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   6476篇
  免费   9篇
  国内免费   29篇
航空   3047篇
航天技术   2166篇
综合类   19篇
航天   1282篇
  2021年   54篇
  2019年   40篇
  2018年   218篇
  2017年   162篇
  2016年   101篇
  2015年   42篇
  2014年   127篇
  2013年   164篇
  2012年   182篇
  2011年   327篇
  2010年   248篇
  2009年   357篇
  2008年   383篇
  2007年   268篇
  2006年   146篇
  2005年   212篇
  2004年   188篇
  2003年   198篇
  2002年   123篇
  2001年   186篇
  2000年   128篇
  1999年   139篇
  1998年   158篇
  1997年   125篇
  1996年   153篇
  1995年   197篇
  1994年   178篇
  1993年   95篇
  1992年   145篇
  1991年   49篇
  1990年   51篇
  1989年   127篇
  1988年   40篇
  1987年   40篇
  1986年   58篇
  1985年   172篇
  1984年   131篇
  1983年   105篇
  1982年   131篇
  1981年   154篇
  1980年   45篇
  1979年   30篇
  1978年   37篇
  1977年   36篇
  1976年   29篇
  1975年   26篇
  1974年   34篇
  1973年   25篇
  1970年   27篇
  1969年   24篇
排序方式: 共有6514条查询结果,搜索用时 687 毫秒
511.
The results of designing the attitude control system of the first Russian nanosatellite TNS-0 no. 1 providing orientation of its longitudinal axis along the local geomagnetic field induction vector are presented. The system consists of a permanent magnet and two sets of hysteresis rods. The magnetic and geometric parameters of the magnet and rods are calculated. The influence of the permanent magnet field on the hysteresis rods and mutual influence of the rods in the case of compact satellite packaging are analyzed. Examples of calculations of transient processes and steady-state angular satellite motion are presented.  相似文献   
512.
513.
We consider the function, the problems being solved and the construction principles for a starting system of warning the critical regimes for a single-rotor helicopter at parking, taxiing and maneuvering on the ground, takeoff and landing as well as at descending and hovering regimes. The structural-functional scheme and the algorithms of system channel warning are presented.  相似文献   
514.
The problem of determining the “potential” number of integration steps by explicit difference schemes is solved within the framework of the prediction model for chemically non-equilibrium processes.  相似文献   
515.
The Juno Waves Investigation   总被引:1,自引:0,他引:1  
Jupiter is the source of the strongest planetary radio emissions in the solar system. Variations in these emissions are symptomatic of the dynamics of Jupiter’s magnetosphere and some have been directly associated with Jupiter’s auroras. The strongest radio emissions are associated with Io’s interaction with Jupiter’s magnetic field. In addition, plasma waves are thought to play important roles in the acceleration of energetic particles in the magnetosphere, some of which impact Jupiter’s upper atmosphere generating the auroras. Since the exploration of Jupiter’s polar magnetosphere is a major objective of the Juno mission, it is appropriate that a radio and plasma wave investigation is included in Juno’s payload. This paper describes the Waves instrument and the science it is to pursue as part of the Juno mission.  相似文献   
516.
The paper discusses a method of designing the neural controller for two-channel control of a technical object by an example of the roll and yaw control depending on deviations, velocities and accelerations of their variation.  相似文献   
517.
The methodology is proposed and the mathematical model is developed for the purpose of numerical simulation of the power circuit of the gas-hydraulic actuator with displacing power source for the gimbaled nozzle control. It provides the highest power efficiency factor of the actuator as a part of aircraft by means of pulling together the profiles of available and required power.  相似文献   
518.
Direct measurements of the geomagnetic field have been made for more than 400 years, beginning with individual determinations of the angle between geographic and magnetic North. This was followed by the start of continuous time series of full vector measurements at geomagnetic observatories and the beginning of geomagnetic repeat stations surveys in the 19th century. In the second half of the 20th century, true global coverage with geomagnetic field measurements was accomplished by magnetometer payloads on low-Earth-orbiting satellites. This article describes the procedures and instruments for magnetic field measurements on ground and in space and covers geomagnetic observatories, repeat stations, automatic observatories, satellites and historic observations. Special emphasis is laid on the global network of geomagnetic observatories.  相似文献   
519.
In this paper, a mathematical model of labor-intensity and a method of searching for optimal control of operating conditions in machining arbitrarily configurated parts with the use of CNC machines are considered. Also given is an example of the process optimization..  相似文献   
520.
The paper presents an improved technique and the results of strength analysis for the aircraft structural elements with a structural defect like an arbitrary shape delamination.  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