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本文用马尔文粒度分析仪测量喷雾的平均液滴尺寸及液滴尺寸分布,研究了气体注入形式对喷雾特性的影响.喷嘴压降为34.5~690kPa,喷嘴气液比为0.002~0.023.试验中使用了两种气体注入形式:一种是直径6.3mm的单孔,另一种是20个直径0.5mm的小孔.它们与三种不同孔径的喷孔配合使用.其孔径分别为0.8,1.6和2.4mm.研究结果表明,雾化质量主要取决于喷嘴压降和气液比,而对气体注入形式和喷孔直径不敏感.测量液体流量看出,此类喷嘴的流量系数很小.雾化液体中含有固体颗粒或其它易堵塞小孔或喷嘴通道的有害物时,使用这种喷嘴将会显示出它的优点. 相似文献
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热处理和冷变形对Ti—Ni合金非线性超弹性的影响 总被引:1,自引:0,他引:1
本文利用拉伸试验系统地研究了冷变形量、热处理工艺对Ti-49.8%(原子分数)Ni合金非线性超弹性的影响。研究表明,不同冷变形量丝材经723K,0.5h退火处理后,冷变形量较大的丝材(大于20%)经一定次数的应力-应变循环处理后,可获得完全的非线性超弹性,而冷变形量较小的丝材,即使经过多次应力-应变循环处理也难以获得完全的非线性超弹性。经同一温度退火处理的不同冷变形量丝材,冷变形量越大,获得完全非 相似文献
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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(4):1296-1305
This paper aims to study on the cooling effect with two types of water spray nozzle on the flame deflector during the four-engine launch vehicle take-off. To accurately simulate the two-phase flow of the rocket gas with multispecies and the water spray, the three-dimensional compressible Navier-Stokes equations, discrete ordinates methods and realizable k-Ɛ turbulence model are used to establish the rocket supersonic plumes impact model. The Eulerian dispersed phase (EDP) model was used to simulate the water spray into the exhaust gas. The accuracy and effectiveness of the gas-liquid flow model are verified by a good agreement between simulation results and experimental data. On this basis, a series of numerical simulation studies under different water injection position are performed. The results show that the high temperature regions, along the axis of engines on the deflector plate, have no significant temperature decreasing effect by water spray from the nozzles mounted on the apex of the deflector, and the high temperature converts a large quantity of water into vapor near the plume boundary, which would decrease the flow conductivity. With the cooling spray nozzle fixed directly to the deflector plate, the temperature decrease effect is obvious and the effect of thermal shock on deflector plate induced by exhaust plume is reduced, so that it can prevent the flame deflector from thermal ablation. The study results provide indepth information and engineering guidance for designing the water spray systems and increasing the safety of the launch process. 相似文献
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水陆两栖飞机的着水性能是体现其综合性能的重要因素之一.应用ALE法对三种水陆两栖飞机船体截面进行入水仿真计算,从着水载荷、喷溅性能及运动响应三个方面对着水性能进行综合评估.对比分析了直线型、带舭弯弧形、复合型三种构型截面在不同速度、不同重量下的压力分布、喷溅性能以及运动响应,得到了三种截面横向压力分布规律.计算结果显示相同状态下,喷溅性能复合型优于带舭弯弧形、带舭弯弧形优于直线型;过载复合型远大于带舭弯弧形,带舭弯弧形稍大于直线型,综合看来带舭弯弧形截面着水性能最佳. 相似文献
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《中国航空学报》2020,33(6):1824-1835
It is imperative to develop multifunctional erosion and corrosion resistant coatings for compressor blades of aircraft engines in harsh environment. PVD (Physical Vapor Deposition) technology has the advances in processing erosion-resistant coatings; however, the performance of PVD coatings to combat corrosion depends on various coating defects. Determining and comparing the corrosion performances of PVD TiN/Ti coating and uncoated TC4 alloy was the main objective of present work. The 960 h salt spray corrosion and 116 h hot corrosion tests were conducted to simulate the grounding and working environments of the aircraft compressors. The corrosion mechanisms due to the coating defects such as pinhole, columnar boundary and large grain were analyzed based on the OM, Confocal microscope, electrochemical measurements, SEM, XRD and EDS results. Owing to the disordered state associated with the columnar boundary and the coating defect, nitrogen could be easily replaced by oxygen in the hot corrosion process, these structures were channels for fast diffusion of oxygen. Moreover, the Gibbs energy changes of Ti oxidation and TiN oxidation were thermodynamically calculated according to the working condition of aircraft compressors, and considerable research effort was focused on mapping out the phase diagram of Ti, TiN and high pressure gases. The findings of this research can provide insights into developing multifunctional coatings for future aircraft engines. 相似文献
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采用相位多普勒粒子分析仪(PDPA)对某型航空发动机双路离心喷嘴的雾化特性进行了实验研究。PDPA可直接测得测点处的喷雾液滴的尺寸分布和速度大小,并据此求出了测点处的索特尔平均直径SMD和液滴的平均速度。在喷雾锥三个横截面上进行了测量,得到了SMD的空间分布,据此得到了喷雾锥的锥角,并与光学照相和计算机图像处理测得喷雾锥角进行了对比。实验结果表明:液滴尺寸随着供油压力的增大而减小,当压力增大到一定程度时,液滴尺寸趋于不变;当主、副油路分别单独工作时,随测量横截面与喷口之间距离Z的增加,SMD减小;在供油压力不变时,同一个测量横截面内,随着径向距离X的增加SMD值变化不大;喷雾锥角基本不随供油压力改变而变化。 相似文献