全文获取类型
收费全文 | 3615篇 |
免费 | 2篇 |
国内免费 | 8篇 |
专业分类
航空 | 1879篇 |
航天技术 | 1013篇 |
综合类 | 6篇 |
航天 | 727篇 |
出版年
2021年 | 15篇 |
2019年 | 14篇 |
2018年 | 190篇 |
2017年 | 158篇 |
2016年 | 58篇 |
2015年 | 39篇 |
2014年 | 57篇 |
2013年 | 70篇 |
2012年 | 92篇 |
2011年 | 217篇 |
2010年 | 191篇 |
2009年 | 234篇 |
2008年 | 245篇 |
2007年 | 202篇 |
2006年 | 57篇 |
2005年 | 117篇 |
2004年 | 89篇 |
2003年 | 94篇 |
2002年 | 49篇 |
2001年 | 106篇 |
2000年 | 47篇 |
1999年 | 86篇 |
1998年 | 85篇 |
1997年 | 64篇 |
1996年 | 64篇 |
1995年 | 88篇 |
1994年 | 97篇 |
1993年 | 42篇 |
1992年 | 62篇 |
1991年 | 23篇 |
1990年 | 29篇 |
1989年 | 56篇 |
1988年 | 21篇 |
1987年 | 36篇 |
1986年 | 20篇 |
1985年 | 75篇 |
1984年 | 42篇 |
1983年 | 47篇 |
1982年 | 55篇 |
1981年 | 77篇 |
1980年 | 26篇 |
1979年 | 24篇 |
1978年 | 22篇 |
1977年 | 18篇 |
1976年 | 15篇 |
1975年 | 18篇 |
1974年 | 12篇 |
1972年 | 17篇 |
1969年 | 13篇 |
1966年 | 8篇 |
排序方式: 共有3625条查询结果,搜索用时 93 毫秒
811.
Optimization of project-ballistic parameters of the spacecraft with propulsion systems with energy accumulation during the orbital transfer between low Earth orbits in the non-central gravitational field of the Earth is considered. The mass model of the spacecraft with an uncontrollable power-limited engine with the energy accumulator is used. The method of the project-ballistic optimization is obtained as an iterative procedure. Energy storage usage efficiency during the orbital transfer between low Earth orbits is estimated. 相似文献
812.
N. Petrova T. Abdulmyanov H. Hanada 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
Targets and problems of the future Japanese project ILOM (In situ Lunar Orientation Measurement), which is planned to be realized as one kind of observations of lunar rotation at the second stage of SELENE-2 mission, are briefly described in the article. Inverse problem of lunar physical libration is formulated and solved. Accuracy of libration angles depending on accuracy of measuring selenographic coordinates is estimated. It is shown that selenographic coordinates of polar stars are insensitive to longitudinal librations τ(t). Comparing coordinates calculated for two models of a rigid and deformable Moon is carried out and components sensitive to Love number k2 and to anelastic time delay are revealed. 相似文献
813.
S. A. Stern H. A. Weaver J. R. Spencer H. A. Elliott the New Horizons Team 《Space Science Reviews》2018,214(4):77
The central objective of the New Horizons prime mission was to make the first exploration of Pluto and its system of moons. Following that, New Horizons has been approved for its first extended mission, which has the objectives of extensively studying the Kuiper Belt environment, observing numerous Kuiper Belt Objects (KBOs) and Centaurs in unique ways, and making the first close flyby of the KBO 486958 2014 MU69. This review summarizes the objectives and plans for this approved mission extension, and briefly looks forward to potential objectives for subsequent extended missions by New Horizons. 相似文献
814.
D. J. McComas E. R. Christian N. A. Schwadron N. Fox J. Westlake F. Allegrini D. N. Baker D. Biesecker M. Bzowski G. Clark C. M. S. Cohen I. Cohen M. A. Dayeh R. Decker G. A. de Nolfo M. I. Desai R. W. Ebert H. A. Elliott H. Fahr P. C. Frisch H. O. Funsten S. A. Fuselier A. Galli A. B. Galvin J. Giacalone M. Gkioulidou F. Guo M. Horanyi P. Isenberg P. Janzen L. M. Kistler K. Korreck M. A. Kubiak H. Kucharek B. A. Larsen R. A. Leske N. Lugaz J. Luhmann W. Matthaeus D. Mitchell E. Moebius K. Ogasawara D. B. Reisenfeld J. D. Richardson C. T. Russell J. M. Sokół H. E. Spence R. Skoug Z. Sternovsky P. Swaczyna J. R. Szalay M. Tokumaru M. E. Wiedenbeck P. Wurz G. P. Zank E. J. Zirnstein 《Space Science Reviews》2018,214(8):116
The Interstellar Mapping and Acceleration Probe (IMAP) is a revolutionary mission that simultaneously investigates two of the most important overarching issues in Heliophysics today: the acceleration of energetic particles and interaction of the solar wind with the local interstellar medium. While seemingly disparate, these are intimately coupled because particles accelerated in the inner heliosphere play critical roles in the outer heliospheric interaction. Selected by NASA in 2018, IMAP is planned to launch in 2024. The IMAP spacecraft is a simple sun-pointed spinner in orbit about the Sun-Earth L1 point. IMAP’s ten instruments provide a complete and synergistic set of observations to simultaneously dissect the particle injection and acceleration processes at 1 AU while remotely probing the global heliospheric interaction and its response to particle populations generated by these processes. In situ at 1 AU, IMAP provides detailed observations of solar wind electrons and ions; suprathermal, pickup, and energetic ions; and the interplanetary magnetic field. For the outer heliosphere interaction, IMAP provides advanced global observations of the remote plasma and energetic ions over a broad energy range via energetic neutral atom imaging, and precise observations of interstellar neutral atoms penetrating the heliosphere. Complementary observations of interstellar dust and the ultraviolet glow of interstellar neutrals further deepen the physical understanding from IMAP. IMAP also continuously broadcasts vital real-time space weather observations. Finally, IMAP engages the broader Heliophysics community through a variety of innovative opportunities. This paper summarizes the IMAP mission at the start of Phase A development. 相似文献
815.
A. A. Vostrukhin D. V. Golovin A. S. Kozyrev M. L. Litvak A. V. Malakhov I. G. Mitrofanov M. I. Mokrousov T. M. Tomilina Yu. I. Bobrovnitskiy A. S. Grebennikov M. M. Laktionova B. N. Bakhtin A. V. Sotov 《Cosmic Research》2018,56(3):208-212
The results of testing a number of space-based detectors that contain PMTs or high-voltage electrodes for the noise from the microphonics that occurs in the signal path due to external mechanical action have been presented. A method for the vibration isolation of instruments aboard a spacecraft has been proposed to reduce their responsivity to vibrations. 相似文献
816.
817.
V. A. Sadovnichii V. V. Alexandrov D. I. Bugrov S. S. Lemak V. B. Pakhomov M. I. Panasyuk V. L. Petrov I. V. Yashin 《Space Science Reviews》2018,214(2):51
The IMISS-1 experiment represents the second step in solving the problem of the creation of the gaze stabilization corrector. This device is designed to correct the effect of the gaze stabilization delay under microgravity. IMISS-1 continues research started by the Tat’yana-2 satellite. This research will be continued on board the International Space Station. At this stage we study the possibility of registration of angular and linear accelerations acting on the sensitive mass in terms of Low Earth Orbit flight, using MEMS sensors. 相似文献
818.
This paper studies the dynamic loads of bevel gears with circular and straight teeth with the overlap factors less than two (εα < 2) and more than two (εα > 2). The advantages of the gears with straight teeth with εα > 2 are shown. 相似文献
819.
T.S. Kiss N. Gyenge R. Erdélyi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(2):611-616
Jets, whatever small (e.g. spicules) or large (e.g. macrospicules) their size, may play a key role in momentum and energy transport from photosphere to chromosphere and at least to the low corona. Here, we investigate the properties of abundant, large-scale dynamic jets observable in the solar atmosphere: the macrospicules (MS). These jets are observationally more distinct phenomena than their little, and perhaps more ubiquitous, cousins, the spicules. Investigation of long-term variation of the properties of macrospicules may help to a better understanding of their underlying physics of generation and role in coronal heating. Taking advantage of the high temporal and spatial resolution of the Solar Dynamics Observatory, a new dataset, with several hundreds of macrospicules, was constructed encompassing a period of observations over six years. Here, we analyse the measured properties and relations between these properties of macrospicules as function of time during the observed time interval. We found that cross-correlations of several of these macrospicule properties display a strong oscillatory pattern. Next, wavelet analysis is used to provide more detailed information about the temporal behaviour of the various properties of MS. For coronal hole macrospicules, a significant peak is found at around 2-year period. This peak also exists partially or is shifted to longer period, in the case of quiet Sun macrospicules. These observed findings may be rooted in the underlying mechanism generating the solar magnetic field, i.e. the global solar dynamo. 相似文献
820.