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101.
Flapping wing micro-aerial-vehicle:Kinematics,membranes, and flapping mechanisms of ornithopter and insect flight 总被引:1,自引:0,他引:1
《中国航空学报》2016,(5):1159-1177
The application of biomimetics in the development of unmanned-aerial-vehicles (UAV) has advanced to an exceptionally small scale of nano-aerial-vehicles (NAV), which has surpassed its immediate predecessor of micro-aerial-vehicles (MAV), leaving a vast range of development possi-bilities that MAVs have to offer. Because of the prompt advancement into the NAV research devel-opment, the true potential and challenges presented by MAV development were never solved, understood, and truly uncovered, especially under the influence of transition and low Reynolds number flow characteristics. This paper reviews a part of previous MAV research developments which are deemed important of notification; kinematics, membranes, and flapping mechanisms ranges from small birds to big insects, which resides within the transition and low Reynolds number regimes. This paper also reviews the possibility of applying a piezoelectric transmission used to pro-duce NAV flapping wing motion and mounted on a MAV, replacing the conventional motorized flapping wing transmission. Findings suggest that limited work has been done for MAVs matching these criteria. The preferred research approach has seen bias towards numerical analysis as com-pared to experimental analysis. 相似文献
102.
Streamwise-body-force-model for rapid simulation combining internal and external flow fields 总被引:2,自引:0,他引:2
《中国航空学报》2016,(5):1205-1212
A streamwise-body-force-model (SBFM) is developed and applied in the overall flow simulation for the distributed propulsion system, combining internal and external flow fields. In view of axial stage effects, fan or compressor effects could be simplified as body forces along the streamline. These body forces which are functions of local parameters could be added as source terms in Navier-Stokes equations to replace solid boundary conditions of blades and hubs. The val-idation of SBFM with uniform inlet and distortion inlet of compressors shows that pressure perfor-mance characteristics agree well with experimental data. A three-dimensional simulation of the integration configuration, via a blended wing body aircraft with a distributed propulsion system using the SBFM, has been completed. Lift coefficient and drag coefficient agree well with wind tun-nel test results. Results show that to reach the goal of rapid integrated simulation combining inter-nal and external flow fields, the computational fluid dynamics method based on SBFM is reasonable. 相似文献
103.
《中国航空学报》2016,(2):305-315
With the implementation of environmental protection, sustainable development and conservation-oriented policies, components and parts of thin-walled welded tubes have gained increasing application in the aircraft and automotive industries because of their advantages: easily achieving forming and manufacturing process at low cost and in a short time. The current research on welded tube plastic forming is mainly concentrated on tube internal high-pressure forming, tube bending forming, and tube spinning forming. The focuses are on the material properties and characterization of welded tubes, finite element modeling for welded tube forming, and inhomogeneous deformation behavior and the mechanism and rules of deformation coordination in welded tube plastic forming. This paper summarizes the research progress in welded tube plastic forming from these aspects. Finally, with a focus on the urgent demand of the aviation, aerospace and automotive industries for high-strength and light-weight tubes, this paper discusses the development trends and challenges in the theory and technology of welded tube plastic forming in the future. Among them,laser tailor-welded technology will find application in the manufacture of high-strength steel tubes.Tube-end forming technology, such as tube flaring and flanging technology, will expand its application in welded tubes. Therefore, future studies will focus on the FE modeling regarding how to consider effects of welding on residual stresses, welding distortions and microstructure, the inhomogeneous deformation and coordination mechanism of the plastic forming process of tailor-welded tubes, and some end-forming processes of welded tubes, and more comprehensive research on the forming mechanism and limit of welded tubes. 相似文献
104.
《中国航空学报》2016,(1):53-65
Applications of a novel curve-fitting technique are presented to efficiently predict the motion of the vortex filament, which is trailed from a rigid body such as wings and rotors. The governing equations of the motion, when a Lagrangian approach with the present curve-fitting method is applied, can be transformed into an easily solvable form of the system of nonlinear ordinary differential equations. The applicability of Be′zier curves, B-spline, and Lagrange interpolating polynomials is investigated. Local Lagrange interpolating polynomials with a shift operator are proposed as the best selection for applications, since it provides superior system characteristics with minimum computing time, compared to other methods. In addition, the Gauss quadrature formula with local refinement strategy has been developed for an accurate prediction of the induced velocity computed with the line integration of the Biot–Savart law. Rotary-wing problems including a vortex ring problem are analyzed to show the efficiency, accuracy, and flexibility in the applications of the proposed method. 相似文献
105.
《中国航空学报》2016,(1):91-103
A theoretical nonlinear aeroelastic response analysis for a flexible high-aspect ratio wing excited by harmonic gust load is presented along with a companion wind tunnel test. A multidisci-plinary coupled numerical calculation is developed to simulate the flexible model wing undergoing gust load in the time domain via discrete nonlinear finite element structural dynamic analysis and nonplanar unsteady vortex lattice aerodynamic computation. A dynamic perturbation analysis about a nonlinear static equilibrium is also used to determine the small perturbation flutter bound-ary. A novel noncontact 3-D camera measurement analysis system is firstly used in the wind tunnel test to obtain the spatial large deformation and responses. The responses of the flexible wing under different static equilibrium states and frequency gust loads are discussed. The fair to good quanti-tative agreements between the theoretical and experimental results demonstrate that the presented analysis method is an acceptable way to predict the geometrically nonlinear gust response for flex-ible wings. 相似文献
106.
针对飞翼布局力矩控制问题,采用纳秒脉冲表面介质阻挡放电(NS-DBD)激励,在来流风速30 m/s时,开展飞翼等离子体流动控制风洞试验,研究了不同激励参数和位置对飞翼升阻特性和力矩特性的影响。结果表明,NS-DBD激励能够有效改善飞翼大迎角气动特性。激励频率对飞翼升阻特性影响较大,激励频率为0.2 kHz时,增升效果最好,最大升力系数提高14.5%,失速迎角推迟5°。随着激励频率的增加,增升效果逐渐变差,减阻效果变好。单侧施加激励时,能够实现大迎角下飞翼模型的力矩控制,随着激励频率的增加,滚转力矩的控制效果减小,激励频率为0.2kHz时,平均滚转力矩系数变化为ΔMX=0.005691;偏航力矩的控制效果增大,激励频率为1kHz时,平均偏航力矩系数变化为ΔMY=-0.001571;俯仰力矩的控制效果减小,激励频率为0.2kHz时,平均俯仰力矩系数变化为ΔMZ=-0.002576。在中翼段和内翼段施加激励,破坏了飞翼的俯仰力矩特性,在外翼段和机翼右侧施加激励,能够显著改善飞翼的俯仰力矩特性。流场测量结果表明:等离子体激励对飞翼气动力矩的控制,主要是通过控制流动分离和控制横向流动来实现的。NS-DBD激励为改善飞翼布局稳定性和操纵性提供一种潜在的技术手段。 相似文献
107.
108.
提出一种上下错开的无尾联接翼,即前翼或者后翼上反一定角度,使得前后翼垂直方向的相对距离从翼根处开始到翼梢处逐渐增大,以达到减小前后翼气动干扰的目的,搭接的小翼具有翼梢小翼作用,可有效减小诱导阻力。采用基于RANS方程的数值方法,研究了前后翼分别上反10°,20°和30°时对总体气动特性的影响,结果表明,当前翼上反且上反角为30°时其联接翼系统气动性能最佳。对该联接翼布局在Ma=0.85,0.95和1.20下进行了数值分析,结果表明,其升力系数变化较小,阻力系数在Ma0.85后才急剧增大,有应用于未来跨声速/超声速客机布局的潜力。 相似文献
109.
110.