全文获取类型
收费全文 | 567篇 |
免费 | 58篇 |
国内免费 | 140篇 |
专业分类
航空 | 343篇 |
航天技术 | 147篇 |
综合类 | 106篇 |
航天 | 169篇 |
出版年
2023年 | 16篇 |
2022年 | 14篇 |
2021年 | 22篇 |
2020年 | 14篇 |
2019年 | 19篇 |
2018年 | 21篇 |
2017年 | 12篇 |
2016年 | 14篇 |
2015年 | 11篇 |
2014年 | 28篇 |
2013年 | 31篇 |
2012年 | 30篇 |
2011年 | 54篇 |
2010年 | 35篇 |
2009年 | 33篇 |
2008年 | 22篇 |
2007年 | 26篇 |
2006年 | 31篇 |
2005年 | 21篇 |
2004年 | 16篇 |
2003年 | 16篇 |
2002年 | 31篇 |
2001年 | 19篇 |
2000年 | 23篇 |
1999年 | 31篇 |
1998年 | 25篇 |
1997年 | 21篇 |
1996年 | 26篇 |
1995年 | 24篇 |
1994年 | 31篇 |
1993年 | 10篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 12篇 |
1986年 | 4篇 |
排序方式: 共有765条查询结果,搜索用时 250 毫秒
761.
《中国航空学报》2023,36(5):1-17
Serpentine nozzles are widely used in combat aircraft to realize strong stealth characteristics. Based on the layout characteristics within a confined space, a series of double serpentine nozzles with spanwise offsets are established. Using computational fluid dynamics and Taguchi method, the influence mechanisms of the Distribution of Area (DA), Distributions of Centerline for the first and second ‘S’ sections in the Vertical direction (DCV1 and DCV2), and Distribution of Centerline in the Spanwise direction (DCS) are analyzed. The impact of these factors on the total pressure recovery coefficient can be ranked as DA > DCV2 > DCS > DCV1, whereas their impacts on the discharge coefficient and axial thrust coefficient can be ranked as DCV2 > DCS > DA > DCV1. Considering the statistical significance of these factors, a nozzle in which DA changes rapidly at the exit and DCV1, DCV2, and DCS change rapidly at the entrance gives the best aerodynamic performance. Compared to the worst configuration, the total pressure recovery coefficient, discharge coefficient, and axial thrust coefficient are improved by 1.6%,3.5% and 3.6%, respectively. DA influences the gas flow acceleration in the entire serpentine channel, resulting in different wall shear stress and friction losses. The various centerline distributions influence the gas flow acceleration effects and form complex wave structures in the constant-area extension section, resulting in different local and friction losses. 相似文献
762.
High dynamic tracking performance is a key technical index of hydraulic flight motion simulator(HFMS). However, the strong nonlinearities, various model uncertainties and measurement noise in hydraulic actuation systems limit the high dynamic performance improvement. In this paper, the outer axis frame of a HFMS is taken as a case study and its nonlinear dynamic model with consideration of strong nonlinearities, matched and mismatched uncertainties is established.A novel cascaded extended state ... 相似文献
763.
It is an inherent uncertainty problem that the application of laminar flow technology to the wing of large passenger aircraft is affected by flight conditions. In order to seek a more robust natural laminar flow control effect, it is necessary to develop an effective optimization design method. Meanwhile, attention must be given to the impact of crossflow(CF) instability brought on by the sweep angle. This paper constructs a robust optimization design framework based on discrete adjoint methods ... 相似文献
764.
《中国航空学报》2022,35(10):35-55
Uncertainty is common in the life cycle of an aircraft, and Robust Aerodynamic Optimization (RAO) that considers uncertainty is important in aircraft design. To avoid the curse of dimensionality in surrogate-based optimization, this study proposes an adjoint RAO technique called “R-Opt”. Polynomial Chaos Expansion (PCE) is coupled with the R-Opt technique to quantify uncertainty in the responses of the target (including its mean and standard deviation). Only one process of PCE model construction is required in each iteration, and the gradients of uncertainty can be inferred via chain rules. The proposed method is more efficient than prevalent methods, and avoids the problem of a disagreement over the best PCE basis from among a number of PCE models (especially in case of sparse PCE). It also supports the application of sparse PCE. Two benchmark tests and two airfoil cases were used to verify R-Opt, and the optimal solutions were deemed to be robust. It improved the mean aerodynamic performance and reduced the standard deviation of the target. 相似文献
765.