全文获取类型
收费全文 | 4599篇 |
免费 | 581篇 |
国内免费 | 284篇 |
专业分类
化学 | 304篇 |
晶体学 | 1篇 |
力学 | 565篇 |
综合类 | 85篇 |
数学 | 2839篇 |
物理学 | 1670篇 |
出版年
2024年 | 5篇 |
2023年 | 59篇 |
2022年 | 81篇 |
2021年 | 87篇 |
2020年 | 118篇 |
2019年 | 88篇 |
2018年 | 113篇 |
2017年 | 175篇 |
2016年 | 193篇 |
2015年 | 135篇 |
2014年 | 278篇 |
2013年 | 330篇 |
2012年 | 289篇 |
2011年 | 265篇 |
2010年 | 199篇 |
2009年 | 260篇 |
2008年 | 278篇 |
2007年 | 296篇 |
2006年 | 268篇 |
2005年 | 245篇 |
2004年 | 195篇 |
2003年 | 214篇 |
2002年 | 187篇 |
2001年 | 179篇 |
2000年 | 153篇 |
1999年 | 137篇 |
1998年 | 116篇 |
1997年 | 93篇 |
1996年 | 94篇 |
1995年 | 75篇 |
1994年 | 29篇 |
1993年 | 33篇 |
1992年 | 34篇 |
1991年 | 23篇 |
1990年 | 20篇 |
1989年 | 8篇 |
1988年 | 11篇 |
1987年 | 15篇 |
1986年 | 11篇 |
1985年 | 20篇 |
1984年 | 11篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 7篇 |
1979年 | 10篇 |
1978年 | 3篇 |
1976年 | 4篇 |
1971年 | 2篇 |
1936年 | 1篇 |
排序方式: 共有5464条查询结果,搜索用时 15 毫秒
71.
Tony Shardlow 《BIT Numerical Mathematics》2006,46(1):111-125
We describe a backward error analysis for stochastic differential equations with respect to weak convergence. Modified equations are provided for forward and backward Euler approximations to Itô SDEs with additive noise, and extensions to other types of equation and approximation are discussed. 相似文献
72.
A. Meister 《Mathematical Methods of Statistics》2007,16(1):63-76
This paper addresses the statistical problem of density deconvolution under the condition that the density to be estimated
has compact support. We introduce a new estimation procedure, which establishes faster rates of convergence for smooth densities
as compared to the optimal rates for smooth densities with unbounded support. This framework also allows us to relax the usual
condition of known error density with non-vanishing Fourier transform, so that a nonparametric class of densities is valid;
therefore, even the shape of the noise density need not be assumed. These results can also be generalized for fast decaying
densities with unbounded support. We prove optimality of the rates in the underlying experiment and study the practical performance
of our estimator by numerical simulations.
相似文献
73.
Yi-rang Yuan 《应用数学学报(英文版)》2007,23(2):255-268
For a coupled system of multiplayer dynamics of fluids in porous media,the characteristic finiteelement domain decomposition procedures applicable to parallel arithmetic are put forward.Techniques suchas calculus of variations,domain decomposition,characteristic method,negative norm estimate,energy methodand the theory of prior estimates are adopted.Optimal order estimates in L~2 norm are derived for the error inthe approximate solution. 相似文献
74.
生长曲线模型中回归系数阵的极大似然估计的精确分布 总被引:2,自引:0,他引:2
对于生长曲线模型,基于理论发展和应用效果的考虑,本文引入了Gauss型误差.在此误差下,本文研究了模型中回归系数阵的极大似然估计的精确分布,求出了此分布的密度和特征函数. 相似文献
75.
1引言 有限体积方法[l]一l’]作为守恒型的离散技术,被广泛应用于工程计算领域.文【2,3} 基于分片常数和分片常向量函数空间,对二维驻定对流扩散方程提出了一类非协调混合 有限体积(Covolume)格式,证明了格式具有。(hl/2)收敛精度.但该格式要求对偶剖分 比较规则,即采用重 相似文献
76.
The logarithmic norm. History and modern theory 总被引:1,自引:0,他引:1
Gustaf Söderlind 《BIT Numerical Mathematics》2006,46(3):631-652
In his 1958 thesis Stability and Error Bounds, Germund Dahlquist introduced the logarithmic norm in order to derive error bounds in initial value problems, using differential inequalities that distinguished between forward and reverse time integration. Originally defined for matrices, the logarithmic norm can be extended to bounded linear operators, but the extensions to nonlinear maps and unbounded operators have required a functional analytic redefinition of the concept.This compact survey is intended as an elementary, but broad and largely self-contained, introduction to the versatile and powerful modern theory. Its wealth of applications range from the stability theory of IVPs and BVPs, to the solvability of algebraic, nonlinear, operator, and functional equations. In memory of Germund Dahlquist (1925–2005).AMS subject classification (2000) 65L05 相似文献
77.
78.
79.
Summary The complete error potential is used for the study of the correlation of molecules. The correlation can be seen as a relaxation of the electrons and a relaxation of the nuclei. From the Fermi sea, the electronic relaxation gives rise to a partial excitation of each orbital which collectively generates a linear, a surface or a volume pressure; the resulting forces acting on the nuclei are defined in a general theory of the intramolecular forces. H3, H
3
+
, the diatoms and the hydrid of the first nine elements are taken as examples. 相似文献
80.
Two simple methods to calculate the area and volume called improved square gridmethod and cube cutting method are proposed in this paper. For any plane curve orspace surface satisfying certain conditions, by our method, the error of measurement isof the second infinitive order of measuring unit (the side length of the square grid or theside length of the little cube) when the unit is small enough. And when some properties ofthe curve or the surface can be found or its varying bounds can be evaluated, it is pointedout, in order to make the error smaller than any given value, how small the length of themeasuring unit should be. 相似文献