全文获取类型
收费全文 | 8309篇 |
免费 | 20篇 |
国内免费 | 24篇 |
专业分类
航空 | 3820篇 |
航天技术 | 2972篇 |
综合类 | 25篇 |
航天 | 1536篇 |
出版年
2021年 | 80篇 |
2019年 | 53篇 |
2018年 | 173篇 |
2017年 | 122篇 |
2016年 | 121篇 |
2015年 | 58篇 |
2014年 | 202篇 |
2013年 | 249篇 |
2012年 | 239篇 |
2011年 | 365篇 |
2010年 | 252篇 |
2009年 | 398篇 |
2008年 | 435篇 |
2007年 | 246篇 |
2006年 | 181篇 |
2005年 | 216篇 |
2004年 | 220篇 |
2003年 | 261篇 |
2002年 | 173篇 |
2001年 | 282篇 |
2000年 | 151篇 |
1999年 | 212篇 |
1998年 | 244篇 |
1997年 | 151篇 |
1996年 | 210篇 |
1995年 | 249篇 |
1994年 | 259篇 |
1993年 | 140篇 |
1992年 | 185篇 |
1991年 | 64篇 |
1990年 | 69篇 |
1989年 | 178篇 |
1988年 | 74篇 |
1987年 | 85篇 |
1986年 | 73篇 |
1985年 | 228篇 |
1984年 | 168篇 |
1983年 | 133篇 |
1982年 | 157篇 |
1981年 | 257篇 |
1980年 | 68篇 |
1979年 | 64篇 |
1978年 | 65篇 |
1977年 | 53篇 |
1976年 | 40篇 |
1975年 | 66篇 |
1974年 | 49篇 |
1972年 | 50篇 |
1971年 | 40篇 |
1970年 | 40篇 |
排序方式: 共有8353条查询结果,搜索用时 15 毫秒
761.
We determine the behavior of onboard gas-generator flowrate for generating the cavitation flow around a hybrid aerial underwater vehicle by using an annular wing on the underwater trajectory section. 相似文献
762.
The requirements for skid landing gear static strength ensuring are examined based on the comparative analysis of the Airworthiness Standards requirements. Probabilistic principle of determining the safety factor of the skid landing gear is presented. The analysis of the experimental data on bench and flight tests is performed for calculating the actual value of this factor. 相似文献
763.
This paper proposes a novel landing gear for spacecraft that allows a weight reduction due to using deformable crash legs. Numerical simulation of the landing process was performed. 相似文献
764.
The paper highlights significance of the interturbine transition duct as part of the high pressure and low pressure turbine spool. The correlations have been suggested allowing us to estimate variation of the average cross section flow swirl while its passing the interturbine transition duct. 相似文献
765.
766.
A novel modular multistep algorithm is proposed for multi-criteria analysis of fracture of aircraft structures with complex geometries. In order to evaluate the algorithm, the crack growth analysis is realized by the following three criteria, namely, the stress intensity factor, the strain energy release rate, and the J-integral. The algorithm implementation by the finite element method is considered and prospects of alternative implementation based on the meshfree methods are assigned. 相似文献
767.
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
768.
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
769.
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
770.
The vortical mixing concept in the ramjet channel is analyzed. The results of simulating the gasodynamic scheme permit the concept of increasing efficiency for ramjet operation to be substantiated. 相似文献