全文获取类型
收费全文 | 2461篇 |
免费 | 28篇 |
国内免费 | 13篇 |
专业分类
航空 | 980篇 |
航天技术 | 907篇 |
综合类 | 12篇 |
航天 | 603篇 |
出版年
2022年 | 13篇 |
2021年 | 27篇 |
2019年 | 24篇 |
2018年 | 73篇 |
2017年 | 61篇 |
2016年 | 49篇 |
2015年 | 20篇 |
2014年 | 78篇 |
2013年 | 91篇 |
2012年 | 71篇 |
2011年 | 137篇 |
2010年 | 102篇 |
2009年 | 146篇 |
2008年 | 148篇 |
2007年 | 77篇 |
2006年 | 63篇 |
2005年 | 76篇 |
2004年 | 78篇 |
2003年 | 81篇 |
2002年 | 56篇 |
2001年 | 75篇 |
2000年 | 39篇 |
1999年 | 47篇 |
1998年 | 52篇 |
1997年 | 49篇 |
1996年 | 41篇 |
1995年 | 56篇 |
1994年 | 34篇 |
1993年 | 38篇 |
1992年 | 50篇 |
1991年 | 13篇 |
1990年 | 16篇 |
1989年 | 41篇 |
1988年 | 19篇 |
1987年 | 16篇 |
1986年 | 13篇 |
1985年 | 60篇 |
1984年 | 51篇 |
1983年 | 41篇 |
1982年 | 41篇 |
1981年 | 56篇 |
1980年 | 34篇 |
1979年 | 16篇 |
1978年 | 17篇 |
1977年 | 9篇 |
1976年 | 16篇 |
1975年 | 15篇 |
1974年 | 12篇 |
1971年 | 7篇 |
1969年 | 7篇 |
排序方式: 共有2502条查询结果,搜索用时 46 毫秒
631.
E. N. Parker 《Space Science Reviews》2009,144(1-4):15-24
We review some longstanding scientific mysteries related to solar magnetism, with final attention to the mystery of the “turbulent diffusion” essential for the theoretical α ω-dynamo that is believed to be the source of the magnetic fields of the Sun. Fundamental difficulties with the concept of turbulent diffusion of magnetic fields suggest that the solar dynamo problem needs to be reformulated. An alternative dynamo model is proposed, but it remains to be shown that the model can provide the quantitative aspects of the cyclic magnetic fields of the Sun. 相似文献
632.
N. Straumann 《Space Science Reviews》2009,148(1-4):25-36
In this written version of a pre-dinner-speech at the workshop “The Nature of Gravity” at ISSI I illustrate Pauli’s science primarily with material that has not formally been published by him, but was communicated in detailed letters to eminent colleagues and friends. 相似文献
633.
634.
The organization principles of constructing the European system of warning about dangerous situations in the outer space are
considered in the paper. 相似文献
635.
Design of a three-axial accelerometer-seismometer, constructed on the basis of two-coordinate sensors (sensitive elements)
of high and low accelerations, is considered in the paper. This instrument is applied for gravi-inertial measurements. Basic
characteristics of the instrument are described, as well as the technique and results of its standardization. 相似文献
636.
637.
K. Abe H. Fuke S. Haino T. Hams M. Hasegawa A. Horikoshi A. Itazaki K.C. Kim T. Kumazawa A. Kusumoto M.H. Lee Y. Makida S. Matsuda Y. Matsukawa K. Matsumoto J.W. Mitchell A.A. Moiseev J. Nishimura M. Nozaki R. Orito J.F. Ormes N. Picot-Clémente K. Sakai M. Sasaki E.S. Seo Y. Shikaze R. Shinoda R.E. Streitmatter J. Suzuki Y. Takasugi K. Takeuchi K. Tanaka N. Thakur T. Yamagami A. Yamamoto T. Yoshida K. Yoshimura 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The Balloon-borne Experiment with a Superconducting Spectrometer (BESS) is configured with a solenoidal superconducting magnet and a suite of precision particle detectors, including time-of-flight hodoscopes based on plastic scintillators, a silica-aerogel Cherenkov detector, and a high resolution tracking system with a central jet-type drift chamber. The charges of incident particles are determined from energy losses in the scintillators. Their magnetic rigidities (momentum/charge) are measured by reconstructing each particle trajectory in the magnetic field, and their velocities are obtained by using the time-of-flight system. Together, these measurements can accurately identify helium isotopes among the incoming cosmic-ray helium nuclei up to energies in the GeV per nucleon region. The BESS-Polar I instrument flew for 8.5 days over Antarctica from December 13th to December 21st, 2004. Its long-duration flight and large geometric acceptance allow the time variations of isotopic fluxes to be studied for the first time. The time variations of helium isotope fluxes are presented here for rigidities from 1.2 to 2.5 GV and results are compared to previously reported proton data and neutron monitor data. 相似文献
638.
N.F. Allard 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
In order to calculate the opacity of a gas it is necessary to consider how its constituent atoms are perturbed by the surrounding medium. This is required both in order to calculate the equation of state, and in order to determine the profiles of the spectrum lines. In this work we report new theoretical Li line profiles perturbed by H2 and their dependence with temperature. 相似文献
639.
S.S. Nikte A.K. Sharma D.P. Nade M.V. Rokade R.N. Ghodpage P.T. Patil R.V. Bhonsle 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
A dual dipole antenna has been installed at low latitude station Kolhapur (Geographic 16.8°N, 74.25°E), Maharashtra, India for the study of cosmic radio noise absorption using Solid State Riometer (which operates at 30 MHz) during pre phase of 24th solar maxima. The aim for this type of study over Kolhapur was to know the response of lower (D region) ionosphere over low latitude by cosmic radio noise absorption using riometer technique during quite period as well as sudden ionospheric disturbances (SID). The observations are being taken for 3 years. Two different sites (∼40 km away from each other) were used for the installation of riometer equipment assuming minimum local noise. It is found that solar noise to cosmic radio noise hence resulting in signal saturation. The night time signal is relatively free of interference but sometimes local noise is responsible for spike-like signatures. Hence it is concluded that Kolhapur (a low latitude station) is not suitable for the study of cosmic radio noise absorption on 30 MHz with riometer and dual dipole antenna. Proper choice for operating frequency of riometer and antenna gain is suggested for low latitude use of this technique for ionospheric deviative and nondeviative absorption studies. 相似文献
640.
V.V. Guryanov A.N. Fahrutdinova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Daily UK Met Office stratospheric assimilated data for the Northern and Southern Hemispheres, accumulated for the period from 2004 to 2012 and pressure range of 1000–0.1 hPa, are used in this paper. The paper presents and thoroughly discusses spatial–temporal distributions of stationary planetary wave (SPW) amplitudes and phases, calculated on the basis of geopotential height, temperature, zonal and meridional wind data for zonal wave numbers 1 and 2 (SPW1 and SPW2). The climatological planetary wave amplitudes and phases are calculated by extracting waves from three types of data: daily, monthly mean and climatological monthly mean. It has been established that magnitude of amplitudes and height-latitude distribution of amplitudes of SPW1 and SPW2 depend on data processing method for all parameters. It has also been established that height-latitude distribution amplitudes and phases significantly differ for geopotential height, temperature, zonal and meridional wind and depend on wave number and hemisphere. However, height-latitude distributions of phases are little different from each other for the used methods of data processing. 相似文献