全文获取类型
收费全文 | 16114篇 |
免费 | 458篇 |
国内免费 | 270篇 |
专业分类
化学 | 2012篇 |
晶体学 | 57篇 |
力学 | 206篇 |
综合类 | 113篇 |
数学 | 13425篇 |
物理学 | 1029篇 |
出版年
2023年 | 42篇 |
2022年 | 172篇 |
2021年 | 133篇 |
2020年 | 115篇 |
2019年 | 453篇 |
2018年 | 530篇 |
2017年 | 274篇 |
2016年 | 215篇 |
2015年 | 254篇 |
2014年 | 514篇 |
2013年 | 939篇 |
2012年 | 568篇 |
2011年 | 925篇 |
2010年 | 852篇 |
2009年 | 1176篇 |
2008年 | 1207篇 |
2007年 | 1243篇 |
2006年 | 984篇 |
2005年 | 629篇 |
2004年 | 595篇 |
2003年 | 524篇 |
2002年 | 372篇 |
2001年 | 327篇 |
2000年 | 359篇 |
1999年 | 376篇 |
1998年 | 332篇 |
1997年 | 282篇 |
1996年 | 313篇 |
1995年 | 332篇 |
1994年 | 301篇 |
1993年 | 241篇 |
1992年 | 166篇 |
1991年 | 114篇 |
1990年 | 96篇 |
1989年 | 109篇 |
1988年 | 73篇 |
1987年 | 68篇 |
1986年 | 66篇 |
1985年 | 81篇 |
1984年 | 85篇 |
1983年 | 47篇 |
1982年 | 91篇 |
1981年 | 65篇 |
1980年 | 47篇 |
1979年 | 33篇 |
1978年 | 44篇 |
1977年 | 26篇 |
1976年 | 26篇 |
1975年 | 8篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Summary. We consider the spline collocation method for a class of parabolic pseudodifferential operators. We show optimal order convergence
results in a large scale of anisotropic Sobolev spaces. The results cover the classical boundary integral equations for the
heat equation in the general case where the spatial domain has a smooth boundary in the plane. Our proof is based on a localization
technique for which we use our recent results proved for parabolic pseudodifferential operators. For the localization we need
also some special spline approximation results in anisotropic Sobolev spaces.
Received May 17, 2001 / Revised version received February 19, 2002 / Published online April 17, 2002 相似文献
102.
103.
A new preconditioned conjugate gradient (PCG)-based domain decomposition method is given for the solution of linear equations
arising in the finite element method applied to the elliptic Neumann problem. The novelty of the proposed method is in the
recommended preconditioner which is constructed by using cyclic matrix. The resulting preconditioned algorithms are well suited
to parallel computation. 相似文献
104.
Franc Forstnerič 《Mathematische Annalen》1992,292(1):163-180
105.
Summary.
This paper is concerned with a high order convergent
discretization for the semilinear reaction-diffusion problem:
,
for , subject to ,
where .
We assume that on
, which
guarantees uniqueness of a solution to
the problem. Asymptotic properties of
this solution are discussed. We consider a
polynomial-based three-point
difference scheme on a simple piecewise
equidistant mesh of Shishkin type.
Existence and local uniqueness of a solution
to the scheme are analysed. We
prove that the scheme is almost fourth order
accurate in the discrete maximum
norm, uniformly in the perturbation parameter
. We present numerical
results in support of this result.
Received February 25, 1994 相似文献
106.
A robust and efficient adaptive reweighted estimator of multivariate location and scatter 总被引:1,自引:0,他引:1
Daniel Gervini 《Journal of multivariate analysis》2003,84(1):116-144
This article proposes a reweighted estimator of multivariate location and scatter, with weights adaptively computed from the data. Its breakdown point and asymptotic behavior under elliptical distributions are established. This adaptive estimator is able to attain simultaneously the maximum possible breakdown point for affine equivariant estimators and full asymptotic efficiency at the multivariate normal distribution. For the special case of hard-rejection weights and the MCD as initial estimator, it is shown to be more efficient than its non-adaptive counterpart for a broad range of heavy-tailed elliptical distributions. A Monte Carlo study shows that the adaptive estimator is as robust as its non-adaptive relative for several types of bias-inducing contaminations, while it is remarkably more efficient under normality for sample sizes as small as 200. 相似文献
107.
代数$A$ 称为不可分解的,如果 $A$ 不能分解成理想的直和.文中将证明满足$C(L_{\bar{0}})=C(L)=\{0\}$的限制李超代数能够分解成不可分解限制理想的直和,这种分解在不计理想次序的前提下是唯一的.而且还证明了限制李超代数的一些结果. 相似文献
108.
In this work, the melting behaviors of nonisothermally and isothermally melt‐crystallized poly(L ‐lactic acid) (PLLA) from the melt were investigated with differential scanning calorimetry (DSC) and temperature‐modulated differential scanning calorimetry (TMDSC). The isothermal melt crystallizations of PLLA at a temperature in the range of 100–110 °C for 120 min or at 110 °C for a time in the range of 10–180 min appeared to exhibit double melting peaks in the DSC heating curves of 10 °C/min. TMDSC analysis revealed that the melting–recrystallization mechanism dominated the formation of the double melting peaks in PLLA samples following melt crystallizations at 110 °C for a shorter time (≤30 min) or at a lower temperature (100, 103, or 105 °C) for 120 min, whereas the double lamellar thickness model dominated the formation of the double melting peaks in those PLLA samples crystallized at a higher temperature (108 or 110 °C) for 120 min or at 110 °C for a longer time (≥45 min). © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 466–474, 2007 相似文献
109.
Sans résumé
相似文献
相似文献
110.
Runge–Kutta based convolution quadrature methods for abstract, well-posed, linear, and homogeneous Volterra equations, non
necessarily of sectorial type, are developed. A general representation of the numerical solution in terms of the continuous
one is given. The error and stability analysis is based on this representation, which, for the particular case of the backward
Euler method, also shows that the numerical solution inherits some interesting qualitative properties, such as positivity,
of the exact solution. Numerical illustrations are provided. 相似文献