全文获取类型
收费全文 | 5081篇 |
免费 | 52篇 |
国内免费 | 24篇 |
专业分类
航空 | 2326篇 |
航天技术 | 1802篇 |
综合类 | 16篇 |
航天 | 1013篇 |
出版年
2021年 | 47篇 |
2019年 | 40篇 |
2018年 | 112篇 |
2017年 | 94篇 |
2016年 | 77篇 |
2015年 | 41篇 |
2014年 | 119篇 |
2013年 | 154篇 |
2012年 | 135篇 |
2011年 | 218篇 |
2010年 | 158篇 |
2009年 | 238篇 |
2008年 | 259篇 |
2007年 | 164篇 |
2006年 | 122篇 |
2005年 | 145篇 |
2004年 | 138篇 |
2003年 | 161篇 |
2002年 | 113篇 |
2001年 | 164篇 |
2000年 | 94篇 |
1999年 | 104篇 |
1998年 | 126篇 |
1997年 | 100篇 |
1996年 | 119篇 |
1995年 | 149篇 |
1994年 | 138篇 |
1993年 | 74篇 |
1992年 | 111篇 |
1991年 | 45篇 |
1990年 | 45篇 |
1989年 | 108篇 |
1988年 | 45篇 |
1987年 | 40篇 |
1986年 | 44篇 |
1985年 | 134篇 |
1984年 | 133篇 |
1983年 | 95篇 |
1982年 | 101篇 |
1981年 | 144篇 |
1980年 | 51篇 |
1979年 | 37篇 |
1978年 | 43篇 |
1977年 | 36篇 |
1976年 | 29篇 |
1975年 | 42篇 |
1974年 | 33篇 |
1973年 | 27篇 |
1972年 | 25篇 |
1971年 | 24篇 |
排序方式: 共有5157条查询结果,搜索用时 15 毫秒
851.
A.H. Manson C.E. Meek K. Labitzke 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(4):51-55
The global developments of the stratospheric events (~20–50 km) are briefly described using balloon and satellite data. Winds data from L.F. drift (52°N, 15°E, Europe) for heights of 90–100 km, and from M.F. radar (52°N, 107°W, Canada) for heights of 60–110 km are then compared with the stratospheric morphology.Data for 1982/3 and 1983/4 show that the planetary wave activity and warmings produced strong westward and southward perturbations in the radar winds. Satellite data from 0.1, 0.01 hPa are consistent with these winds; and also show smaller scale structures in the mesosphere than the stratosphere. The semi-diurnal tide responded strongly to the atmospheric disturbances in Europe and Canada: for the latter vertical wavelength changes occurred for heights of 70–100 km. However the correlation between these tidal fluctuations was not high indicating that the tidal adjustments were continental rather than hemispheric. 相似文献
852.
Marcos E. Machado Gustavo Lerner 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(7):239-241
We show that the observations of a limb flare, in which a hard X-ray (16–30 keV) source is seen at the boundary between two interacting magnetic structures, indicate the presence of hot (T ? 6 × 107 K) plasma within the region. Non thermal bremsstrahlung processes do not agree with these observations. We discuss the possible causes of the heating. 相似文献
853.
854.
D.J. Michels N.R. Sheeley R.A. Howard M.J. Koomen R. Schwenn K.H. Mulhauser H. Rosenbauer 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(7):311-321
A small coronagraph has been placed in orbit to monitor the sun's outer corona from 2.5 to 10.0 solar radii, and five years of nearly continuous synoptic observations have now been completed. Rapid and sensitive image processing techniques have been developed to screen the data for transient phenomena, particularly coronal mass ejections (CMEs). About 50,000 coronal images have been examined, out of a five-year total of 68,000, and a standardized listing of more than 1,200 coronal transients for the period 1979–1982 has been prepared. These data have been analysed in the light of other available information, particularly on conditions in the interplanetary plasma. The dynamical characteristics of the active corona, as they are beginning to emerge from the data, are presented. We find that coronal mass ejections exercise significant influence on the interplanetary solar wind. They are the source of disturbances that are frequent and energetic, that tend to be somewhat focussed, that often reach shock intensity, and that propagate to large heliocentric distances, sometimes causing major geomagnetic storms. 相似文献
855.
S.S. Gaigerov M.Ya. Kalikhman V.V. Fedorov E.D. Zhorova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(1):29-32
Circulation and thermal structure for the 90–95 km region is described on the basis of the joint analysis of direct and indirect sounding data. Mean season charts of the 0.001 mb surface were compiled using data from meteor trials, ionospheric drifts, rocket launchings and data of the rotational temperature of hydroxyl emission. 相似文献
856.
Tomas E. Gergely 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(11):271-284
Using data available at the present time, a summary of the significant solar-terrestrial events of STIP Interval XII (April 10–July 1, 1981) has been prepared. The first half of the interval was extremely active, several of the largest X-ray flares, particle events, and shocks of the present solar cycle took place during April and the first half of May. The second half of the interval, on the other hand, was characterized by relatively quiet conditions. Several large events which occurred on 10, 24 and 27 April and on 8 and 16 May are discussed in some detail. It is suggested that one of the most interesting subjects of future study could be the comparison and statistical analysis of the numerous events for which excellent observations are available, e.g. on what causes a type II burst to propagate in the interplanetary medium. 相似文献
857.
R. E. Halpern 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1988,8(12):89-95
The United States has begun the development of an international Space Station complex in cooperation with Japan, Canada, and the European Space Agency. The planned uses of the facility encompass a broad spectrum of research disciplines including life sciences, material sciences, astrophysics, earth sciences and planetary sciences. Activity has already started on the preparation of scientific proposals, and in some cases on specific pieces of instrumentation, in many of these areas. Long-duration, continuous research in space in a manned facility presents situations, problems and opportunities which have never before needed to be addressed. This paper presents current thinking in the United States on several of these issues related specifically to the microgravity sciences and an initial paradigm for their solution. 相似文献
858.
Stark L. Tendick F. Kim W. Anderson R. Hisey M. Mills B. Matsunaga K. An Nguyen Ramos C. Tyler M. Zahalak G. Amick M. Baker B. Brown N. Brown T. Chang J. Jyh-Horng Chen Chik J. Cohen D. Cox D. Dubey J. Ellis K. Engdahl E. Frederickson C. Halamka J. Hauser R. Jacobs J. Lee C. Lee D. Liu A. Ninomiya R. Rudolph J. Schafer S. Schendel E. So G. Takeda M. Tam L. Thompson M. Wood E. Woodruff T. 《IEEE transactions on aerospace and electronic systems》1988,24(5):542-551
With major emphasis on simulation, a university laboratory telerobotics facility permits problems to be approached by groups of graduate students. Helmet-mounded displays provide realism; the slaving of the display to the human operator's viewpoint gives a sense of `telepresence' that may be useful for prolonged tasks. Using top-down 3-D model control of distant images allows distant images to be reduced to a few parameters to update the model used for display to the human operator in a preview model to circumvent, in part, the communication delay. Also, the model can be used as a format for supervisory control and permit short-term local autonomous operations. Image processing algorithms can be made simpler and faster without trying to construct sensible images from the bottom. Control studies of telerobots lead to preferential manual control modes and, in this university environment, to basic paradigms for human motion and thence, perhaps, to redesign of robotic control, trajectory path planning, and rehabilitation prosthetics. Speculation as to future industrial drives for this telerobotic field suggests efficient roles for government agencies such as NASA 相似文献
859.
860.
Buongiorno C. Vallerani E. Borriello G. 《Aerospace and Electronic Systems Magazine, IEEE》1989,4(5):17-25
The authors present the plan under discussion in Italy between the government entities and Aeritalia, the leading Italian aerospace company, for the technology development needed to support advanced transportation systems. The plan centers around the following areas: thermal protection and control; advanced structures and materials; guidance, navigation, and control; and tests and computation methods. Experimental activities needed to support the development of such systems and the difficulties involved are examined 相似文献