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191.
V型沟槽尖峰形状对减阻效果及流场特性影响的数值分析 总被引:10,自引:1,他引:9
采用雷诺平均N-S方程和RNG k-ε湍流模型计算V型沟槽面的湍流边界层流动和黏性阻力,研究了V型沟槽尖峰形状对减阻效果、湍流边界层内的速度分布以及沟槽壁面切应力的影响.计算结果表明,沟槽尖峰处的圆角半径越小其减阻效果越好,最大减阻率可达6.6%;沟槽斜面中下部的壁面应力随着圆角半径的减小而降低,但尖峰处的局部壁面应力会随之而增大.沟槽尖峰处生成的二次涡是产生并影响减阻效果的根本原因. 相似文献
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193.
Masahiko Nakase Yuto Matsuzawa Kenji Takeshita 《Journal of Nuclear Science and Technology》2018,55(8):829-837
Extraction with multiple theoretical stages by a single contactor is possible when a liquid–liquid countercurrent centrifugal contactor with Taylor vortices (TVs) is used. A series of TVs inside the flow region between the coaxial inner rotor and static outer wall can sustain stable concentration gradients, thereby improving the extraction performance. In the TVs, an axial force driving the dispersed organic phase arises from the different specific weights of the organic and aqueous phases. In this study, the geometry of the flow region was modified using (1) different aspect ratios and (2) tapered and (3) eccentric geometries for better extraction performance. The flows were observed experimentally and simulated numerically using the volume-of-fluid method to understand the flow inside the TVs. Changing the geometry greatly affected the size of the TVs, the flow stability, and the emulsification behavior. In continuous-extraction experiments involving zinc ions with bis(2-ethylhexyl)phosphoric acid, the tapered geometry showed the highest number of theoretical stages because of its simultaneous vigorous agitation, stable TV arrangement, and phase separation. 相似文献
194.
Three‐dimensional numerical simulations are performed on a plate‐fin heat exchanger (with triangular fins as inserts between the plates) to evaluate the laminar heat transfer and fluid flow characteristics with longitudinal vortex generators (LVGs). The effect with an inline rectangular winglet pair (RWP) with a common‐flow‐down (CFD) configuration is studied. The numerical results indicate that the application of inline LVGs effectively enhances the heat transfer of the channel. The heat transfer further increases with the increase in the Reynolds number from 200 to 500 and angle of attack from β = 15° to 22.5°. The computations are also performed to find the best location for the second RWP. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20414 相似文献
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196.
Farouk Hachem Mahmoud Khaled Mohamad Ramadan Charbel Habchi 《能源与动力工程:英文版》2014,(7):1177-1182
Gortler vortices are key issues in the design of gas turbine blades. The present study deals with flow visualization over concave surface for gas turbine applications. The aim is to comprehend qualitatively the flow trends, particularly the Gortler vortices formation and development. Gortler vortices have the shape of mushroom-like vortices regularly spaced at 25 mm. These vortices grow and increase in strength more rapidly along the surface in the case of the same grid of turbulence applied to the measuring section. The curvature radius of the studied blade is 0.5 m and the stream turbulence intensity level is 2.6%. The velocity field is measured by hot wire anemometer in the streamwise direction. The velocity profile is found to be highly distorted by the momentum transfer associated with Gortler vortices. The results are compared to Blasius flow and to literature data for a blade with curvature radius equal to 2 m. 相似文献
197.
光具有由偏振性决定的自旋角动量(SAM)和由光场空间分布决定的轨道角动量(OAM)两种不同的物理性质。重点对光的自旋和轨道角动量在光束生成和变换性质、存在形式和描述方法、力学效应、空间相干性和时间相干性、角向多普勒频移效应及参量转换与量子纠缠等方面进行对比,探索它们的现象学差别,以期更好地理解光的本性,为该领域的研究提供启发和拓展思路。总结和分析了轨道角动量的最新研究成果,并展望了该领域的最新研究动态。 相似文献
198.
199.
Roland Mallier 《Journal of Engineering Mathematics》2003,47(2):121-136
Asymptotic techniques are used to model the quasi-steady state vortices that have been observed in two-dimensional simulations of vortex roll-up in stratified shear layers. A time-independent nonlinear critical layer analysis is used to find a family of steady-state finite amplitude vortices in the Holmboe model of an inviscid stratified shear layer, with the vorticity inside closed streamlines based on the Stuart vortex. The vortices are compared to results of simulations and also an alternative model where the vorticity was constant inside closed streamlines. 相似文献
200.
T型混合器是微尺度条件下探索传递现象的理想模型,通过CFD方法对其内部流体力学性能及混合特征进行研究分析。首先,通过对不同Re数下T型微反应器内混合状态的模拟及分析,验证该方法对T型结构混合的可靠性;其次,通过对T型微反应器内流动形态的分析,发现涡结构的产生能够强化混合过程,并提出一种能产生强化混合的涡结构的新型T型反应器的设计理念;最后,对影响新型混合器的不同结构参数进行模拟并分析,得到该设计理念下的最优结构,并对该结构进行进一步分析,发现该结构能够扭曲混合界面以增大接触面积,从而强化混合效果。 相似文献