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41.
本文定量分析了"瑞利球"实验的动力学过程。"瑞利球"实验中构建了一个"怪坡",通过对两导轨的控制,使均质圆球看起来像在"爬坡"。文中据刚体运动原理构建了物理模型,并分析系统的受力情况和运动过程,导出了均质圆球"爬坡"的最大高度的公式。在忽略空气阻力与摩擦力情况下,当两导轨杆初始距离远小于圆球半径、小球刚好不能掉落时突然合拢两导轨使其平行、两导轨初始夹角等于两倍导轨倾斜角时,均质圆球可以达到最大高度和最远距离。 相似文献
42.
V. N. Zaikovskii S. P. Kiselev V. P. Kiselev 《Journal of Applied Mechanics and Technical Physics》2005,46(5):670-676
Large-scale streamwise vortices in the vicinity of a perforated wall in the supersonic part of the nozzle are studied. The governing effect of gas inflow through a perforated wall on origination and parameters of streamwise vortices is experimentally established.__________Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 5, pp. 68–75, September–October, 2005. 相似文献
43.
位错和夹杂的干涉效应对于理解材料的强化和韧化机理具有十分重要的意义。文中研究了晶体材料中刃型位错和多条共圆弧刚性线夹杂的干涉作用。利用Riemann—Schwarz反照原理和复势函数的奇性主部分析技术,得到了问题的一般解答;对于只含一条刚性线夹杂的情况,给出了复势函数的封闭形式解。由Peach-Koehler公式求出了作用在刃型位错上的位错力,并讨论了圆弧形刚性线夹杂对位错力的影响规律,发现弧形刚性线对刃型位错有很强的排斥作用。本文解答不但可作为格林函数获得任意分布位错的相应解答,而且可以用于研究刚性线夹杂和任意形状裂纹的干涉效应问题。 相似文献
44.
45.
Pulsatile flows in a lateral aneurysm anchored on a stented and curved parent vessel 总被引:5,自引:0,他引:5
We present particle tracking velocimetry measurements and flow visualization of pulsatile flow fields in a stented cerebrovascular
lateral aneurysm model with a wide ostium anchored on a curved parent vessel. Among the stent parameters, the blocking ratioC
α ranging from 0% to 75% was selected to study its effect on the changes of intra-aneurysmal hemodynamics for the reference
of minimally invasive endovascular aneurysm treatment. The Womersley number was 3.9 and the mean, peak, and minimal Reynolds
numbers based on the bulk average velocity and diameter of the parent vessel were 600, 850, and 300, respectively. The results
are characterized in terms of velocity vector field, coded streak images, region averaged velocity, vorticity, and wall shear
stress. A critical range ofC
α related to the inflow location as well as the shape and number of intra-aneurysmal vortices is identified. The intra-aneurysmal
flow activity, vortex strength, and wall shear stress are found to decrease with increasingC
α. Among theC
α examined,C
α=75% is the most favorable in attenuating the risk of aneurysmal rupture and promoting intra-aneurysmal thrombus. 相似文献
46.
47.
本文将空间轴对称问题的Папковиц-Neuber通解用复变量广义解析函数表示,推导出用复变函数法求解空间轴对称问题的基本公式,并以此为工具求得了含球形空腔或刚性夹杂的中厚圆板在轴对称弯曲变形时的完全解. 相似文献
48.
49.
Faruk Civan 《Transport in Porous Media》2007,67(2):329-334
An Arrhenius-type asymptotic-exponential function is derived to describe the temperature dependence of the power needed for
detachment of fine particles from pore walls in porous media. 相似文献
50.
Experimental investigation on tunnel sonic boom 总被引:1,自引:0,他引:1
Upon the entrance of a high-speed train into a relatively long train tunnel, compression waves are generated in front of the train. These compression waves subsequently coalesce into a weak shock wave so that a unpleasant sonic boom is emitted from the tunnel exit. In order to investigate the generation of the weak shock wave in train tunnels and the emission of the resulting sonic boom from the train tunnel exit and to search for methods for the reduction of these sonic booms, a 1300 scaled train tunnel simulator was constructed and simulation experiments were carried out using this facility.In the train tunnel simulator, an 18 mm dia. and 200 mm long plastic piston moves along a 40 mm dia. and 25 m long test section with speed ranging from 60 to 100 m/s. The tunnel simulator was tilted 8° to the floor so that the attenuation of the piston speed was not more than 10 % of its entrance speed. Pressure measurements along the tunnel simulator and holographic interferometric optical flow visualization of weak shock waves in the tunnel simulator clearly showed that compression waves, with propagation, coalesced into a weak shock wave. Although, for reduction of the sonic boom in prototype train tunnels, the installation of a hood at the entrance of the tunnels was known to be useful for their suppression, this effect was confirmed in the present experiment and found to be effective particularly for low piston speeds. The installation of a partially perforated wall at the exit of the tunnel simulator was found to smear pressure gradients at the shock. This effect is significant for higher piston speeds. Throughout the series of train tunnel simulator experiments, the combination of both the entrance hood and the perforated wall significantly reduces shock overpressures for piston speeds ofu
p
ranging from 60 to 100 m/s. These experimental findings were then applied to a real train tunnel and good agreement was obtained between the tunnel simulator result and the real tunnel measurements. 相似文献