全文获取类型
收费全文 | 4655篇 |
免费 | 60篇 |
国内免费 | 42篇 |
专业分类
航空 | 2328篇 |
航天技术 | 1347篇 |
综合类 | 71篇 |
航天 | 1011篇 |
出版年
2022年 | 21篇 |
2021年 | 39篇 |
2018年 | 179篇 |
2017年 | 169篇 |
2016年 | 73篇 |
2015年 | 54篇 |
2014年 | 78篇 |
2013年 | 102篇 |
2012年 | 117篇 |
2011年 | 279篇 |
2010年 | 229篇 |
2009年 | 259篇 |
2008年 | 292篇 |
2007年 | 242篇 |
2006年 | 110篇 |
2005年 | 165篇 |
2004年 | 96篇 |
2003年 | 116篇 |
2002年 | 90篇 |
2001年 | 106篇 |
2000年 | 88篇 |
1999年 | 102篇 |
1998年 | 107篇 |
1997年 | 101篇 |
1996年 | 88篇 |
1995年 | 104篇 |
1994年 | 107篇 |
1993年 | 69篇 |
1992年 | 77篇 |
1991年 | 39篇 |
1990年 | 44篇 |
1989年 | 74篇 |
1988年 | 39篇 |
1987年 | 32篇 |
1986年 | 35篇 |
1985年 | 114篇 |
1984年 | 79篇 |
1983年 | 80篇 |
1982年 | 60篇 |
1981年 | 103篇 |
1980年 | 25篇 |
1979年 | 27篇 |
1978年 | 33篇 |
1977年 | 25篇 |
1976年 | 23篇 |
1975年 | 39篇 |
1972年 | 33篇 |
1971年 | 25篇 |
1969年 | 22篇 |
1967年 | 23篇 |
排序方式: 共有4757条查询结果,搜索用时 0 毫秒
41.
D. L. Judge H. S. Ogawa D. R. McMullin P. Gangopadhyay J. M. Pap 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2002,29(12):502-1968
The SOHO Solar EUV Monitor has been in operation since December 1995 onboard the SOHO spacecraft. This instrument is a highly stable transmission grating solar extreme ultraviolet spectrometer. It has made nearly continuous full disk solar irradiance measurements both within an 8 nm bandpass centered at 30.4 nm and throughout the 0.1 to 50 nm solar flux region since launch. The 30.4 nm flux, the 0.1 to 50 nm flux and the extracted soft X-ray (0.1 to 5 nm) flux are presented and compared with the behavior of solar proxies. 相似文献
42.
F A Cucinotta L W Townsend J W Wilson M J Golightly M Weyland 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(10):661-670
The solar particle events (SPE) will contain a primary alpha particle component, representing a possible increase in the potential risk to astronauts during an SPE over the often studied proton component. We discuss the physical interactions of alpha particles important in describing the transport of these particles through spacecraft and body shielding. Models of light ion reactions are presented and their effects on energy and linear energy transfer (LET) spectra in shielding discussed. We present predictions of particle spectra, dose, and dose equivalent in organs of interest for SPE spectra typical of those occurring in recent solar cycles. The large events of solar cycle 19 are found to have substantial increase in biological risk from alpha particles, including a large increase in secondary neutron production from alpha particle breakup. 相似文献
43.
44.
F. S. Khairullin 《Russian Aeronautics (Iz VUZ)》2009,52(4):480-483
We consider a possibility to apply the method of analyzing the complex-shaped shells, proposed in [1], for determining the
stress strain state of thin shells with a degenerating domain. The results of numerical calculations are presented. 相似文献
45.
A. Sh. Dzhabrailov Yu. V. Klochkov S. S. Marchenko A. P. Nikolaev 《Russian Aeronautics (Iz VUZ)》2007,50(2):115-120
We demonstrate that it is possible to express each component of the displacement vector for the interior point of the finite element (FE) through all components of nodal unknowns in curvilinear coordinates. The effectiveness of the valid technique of vector approximation for displacement fields has been verified on an example. 相似文献
46.
N. N. Makarov 《Russian Aeronautics (Iz VUZ)》2008,51(1):60-66
The problem is formulated and a technique is revealed for synthesizing the optimal strategy of troubleshooting and constructing an operation algorithm for the information-control system of inspection and diagnostics of the aircraft equipment state. 相似文献
47.
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
48.
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
49.
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
50.
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