全文获取类型
收费全文 | 5269篇 |
免费 | 5篇 |
国内免费 | 10篇 |
专业分类
航空 | 2467篇 |
航天技术 | 1644篇 |
综合类 | 12篇 |
航天 | 1161篇 |
出版年
2021年 | 46篇 |
2019年 | 24篇 |
2018年 | 191篇 |
2017年 | 159篇 |
2016年 | 84篇 |
2015年 | 43篇 |
2014年 | 91篇 |
2013年 | 133篇 |
2012年 | 146篇 |
2011年 | 277篇 |
2010年 | 225篇 |
2009年 | 293篇 |
2008年 | 305篇 |
2007年 | 230篇 |
2006年 | 91篇 |
2005年 | 161篇 |
2004年 | 148篇 |
2003年 | 141篇 |
2002年 | 97篇 |
2001年 | 143篇 |
2000年 | 75篇 |
1999年 | 98篇 |
1998年 | 128篇 |
1997年 | 82篇 |
1996年 | 88篇 |
1995年 | 121篇 |
1994年 | 145篇 |
1993年 | 76篇 |
1992年 | 87篇 |
1991年 | 34篇 |
1990年 | 44篇 |
1989年 | 79篇 |
1988年 | 35篇 |
1987年 | 34篇 |
1986年 | 39篇 |
1985年 | 144篇 |
1984年 | 122篇 |
1983年 | 98篇 |
1982年 | 84篇 |
1981年 | 169篇 |
1980年 | 34篇 |
1979年 | 36篇 |
1978年 | 41篇 |
1977年 | 35篇 |
1976年 | 32篇 |
1975年 | 39篇 |
1974年 | 34篇 |
1973年 | 32篇 |
1972年 | 49篇 |
1970年 | 24篇 |
排序方式: 共有5284条查询结果,搜索用时 379 毫秒
231.
232.
233.
D. V. Nedel’ko 《Russian Aeronautics (Iz VUZ)》2016,59(3):297-302
A method of determining the maximum permissible values for diagnostic signs, being an integral part of health and usage monitoring systems (HUMS) of the helicopter transmission units, has been developed based on a probabilistic approach. 相似文献
234.
A.K. Sharma O.B. Gurav Anindya Bose H.P. Gaikwad G.A. Chavan Atanu Santra S.S. Kamble R.S. Vhatkar 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(10):3131-3138
Indian Space Research Organization (ISRO) has developed an indigenous system named Indian Regional Navigation Satellite System (IRNSS) or NavIC (Navigation with Indian Constellation), that consists of 7 satellites and transmits navigation signal in L and S bands. ISRO, for validation of the system, has installed many IGS (IRNSS/GPS/SBAS) receivers scattered over the Indian region. Using preliminary data from two geographically widely separated stations over India, this paper presents the results on studies on parameters of IRNSS signal quality and discusses how these parameters may be used to study the ionospheric behavior over the Indian region. The results show the importance and advantages of using IRNSS data for such studies. 相似文献
235.
Based on an integrated approach, we solve the optimization problem for energy content and weight-dimensional characteristics of the electric servo drive by synthesis of structure and analysis of characteristics for different power supplies. The generalized power supply model, developed for different power supply of drive control systems, is given. 相似文献
236.
E. O. Ariskin A. V. Nikitin V. V. Soldatkin V. M. Soldatkin 《Russian Aeronautics (Iz VUZ)》2015,58(4):454-460
The problem and features of measuring the speed and the direction angle of the wind vector relative to the longitudinal helicopter axis during parking, starting and takeoff-landing modes by onboard means are considered. The construction principles, information processing algorithms and advantages of onboard system for measuring the wind vector parameters based on ion-beacon and aerometric measuring channels, are disclosed. 相似文献
237.
Q. Wang G. Xu S. Petrovic U. Schaefer U. Meyer T. Xu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
A regional tropospheric model can be constructed using surveys from GPS ground networks. Using this model the tropospheric delays of a kinematic station within the region can be interpolated. However, such a model is generally not suitable for an airborne platform high above the ground networks. In this paper, a method of constructing a regional tropospheric model for airborne GPS applications is described. First, the kinematic station in the air is projected onto the ground. Then the tropospheric delays at projected point are interpolated from those of the ground networks. Finally, the tropospheric delays at projected point are extended upward to the airborne platform using pressure and temperature gradients and humidity exponential function. For validation of this method, the data of airborne campaign carried out by BKG in cooperation with GFZ and BGR 2008 in the northern Alps are used. The results show that GPS kinematic positioning precision in height component can be improved using this method. 相似文献
238.
239.
A methodology of creating a loading imitation model of a single-rotor helicopter with artificial neural network algorithms is considered. Stages of creation, the structure, and an algorithm of searching for an optimal neural networks configuration of loading imitation model are presented. 相似文献
240.
This paper presents the results of analyzing the shaping of thin-walled conical parts with the uniform thickness along generatrix. 相似文献