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151.
Experimental investigation on static/dynamic characteristics of a fast-response pressure sensitive paint 总被引:2,自引:0,他引:2
An optical-based technique using Pressure-Sensitive Paint(PSP) is a promising method to measure the distribution of surface pressure on an aerodynamic model. The static and dynamic characteristics of a fast-response PSP that is developed in the Chinese Academy of Sciences(CAS)are analyzed and tested to serve as the basis for experiments on unsteady surface measurement using a fast-response PSP. Two calibration systems used for this study are set up to investigate the temperature dependency, response time, and resolution. A data processing method, used for dynamic data, is analyzed and selected carefully to determine the optimum signal. Results show that the fastresponse PSP can be used normally at temperatures from 25 ℃ to 80 ℃. The effect of temperature on the accuracy of the measurement must be considered when temperatures are beyond the temperature range of 30–40 ℃. The dynamic calibration device with a solenoid valve can achieve a pressure jump within a millisecond order. The resolution is determined by the signal-to-noise ratio of the photo-multiplier tube. Results of the measurement show that the response time of the PSP decreases with a large pressure variation, and the response time is below 0.016 s when the pressure variation is under 40 kPa. 相似文献
152.
153.
为探索与预浸料先进拉挤成型技术相适应的工艺方案,采用DSC研究了碳纤维/环氧预浸料USN12500的固化放热过程,对USN 12500的典型固化工艺进行改进,以此为基础设计了不同压力和加压时机下的试验方案,采用实验室现有设备模拟先进拉挤过程制备了试样,以制品的孔隙率作为考察指标优选了的拉挤成型固化的工艺参数.结果表明:制品在110℃下处理20 min,热压阶段130℃下处理15 min同时保持0.4MPa的工艺压力,后固化150℃下处理1.5h为工艺试验的优化方案,并且能够制得孔隙率<1.1%的制品. 相似文献
154.
针对6种高致密多孔层板结构,利用CFD软件进行流动与换热的数值模拟,分析了冲击孔、扰流柱以及气膜孔的排列方式对层板流动特性和冷却效率的影响。计算结果表明:6种不同的排列方式,总压力损失均为4.5%左右,其中气流流经冲击壁与气膜壁的压力损失为2.2%左右;不同结构的双层板当量流量系数在0.86左右;层板的排列方式对综合冷却效果影响较大,在其他结构参数不变的情况下,不同的排列方式之间的综合冷却效率最大差值达到10%,在流体流动方向上,各排列的气膜壁面的温度梯度由最初的21K/mm减小到15K/mm;综合考虑各项因素的影响,气膜孔呈梭形排布最优的排列方式,其综合冷却效率最好。 相似文献
155.
Cryogenic propellant usually experiences long term on orbit storage. The pressure increase in cryogenic storage tank is faced by most of space missions. The thermodynamic vent system (TVS) is treated as the promising method to control the increase of the tank pressure by scholars both at home and abroad. Based on the investigation conducted by different research agencies, literature review and management are conducted to reflect the recent research statue on TVS. The development profile of the experimental research on the pressure control performance of TVS is specially summarized. The condition setting and performance difference of TVS conducted by different agencies are compared and analyzed. The key technique and related conclusion are refined during the operation of TVS. Finally, based on the requirement of the large scale using of cryogenic propellant in deep space exploration in China, the development plan is proposed on the aspect of TVS pressure control on cryogenic storage tanks. 相似文献
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157.
《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(5):1424-1431
Monthly variations of averaged nighttime thermospheric winds have been investigated over Abuja, Nigeria (Geographic: 9.06°N, 7.5°E; Geomagnetic: 1.60°S). The reports are based on Fabry-Perot interferometer measurements of Doppler shifts and Doppler broadening of the 630.0 nm spectral emission. The results were obtained during a period of weak solar activity with the solar flux (F10.7) typically below 70 solar flux units. Inspection of the average monthly thermospheric winds from October 2017 to December 2017 found December meridional winds to be more equatorward than the October and November winds. Zonal winds are eastward with pre-midnight maximum speeds going above 100 m/s. Compared to Jicamarca zonal winds in the Peruvian sector for the same month of October, the magnitude of maximum Abuja zonal wind speed is weaker. We compare the observed diurnal variation with the recently updated Horizontal wind model (HWM 14). Most of the observational features of thermospheric wind diurnal variation are captured in the model variation. The HWM14 generally showed good agreement with the Abuja October and November zonal wind observations but overestimates the December meridional winds. Expected longer period analysis of the results from Abuja will stimulate a better understanding of wind climatology over the West African sector. 相似文献
158.
用扰流插板使涡扇发动机进气道内产生不对称分布的总压畸变并使发动机出现喘振。在进气道出口即发动机进口截面测取两种不同转速下发动机的喘振压力波。应用小波分析奇异点理论,采用模极大值原理和高阶Daubechies小波多尺度分析,对喘振压力信号进行处理,得到发动机喘振波在其进口截面的波形分布特征。揭示了在两种转速下,喘振波在截面上的分布相似,其频率和幅值与转速成正比。截面中心部分表现为正脉冲,周围部分为负脉冲。在垂直方向上的幅值较大,而两翼较小。对该分布特征进行了分析,初步的推论为:高压压气机引起喘振,稳态压力畸变最严重的区域和未受到畸变扰动的区域,喘振波最为强烈。 相似文献
159.
受宽带噪声激励的二元机翼随机振动系统的矩Lyapunov指数 总被引:1,自引:0,他引:1
通过计算受宽带噪声参激的二元机翼随机振动系统的矩Lyapunov指数,研究了系统的矩稳定和概率1稳定。首先在经典二元机翼颤振方程中加入随机激励,通过随机平均法、Girsanov定理和Feynmann-Kac公式得到关于矩Lyapunov指数的特征值问题。其次采用Fourier余弦级数对特征函数进行正交展开,得到系统矩Lyapunov指数的近似解析式。最后,通过Monte Carlo仿真验证了矩Lyapunov指数近似解析式的可信性,并讨论了系统参数、来流平均速度以及随机噪声谱密度对机翼稳定性的影响。 相似文献
160.