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   2296篇
  免费   11篇
  国内免费   5篇
航空   876篇
航天技术   762篇
综合类   8篇
航天   666篇
  2022年   6篇
  2021年   23篇
  2019年   7篇
  2018年   132篇
  2017年   88篇
  2016年   58篇
  2015年   23篇
  2014年   69篇
  2013年   70篇
  2012年   66篇
  2011年   119篇
  2010年   84篇
  2009年   126篇
  2008年   147篇
  2007年   86篇
  2006年   51篇
  2005年   67篇
  2004年   72篇
  2003年   83篇
  2002年   53篇
  2001年   94篇
  2000年   38篇
  1999年   41篇
  1998年   43篇
  1997年   34篇
  1996年   49篇
  1995年   40篇
  1994年   33篇
  1993年   24篇
  1992年   37篇
  1991年   9篇
  1990年   12篇
  1989年   34篇
  1988年   13篇
  1987年   18篇
  1986年   20篇
  1985年   67篇
  1984年   35篇
  1983年   25篇
  1982年   37篇
  1981年   66篇
  1980年   16篇
  1979年   6篇
  1978年   7篇
  1977年   13篇
  1976年   9篇
  1975年   14篇
  1974年   15篇
  1973年   8篇
  1970年   4篇
排序方式: 共有2312条查询结果,搜索用时 15 毫秒
681.
682.
    
Using the Dst and AE geomagnetic index values and parameters of interplanetary magnetic field and solar wind we have examined the geoeffectiveness of transient ejections in the solar wind, namely, magnetic clouds and high-speed streams. It is found that for magnetic clouds the dependences of indices on the solar wind electric field are nonlinear of different kind. In contrast to magnetic clouds, the dependence of Dst and AE geomagnetic index values on the solar wind electric field agrees closely with the linear one for high-speed streams. We suggest approximating formulas to describe dependences obtained taking into account the relation of the electric field transpolar potential to the electric field and dynamic pressure of the solar wind. We suppose that the interplanetary magnetic field fluctuations also contribute to these dependences.  相似文献   
683.
684.
    
In the design of an aircraft at the stage of selecting its geometrical parameters, a method is proposed for evaluating the performance capabilities of manual control to ensure the quality of a given flight stabilization mode. The attainability of the given aircraft-pilot dynamic properties is evaluated by a frequency-domain method for permissible values of the aircraft and the pilot model parameters. The quality of the manual control for the longitudinal motion of the aircraft is evaluated.  相似文献   
685.
Frolov  V. L.  Luk’yanova  R. Yu.  Ryabov  A. O.  Bolotin  I. A. 《Cosmic Research》2021,59(4):231-249
Cosmic Research - We have analyzed the experimental data obtained in 2016–2019 from the measurements of plasma disturbances and electric currents induced at ionospheric altitudes upon the...  相似文献   
686.
Cosmic Research - A special version of the SHIELD transport code has been developed intended for radiation protection purposes in space. The calculation of the fluxes of primary and secondary...  相似文献   
687.
A concept of a universal fitting-out module applicable for space flight test of a solar-powered electric propulsion (EP) as well as for the assembly and deployment of small spacecraft (S/C) from the international space station (ISS) is proposed.  相似文献   
688.
A method of measuring the particle energy in the range higher than 1 TeV based on detection of the maximum specific energy release in hadron cascades that develop in dense media is proposed and studied. This method makes it possible to improve the accuracy of energy measurements carried out with partial-absorption ionization calorimeters in the high-altitude studies of energy spectra of high-energy cosmic rays. The attainable accuracies of energy measurements are considered for light, intermediate, and heavy nuclei in iron and lead absorbers. The results of modeling are compared with the data of an experiment onboard the Kosmos-1713 satellite.  相似文献   
689.
    
The results of observations of interplanetary scintillations of a statistical ensemble of radio sources in the period of 2007–2011 are presented. Observation were carried out in the monitoring regime with the BSA LPI radio telescope at the frequency 111 MHz. Fluctuations of radio emission flux of all sources (a few hundred in total) were recorded 24 hours a day. Those sources were investigated, which had a scintillating flux greater than 0.2 Jy and fell within the sky band of 8° width in declination, corresponding to radio telescope’s 16-beam system. The statistical ensemble of radio sources is characterized by the mean variance of a scintillating radiation flux, which is proportional to the squared scintillation index. It follows from the obtained data that the radial dependence of a mean scintillation index during a deep solar activity minimum of 2008–2009 occurs to be weaker than one could expect in the case of spherically symmetric geometry of the solar wind. Suppression of a radial dependence of the mean scintillation index is explained by the effect of the heliospheric current sheet, which reveals itself in a high density of solar wind’s turbulent plasma in the helioequator plane. It is shown that the level of scintillations, averaged over monthly series of observations, was changing synchronously with the solar activity level.  相似文献   
690.
    
Analysis of errors in atmospheric density measurements by lidar on board the ISS is performed. It is shown that using as the lidar transmitter a Nd:YAG laser with moderate parameters of emission at a wavelength of 353 nm and a receiving mirror diameter of 0.4 m, it is possible to cover with a 10% measurement error a height range, on average, from 40–60 km and 30–40 km in the nighttime and daytime, respectively, down to the troposphere. Working with emission at 266 nm with a 10% error, it is possible to move to the heights of the mesosphere (70 km) and penetrate the atmosphere down to a height of 40 km. Thus, the use of two harmonics makes it possible to assimilate the height range of atmospheric density measurements from on board the ISS beginning from 70 km and down to the troposphere.  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