全文获取类型
收费全文 | 8030篇 |
免费 | 12篇 |
国内免费 | 37篇 |
专业分类
航空 | 3670篇 |
航天技术 | 2944篇 |
综合类 | 27篇 |
航天 | 1438篇 |
出版年
2021年 | 66篇 |
2019年 | 52篇 |
2018年 | 148篇 |
2017年 | 107篇 |
2016年 | 88篇 |
2014年 | 166篇 |
2013年 | 227篇 |
2012年 | 211篇 |
2011年 | 318篇 |
2010年 | 217篇 |
2009年 | 338篇 |
2008年 | 421篇 |
2007年 | 236篇 |
2006年 | 185篇 |
2005年 | 234篇 |
2004年 | 236篇 |
2003年 | 272篇 |
2002年 | 172篇 |
2001年 | 260篇 |
2000年 | 163篇 |
1999年 | 187篇 |
1998年 | 222篇 |
1997年 | 168篇 |
1996年 | 188篇 |
1995年 | 248篇 |
1994年 | 260篇 |
1993年 | 135篇 |
1992年 | 187篇 |
1991年 | 76篇 |
1990年 | 82篇 |
1989年 | 170篇 |
1988年 | 68篇 |
1987年 | 62篇 |
1986年 | 88篇 |
1985年 | 245篇 |
1984年 | 207篇 |
1983年 | 161篇 |
1982年 | 178篇 |
1981年 | 260篇 |
1980年 | 69篇 |
1979年 | 55篇 |
1978年 | 66篇 |
1977年 | 54篇 |
1976年 | 45篇 |
1975年 | 54篇 |
1974年 | 56篇 |
1973年 | 47篇 |
1972年 | 58篇 |
1971年 | 41篇 |
1970年 | 47篇 |
排序方式: 共有8079条查询结果,搜索用时 250 毫秒
381.
Aerodynamic characteristics of two-dimensional smart flap under the ground effect have been assessed by a numerical simulation. In this process, a pressure-based implicit procedure to solve Navier–Stokes equations on a nonorthogonal mesh with collocated finite volume formulation is used. The boundedness criteria for this procedure are determined from the Normalized Variable Diagram (NVD) scheme. The procedure incorporates the k–ε eddy–viscosity turbulence model. Cantilever beam with uniformly varying load with roller support at the free end is considered for the configuration of the smart flap. The method is first validated against experimental data. Then, the algorithm is applied for turbulent aerodynamic flows around airfoil with smart and conventional flaps for different attack angle, flap angle and ground clearance where the results of two flaps are compared. The comparisons show that the quality of the solution is considerable. 相似文献
382.
The results of investigating free oscillations of the International Space Station construction appearing during spacecraft docking and undocking are described. The study is carried out using the measurement
data of the low-frequency MAMS accelerometer. Several intervals of measurements performed in 2005 and 2006 were chosen to
be studied. For chosen intervals, only the data intervals corresponding to the process of free attenuation of the oscillations
construction elements were analyzed. Characteristic frequencies of elastic oscillations of the station construction and attenuation
coefficients corresponding to them are found. The comparative analysis of the results obtained for various docking ports (nodes)
is carried out. The described study is performed as a part of the technical experiment “The ISS Environment” carried out onboard the station in accordance with the Russian program of scientific and engineering experiments. 相似文献
383.
384.
J. Mazur L. Friesen A. Lin D. Mabry N. Katz Y. Dotan J. George J. B. Blake M. Looper M. Redding T. P. O’Brien J. Cha A. Birkitt P. Carranza M. Lalic F. Fuentes R. Galvan M. McNab 《Space Science Reviews》2013,179(1-4):221-261
The Relativistic Proton Spectrometer (RPS) on the Radiation Belt Storm Probes spacecraft is a particle spectrometer designed to measure the flux, angular distribution, and energy spectrum of protons from ~60 MeV to ~2000 MeV. RPS will investigate decades-old questions about the inner Van Allen belt proton environment: a nearby region of space that is relatively unexplored because of the hazards of spacecraft operation there and the difficulties in obtaining accurate proton measurements in an intense penetrating background. RPS is designed to provide the accuracy needed to answer questions about the sources and losses of the inner belt protons and to obtain the measurements required for the next-generation models of trapped protons in the magnetosphere. In addition to detailed information for individual protons, RPS features count rates at a 1-second timescale, internal radiation dosimetry, and information about electrostatic discharge events on the RBSP spacecraft that together will provide new information about space environmental hazards in the Earth’s magnetosphere. 相似文献
385.
Concept of monitoring for thermostressed state and service life of aircraft gas turbine engine blades 总被引:1,自引:0,他引:1
G. G. Kulikov V. A. Trushin A. I. Abdulnagimov A. A. Ganeev 《Russian Aeronautics (Iz VUZ)》2016,59(1):77-83
A concept of monitoring for material properties with residual life estimation of rotor blades for gas turbine engines is proposed. The structure of on-board control and conditionmonitoring system based on the intelligent pyrometer module with the algorithm for calculating the residual life of turbine rotor blades is described. 相似文献
386.
387.
388.
389.
390.