全文获取类型
收费全文 | 2956篇 |
免费 | 70篇 |
国内免费 | 11篇 |
专业分类
化学 | 41篇 |
晶体学 | 1篇 |
力学 | 35篇 |
综合类 | 1篇 |
数学 | 2839篇 |
物理学 | 120篇 |
出版年
2022年 | 4篇 |
2021年 | 3篇 |
2020年 | 9篇 |
2019年 | 74篇 |
2018年 | 87篇 |
2017年 | 46篇 |
2016年 | 35篇 |
2015年 | 43篇 |
2014年 | 80篇 |
2013年 | 174篇 |
2012年 | 100篇 |
2011年 | 196篇 |
2010年 | 183篇 |
2009年 | 234篇 |
2008年 | 208篇 |
2007年 | 245篇 |
2006年 | 167篇 |
2005年 | 123篇 |
2004年 | 90篇 |
2003年 | 91篇 |
2002年 | 62篇 |
2001年 | 66篇 |
2000年 | 57篇 |
1999年 | 70篇 |
1998年 | 57篇 |
1997年 | 40篇 |
1996年 | 68篇 |
1995年 | 59篇 |
1994年 | 64篇 |
1993年 | 55篇 |
1992年 | 41篇 |
1991年 | 26篇 |
1990年 | 21篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 11篇 |
1985年 | 14篇 |
1984年 | 15篇 |
1983年 | 12篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1980年 | 12篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有3037条查询结果,搜索用时 15 毫秒
21.
We study a generalized Crank–Nicolson scheme for the time discretization of a fractional wave equation, in combination with
a space discretization by linear finite elements. The scheme uses a non-uniform grid in time to compensate for the singular
behaviour of the exact solution at t = 0. With appropriate assumptions on the data and assuming that the spatial domain is convex or smooth, we show that the
error is of order k
2 + h
2, where k and h are the parameters for the time and space meshes, respectively. 相似文献
22.
For a general K3 surface S of genus g, with 2 ≤ g ≤ 10, we prove that the intermediate Jacobians of the family of prime Fano threefolds of genus g containing S as a hyperplane section, form generically an algebraic completely integrable Hamiltonian system.
The first author is partially supported by grant MI1503/2005 of the Bulgarian Foundation for Scientific Research. 相似文献
23.
In this paper we investigate the electrostatic problem of determining conductivity profiles from the knowledge of boundary
currents and voltages. We obtain an improved estimate for the voltage potential of a two-dimensional conductor having finitely
many circular inclusions and piecewise constant conductivity profile. We derive an asymptotic expansion for the voltage potential
in terms of the reference voltage potential and the location, size, and conductivity of the inhomogeneities. This representation
is used to formulate the nonlinear least squares problem for estimating the location and size of the inhomogeneities. Required
boundary data for the voltage potential are generated numerically by solving a system of integral equations. Computational
experiments are presented to demonstrate the effectiveness of our identification procedure. 相似文献
24.
By exploiting the construction of charged field algebras as canonical extensions of CCR current algebras in 1+1 dimensions and nonregular representations of extended algebras, we provide an algebraic construction of local Fermi fields as ultrastrong limits of bosonic variables in all representations which are locally Fock with respect to the ground-state representation of the massless scalar field. 相似文献
25.
Non-local approximation of the Mumford-Shah functional 总被引:3,自引:0,他引:3
The Mumford-Shah functional, introduced to study image segmentation problems, is approximated in the sense of -convergence by a sequence of non-local integral functionals.
Received June 6, 1996 / Accepted July 11, 1996 相似文献
26.
Michael Demuth Peter Stollmann Günter Stolz Jan van Casteren 《Integral Equations and Operator Theory》1995,23(2):145-153
We give trace norm estimates for products of integral operators and for diffusion semigroups. These are applied to differences of heat semigroups. A natural example of an integral operator with finite trace which is not trace class is given. 相似文献
27.
28.
Wen-Rong Dai 《Journal of Differential Equations》2007,235(1):127-165
In this paper, we study the global existence and the asymptotic behavior of classical solution of the Cauchy problem for quasilinear hyperbolic system with constant multiple and linearly degenerate characteristic fields. We prove that the global C1 solution exists uniquely if the BV norm of the initial data is sufficiently small. Based on the existence result on the global classical solution, we show that, when the time t tends to the infinity, the solution approaches a combination of C1 traveling wave solutions. Finally, we give an application to the equation for time-like extremal surfaces in the Minkowski space-time R1+n. 相似文献
29.
In the present paper the problems of existence and uniqueness of almost periodic solutions for impulsive cellular neural networks with delay are considered. 相似文献
30.
This article deals with Leibniz's reception of Descartes' “geometry.” Leibnizian mathematics was based on five fundamental notions: calculus, characteristic, art of invention, method, and freedom. On the basis of methodological considerations Leibniz criticized Descartes' restriction of geometry to objects that could be given in terms of algebraic (i.e., finite) equations: “Descartes's mind was the limit of science.” The failure of algebra to solve equations of higher degree led Leibniz to develop linear algebra, and the failure of algebra to deal with transcendental problems led him to conceive of a science of the infinite. Hence Leibniz reconstructed the mathematical corpus, created new (transcendental) notions, and redefined known notions (equality, exactness, construction), thus establishing “a veritable complement of algebra for the transcendentals”: infinite equations, i.e., infinite series, became inestimable tools of mathematical research. 相似文献