. Boretskij 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Plasma of the free burning electric arc between Ag–SnO2–ZnO composite electrodes as well as brass electrodes were investigated. The plasma temperature distributions were obtained by Boltzmann plot method involving Cu I, Ag I or Zn I spectral line emissions. The electron density distributions were obtained from the width and from absolute intensity of spectral lines. The laser absorption spectroscopy was used for measurement of copper atom concentration in plasma. Plasma equilibrium composition was calculated using two independent groups of experimental values (temperature and copper atom concentration, temperature and electron density). It was found that plasma of the free burning electric arc between brass electrodes is in local thermodynamical equilibrium. The experimental verification of the spectroscopic data of Zn I spectral lines was carried out. 相似文献
310.
A.K. Sharma O.B. Gurav Anindya Bose H.P. Gaikwad G.A. Chavan Atanu Santra S.S. Kamble R.S. Vhatkar 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(10):3131-3138
Indian Space Research Organization (ISRO) has developed an indigenous system named Indian Regional Navigation Satellite System (IRNSS) or NavIC (Navigation with Indian Constellation), that consists of 7 satellites and transmits navigation signal in L and S bands. ISRO, for validation of the system, has installed many IGS (IRNSS/GPS/SBAS) receivers scattered over the Indian region. Using preliminary data from two geographically widely separated stations over India, this paper presents the results on studies on parameters of IRNSS signal quality and discusses how these parameters may be used to study the ionospheric behavior over the Indian region. The results show the importance and advantages of using IRNSS data for such studies. 相似文献