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   4649篇
  免费   44篇
  国内免费   28篇
航空   2328篇
航天技术   1325篇
综合类   71篇
航天   997篇
  2021年   35篇
  2018年   175篇
  2017年   168篇
  2016年   66篇
  2015年   54篇
  2014年   75篇
  2013年   101篇
  2012年   117篇
  2011年   279篇
  2010年   229篇
  2009年   259篇
  2008年   292篇
  2007年   242篇
  2006年   110篇
  2005年   165篇
  2004年   96篇
  2003年   116篇
  2002年   90篇
  2001年   106篇
  2000年   88篇
  1999年   102篇
  1998年   107篇
  1997年   101篇
  1996年   88篇
  1995年   104篇
  1994年   107篇
  1993年   69篇
  1992年   77篇
  1991年   39篇
  1990年   44篇
  1989年   74篇
  1988年   39篇
  1987年   32篇
  1986年   35篇
  1985年   113篇
  1984年   79篇
  1983年   80篇
  1982年   59篇
  1981年   103篇
  1980年   25篇
  1979年   27篇
  1978年   33篇
  1977年   25篇
  1976年   23篇
  1975年   39篇
  1974年   20篇
  1972年   33篇
  1971年   25篇
  1969年   22篇
  1967年   23篇
排序方式: 共有4721条查询结果,搜索用时 843 毫秒
61.
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   
62.
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   
63.
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   
64.
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   
65.
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   
66.
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   
67.
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   
68.
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   
69.
Human exposure to large solar particle events in space.   总被引:4,自引:0,他引:4  
Whenever energetic solar protons produced by solar particle events traverse bulk matter, they undergo various nuclear and atomic collision processes which significantly alter the physical characteristics and biologically important properties of their transported radiation fields. These physical interactions and their effect on the resulting radiation field within matter are described within the context of a recently developed deterministic, coupled neutron-proton space radiation transport computer code (BRYNTRN). Using this computer code, estimates of human exposure in interplanetary space, behind nominal (2 g/cm2) and storm shelter (20 g/cm2) thicknesses of aluminum shielding, are made for the large solar proton event of August 1972. Included in these calculations are estimates of cumulative exposures to the skin, ocular lens, and bone marrow as a function of time during the event. Risk assessment in terms of absorbed dose and dose equivalent is discussed for these organs. Also presented are estimates of organ exposures for hypothetical, worst-case flare scenarios. The rate of dose equivalent accumulation places this situation in an interesting region of dose rate between the very low values of usual concern in terrestrial radiation environments and the high dose rate values prevalent in radiation therapy.  相似文献   
70.
This paper discusses the advantages of incorporating active sidesticks into a modern aircraft cockpit. Active sidestick controllers for manual pilot inputs in pitch and roll are examined for commercial transport aircraft. Options and requirements for sidesticks are reviewed. The recommendation of an active sidestick controller is developed providing both cross-cockpit coupling and autopilot backdrive capability. These characteristics provide pilot cues identical to traditional cable-linked column/yoke configurations  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