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141.
After a formal explanation of Mayer's enthalpy balance method as applied to biological reaction rates, the history of its application is traced from Rubner's dog to accounting for the energy of muscle contraction. The introduction of microcalorimetry allowed the method generally to be used for cells in vitro and now particular emphasis can be paid to the growth of cells for the production of therapeutically-important heterologous proteins. In these systems, enthalpy balance studies contribute to defining catabolic processes, designing media, understanding the mechanisms of growth and controlling cultures using heat flux as an on-line sensor of metabolic activity.Plenary LectureThe authors are grateful to the BBSRC (UK) for a research grant, 2/3680. 相似文献
142.
143.
Pierre Gaspard 《Journal of statistical physics》1996,88(5-6):1215-1240
We describe a mechanism leading to positive entropy production in volume-preserving systems under nonequilibrium conditions.
We consider volume-preserving systems sustaining a diffusion process like the multibaker map or the Lorentz gas. A continuous
flux of particles is imposed across the system resulting in a steady gradient of concentration. In the limit where such flux
boundary conditions are imposed at arbitrarily separated boundaries for a fixed gradient, the invariant measure becomes singular.
For instance, in the multibaker map, the limit invariant measure has a cumulative function given in terms of the nondifferentiable
Takagi function. Because of this singularity of the invariant measure, the entropy must be defined as a coarse-grained entropy
instead of the fined-grained Gibbs entropy, which would require the existence of a regular measure with a density. The coarse-grained
entropy production is then shown to be asymptotically positive and, moreover, given by the entropy production expected from
irreversible thermodynamics. 相似文献
144.
For two‐phase flow models, upwind schemes are most often difficult do derive, and expensive to use. Centred schemes, on the other hand, are simple, but more dissipative. The recently proposed multi‐stage (MUSTA ) method is aimed at coming close to the accuracy of upwind schemes while retaining the simplicity of centred schemes. So far, the MUSTA approach has been shown to work well for the Euler equations of inviscid, compressible single‐phase flow. In this work, we explore the MUSTA scheme for a more complex system of equations: the drift‐flux model, which describes one‐dimensional two‐phase flow where the motions of the phases are strongly coupled. As the number of stages is increased, the results of the MUSTA scheme approach those of the Roe method. The good results of the MUSTA scheme are dependent on the use of a large‐enough local grid. Hence, the main benefit of the MUSTA scheme is its simplicity, rather than CPU ‐time savings. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
145.
We consider the Navier–Stokes equations in an aperture domain of the three‐dimensional Euclidean space. We are interested in proving the existence of regular solutions corresponding to small initial data and flux through the aperture. The flux is assumed to be smooth and bounded on (0, +∞). As a consequence, we prove the existence of a time‐periodic solution corresponding to a time‐periodic flux through the aperture. Finally, we compare our solution with a solution belonging to a wider class, showing that, if such a solution does exist, then the two solutions coincide. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
146.
S. F. Garanin D. V. Karmishin 《Journal of Applied Mechanics and Technical Physics》2004,45(5):639-646
This paper considers a stationary surface discharge that arises when a magnetic flux emerges through an insulator surface (H-pushed discharge). It is assumed that the heat flux in the discharge is determined only by the electron thermal conductivity of the ionized vapor of the insulator and the Nernst effect. The main parameters of the discharge and the structure of the current layer are determined for the case of strong magnetic fields (above 0.1 MOe) and an aluminum oxide insulator. 相似文献
147.
The desorption of CO from an anisotropic surface of polycrystalline tungsten after different periods of annealing has been studied. Anisotropy in the spatial distribution of CO molecules in the desorbing flux was detected at early stages of annealing. Smoothing out of the surface texture during annealing recorded by means of STM resulted in the disappearance of the spatial distribution anisotropy. The results are quantitatively explained by the model of a rough surface.7
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 999–1002, June, 1994.The authors express their profound gratitude to Prof. V. I. Panov and his collaborators for making it possible to carry out measurements with a tunneling microscope and for their help. 相似文献
148.
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150.
Jae-Soo Kim 《国际流体数值方法杂志》1993,17(7):567-587
The unsteady flow over an oscillatory NACA0012 aerofoil has been simulated by the calculation with Euler equations. The equations are discretized by an implicit Euler in time, and a second-order space-accurate TVD scheme based on flux vector splitting with van Leer's limiter. Modified eigenvalues are proposed to overcome the slope discontinuities of split eigenvalues at Mach = 0·0 and ± 1·0, and to generate a bow shock in front of the aerofoil. A moving grid system around the aerofoil is generated by Sorenson's boundary fitted co-ordinates for each time step. The calculations have been done for two angles of attack θ = 5·0° sin (ωt) and θ = 3·0° + 3·0° sin (ωt) for the free-stream Mach numbers 2·0 and 3·0. The results show that pressure and Mach cells flow along characteristic lines. To examine unsteady effects, the responses of wall pressure and normal force coefficients are analysed by a Fourier series expansion. 相似文献