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251.
单相流体回路辐射器性能优化方法 总被引:1,自引:0,他引:1
文章以“神舟”飞船辐射器为例,对管肋式单相流体回路辐射器的肋宽进行了优化分析。采用理论分析与数值求解相结合的方法,分析了管肋式辐射器常用性能评价方法--能质比及微元能质比(单位质量散热能力)随肋片宽度的变化规律;而后以提高辐射器能质比为优化目的,对辐射器肋宽进行了优化,得出了辐射器的最佳能质比对应的肋宽表达式;最后给出了“神舟”飞船辐射器优化前后的参数对比。文章对管肋式辐射器的优化设计具有很好的参考价值。 相似文献
252.
M. Amenomori S. Ayabe X.J. Bi D. Chen S.W. Cui Danzengluobu L.K. Ding X.H. Ding C.F. Feng Zhaoyang Feng Z.Y. Feng X.Y. Gao Q.X. Geng H.W. Guo H.H. He M. He K. Hibino N. Hotta Haibing Hu H.B. Hu J. Huang Q. Huang H.Y. Jia F. Kajino K. Kasahara Y. Katayose C. Kato K. Kawata Labaciren G.M. Le A.F. Li J.Y. Li Y.-Q. Lou H. Lu S.L. Lu X.R. Meng K. Mizutani J. Mu K. Munakata A. Nagai H. Nanjo M. Nishizawa M. Ohnishi I. Ohta H. Onuma T. Ouchi S. Ozawa J.R. Ren T. Saito T.Y. Saito 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
253.
传统的平台惯导系统加速度计所采用的自标定方法受到加速度计零偏预装值的影响存在着一定的误差,而且加速度计标定参数准确性的验证方法也较为烦琐,不利于操作。基于压缩映射原理,针对平台惯导系统加速度计提出了一种迭代式标定方法,消除了传统加速度计自标定方法中的误差,同时提出了一种简单、有效地验证加速度计标定参数准确性的方法,并对这种迭代式加速度计标定方法的收敛性进行了证明以及试验验证。 相似文献
254.
以重塑模拟月壤为介质,利用深空探测车车轮牵引特性实验台,研究了月面巡视探测器的刚性轮齿车轮与模拟月壤的交互作用,分析了车轮转速、轮上载荷等试验因素对车轮牵引通过性的影响.研究结果表明,当车轮转速较低时,挂钩牵引力随滑转率的增加而不断提高;当车轮转速较高时,存在着临界滑转率点.轮上载荷的增加有利于提高车轮的挂钩牵引力,但对挂钩牵引力系数的影响较小. 相似文献
255.
256.
Fault diagnosis based on measurement reconstruction of HPT exit pressure for turbofan engine 总被引:1,自引:0,他引:1
Aero-engine gas path health monitoring plays a critical role in Engine Health Management(EHM). To achieve unbiased estimation, traditional filtering methods have strict requirements on measurement parameters which sometimes cannot be measured in engineering. The most typical one is the High-Pressure Turbine(HPT) exit pressure, which is vital to distinguishing failure modes between different turbines. For the case of an abrupt failure occurring in a single turbine component, a model-based sensor measurement reconstruction method is proposed in this paper. First,to estimate the missing measurements, the forward algorithm and the backward algorithm are developed based on corresponding component models according to the failure hypotheses. Then,a new fault diagnosis logic is designed and the traditional nonlinear filter is improved by adding the measurement estimation module and the health parameter correction module, which uses the reconstructed measurement to complete the health parameters estimation. Simulation results show that the proposed method can well restore the desired measurement and the estimated measurement can be used in the turbofan engine gas path diagnosis. Compared with the diagnosis under the condition of missing sensors, this method can distinguish between different failure modes, quantify the variations of health parameters, and achieve good performance at multiple operating points in the flight envelope. 相似文献
257.
基于遗传优化算法,进行了T2紫铜同种材料扩散连接工艺研究。采用正交试验方法,结合BP神经网络和多目标遗传算法,以扩散连接时的温度、压力、保温时间为输入变量,以扩散连接后的试样焊合率和变形量为输出变量,对扩散连接工艺参数进行优化,并实施相应的扩散连接验证试验。结果表明:T2紫铜合适的扩散连接工艺参数为:温度780℃、压力7. 5 MPa、保温时间120 min,此条件下焊合率可达95. 26%,变形量为0. 166 mm。采用此工艺参数进行微通道热交换器零件制造,厚度方向变形量0. 162 mm,经超声C扫描后连接情况良好,经耐压防漏检测后满足密封性及设计要求。 相似文献
258.
Electrostatic monitoring technology of particle charging information can facilitate online monitoring of aero-engine,which effectively enhances engine fault diagnosis and health managements.Unlike traditional engine state monitoring technologies,aircraft engine monitoring by gas path electrostatic monitoring not only covers the predicted information source itself,but also detects the information that can provide an early warnings for initial fault states through gas path charging levels.This paper establishes a non-stationary time sequence change-point model for anomaly recognition of electrostatic signals based on change-point theory combined with difference method of non-stationary time series.Finally,electrostatic induction data were utilized by the engine life test for a particular aircraft to validate the proposed algorithm.The results indicate that the activity level and the event rate were0.5—0.8(nc)and 50%,respectively,which were far greater than 4—12(pc)and 0—4% under normal working conditions of the engine. 相似文献
259.
Experimental investigation on the aerodynamic performance and aeroacoustic characteristics of model rotors with different tip anhedral angles in hover are conducted in the paper.Three sets of model rotors with blade-tip anhedral angle 0°(reference rotor),20°and 45°respectively are designed to analyze the influence of the anhedral angle on the hovering performance and aeroacoustics of rotor.In the environment of anechoic chamber,the hover experiments under the different collective pitch and blade numbers,are carried out to measure the figure of merit(FM),time history of sound pressure and sound pressure level(SPL)of the three rotor models.Based on test results,the comparison and analysis of hovering performance and aeroacoustic characteristics among the three rotor models have been done.Meanwhile,for the sake of analysis,the rotor wake and blade pressure distribution are simulated by means of computational fluid method(CFD).At last,some conclusions about the effects of blade-tip anhedral angle on the aerodynamic performance and aeroacoustic characteristics in hover are obtained.An anhedral blade tip can enhance the FM of the rotor,and decrease the rotor loads noise to some extent. 相似文献
260.