全文获取类型
收费全文 | 8791篇 |
免费 | 661篇 |
国内免费 | 509篇 |
专业分类
航空 | 4959篇 |
航天技术 | 2311篇 |
综合类 | 598篇 |
航天 | 2093篇 |
出版年
2023年 | 52篇 |
2022年 | 115篇 |
2021年 | 187篇 |
2020年 | 138篇 |
2019年 | 134篇 |
2018年 | 295篇 |
2017年 | 265篇 |
2016年 | 186篇 |
2015年 | 184篇 |
2014年 | 261篇 |
2013年 | 276篇 |
2012年 | 333篇 |
2011年 | 476篇 |
2010年 | 462篇 |
2009年 | 542篇 |
2008年 | 456篇 |
2007年 | 405篇 |
2006年 | 241篇 |
2005年 | 273篇 |
2004年 | 212篇 |
2003年 | 251篇 |
2002年 | 324篇 |
2001年 | 299篇 |
2000年 | 196篇 |
1999年 | 222篇 |
1998年 | 220篇 |
1997年 | 176篇 |
1996年 | 200篇 |
1995年 | 238篇 |
1994年 | 199篇 |
1993年 | 134篇 |
1992年 | 169篇 |
1991年 | 92篇 |
1990年 | 89篇 |
1989年 | 142篇 |
1988年 | 76篇 |
1987年 | 68篇 |
1986年 | 61篇 |
1985年 | 164篇 |
1984年 | 128篇 |
1983年 | 111篇 |
1982年 | 124篇 |
1981年 | 167篇 |
1980年 | 58篇 |
1979年 | 48篇 |
1978年 | 60篇 |
1975年 | 48篇 |
1974年 | 42篇 |
1972年 | 50篇 |
1971年 | 47篇 |
排序方式: 共有9961条查询结果,搜索用时 0 毫秒
51.
V. A. Ovchinnikov 《Russian Aeronautics (Iz VUZ)》2007,50(2):146-149
We analyze the effect of injection both of uniformly distributed over the entire cylinder surface and of the optimal one on the velocity distribution at the outer border of the boundary layer and, as a result, on friction. 相似文献
52.
The results of studying an incompressible gas flow field in a periodic element of the porous structure made up of the same radius spheres are presented; the studies were based on the solution of the Navier-Stokes equations using FLUENT software. The possibilities to accelerate the solution process with the use of parallel calculations are investigated and the calculation results under changes of pressure differential in the periodic element are given. 相似文献
53.
T. Yu. Gainutdinova 《Russian Aeronautics (Iz VUZ)》2007,50(2):215-217
In this paper, a program package for solving problems in the field of thin-walled three-dimensional FV structure design is described. 相似文献
54.
D.R. Japaridze M.Sh. Gigolashvili V.J. Kukhianidze 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2007,40(12):1912-1916
The differential rotation of the patterns of the large-scale solar magnetic field during solar activity cycles 20 and 21 is investigated. Compact magnetic elements with the polarity of the general solar magnetic field have larger speed of rotation than the elements with the opposite polarity. The surface of the Sun was divided by 10°-zones. In all of them the average rotation rate of the magnetic elements with negative polarity is little higher than that of the magnetic elements with positive polarity, except for 50°-zone of the south hemisphere and at the 10° latitude of the north hemisphere.
The rates of differential rotation for large-scale magnetic elements with negative and positive polarities have similar behavior for both cycles of the solar activity.
The rotation rate varies at polarity reversal of the circumpolar magnetic fields. For the cycle No 20 in 1969–1970 the threefold reversal took place in the northern hemisphere and variations of rotation rate can be noticed for magnetic elements both with positive and negative polarity for each 10°-zone in the same hemisphere. 相似文献
55.
A. I. Belousov S. V. Falaleev A. S. Vinogradov P. V. Bondarchuk 《Russian Aeronautics (Iz VUZ)》2007,50(4):390-394
Problems arising in introduction of gasodynamic seals in aircraft engines are considered. The operation of a face gasodynamic seal as part of a natural gas pump is analyzed and its efficiency in the presence of oil is shown. 相似文献
56.
A system for measuring the altitude-airspeed parameters of rotorcraft and very light flight vehicles
In this paper, a problem on measuring the altitude-airspeed parameters (AAPs) of rotorcraft and very light flight vehicles is considered. Some ways of improving systems used to measure the parameters of FV elements and units have been determined. Also suggested and substantiated are the principles and designs of the basic variants of these measuring systems as well as the algorithms of their operation. 相似文献
57.
Kacelenga R. Erickson D. Palmer D. 《Aerospace and Electronic Systems Magazine, IEEE》2003,18(8):13-19
This paper presents a voting fusion application for use with a remotely controlled multisensor vehicle platform for antitank landmine detection. Data from three landmine detection sensors mounted at the front of the vehicle enhance the probability of detection and, when combined via data fusion, limit the false alarm density to practical levels. The performance of the voting fusion scheme presented in this paper is contrasted with a heuristic data fusion approach developed by General Dynamics Canada. 相似文献
58.
59.
60.