首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   7542篇
  免费   47篇
  国内免费   54篇
航空   3498篇
航天技术   2442篇
综合类   48篇
航天   1655篇
  2021年   86篇
  2019年   50篇
  2018年   245篇
  2017年   176篇
  2016年   132篇
  2015年   68篇
  2014年   195篇
  2013年   234篇
  2012年   235篇
  2011年   391篇
  2010年   283篇
  2009年   387篇
  2008年   403篇
  2007年   284篇
  2006年   159篇
  2005年   222篇
  2004年   192篇
  2003年   232篇
  2002年   181篇
  2001年   234篇
  2000年   131篇
  1999年   171篇
  1998年   190篇
  1997年   111篇
  1996年   174篇
  1995年   205篇
  1994年   192篇
  1993年   131篇
  1992年   151篇
  1991年   49篇
  1990年   48篇
  1989年   145篇
  1988年   59篇
  1987年   56篇
  1986年   65篇
  1985年   184篇
  1984年   147篇
  1983年   107篇
  1982年   116篇
  1981年   214篇
  1980年   51篇
  1979年   45篇
  1978年   50篇
  1977年   42篇
  1975年   54篇
  1974年   39篇
  1973年   32篇
  1972年   40篇
  1971年   35篇
  1970年   39篇
排序方式: 共有7643条查询结果,搜索用时 78 毫秒
301.
Junocam is a wide-angle camera designed to capture the unique polar perspective of Jupiter offered by Juno’s polar orbit. Junocam’s four-color images include the best spatial resolution ever acquired of Jupiter’s cloudtops. Junocam will look for convective clouds and lightning in thunderstorms and derive the heights of the clouds. Junocam will support Juno’s radiometer experiment by identifying any unusual atmospheric conditions such as hotspots. Junocam is on the spacecraft explicitly to reach out to the public and share the excitement of space exploration. The public is an essential part of our virtual team: amateur astronomers will supply ground-based images for use in planning, the public will weigh in on which images to acquire, and the amateur image processing community will help process the data.  相似文献   
302.
The paper discusses the applicability of cold gaseous nitrogen as a model working fluid in testing the hydrogen pump seals for power plants by three-dimensional modeling.  相似文献   
303.
This paper considers the axisymmetric transverse vibrations of aircraft nonuniform structural elements that are introduced by a thermal shock. Analytical solutions have been obtained and their numerical analysis has been performed.  相似文献   
304.
The CORONAS-F mission experiments and results have been reviewed. The observations with the DIFOS multi-channel photometer in a broad spectral range from 350 to 1500 nm have revealed the dependence of the relative amplitudes of p-modes of the global solar oscillations on the wavelength that agrees perfectly well with the earlier data obtained in a narrower spectral ranges. The SPIRIT EUV observations have enabled the study of various manifestations of solar activity and high-temperature events on the Sun. The data from the X-ray spectrometer RESIK, gamma spectrometer HELICON, flare spectrometer IRIS, amplitude–temporal spectrometer AVS-F, and X-ray spectrometer RPS-1 have been used to analyze the X- and gamma-ray emission from solar flares and for diagnostics of the flaring plasma. The absolute and relative content of various elements (such as potassium, argon, and sulfur) of solar plasma in flares has been determined for the first time with the X-ray spectrometer RESIK. The Solar Cosmic Ray Complex monitored the solar flare effects in the Earth’s environment. The UV emission variations recorded during solar flares in the vicinity of the 120-nm wavelength have been analyzed and the amplitude of relative variations has been determined.  相似文献   
305.
The work is devoted to observations of sharp growths of magnetospheric electron fluxes in the vicinity of the polar boundary of the outer radiation belt of the Earth according to the data of measurements on the Vernov and Lomonosov satellites. This precipitation was observed at the high-latitude boundary of the outer radiation belt toward the equator from the isotropization boundary, and can be caused by scattering waves of various physical natures, including electromagnetic and electrostatic waves.  相似文献   
306.
A high-accuracy numerical scheme is proposed for vortex methods of flow simulation around airfoils of arbitrary shape including airfoils with sharp edges, because it does not require the solution continuity on the airfoil.  相似文献   
307.
This paper considers issues of designing a gas-turbine engine in the helicopter system at the early design stages. The optimum and rational values of engine working process parameters at different flight speeds of the flight vehicle (FV) are analyzed. Several characteristics of mathematical models (MM) that form the helicopter–engine system, are described.  相似文献   
308.
We analyzed high-angular rate streaks first recorded by OSIRIS-REx’s MapCam during a 2017 search for Earth Trojan asteroids. We interpret them as water-ice particles that translated across the imager’s field of view, originating from the spacecraft itself. Their translation velocities approximated 0.1–1?m/s based on reasonable conclusions about their range. Pursuing several lines of investigation to seek a coherent hypothesis, we conclude that the episodic releases of the water ice particles are associated with spacecraft attitudes that resulted in solar illumination of previously shadowed regions. This correlation suggests that the OSIRIS-REx spacecraft itself possesses micro-climatic zones consisting of hot regions and cold traps that may temporarily potentially pass volatiles back and forth before losing most of them.  相似文献   
309.
310.
An exact solution of the Navier - Stokes equations is given that describes the vorticity of a viscous incompressible liquid or gas, dissipative mediums, stationary shear counter-current of continuous vortical medium in the absence of the Coriolis field.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号