全文获取类型
收费全文 | 2161篇 |
免费 | 19篇 |
国内免费 | 4篇 |
专业分类
航空 | 1140篇 |
航天技术 | 473篇 |
综合类 | 15篇 |
航天 | 556篇 |
出版年
2022年 | 6篇 |
2021年 | 12篇 |
2019年 | 7篇 |
2018年 | 165篇 |
2017年 | 142篇 |
2016年 | 48篇 |
2015年 | 30篇 |
2014年 | 23篇 |
2013年 | 24篇 |
2012年 | 72篇 |
2011年 | 174篇 |
2010年 | 158篇 |
2009年 | 179篇 |
2008年 | 186篇 |
2007年 | 166篇 |
2006年 | 29篇 |
2005年 | 99篇 |
2004年 | 51篇 |
2003年 | 30篇 |
2002年 | 25篇 |
2001年 | 53篇 |
2000年 | 19篇 |
1999年 | 35篇 |
1998年 | 36篇 |
1997年 | 13篇 |
1996年 | 32篇 |
1995年 | 20篇 |
1994年 | 33篇 |
1993年 | 26篇 |
1992年 | 31篇 |
1991年 | 10篇 |
1990年 | 14篇 |
1989年 | 31篇 |
1988年 | 14篇 |
1987年 | 6篇 |
1986年 | 12篇 |
1985年 | 19篇 |
1984年 | 27篇 |
1983年 | 22篇 |
1982年 | 22篇 |
1981年 | 24篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 6篇 |
1974年 | 3篇 |
1970年 | 3篇 |
1969年 | 4篇 |
排序方式: 共有2184条查询结果,搜索用时 0 毫秒
131.
C.T. Russell T.L. Zhang R.J. Strangeway H.Y. Wei M. Delva W. Magnes 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(1):113-117
The magnetometer on Venus Express was designed to be able to obtain 128 Hz samples of the magnetic field from two sensors in a gradiometer configuration. This mode is used around periapsis to determine whether the signals reported at low altitudes near 100 Hz, had the properties of electromagnetic waves generated by electric discharges in the Venus atmosphere. The lack of a magnetic cleanliness program and the shortness of the magnetometer boom make this a challenging measurement. Fortunately the signals are sufficiently strong that they can be easily resolved with rather straightforward analysis techniques. 相似文献
132.
S. I. Solovyev V. A. Mullayarov D. G. Baishev E. S. Barkova S. N. Samsonov 《Cosmic Research》2004,42(6):607-613
Modulation of the VLF emission and riometric absorption by Pc5 geomagnetic pulsations is studied in the period of strong geomagnetic disturbances on October 30–31, 2003. Some conclusions about the regime of pitch-angular diffusion into the loss cone are made. The better coincidence of VLF emission modulation with geomagnetic pulsations in other longitude sectors is explained by the global character of excitation of the pulsations and by damping of their amplitudes at the meridian of observation of the VLF emission, which is associated with intensification of auroral electrojets.Translated from Kosmicheskie Issledovaniya, Vol. 42, No. 6, 2004, pp. 632–639.Original Russian Text Copyright © 2004 by Solovyev, Mullayarov, Baishev, Barkova, Samsonov. 相似文献
133.
Spatial structure of the magnetosheath of the Earth was studied under the conditions when no sharp (more than 40° during 5
min) changes in the interplanetary magnetic field direction were observed. On the basis of 24 flights of the Interball-1 satellite through the magnetosheath, it is found that three regions differing from each other by parameters of the field
and plasma can be observed in the magnetosheath under the above-indicated conditions. These regions also differ from the solar
wind region before front of the Earth’s magnetospheric bow shock. Empirical distributions of parameters were studied in each
region. Taking into account the influence of the interplanetary magnetic field direction on the processes in the magnetosheath,
the cases of quasi-perpendicular and quasi-parallel shock waves were considered separately. The study showed that the distribution
of parameters in the selected regions (in the solar wind before front of the bow shock, in the magnetosheath behind the bow
shock (post-shock), in the region of the magnetosheath with minimal fluctuations in the field, and in the inner magnetosheath)
differ from each other at any interplanetary magnetic field direction. 相似文献
134.
A. N. Denisov N. V. Kuznetsov R. A. Nymmik M. I. Panasyuk N. M. Sobolevskii 《Cosmic Research》2010,48(6):509-516
In connection with projects of manned bases on the Moon it becomes topical to estimate radiation danger for their inhabitants.
In this paper we describe a method of evaluation of the radiation environment on the lunar surface produced by galactic and
solar cosmic rays. The roles of both primary and secondary radiations generated in the depth of the lunar soil under the action
of high-energy protons and nuclei are taken into account. Calculated fluxes of particles are used in order to estimate annual
averaged absorbed and equivalent local dose rates in tissues. It is established that in the lunar rock the contribution of
secondary neutrons to the dose rate exceeds that of protons. The contribution of the secondary particles generated by nuclei
of galactic cosmic rays to the dose rate is estimated. 相似文献
135.
The results of a preliminary analysis of microperturbations on the International Space Station during physical exercises of the crew are presented. The goal of this paper is to identify the parameters of perturbations
when physical exercises are performed. The results of measurements by sensors of microaccelerations of both Russian and American
segments during physical exercises in the service module of the Russian segment are analyzed. 相似文献
136.
A method is substantiated to ensure energy security for the satellite communication systems (SCS) at a close position of the
radio interception receiver. This is done by lowering the carrier frequency down to f
0 = 60…80 MHz and by applying spaced measurements with n ≥ 4 receiving antennas. 相似文献
137.
A. V. Tavrov O. I. Korablev A. V. Rodin I. I. Vinogradov A. Yu. Trokhimovsky A. Yu. Ivanov L. V. Ksanfomaliti D. A. Orlov 《Cosmic Research》2011,49(2):99-109
In order to observe exoplanets we propose a space-based achromatic stellar coronagraph combined with a 0.8–1.5 m telescope.
We develop an achromatic common path interferometer for observing an exoplanet (a faint off-axis source) on the background
of a hoste star (bright axial source). An image of the star and its copy acquire an achromatic phase shift by 180° and interfere
in antiphase. The achromatic phase shift is caused by geometric phase in the scheme of a three-dimensional interferometer.
The interference process divides spatially the dark and light fields of the star image redirecting them to the opposite sides
of a beam splitter. The interference process does not weaken the image of a planet, with equal intensities it is redirected
to both sides of a beam splitter. The suggested scheme of common path interferometer ensures mechanical stability. The background
signal is experimentally demonstrated to be reduced by six orders of magnitude. 相似文献
138.
I. A. Galiullin 《Cosmic Research》2011,49(2):175-178
The constraints imposed on parameters of a force field and of a symmetrical gyrostat in it are determined, at which regular
precession of this gyrostat demonstrate Lyapunov stability (or, respectively, instability). 相似文献
139.
Possible consequences of collisions of natural cosmic bodies with the Earth’s atmosphere and surface are described. The methodological
basis of classification of consequences is the solution of meteor physics equations characterizing the trajectory of a body
in the atmosphere, namely, the dependence of the body’s velocity and mass on the flight altitude. The solution depends on
two dimensionless parameters characterizing the drag altitude and the role of mass loss by a meteoroid during its motion in
the atmosphere. Depending on values of these parameters, the degree of effect on the planetary surface considerably changes.
In particular, the conditions of cratering and meteorite fall on the planetary surface are obtained. The results are presented
in a simple analytical form. They quite match to the real events considered in the paper. Recommendations are given on further
investigations into the important problem of interaction of cosmic bodies with planetary atmospheres. 相似文献
140.
B. A. Antuf’ev 《Russian Aeronautics (Iz VUZ)》2008,51(3):227-231
A problem on low vibrations of a thin spherical shell is considered. A solid of finite dimensions is discretely attached to the shell by means of an elastic rod system. The calculation examples are presented. 相似文献