全文获取类型
收费全文 | 828篇 |
免费 | 96篇 |
国内免费 | 225篇 |
专业分类
航空 | 886篇 |
航天技术 | 87篇 |
综合类 | 157篇 |
航天 | 19篇 |
出版年
2024年 | 2篇 |
2023年 | 7篇 |
2022年 | 18篇 |
2021年 | 31篇 |
2020年 | 35篇 |
2019年 | 33篇 |
2018年 | 36篇 |
2017年 | 36篇 |
2016年 | 55篇 |
2015年 | 57篇 |
2014年 | 52篇 |
2013年 | 41篇 |
2012年 | 56篇 |
2011年 | 60篇 |
2010年 | 66篇 |
2009年 | 52篇 |
2008年 | 48篇 |
2007年 | 53篇 |
2006年 | 37篇 |
2005年 | 29篇 |
2004年 | 29篇 |
2003年 | 32篇 |
2002年 | 21篇 |
2001年 | 20篇 |
2000年 | 25篇 |
1999年 | 17篇 |
1998年 | 19篇 |
1997年 | 23篇 |
1996年 | 18篇 |
1995年 | 18篇 |
1994年 | 22篇 |
1993年 | 16篇 |
1992年 | 17篇 |
1991年 | 9篇 |
1990年 | 20篇 |
1989年 | 16篇 |
1988年 | 21篇 |
1987年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有1149条查询结果,搜索用时 546 毫秒
511.
512.
513.
514.
515.
前体边条控制技术应用 总被引:3,自引:0,他引:3
采用各种不同形状和安装位置的前体边条对前体涡进行控制,研究各种前体边条对全机大迎角气动特性的影响。 相似文献
516.
517.
Airfoil Aeroelastic Flutter Analysis Based on Modified Leishman-Beddoes Model at Low Mach Number 总被引:1,自引:0,他引:1
SHAO Song ZHU Qinghua ZHANG Chenglin NI Xianping Science Technology on Rotorcraft Aeromechanics Laboratory Nanjing University of Aeronautics Astronautics Nanjing China 《中国航空学报》2011,24(5):550-557
Based on modified Leishman-Beddoes (L-B) state space model at low Mach number (lower than 0.3), the airfoil aeroelastic system is presented in this paper. The main modifications for L-B model include a new dynamic stall criterion and revisions of normal force and pitching moment coefficient. The bifurcation diagrams, the limit cycle oscillation (LCO) phase plane plots and the time domain response figures are applied to investigating the stall flutter bifurcation behavior of airfoil aeroelastic systems with symmetry or asymmetry. It is shown that the symmetric periodical oscillation happens after subcritical bifurcation caused by dynamic stall, and the asymmetric periodical oscillation, which is caused by the interaction of dynamic stall and static divergence, only happens in the airfoil aeroelastic system with asymmetry. Validations of the modified L-B model and the airfoil aeroelastic system are presented with the experimental airload data of NACA0012 and OA207 and experimental stall flutter data of NACA0012 respectively. Results demonstrate that the airfoil aeroelastic system presented in this paper is effective and accurate, which can be applied to the investigation of airfoil stall flutter at low Mach number. 相似文献
518.
Limit cycle oscillations (LCOs) as well as nonlinear aeroelastic analysis of a 3-DOF aeroelastic airfoil motion with cubic restoring moments in the pitch degree of freedom are investigated.Aeroelastic equations of an airfoil with control surface in an incompressible potential flow are presented in the time domain.The harmonic balance (HB) method is utilized to calculate the LCO frequency and amplitude for the airfoil.Also the semi-analytical method has revealed the presence of stable and unstable limit cycles,along with stability reversal in the neighborhood of a Hopf bifurcation.The system response is determined by numerically integrating the governing equations using a standard Runge-Kutta algorithm and the obtained results are compared with the HB method.Also the results by the third order HB (HB3) method for control surface are consistent with the other numerical solution.Finally,by combining the numerical and the HB methods,types of bifurcation,be it supercritical,subcritical,or divergent flutter area are identified. 相似文献
519.
提出了一种逆向涡流发生器控制叶尖泄漏流的新技术,利用压力面和叶顶面的压力差将气流从压力面引入,在叶顶面逆着叶尖泄漏流方向高速射出从而控制和减小叶尖泄漏流。对某典型毫米尺度涡轮叶栅进行了有/无逆向涡流发生器流场的数值研究,分析了逆向涡流发生器对流场及叶栅性能的影响。结果表明在典型进口条件下,逆向涡流发生器使得叶尖间隙泄漏流量降低了2.8%,周向载荷升高了7.7%;与无逆向涡流器情形相比,有逆向涡流器时涡轮效率提高了约1.2%。 相似文献
520.