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921.
922.
TC11材料高低周疲劳裂纹萌生与扩展特性研究 总被引:2,自引:0,他引:2
通过对航空发动机叶片用TC11材料在高低周复合载荷下进行裂纹扩展试验,研究了TC11材料高低周复合疲劳裂纹扩展规律,得到了高低周载荷条件下的裂纹稳态扩展曲线及断口特征。其结果可对风扇/压气机叶片抗高低周复合载荷下的裂纹扩展能力进行分析和评估,为下一代先进航空发动机设计提供技术支撑。 相似文献
923.
尾缘锯齿修形对波瓣强迫混合排气系统性能影响 总被引:1,自引:1,他引:0
针对某涡扇发动机波瓣强迫混合排气系统建立了尾缘锯齿修形流场数值计算模型,通过三维数值模拟研究,得到了不同尾缘锯齿修形波瓣强迫混合排气系统流场的演变规律和热混合效率、总压恢复系数的变化规律.结果表明:在强迫混合排气系统出口截面处,热混合效率随修形量的增加而增大,总压恢复系数随修形量的增加而减少.1个三角形(1-SJ)锯齿修形模型的热混合效率最大,达到79.73%;2个梯形修形(2-TX)的综合效果最优,其热混合效率达到77.50%,总压恢复系数比1-SJ高出0.5%. 相似文献
924.
925.
航空发动机机匣损伤容限评估及剩余寿命预测 总被引:1,自引:0,他引:1
使用有限元的方法,建立了某航空发动机机匣安装座处局部模型,计算得到了不同尺寸裂纹的应力强度因子的形状因子Y.基于BS7910评定方法,利用失效评估图(FAD,Failure Assessment Diagram)确定了机匣安装座结构在工作应力下的可接受裂纹尺寸为84.8 mm,结构的剩余强度随裂纹尺寸的增加而显著降低,焊缝较母材具有更低的损伤容限和剩余强度.使用缩小宽度模拟验证件模拟工作状态载荷进行了验证试验,当裂纹尺寸与试样宽度比值较小时,与模拟验证件的评估结果基本吻合.根据Paris公式,构件在工作应力下的剩余寿命为74 238周次. 相似文献
926.
927.
928.
S.K. Chakrabarti D. Debnath S. Nagarkoti 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(11):3749-3759
The Galactic transient black hole candidate H 1743–322 exhibited a long duration outburst in 2003 after more than two and a half decades of inactivity. The 2003 event was extensively studied in multi-wavelength bands by many groups. The striking feature is that the total energy released is extremely high as compared to that in tens of outbursts which followed. In this paper, we look at this event and study both the spectral and temporal properties of the source using two component advective flow (TCAF) paradigm. We extract accretion flow parameters for each observation from spectral properties of the decay phase and determine the mass of the black hole. We computed the energy released during all the known outbursts since 2003 and showed that on an average, the energy release in an outburst is proportional to the duration of the quiescent state just prior to it, with the exception of the 2004 outburst. A constant rate of supply of matter from the companion cannot explain the energy release in 2004 outburst. However, if the energy release of 2003 is incomplete and the leftover is released in 2004, then the companion’s rate of matter supply can be constant since 1977 till date. We believe that erratic behaviour of viscosity at the accumulation radius of matter as well as location the itself, rather than the random variation of mass transfer rate from the companion, could be responsible for non-uniformity in outburst pattern. We discuss several factors on which the waiting time and duration of the next outburst could depend. 相似文献
929.
针对某型发动机压气机转子叶片叶尖裂纹故障,制订了4种排故方案。进行了振动特性、应力分布测量及台架动频动应力测量对比试验,对各排故方案作出了评价,从而确定了最终的排故方案。试验表明4种排故方案均能有效降低振动应力,但方案4优于其它3种方案,能使振动应力水平降低60.6%,频率提高11.5%。 相似文献
930.
In this study, in-plane mixed mode-I/II fatigue crack growth simulations and experiments are performed for the Al 7075-T651 aluminum alloy which is widely used in the aerospace industry. Tests are carried out under different mode mixity ratios to evaluate the applicability of a fracture criterion developed in a previous study to mixed mode-I/II fatigue crack growth tests. Results obtained from the analyses and experiments are compared with existing and developed criteria in terms of crack growth lives. Compact Tension Shear (CTS) specimens, which enable mixed mode loading with loading devices under different loading angles, are used in the simulations and experiments. In an effort to model and simulate the actual conditions in the experiments, crack surfaces of fractured specimens are scanned, crack paths are modeled exactly, and contacts are defined between the contact surfaces of a specimen and the loading device for each crack propagation step in the analyses. Having computed the mixed mode stress intensity factors from the numerical analyses, propagation life cycles are predicted by existing and the developed mixed mode-I/II criteria and then compared with experimental results. 相似文献