全文获取类型
收费全文 | 8176篇 |
免费 | 42篇 |
国内免费 | 30篇 |
专业分类
航空 | 3709篇 |
航天技术 | 2823篇 |
综合类 | 30篇 |
航天 | 1686篇 |
出版年
2021年 | 91篇 |
2019年 | 61篇 |
2018年 | 237篇 |
2017年 | 158篇 |
2016年 | 132篇 |
2015年 | 60篇 |
2014年 | 202篇 |
2013年 | 252篇 |
2012年 | 245篇 |
2011年 | 384篇 |
2010年 | 278篇 |
2009年 | 403篇 |
2008年 | 436篇 |
2007年 | 265篇 |
2006年 | 194篇 |
2005年 | 220篇 |
2004年 | 219篇 |
2003年 | 244篇 |
2002年 | 177篇 |
2001年 | 255篇 |
2000年 | 150篇 |
1999年 | 179篇 |
1998年 | 218篇 |
1997年 | 142篇 |
1996年 | 192篇 |
1995年 | 229篇 |
1994年 | 203篇 |
1993年 | 137篇 |
1992年 | 177篇 |
1991年 | 56篇 |
1990年 | 58篇 |
1989年 | 162篇 |
1988年 | 74篇 |
1987年 | 70篇 |
1986年 | 72篇 |
1985年 | 217篇 |
1984年 | 177篇 |
1983年 | 132篇 |
1982年 | 139篇 |
1981年 | 236篇 |
1980年 | 75篇 |
1979年 | 54篇 |
1978年 | 64篇 |
1977年 | 45篇 |
1975年 | 61篇 |
1974年 | 47篇 |
1973年 | 38篇 |
1972年 | 41篇 |
1971年 | 41篇 |
1970年 | 40篇 |
排序方式: 共有8248条查询结果,搜索用时 15 毫秒
331.
332.
Paul A. Crowther Joanne L. Bibby James P. Furness J. Simon Clark 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
We highlight how the downward revision in the distance to the star cluster associated with SGR 1806–20 by Bibby et al. (2008) reconciles the apparent low contamination of BATSE short GRBs by intense flares from extragalactic magnetars without recourse to modifying the frequency of one such flare per 30 years per Milky Way galaxy. We also discuss the variety in progenitor initial masses of magnetars based upon cluster ages, ranging from ∼50 M⊙ for SGR 1806–20 and AXP CXOU J164710.2–455216 in Westerlund 1 to ∼17 M⊙ for SGR 1900+14 according to Davies et al. (2009) and presumably also 1E 1841–045 if it originated from one of the massive RSG clusters #2 or #3. 相似文献
333.
V.D. Kuznetsov I.I. Sobelman I.A. Zhitnik S.V. Kuzin Yu.D. Kotov Yu.E. Charikov S.N. Kuznetsov E.P. Mazets A.A. Nusinov A.M. Pankov J. Sylwester 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
The CORONAS-F mission experiments and results have been reviewed. The observations with the DIFOS multi-channel photometer in a broad spectral range from 350 to 1500 nm have revealed the dependence of the relative amplitudes of p-modes of the global solar oscillations on the wavelength that agrees perfectly well with the earlier data obtained in a narrower spectral ranges. The SPIRIT EUV observations have enabled the study of various manifestations of solar activity and high-temperature events on the Sun. The data from the X-ray spectrometer RESIK, gamma spectrometer HELICON, flare spectrometer IRIS, amplitude–temporal spectrometer AVS-F, and X-ray spectrometer RPS-1 have been used to analyze the X- and gamma-ray emission from solar flares and for diagnostics of the flaring plasma. The absolute and relative content of various elements (such as potassium, argon, and sulfur) of solar plasma in flares has been determined for the first time with the X-ray spectrometer RESIK. The Solar Cosmic Ray Complex monitored the solar flare effects in the Earth’s environment. The UV emission variations recorded during solar flares in the vicinity of the 120-nm wavelength have been analyzed and the amplitude of relative variations has been determined. 相似文献
334.
R.N.C. Eze 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Hard X-ray emitting symbiotic stars are candidates for SN Ia progenitors. The importance of Type Ia SNe as standard candles for cosmology makes the study of their progenitor systems particularly important. Additionally, they provide one of the most promising laboratories for the study of astrophysical jets. Typically, the X-ray emission in these systems is modeled with a collisional plasma model, sometimes with an emission measure distribution taken from a cooling flow model. The lack of any coherent periods in both X-rays and optical wave band strongly suggests that the accreting white dwarfs in the hard X-ray symbiotic stars are non-magnetic. Although relatively few have been discovered to date, but we believe that there are very many of them in our galaxy and could be possible candidates for the Galactic Ridge X-ray Emissions (GRXE). 相似文献
335.
B. Rizk C. Drouet dAubigny C.W. Hergenrother B.J. Bos D.R. Golish R. Malhotra D.S. Lauretta J. Butt J. Patel M. Fitzgibbon C. May E.B. Bierhaus S. Freund M. Fisher S. Cambioni C.A. Bennett S.S. Balram-Knutson K. Harshman M. Moreau 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(1):672-691
We analyzed high-angular rate streaks first recorded by OSIRIS-REx’s MapCam during a 2017 search for Earth Trojan asteroids. We interpret them as water-ice particles that translated across the imager’s field of view, originating from the spacecraft itself. Their translation velocities approximated 0.1–1?m/s based on reasonable conclusions about their range. Pursuing several lines of investigation to seek a coherent hypothesis, we conclude that the episodic releases of the water ice particles are associated with spacecraft attitudes that resulted in solar illumination of previously shadowed regions. This correlation suggests that the OSIRIS-REx spacecraft itself possesses micro-climatic zones consisting of hot regions and cold traps that may temporarily potentially pass volatiles back and forth before losing most of them. 相似文献
336.
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
337.
V. A. Kudinov A. V. Eremin A. E. Kuznetsova E. V. Stefanyuk 《Russian Aeronautics (Iz VUZ)》2014,57(1):37-44
An exact analytical solution of the thermoelasticity problem is presented for a multilayer shallow cylinder with physical properties of the medium that are constant in the limits of each layer. The effect of thermal shock of different intensity as well as the penetration depth of thermal disturbance on the distribution of radial and circumferential thermal stresses has been studied as applied to the one- and two-layer cylinder. It has been shown that the circumferential compressive stresses appear on the external surface of the cylinder under thermal shock while the tensile stresses appear on the internal surface. 相似文献
338.
339.
340.