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171.
JOHN POPE 《Natural Resource Modeling》2003,16(4):439-464
ABSTRACT. The paper is an attempt to refute Quinn's ‘the Golden Age of fisheries population models has ended “hypothesis. The approach is to show it is possible to provide simple matrix based theory for use with delay difference equations applied to products of the 0th to 4th powers of length and numbers at length (Alias” proto‐moments“). It compares these to models just based upon numbers and biomass. It also shows examples (of comparatively little moment) indicating how using multiple proto‐moments could improve the ability of delay difference equations to handle the size dependent processes of maturity, selection, natural mortality rates and predation rates and thus improving the biological reality of these models. 相似文献
172.
We study a system of quasilinear equations describing one-dimensional flow of a viscous compressible heat-conducting medium with a nonmonotone state function and mass force. The large-time behavior of solutions is considered for arbitrarily large initial data. In spite of possible nonuniqueness and discontinuity of the stationary solution, we prove L2-stabilization for the stress and heat flux as t → ∞ along with corresponding global energy estimates for them. The new method of proof utilizes a combination of energy type equalities for the stress and heat flux. Consequently, H1-stabilization of the velocity and temperature along with global estimates for their derivatives are valid as well. 相似文献
173.
The effect of the temperature factor, that is, the ratio of the body temperature to the freestream stagnation temperature, on the structure of the separated flow formed in the presence of a concave corner in a supersonic stream is studied. The strong influence of the temperature factor on the separation zone length and the flow-generated aerodynamic characteristics is established. It is shown that for fairly large deflection angles this flow cannot be described by free interaction, or triple deck, theory. 相似文献
174.
Jean-Pierre Françoise 《Journal of Dynamics and Differential Equations》2008,20(4):777-786
This article is devoted to one-dimensional perturbative theory on R × S
1. There is a recursive formula for the successive obstructions to parametric center at any order of the perturbation parameter.
The first obstruction is studied by means of complex analysis techniques. This extends to the trigonometric case what was
done previously for the polynomial case (Israel J. Math. 142, 273–283, 2004).
This article is dedicated to Professor Zhang Zhi-Fen on the occasion of her 80th Birthday 相似文献
175.
Shoufu Li 《中国科学A辑(英文版)》2003,46(5):662-674
B-stability andB-convergence theories of Runge-Kutta methods for nonlinear stiff Volterra functional differential equations (VFDEs) are established
which provide unified theoretical foundation for the study of Runge-Kutta methods when applied to nonlinear stiff initial
value problems (IVPs) in ordinary differential equations (ODEs), delay differential equations (DDEs), integro-differential
equations (IDEs) and VFDEs of other type which appear in practice. 相似文献
176.
The frequency or dispersion relation for the least‐squares mixed formulation of the shallow‐water equations is analysed. We consider the use of different approximation spaces corresponding to co‐located and staggered meshes, respectively. The study includes the effect of Coriolis, and the dispersion properties are compared analytically and graphically with those of the mixed Galerkin formulation. Numerical solutions of a test problem to simulate slow Rossby modes illustrate the theoretical results. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
177.
Marco Caliari Marco Vianello Luca Bergamaschi 《Journal of Computational and Applied Mathematics》2007,210(1-2):56-63
We implement a second-order exponential integrator for semidiscretized advection–diffusion–reaction equations, obtained by coupling exponential-like Euler and Midpoint integrators, and computing the relevant matrix exponentials by polynomial interpolation at Leja points. Numerical tests on 2D models discretized in space by finite differences or finite elements, show that the Leja–Euler–Midpoint (LEM) exponential integrator can be up to 5 times faster than a classical second-order implicit solver. 相似文献
178.
179.
高阶非线性波动方程的有限差分方法 总被引:2,自引:0,他引:2
本文研究一类广泛的高阶非线性波动方程组初边值问题的有限差分格式,用离散泛函分析方法和先验估计的技巧得到了有限差分格式的收敛性。 相似文献
180.
Luciano Galeone Roberto Garrappa 《Journal of Computational and Applied Mathematics》1997,80(2):377-195
We study convergence properties of time-point relaxation (TR) Runge-Kutta methods for linear systems of ordinary differential equations. TR methods are implemented by decoupling systems in Gauss-Jacobi, Gauss-Seidel and successive overrelaxation modes (continuous-time iterations) and then solving the resulting subsystems by means of continuous extensions of Runge-Kutta (CRK) methods (discretized iterations). By iterating to convergence, these methods tend to the same limit called diagonally split Runge-Kutta (DSRK) method. We prove that TR methods are equivalent to decouple in the same modes the linear algebraic system obtained by applying DSRK limit method. This issue allows us to study the convergence of TR methods by using standard principles of convergence of iterative methods for linear algebraic systems. For a particular problem regions of convergence are plotted. 相似文献