全文获取类型
收费全文 | 10290篇 |
免费 | 831篇 |
国内免费 | 861篇 |
专业分类
化学 | 805篇 |
晶体学 | 14篇 |
力学 | 631篇 |
综合类 | 252篇 |
数学 | 8765篇 |
物理学 | 1515篇 |
出版年
2024年 | 8篇 |
2023年 | 99篇 |
2022年 | 131篇 |
2021年 | 181篇 |
2020年 | 248篇 |
2019年 | 277篇 |
2018年 | 250篇 |
2017年 | 321篇 |
2016年 | 320篇 |
2015年 | 200篇 |
2014年 | 443篇 |
2013年 | 785篇 |
2012年 | 537篇 |
2011年 | 533篇 |
2010年 | 458篇 |
2009年 | 661篇 |
2008年 | 628篇 |
2007年 | 642篇 |
2006年 | 550篇 |
2005年 | 492篇 |
2004年 | 444篇 |
2003年 | 407篇 |
2002年 | 422篇 |
2001年 | 391篇 |
2000年 | 343篇 |
1999年 | 311篇 |
1998年 | 279篇 |
1997年 | 273篇 |
1996年 | 216篇 |
1995年 | 165篇 |
1994年 | 142篇 |
1993年 | 107篇 |
1992年 | 78篇 |
1991年 | 74篇 |
1990年 | 78篇 |
1989年 | 53篇 |
1988年 | 38篇 |
1987年 | 41篇 |
1986年 | 37篇 |
1985年 | 47篇 |
1984年 | 40篇 |
1983年 | 23篇 |
1982年 | 42篇 |
1981年 | 25篇 |
1980年 | 23篇 |
1979年 | 28篇 |
1978年 | 28篇 |
1977年 | 20篇 |
1976年 | 14篇 |
1974年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
In this paper, we give a convergence theorem and error estimates for an iteration method under new Kantorovitch-Ostrowski type condition using the information of higher derivatives at initial points. Compared with the corresponding study in [3],the convergence determination is established under one global condition, instead of two , on the function. 相似文献
72.
73.
Liqun Qi 《Operations Research Letters》1997,20(5):223-228
We show that strong differentiability at solutions is not necessary for superlinear convergence of quasi-Newton methods for solving nonsmooth equations. We improve the superlinear convergence result of Ip and Kyparisis for general quasi-Newton methods as well as the Broyden method. For a special example, the Newton method is divergent but the Broyden method is superlinearly convergent. 相似文献
74.
The object of the paper is to study the absolute matrix summability problem of Fourier series, conjugate series and some associated
series under a new set of conditions on matrix methods, generalising many known results in the literature. 相似文献
75.
Under suitable assumptions, a functional central limit theorem is obtained for a three-dimensional model of Maxwellian molecules. This model is related to a nonlinear Boltzmann-type equation. It will be proved that the family of the distributions induced by fluctuation processes converges weakly. 相似文献
76.
A time‐marching formulation is derived from the space–time integrated least squares (STILS) method for solving a pure hyperbolic convection equation and is numerically compared to various known methods. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
77.
We propose a minimum mean absolute error linear interpolator (MMAELI), based on theL
1 approach. A linear functional of the observed time series due to non-normal innovations is derived. The solution equation
for the coefficients of this linear functional is established in terms of the innovation series. It is found that information
implied in the innovation series is useful for the interpolation of missing values. The MMAELIs of the AR(1) model with innovations
following mixed normal andt distributions are studied in detail. The MMAELI also approximates the minimum mean squared error linear interpolator (MMSELI)
well in mean squared error but outperforms the MMSELI in mean absolute error. An application to a real series is presented.
Extensions to the general ARMA model and other time series models are discussed.
This research was supported by a CityU Research Grant and Natural Science Foundation of China. 相似文献
78.
In this paper,the authors obtain the Backlund transformation on time-like surfaces with constant mean curvature in R2,1.Using this transformation,families of surfaces with constant mean curvature from known ones can be constructed. 相似文献
79.
Transmission fluctuation spectrometry (TFS) is a method for the analysis of particle size distributions based on the statistical fluctuations of a transmission signal. Complete information on the PSD and particle concentration can be retrieved by a special transformation of the transmission signal, whereby the expectancy of the transmission square (ETS) is determined after the signal has been subjected to a procedure of spatial and temporal averaging. By varying the averaging parameters over a wide range, a spectrum of ETSs is obtained and introduced into a linear equation system, which yields the PSD. In the experimental realization presented here, variable temporal averaging is realized in the frequency domain with a series of low pass filters at different cutoff frequencies while spatial averaging inevitably occurs as the particles pass through a focused Gaussian beam of finite cross section. Experimental results on spherical particles (glass beads) and non‐spherical particles (SiC) are presented. The PSDs are resolved in 30 intervals within a particle size range from 1–1000 μm, employing a modified Chahine inversion algorithm. So far, the measurements are limited to moderate particle concentrations. Some influences affecting the measurements, especially for higher particle concentrations, are discussed in detail. 相似文献
80.
Ioannis K. Argyros 《Journal of Mathematical Analysis and Applications》2004,298(2):374-397
We provide a local as well as a semilocal convergence analysis for two-point Newton-like methods in a Banach space setting under very general Lipschitz type conditions. Our equation contains a Fréchet differentiable operator F and another operator G whose differentiability is not assumed. Using more precise majorizing sequences than before we provide sufficient convergence conditions for Newton-like methods to a locally unique solution of equation F(x)+G(x)=0. In the semilocal case we show under weaker conditions that our error estimates on the distances involved are finer and the information on the location of the solution at least as precise as in earlier results. In the local case a larger radius of convergence is obtained. Several numerical examples are provided to show that our results compare favorably with earlier ones. As a special case we show that the famous Newton-Kantorovich hypothesis is weakened under the same hypotheses as the ones contained in the Newton-Kantorovich theorem. 相似文献