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   5499篇
  免费   11篇
  国内免费   15篇
航空   2552篇
航天技术   1586篇
综合类   184篇
航天   1203篇
  2021年   48篇
  2019年   33篇
  2018年   224篇
  2017年   165篇
  2016年   89篇
  2015年   53篇
  2014年   120篇
  2013年   147篇
  2012年   177篇
  2011年   306篇
  2010年   232篇
  2009年   315篇
  2008年   321篇
  2007年   245篇
  2006年   119篇
  2005年   188篇
  2004年   125篇
  2003年   134篇
  2002年   187篇
  2001年   206篇
  2000年   73篇
  1999年   99篇
  1998年   126篇
  1997年   90篇
  1996年   121篇
  1995年   134篇
  1994年   108篇
  1993年   65篇
  1992年   91篇
  1991年   35篇
  1990年   31篇
  1989年   78篇
  1988年   34篇
  1987年   34篇
  1986年   34篇
  1985年   138篇
  1984年   116篇
  1983年   74篇
  1982年   93篇
  1981年   123篇
  1980年   35篇
  1978年   27篇
  1977年   26篇
  1975年   25篇
  1974年   35篇
  1972年   26篇
  1971年   24篇
  1970年   23篇
  1969年   26篇
  1967年   23篇
排序方式: 共有5525条查询结果,搜索用时 796 毫秒
51.
We demonstrate that it is possible to express each component of the displacement vector for the interior point of the finite element (FE) through all components of nodal unknowns in curvilinear coordinates. The effectiveness of the valid technique of vector approximation for displacement fields has been verified on an example.  相似文献   
52.
The fastest pulsar and the slowest nova; the oldest galaxies and the youngest stars; the weirdest life forms and the commonest dwarfs; the highest energy particles and the lowest energy photons. These were some of the extremes of Astrophysics 2006. We attempt also to bring you updates on things of which there is currently only one (habitable planets, the Sun, and the Universe) and others of which there are always many, like meteors and molecules, black holes and binaries.  相似文献   
53.
The problem is formulated and a technique is revealed for synthesizing the optimal strategy of troubleshooting and constructing an operation algorithm for the information-control system of inspection and diagnostics of the aircraft equipment state.  相似文献   
54.
We analyze the effect of injection both of uniformly distributed over the entire cylinder surface and of the optimal one on the velocity distribution at the outer border of the boundary layer and, as a result, on friction.  相似文献   
55.
The results of studying an incompressible gas flow field in a periodic element of the porous structure made up of the same radius spheres are presented; the studies were based on the solution of the Navier-Stokes equations using FLUENT software. The possibilities to accelerate the solution process with the use of parallel calculations are investigated and the calculation results under changes of pressure differential in the periodic element are given.  相似文献   
56.
In this paper, a program package for solving problems in the field of thin-walled three-dimensional FV structure design is described.  相似文献   
57.
Problems arising in introduction of gasodynamic seals in aircraft engines are considered. The operation of a face gasodynamic seal as part of a natural gas pump is analyzed and its efficiency in the presence of oil is shown.  相似文献   
58.
In this paper, a problem on measuring the altitude-airspeed parameters (AAPs) of rotorcraft and very light flight vehicles is considered. Some ways of improving systems used to measure the parameters of FV elements and units have been determined. Also suggested and substantiated are the principles and designs of the basic variants of these measuring systems as well as the algorithms of their operation.  相似文献   
59.
On March 2003, IBIS, the γ-ray imager on board the INTEGRAL satellite, detected an outburst from a new source, IGR J17464-3213, that turned out to be an HEAO-1 transient, namely H1743-322. The spectral and temporal evolutions of the source were observed by INTEGRAL in different periods. Also RXTE observed the source for the first time on 2003 March 29 during a PCA Galactic bulge scan. The source flux decayed below the RXTE PCA sensitivity limit in November 2003, then in April 2004 it was again detected by INTEGRAL. On July 3, 2004 the source was again detected by RXTE/PCA at a 2–10 keV intensity of 16 mCrab and on July 7, reached 69 mCrab. Recently, a new outburst was observed on August 2005. We briefly summarise here the behaviour of the source observed by INTEGRAL from March 2003 to August 2005. The new outbursts of the source and the analysis of all the data collected (now public) give a global view of the spectral and time behaviour of this X-ray transient.  相似文献   
60.
Unmanned aircraft navigation for shipboard landing using infrared vision   总被引:2,自引:0,他引:2  
This paper addresses the problem of determining the relative position and orientation of an unmanned air vehicle with respect to a ship using three visible points of known separation. The, images of the points are obtained from an onboard infrared camera. The paper develops a numerical solution to this problem. Both simulation and flight test results are presented.  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