全文获取类型
收费全文 | 2846篇 |
免费 | 3篇 |
国内免费 | 8篇 |
专业分类
航空 | 1357篇 |
航天技术 | 1067篇 |
综合类 | 8篇 |
航天 | 425篇 |
出版年
2021年 | 16篇 |
2019年 | 18篇 |
2018年 | 43篇 |
2017年 | 39篇 |
2016年 | 27篇 |
2015年 | 13篇 |
2014年 | 57篇 |
2013年 | 75篇 |
2012年 | 54篇 |
2011年 | 123篇 |
2010年 | 76篇 |
2009年 | 135篇 |
2008年 | 166篇 |
2007年 | 78篇 |
2006年 | 62篇 |
2005年 | 72篇 |
2004年 | 78篇 |
2003年 | 106篇 |
2002年 | 55篇 |
2001年 | 106篇 |
2000年 | 60篇 |
1999年 | 95篇 |
1998年 | 94篇 |
1997年 | 68篇 |
1996年 | 70篇 |
1995年 | 91篇 |
1994年 | 100篇 |
1993年 | 39篇 |
1992年 | 60篇 |
1991年 | 26篇 |
1990年 | 29篇 |
1989年 | 59篇 |
1988年 | 25篇 |
1987年 | 39篇 |
1986年 | 30篇 |
1985年 | 90篇 |
1984年 | 44篇 |
1983年 | 49篇 |
1982年 | 57篇 |
1981年 | 81篇 |
1980年 | 29篇 |
1979年 | 27篇 |
1978年 | 24篇 |
1977年 | 19篇 |
1976年 | 15篇 |
1975年 | 19篇 |
1974年 | 14篇 |
1972年 | 17篇 |
1969年 | 13篇 |
1968年 | 13篇 |
排序方式: 共有2857条查询结果,搜索用时 221 毫秒
791.
R. Hudec Z. Ceplecha J. Ehrlich J. Borovi
ka K. Hurley J.-L. Ateia C. Barat M. Niel G. Vedrenne I.V. Estulin A.K. Kuznetsov V.M. Zenchenko T.L. Cline U. Desai W.D. Evans E. Fenimore R. Klebesadel J. Laros 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,3(10-12)
The preliminary results from optical search for light pulses associated with gamma ray bursts by means of the Czechoslovak Fireball Network plate collection at the Ondřejov observatory are given. Optical monitoring represents more than 7700 hours, but no real optical counterpart was found. Problems associated with the optical search for gamma ray bursts are discussed. 相似文献
792.
D.N. Baker T.I. Pulkkinen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,19(12):1923-1927
Methods are discussed to estimate energy transfer from the solar wind to the magnetosphere during substorm growth phases. Observational and modeling constraints are then used to assess quantitatively the total amount of energy stored in the magnetotail. The major avenues of energy dissipation are examined and the energy that is released in the form of plasma sheet heating, ionospheric Joule heating, plasmoids, and energetic particle production during substorms is assessed. Energy sources are evaluated to drive substorm evolution in a particularly well-observed case: stored tail-lobe energy is sufficient to drive observed substorm dissipation processes (by large margins). On the other hand, energy in the closed field lines of the plasma sheet is insufficient to supply the substorm energy. Hence, magnetic reconnection is required on energy grounds during well-observed substorm cases. 相似文献
793.
T. Yokoyama H. Nakajima K. Shibasaki V.F. Melnikov A.V. Stepanov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2003,32(12):2517-2520
We report a Nobeyama Radioheliograph (NoRH) microwave observation of a propagating feature of non thermal emission in a solar flare. The flare had a very extended source well resolved by NoRH. In the rising phase of the microwave burst, a non-thermal gyrosynchrotron source was observed by the high-rate (10 images per second) observations to propagate from one end of the loop to the other with a speed of 9 × 104 km s−1. We interpret this non-thermal propagating source is emitted from streaming electrons. 相似文献
794.
K. T. Lee T. Cleghorn F. Cucinotta L. Pinsky C. Zeitlin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2004,33(12):2211-2214
The charged particle spectrum for nuclei from protons to neon, (charge Z=10) was observed during the cruise phase and orbit around Mars by the MARIE charged particle spectrometer on the Odyssey spacecraft. The cruise data were taken between April 23, 2001 and mid-August 2001. The Mars orbit data were taken March 5, 2002 through May 2002 and are scheduled to continue until August 2004. Charge peaks are clearly separated for charges up to Z=10. Especially prominent are the carbon and oxygen peaks, with boron and nitrogen also clearly visible. Although heavy ions are much less abundant than protons in the cosmic ray environment, it is important to determine their abundances because their ionization energy losses (proportional to Z2) are far more dangerous to humans and to instruments. Thus the higher charged nuclei make a significant contribution to dose and dose equivalent received in space. Results of the charged particle spectrum measurements will be reported. 相似文献
795.
S. Pojoga T.S. Huang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2003,32(12):2641-2646
Sudden disappearances of prominences/filaments were identified from the Prairie View Solar Observatory H imagesand Meudon Observatory spectroheliograms for the period January 1, 2000 to March 31, 2000. Three classes of disappearances were considered for the purpose of this study: eruptive, quasi-eruptive and vanishing filaments. The H events were compared with CME data from LASCO C2 and C3 coronographs aboard SOHO. Our study shows that the eruptive events are strongly associated with CMEs while the other types are not. 相似文献
796.
Loto’aniu T. M. Redmon R. J. Califf S. Singer H. J. Rowland W. Macintyre S. Chastain C. Dence R. Bailey R. Shoemaker E. Rich F. J. Chu D. Early D. Kronenwetter J. Todirita M. 《Space Science Reviews》2019,215(4):1-25
Space Science Reviews - The Modular Multispectral Imaging Array (MMIA) is a suite of optical sensors mounted on an external platform of the European Space Agency’s Columbus Module on the... 相似文献
797.
The authors present proposals for establishing an international environmental resources satellite consortium. All countries share a need for data on the Earth and its resources, and economies of scale could be achieved through an international system. The formation of Inmarsat could serve as a model for setting up Envirosat. The role of Envirosat could expand as international confidence in it grows. 相似文献
798.
B. N. Korchuganov G. G. Dol'nikov M. V. Gerasimov O. F. Prilutskii R. Rider G. Waenke T. Economou 《Cosmic Research》2004,42(1):19-22
A theoretical and experimental feasibility study of possible determination of the hydrogen and deuterium concentrations in the surface layers of planetary bodies is presented. The method under study is the recoil proton and deuteron spectrometry of forward scattering in the course of elastic interaction of alpha particles with the nuclei of hydrogen isotopes. The spectra of recoil protons and deuterons were recorded using a prototype model of a hydrogen spectrometer, and these spectra were used to determine the hydrogen concentrations in the samples of different compositions. 相似文献
799.
Six-month space greenhouse experiments--a step to creation of future biological life support systems
Ivanova TN Kostov PT Sapunova SM Dandolov IW Salisbury FB Bingham GE Sytchov VN Levinskikh MA Podolski IG Bubenheim DB Jahns G 《Acta Astronautica》1998,42(1-8):11-23
SVET Space Greenhouse (SG)--the first automated facility for growing of higher plants in microgravity was designed in the eighty years to be used for the future BLSS. The first successful experiment with vegetables was carried out in 1990 on the MIR Space Station (SS). The experiments in SVET SG were resumed in 1995, when an American Gas Exchange Measurement System (GEMS) was added. A three-month wheat experiment was carried out as part of MIR-SHUTTLE'95 program. SVET-2 SG Bulgarian equipment of a new generation with optimised characteristics was developed (financed by NASA). The new SVET-GEMS equipment was launched on board the MIR SS and a successful six-month experiments for growing up of two crops of wheat were conducted in 1996 - 97 as part of MIR-NASA-3 program. The first of these "Greenhouse" experiments (123 days) with the goal to grow wheat through a complete life cycle is described. Nearly 300 heads developed but no seeds were produced. A second crop of wheat was planted and after 42 days the plants were frozen for biochemical investigations. The main environmental parameters during the six-month experiments in SVET (substrate moisture and lighting period) are given. The results and the contribution to BLSS are discussed. 相似文献
800.
Cosmic Research - On January 21, 1972, the Mars 3 satellite recorded a strong (~27 nT) regular magnetic field in the region of the spacecraft’s closest approach to the dayside of Mars. Many... 相似文献