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   7286篇
  免费   36篇
  国内免费   39篇
航空   3329篇
航天技术   2650篇
综合类   30篇
航天   1352篇
  2021年   73篇
  2019年   56篇
  2018年   214篇
  2017年   135篇
  2016年   102篇
  2015年   42篇
  2014年   169篇
  2013年   212篇
  2012年   193篇
  2011年   304篇
  2010年   218篇
  2009年   357篇
  2008年   395篇
  2007年   220篇
  2006年   173篇
  2005年   213篇
  2004年   222篇
  2003年   246篇
  2002年   162篇
  2001年   236篇
  2000年   151篇
  1999年   172篇
  1998年   193篇
  1997年   154篇
  1996年   176篇
  1995年   226篇
  1994年   194篇
  1993年   114篇
  1992年   172篇
  1991年   59篇
  1990年   62篇
  1989年   147篇
  1988年   55篇
  1987年   54篇
  1986年   68篇
  1985年   210篇
  1984年   161篇
  1983年   132篇
  1982年   152篇
  1981年   197篇
  1980年   76篇
  1979年   42篇
  1978年   49篇
  1977年   42篇
  1976年   43篇
  1975年   39篇
  1974年   44篇
  1973年   32篇
  1970年   31篇
  1969年   30篇
排序方式: 共有7361条查询结果,搜索用时 468 毫秒
351.
We considered the influence of temperature on the nitric oxide emission under combustion of the near-stoichiometric mixtures with and without water feed. We revealed the advantage of the method of fuel-water-air mixture combustion over that of the leaned mixture combustion.  相似文献   
352.
A technique for calculating the energy parameters of shock waves at electrical discharge in water is presented for the transition region of discharge channel expansion using as the base the predetermined characteristics of discharge circuit. The technique is based on the solution of energy transport equation that is similar in form to that of radiative transfer. The validity of the presented approach was experimentally verified.  相似文献   
353.
Aerodynamic characteristics of two-dimensional smart flap under the ground effect have been assessed by a numerical simulation. In this process, a pressure-based implicit procedure to solve Navier–Stokes equations on a nonorthogonal mesh with collocated finite volume formulation is used. The boundedness criteria for this procedure are determined from the Normalized Variable Diagram (NVD) scheme. The procedure incorporates the kε eddy–viscosity turbulence model. Cantilever beam with uniformly varying load with roller support at the free end is considered for the configuration of the smart flap. The method is first validated against experimental data. Then, the algorithm is applied for turbulent aerodynamic flows around airfoil with smart and conventional flaps for different attack angle, flap angle and ground clearance where the results of two flaps are compared. The comparisons show that the quality of the solution is considerable.  相似文献   
354.
The results of investigating free oscillations of the International Space Station construction appearing during spacecraft docking and undocking are described. The study is carried out using the measurement data of the low-frequency MAMS accelerometer. Several intervals of measurements performed in 2005 and 2006 were chosen to be studied. For chosen intervals, only the data intervals corresponding to the process of free attenuation of the oscillations construction elements were analyzed. Characteristic frequencies of elastic oscillations of the station construction and attenuation coefficients corresponding to them are found. The comparative analysis of the results obtained for various docking ports (nodes) is carried out. The described study is performed as a part of the technical experiment “The ISS Environment” carried out onboard the station in accordance with the Russian program of scientific and engineering experiments.  相似文献   
355.
356.
The Relativistic Proton Spectrometer (RPS) on the Radiation Belt Storm Probes spacecraft is a particle spectrometer designed to measure the flux, angular distribution, and energy spectrum of protons from ~60 MeV to ~2000 MeV. RPS will investigate decades-old questions about the inner Van Allen belt proton environment: a nearby region of space that is relatively unexplored because of the hazards of spacecraft operation there and the difficulties in obtaining accurate proton measurements in an intense penetrating background. RPS is designed to provide the accuracy needed to answer questions about the sources and losses of the inner belt protons and to obtain the measurements required for the next-generation models of trapped protons in the magnetosphere. In addition to detailed information for individual protons, RPS features count rates at a 1-second timescale, internal radiation dosimetry, and information about electrostatic discharge events on the RBSP spacecraft that together will provide new information about space environmental hazards in the Earth’s magnetosphere.  相似文献   
357.
358.
359.
360.
对旋转畸变条件下轴流压气机的失稳特性进行了实验研究,结果表明,畸变影响区内叶顶泄漏流的前缘溢出造成了旋转失速的提前发生,缩减了压气机的失稳裕度.叶顶微喷气方法有效地提高了旋转畸变条件下轴流压气机的失稳裕度,其原因在于,实施叶顶微喷气后,临近失速时,压气机顶部畸变区诱发的分离团受到抑制,减少了其诱发旋转失速的可能性,从而实现扩稳目的.   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