全文获取类型
收费全文 | 16642篇 |
免费 | 524篇 |
国内免费 | 499篇 |
专业分类
化学 | 3133篇 |
晶体学 | 248篇 |
力学 | 234篇 |
综合类 | 66篇 |
数学 | 12362篇 |
物理学 | 1622篇 |
出版年
2023年 | 65篇 |
2022年 | 109篇 |
2021年 | 117篇 |
2020年 | 126篇 |
2019年 | 450篇 |
2018年 | 494篇 |
2017年 | 299篇 |
2016年 | 241篇 |
2015年 | 275篇 |
2014年 | 526篇 |
2013年 | 959篇 |
2012年 | 605篇 |
2011年 | 1030篇 |
2010年 | 958篇 |
2009年 | 1254篇 |
2008年 | 1263篇 |
2007年 | 1243篇 |
2006年 | 970篇 |
2005年 | 678篇 |
2004年 | 631篇 |
2003年 | 548篇 |
2002年 | 575篇 |
2001年 | 355篇 |
2000年 | 353篇 |
1999年 | 384篇 |
1998年 | 335篇 |
1997年 | 251篇 |
1996年 | 330篇 |
1995年 | 334篇 |
1994年 | 317篇 |
1993年 | 218篇 |
1992年 | 172篇 |
1991年 | 101篇 |
1990年 | 74篇 |
1989年 | 83篇 |
1988年 | 56篇 |
1987年 | 50篇 |
1986年 | 47篇 |
1985年 | 93篇 |
1984年 | 67篇 |
1983年 | 57篇 |
1982年 | 84篇 |
1981年 | 88篇 |
1980年 | 64篇 |
1979年 | 30篇 |
1978年 | 56篇 |
1977年 | 57篇 |
1976年 | 59篇 |
1975年 | 26篇 |
1974年 | 33篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
A fictitious domain approach to the numerical solution of PDEs in stochastic domains 总被引:1,自引:0,他引:1
We present an efficient method for the numerical realization of elliptic PDEs in domains depending on random variables. Domains
are bounded, and have finite fluctuations. The key feature is the combination of a fictitious domain approach and a polynomial
chaos expansion. The PDE is solved in a larger, fixed domain (the fictitious domain), with the original boundary condition
enforced via a Lagrange multiplier acting on a random manifold inside the new domain. A (generalized) Wiener expansion is
invoked to convert such a stochastic problem into a deterministic one, depending on an extra set of real variables (the stochastic
variables). Discretization is accomplished by standard mixed finite elements in the physical variables and a Galerkin projection
method with numerical integration (which coincides with a collocation scheme) in the stochastic variables. A stability and
convergence analysis of the method, as well as numerical results, are provided. The convergence is “spectral” in the polynomial
chaos order, in any subdomain which does not contain the random boundaries. 相似文献
102.
This article introduces and analyzes a p-version FEM for variational inequalities resulting from obstacle problems for some quasi-linear elliptic partial differential
operators. We approximate the solution by controlling the obstacle condition in images of the Gauss–Lobatto points. We show
existence and uniqueness for the discrete solution u
p
from the p-version for the obstacle problem. We prove the convergence of u
p
towards the solution with respect to the energy norm, and assuming some additional regularity for the solution we derive
an a priori error estimate. In numerical experiments the p-version turns out to be superior to the h-version concerning the convergence rate and the number of unknowns needed to achieve a certain exactness of the approximation. 相似文献
103.
In this paper, we establish a theorem on the distribution of primes in quadratic progressions on average. 相似文献
104.
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
105.
Tokuzo Shiga 《Probability Theory and Related Fields》1997,108(3):417-439
Summary. We study the exponential decay rate of the survival probability up to time t>0 of a random walker moving in Zopf;
d
in a temporally and spatially fluctuating random environment. When the random walker has a speed parameter κ>0, we investigate
the influence of κ on the exponential decay rate λ(d,κ). In particular we prove that for any fixed d≥1, λ(d,κ) behaves like as logκ as κ↘0.
Received: 21 May 1996 / In revised form: 2 February 1997 相似文献
106.
Reinhard Farwig 《Acta Appl Math》1994,37(1-2):41-51
In this note, we discuss the reflection principle of the Stokes system in a half space for the threedimensional case, and of the biharmonic equation. Admitting different boundary conditions, we use the reflection principle to prove uniqueness of solutions of the Stokes system or the biharmonic equation in weightedLq-spaces 相似文献
107.
108.
109.
We answer some questions posed in [L. Grunenfelder, M. Mastnak, On bimeasurings, J. Pure Appl. Algebra 204 (2006) 258-269] concerning the universal bimeasuring bialgebra via a construction of suitable subcoalgebras of the universal measuring coalgebra. 相似文献
110.
In this article, we generalize the theory of motivic integration on formal schemes topologically of finite type and the notion
of motivic Serre invariant, to a relative point of view. We compute the relative motivic Serre invariant for curves defined
over the field of fractions of a complete discrete valuation ring R of equicharacteristic zero. One aim of this study is to understand the behavior of motivic Serre invariants under ramified
extension of the ring R. Thanks to our constructions, we obtain, in particular, an expression for the generating power series, whose coefficients
are the motivic Serre invariant associated to a curve, computed on a tower of ramified extensions of R. We give an interpretation of this series in terms of the motivic zeta function of Denef and Loeser. 相似文献