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961.
962.
飞机供电系统是现代飞机核心组成部分之一,其性能和可靠性对飞机安全至关重要,仿真方法为高品质飞机供电系统设计提供了重要手段。传统的手动仿真方法需要耗费大量人力和时间资源,且无法完全考虑系统的复杂性和不确定性,因此无法满足飞机供电系统全面分析和评估的需求。文中提出了一种将虚拟仿真和实物系统相结合的飞机供电系统自动化仿真技术,能够提高仿真效率和准确性,且可快速、高效地评估飞机供电系统的性能,发现潜在问题,指导系统的优化与改进,对提高飞机供电系统的设计、分析和优化具有重要意义。 相似文献
963.
航空发动机转子遥测系统旋转电源变换器 总被引:2,自引:0,他引:2
针对航空发动机转子遥测系统中旋转测量设备的电能获取问题,提出了一种基于反激式开关电源原理的可旋转电源变换器技术方案。该电源变换器通过罐形磁芯建立旋转变压器在转子和静子之间的磁路。设计了输出功率最大为10 W的电源变换器。验证了变压器的磁路不受旋转工况的影响。试验并分析了空气隙的大小、旋转偏心等因素对电源变换器性能的影响。所设计的电源变换器能够以非接触方式向发动机转子传输电能。相对于导电滑环等转子遥测系统供电方式,这种电源变换器具有使用寿命不受限制、工作转速范围大的优点。 相似文献
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966.
《中国航空学报》2020,33(8):2133-2145
The spaceplane is perspective vehicle due to wide maneuverability in comparison with a space capsule. Its maneuverability is expressed by the larger flight range and also by a possibility to rotate orbital inclination in the atmosphere by the aerodynamic and thrust forces. Orbital plane atmospheric rotation maneuvers can significantly reduce fuel costs compared to rocket-dynamic non-coplanar maneuver. However, this maneuver occurs at Mach numbers about 25, and such velocities lead to non-equilibrium chemical reactions in the shock wave. Such reactions change a physicochemical air property, and it affects aerodynamic coefficients. This paper investigates the influence of non-equilibrium reactions on the aerothrust aeroassisted maneuver with orbital change. The approach is to solve an optimization problem using the differential evolution algorithm with a temperature limitation. The spaceplane aerodynamic coefficients are determined by the numerical solution of the Reynolds-averaged Navier-Stokes equations. The aerodynamic calculations are conducted for the cases of perfect and non-equilibrium gases. A comparison of optimal trajectories, control laws, and fuel costs is made between models of perfect and non-equilibrium gases. The effect of a chemically reacting gas on the finite parameters is also evaluated using control laws obtained for a perfect gas. 相似文献
967.
《中国航空学报》2020,33(2):448-455
The reliability of the on-wing aircraft Auxiliary Power Unit (APU) decides the cost and the comfort of flight to a large degree. The most important function of APU is to help start main engines by providing compressed air. Especially on the condition of sudden shutdown in the air, APU can offer additional thrust for landing. Therefore, its condition monitoring has drawn much attention from the academic and industrial field. Among the on-wing sensing data which can reflect its condition, Exhaust Gas Temperature (EGT) is one of the most important parameters. To ensure the reliability of EGT, one kind of data-driven anomaly detection framework for EGT sensing data is proposed based on the Gaussian Process Regression and Kernel Principal Component Analysis. The situations of one-dimensional and two-dimensional input data for EGT anomaly detection are considered, respectively. The cross-validation experiments are carried out by utilizing the real condition data of APU, which are provided by China Southern Airlines Company Limited Shenyang Maintenance Base. The anomalous stuck condition of EGT sensing data is also detected. Experimental results show that the proposed EGT sensing data anomaly detection method can achieve better performance of false positive ratio, false negative ratio and accuracy. 相似文献
968.
《中国航空学报》2020,33(11):2864-2876
The increasing gross weight of electric Unmanned Aerial Vehicle (UAV) poses a challenge in practical applications. The range and endurance of the electric UAV are limited by the fixed mass of the battery package. In this work, a design optimization method for the battery package topology of small electric UAV is proposed to enhance the performance. To improve the accuracy of the method, the dynamic battery model and simplified electric component models are presented. These models are utilized by the trajectory optimization method, which takes the dynamic characteristic into consideration to calculate the aircraft performance. The direct optimal control method is used for solving the trajectory optimization problem, and this method is tested on a small blended-wing-body electric aircraft. The test result shows that the range and energy-consumption are mainly influenced by the parallel topology of the battery package, while the flight time in climb phase is more sensitive to the series topology. It is deduced that the range- and energy-optimal design points can be considered concurrently in design optimization. The work proves the feasibility of integrating the trajectory optimization and battery package design. 相似文献
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970.
Jun Chen Wenting Quan Zhenhe Wen Tingwei Cui 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
“Clear water” is a scale-dependent concept, so it is more likely to successfully find the “clear water” from images with smaller scale than that with larger scale data. In this study, an optimal spectral relationship of moderate-resolution imaging spectroradiometer (MODIS) 250 m and 1 km resolution data at near-infrared bands (OSRLM) is constructed for converting pseudo “clear water” reflectance at 859 nm to those at 748 and 869 nm. According to scale effects, the satellite-observed pseudo “clear water” reflectance is greater than 5.18%, larger than that derived from OSRLM model. An atmospheric correction model for MODIS 1km data using pseudo “clear water” reflectance of MODIS 250 m data (ACMM) was developed for improving the performance of traditional “clear water” atmospheric correction model (CWAC). The model validation results indicate that ACMM model has a better performance than CWAC model. By comparison, the uncertainty decreases by 19.18% in the use of ACMM model over CWAC model for deriving water-leaving reflectance in Taihu Lake, China. This uncertainty is significantly reduced in water-leaving reflectance estimation due to partial removal of scale effects on “clear water”. These findings imply that satellite-derived aerosol scattering contribution at smaller scale usually has a better performance than that at larger scale. 相似文献