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A primitive-variable Riemann method for solution of the shallow water equations with wetting and drying 总被引:1,自引:0,他引:1
P. Sivakumar D.G. Hyams L.K. Taylor W.R. Briley 《Journal of computational physics》2009,228(19):7452-7472
A Riemann flux that uses primitive variables rather than conserved variables is developed for the shallow water equations with nonuniform bathymetry. This primitive-variable flux is both conservative and well behaved at zero depth. The unstructured finite-volume discretization used is suitable for highly nonuniform grids that provide resolution of complex geometries and localized flow structures. A source-term discretization is derived for nonuniform bottom that balances the discrete flux integral both for still water and in dry regions. This primitive-variable formulation is uniformly valid in wet and dry regions with embedded wetting and drying fronts. A fully nonlinear implicit scheme and both nonlinear and time-linearized explicit schemes are developed for the time integration. The implicit scheme is solved by a parallel Newton-iterative algorithm with numerically computed flux Jacobians. A concise treatment of characteristic-variable boundary conditions with source terms is also given. Computed results obtained for the one-dimensional dam break on wet and dry beds and for normal-mode oscillations in a circular parabolic basin are in very close agreement with the analytical solutions. Other results for a forced breaking wave with friction interacting with a sloped bottom demonstrate a complex wave motion with wetting, drying and multiple interacting wave fronts. Finally, a highly nonuniform, coastline-conforming unstructured grid is used to demonstrate an unsteady simulation that models an artificial coastal flooding due to a forced wave entering the Gulf of Mexico. 相似文献
64.
在强光一号脉冲加速器上进行了国内首次的实验室软X光辐射三种材料的喷射冲量研究。结果表明,在能量为(0.2~0.33)keV、平均脉宽为39ns左右的X光辐射下,对灰漆、白漆和硬铝,在能注量分别为(92~152)J/cm2、(115~136)J/cm2和(163~192)J/cm2时,它们的冲量耦合系数分别为(0.61~0.80)Pa·s/(J·cm-2)、(0.58~0.97)Pa·s/(J·cm-2)和(0.61~0.84)Pa·s/(J·cm-2)。 相似文献
65.
YbSi2 and the derivatives YbTxSi2–x (T = Cr, Fe, Co) crystallizing in the α‐ThSi2 structure type were obtained as single crystals from reactions run in liquid indium. All silicides were investigated by single‐crystal X‐ray diffraction, I41/amd space group and the lattice constants are: a = 3.9868(6) Å and c = 13.541(3) Å for YbSi2, a = 4.0123(6) Å and c = 13.542(3) Å for YbCr0.27Si1.73, a = 4.0142(6) Å and c = 13.830(3) Å for YbCr0.71Si1.29, a = 4.0080(6) Å and c = 13.751(3) Å for YbFe0.34Si1.66, and a = 4.0036(6) Å, c = 13.707(3) Å for YbCo0.21Si1.79. YbSi2 and YbTxSi2–x compounds are polar intermetallics with three‐dimensional Si and M (T+Si) polyanion sub‐networks, respectively, filled with ytterbium atoms. The degree of substitution of transition metal at the silicon site is signficant and leads to changes in the average bond lengths and bond angles substantially. 相似文献
66.
We have applied our two recent results [depending on its helicity photon carries a quantum flux of ± Φ 0 = ± hc/e and the quantized magnetic fluxes through the electronic orbits of the Dirac hydrogen atom are given by: Φ (n,l,mj) = (n‐l‐mj)Φ0) ] to the 1s‐2p and 2p‐3d excitonic transitions in nanostructures. It is shown that the flux changes for the non‐zero matrix elements in the 1s‐2p and 2p‐3d excitonic transitions is either ± Φ0 or zero. The present result supports the previous results stated above. It is also shown that spin flip is possible in the 1s‐2p and 2p‐3d excitonic transitions. 相似文献
67.
This study extends the upstream flux‐splitting finite‐volume (UFF) scheme to shallow water equations with source terms. Coupling the hydrostatic reconstruction method (HRM) with the UFF scheme achieves a resultant numerical scheme that adequately balances flux gradients and source terms. The proposed scheme is validated in three benchmark problems and applied to flood flows in the natural/irregular river with bridge pier obstructions. The results of the simulations are in satisfactory agreement with the available analytical solutions, experimental data and field measurements. Comparisons of the present results with those obtained by the surface gradient method (SGM) demonstrate the superior stability and higher accuracy of the HRM. The stability test results also show that the HRM requires less CPU time (up to 60%) than the SGM. The proposed well‐balanced UFF scheme is accurate, stable and efficient to solve flow problems involving irregular bed topography. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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A solid state metathesis (SSM) reaction was investigated with respect to the formation of rare‐earth carbodiimides, the role of the co‐produced salt (LiCl), and the eutectic flux medium (LiCl/KCl). A SSM reaction is characterized by an exothermic reaction in which a salt (often LiCl) is coproduced. When the salt melts, it can serve as a useful medium for the crystallization of a desired product. An improved crystal growth can be observed by using an eutectic flux. However, the composition of an eutectic LiCl/KCl flux is altered when LiCl is produced during the reaction. The thermal effects concerning the endothermic melting of the flux and the exothermic ingnition of the SSM reaction may compensate each other, which is not necessarily a drawback for the reaction to proceed. 相似文献
70.
R. Bjørk C.R.H. Bahl A. Smith N. Pryds 《Journal of magnetism and magnetic materials》2010,322(22):3664-3671
A permanent magnet assembly in which the flux density can be altered by a mechanical operation is often significantly smaller than comparable electromagnets and also requires no electrical power to operate. In this paper five permanent magnet designs in which the magnetic flux density can be altered are analyzed using numerical simulations, and compared based on the generated magnetic flux density in a sample volume and the amount of magnet material used. The designs are the concentric Halbach cylinder, the two half Halbach cylinders, the two linear Halbach arrays and the four and six rod mangle. The concentric Halbach cylinder design is found to be the best performing design, i.e. the design that provides the most magnetic flux density using the least amount of magnet material. A concentric Halbach cylinder has been constructed and the magnetic flux density, the homogeneity and the direction of the magnetic field are measured and compared with numerical simulation and a good agrement is found. 相似文献