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   5472篇
  免费   11篇
  国内免费   15篇
航空   2471篇
航天技术   1789篇
综合类   22篇
航天   1216篇
  2021年   47篇
  2019年   37篇
  2018年   231篇
  2017年   172篇
  2016年   105篇
  2015年   53篇
  2014年   121篇
  2013年   146篇
  2012年   149篇
  2011年   275篇
  2010年   220篇
  2009年   310篇
  2008年   361篇
  2007年   241篇
  2006年   128篇
  2005年   163篇
  2004年   140篇
  2003年   163篇
  2002年   110篇
  2001年   173篇
  2000年   89篇
  1999年   95篇
  1998年   111篇
  1997年   84篇
  1996年   109篇
  1995年   122篇
  1994年   121篇
  1993年   70篇
  1992年   100篇
  1991年   47篇
  1990年   42篇
  1989年   100篇
  1988年   36篇
  1987年   44篇
  1986年   45篇
  1985年   153篇
  1984年   102篇
  1983年   89篇
  1982年   105篇
  1981年   145篇
  1980年   43篇
  1979年   44篇
  1978年   32篇
  1977年   30篇
  1976年   21篇
  1975年   25篇
  1974年   28篇
  1973年   23篇
  1972年   16篇
  1970年   16篇
排序方式: 共有5498条查询结果,搜索用时 15 毫秒
211.
This paper deals with the technical features of designing an information-controlling system to prevent critical operating conditions of the helicopter flight, a technique for evaluating its effectiveness, analysis and synthesis of the measurement channels, forming of warning signals, and information support of the crew in abnormal situations.  相似文献   
212.
We determine the behavior of onboard gas-generator flowrate for generating the cavitation flow around a hybrid aerial underwater vehicle by using an annular wing on the underwater trajectory section.  相似文献   
213.
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   
214.
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   
215.
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   
216.
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   
217.
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   
218.
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   
219.
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   
220.
The paper provides a method for multi-criteria selection of the optimal structural layout option based on a fuzzy logic inference that allows for uncertainties in engineering and operates with heterogeneous information of the qualitative and quantitative nature for the systems being designed.  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