全文获取类型
收费全文 | 180篇 |
免费 | 35篇 |
国内免费 | 18篇 |
专业分类
航空 | 114篇 |
航天技术 | 95篇 |
综合类 | 4篇 |
航天 | 20篇 |
出版年
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 5篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 10篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 8篇 |
2014年 | 5篇 |
2013年 | 10篇 |
2012年 | 12篇 |
2011年 | 10篇 |
2010年 | 18篇 |
2009年 | 11篇 |
2008年 | 13篇 |
2007年 | 8篇 |
2006年 | 9篇 |
2005年 | 17篇 |
2004年 | 3篇 |
2003年 | 12篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 5篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 9篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1984年 | 1篇 |
排序方式: 共有233条查询结果,搜索用时 732 毫秒
31.
采用均相流模型并结合FBM湍流模型,对绕轴对称回转体通气云状空泡流动特性进行了三维数值模拟,基于实验结果对数值方法进行验证,同时利用基于拉格朗日体系的有限时间李雅普诺夫指数(FTLE)、拉格朗日拟序结构(LCS)和粒子追踪方法分析了其三维非定常脱落特性。研究结果表明:纵截面上空泡覆盖区域的拉格朗日拟序结构整体呈椭球状分布,内部为不规律的复杂拟序结构;不同横截面上拟序结构分布存在很大差异。空泡内部的非对称流动结构和周向流动导致空泡呈现很强的三维运动特性。反向射流在周向上推进的不同步性,是造成空泡呈现不规则断裂和大尺度U型空泡团脱落的主要原因。 相似文献
32.
应用细观力学方法对三维编织结构复合材料的有效性能进行预测是研究编织复合材料宏观性能的重要途径。细观结构参数决定编织体内纤维束的结构形态特征及复合材料的各种性能。根据作者提出的三维四向编织复合材料代表单元模型 ,文章应用选择平均法 (SAM)详细的分析了主要细观结构参数(单步步长、纤维束弯曲半径 )与编织体有效弹性模量之间的变化关系 ,分析了细观结构参数对编织体有效弹性模量的影响 ,为材料优化设计奠定基础 相似文献
33.
34.
《中国航空学报》2021,34(4):451-464
For higher efficiency and precision manufacturing, more and more attentions are focused on the surface roughness and residual stress of machined parts to obtain a good fatigue life. At present, the in-situ TiB2/7050Al metal matrix composites are widely researched due to its attractive properties such as low density, good wear resistance and improved strength. It is of great significance to investigate the machined surface roughness, residual stress and fatigue life for higher efficiency and precision manufacturing of this new kind material. In this study, the surface roughness including two-dimensional and three-dimensional roughness, residual stress and fatigue life of milling in-situ TiB2/7050Al metal matrix composites were analyzed. It was found from comparative investigation that the three-dimensional surface roughness would be more appropriate to represent the machined surface profile of milling particle reinforced metal matrix composites. The cutting temperature played a great role on the residual stress. However, the effect of increasing cutting force could slow down the transformation from compressive stress to tensile stress under 270 °C. An exponential relationship between three-dimensional roughness and fatigue life was established and the main fracture mechanism was brittle fracture with observation of obvious shellfish veins, river pattern veins and wave shaped veins in fracture surface. 相似文献
35.
R. D’Amicis R. BrunoB. Bavassano 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
Within the framework of the solar wind—magnetosphere coupled system, intense perturbations in the solar wind, causing geomagnetic storms and substorms, have been widely studied by means of the so-called coupling parameters. However, remarkable variations in the geomagnetic field occur even in absence of such perturbations. In those conditions, solar wind MHD turbulence might have a role. Recent results have shown that solar wind turbulence can be described not only as a mixture of inward and outward stochastic Alfvénic fluctuations, but includes also advected structures, dominated by an excess of magnetic energy. 相似文献
36.
Daniel Gómez 《Space Science Reviews》2006,122(1-4):231-238
37.
B. V. Somov 《Space Science Reviews》1994,70(1-2):161-166
Symmetrical broadening in the emission spectral lines is the ultimate observational effect of magnetic reconnection in the solar corona. Reconnection can create plasmas of very different temperatures and, hence, very different electrical conductivities in the corona. The electrodynamical effect of such a mass supply is considered. Electromagnetic expulsion force, different from Parker's well-known magnetic buoyancy force, can effectively balance gravity in prominences and generate fast vortex flows in the vicinity of fine threads inside prominences. The possibility of observing this effect from SOHO is discussed. 相似文献
38.
We present grid-adaptive numerical simulations of magnetized plasma jets, modeled by means of the compressible magnetohydrodynamic
equations. The Adaptive Mesh Refinement strategy makes it possible to investigate long-term jet dynamics where both large-scale
and small-scale effects are at play. We extend recent findings for uniformly magnetized, periodic shear layers to planar and
fully 3D extended jet segments. The jet lengths cover multiple, typically 10, axial wavelengths of the fastest growing Kelvin–Helmholtz
(KH) like modes. The dominant linear MHD instabilities of the jet flows are quantified by means of MHD spectroscopic analysis.
In cases characterized by sonic Mach numbers about unity and large plasma beta values, both single and double shear layers
(planar jets) manifest self-organizing trends to large scales, e.g. by continuous pairing/merging between co-rotating vortices,
simultaneously with the introduction of small-scale features by magnetic reconnection events. The vortices form as a result
of KH unstable shear-flow layers, and their coalescence arises from the growth of subharmonic modes at multiple wavelengths
of the fastest growing KH instability. In extended two-dimensional jet segments, we investigate how varying jet width alters
this coalescence process occurring at both edges, e.g. by introducing Batchelor-like coupling between counter-rotating vortices
formed at opposing weakly magnetized, close shear layers. Finally, periodic segments of supersonic magnetized jets are simulated
in two- and three-dimensional cases, which are characterized by violent shock-dominated transients. 相似文献
39.
The magnetopause is in continuous motion and shock waves and impulsive acceleration events can occur. As an example, we show
that the interaction of an interplanetary shock with the bow shock can generate a shock wave that after passing through the
magnetosheath can interact with the magnetopause. In fluid dynamics, when a shock wave encounters a fluid discontinuity, the
interface may become unstable and form bubbles and spikes. We consider this Richtmyer-Meshkov instability in magnetohydrodynamics.
At the dayside magnetopause, the instability tends to be stabilized by the magnetic field. However, the shock wave interaction
can initiate magnetic field reconnection for the southward IMF, which may be important in strong interplanetary shock events.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
40.
Iñigo Arregui 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(2):655-672
In contrast to the situation in a laboratory, the study of the solar atmosphere has to be pursued without direct access to the physical conditions of interest. Information is therefore incomplete and uncertain and inference methods need to be employed to diagnose the physical conditions and processes. One of such methods, solar atmospheric seismology, makes use of observed and theoretically predicted properties of waves to infer plasma and magnetic field properties. A recent development in solar atmospheric seismology consists in the use of inversion and model comparison methods based on Bayesian analysis. In this paper, the philosophy and methodology of Bayesian analysis are first explained. Then, we provide an account of what has been achieved so far from the application of these techniques to solar atmospheric seismology and a prospect of possible future extensions. 相似文献