全文获取类型
收费全文 | 6745篇 |
免费 | 747篇 |
国内免费 | 519篇 |
学科分类
数理化 | 8011篇 |
出版年
2024年 | 9篇 |
2023年 | 45篇 |
2022年 | 80篇 |
2021年 | 111篇 |
2020年 | 180篇 |
2019年 | 155篇 |
2018年 | 181篇 |
2017年 | 168篇 |
2016年 | 209篇 |
2015年 | 115篇 |
2014年 | 290篇 |
2013年 | 476篇 |
2012年 | 268篇 |
2011年 | 358篇 |
2010年 | 301篇 |
2009年 | 395篇 |
2008年 | 421篇 |
2007年 | 433篇 |
2006年 | 395篇 |
2005年 | 377篇 |
2004年 | 307篇 |
2003年 | 303篇 |
2002年 | 326篇 |
2001年 | 255篇 |
2000年 | 226篇 |
1999年 | 219篇 |
1998年 | 176篇 |
1997年 | 163篇 |
1996年 | 147篇 |
1995年 | 86篇 |
1994年 | 109篇 |
1993年 | 66篇 |
1992年 | 61篇 |
1991年 | 77篇 |
1990年 | 63篇 |
1989年 | 38篇 |
1988年 | 46篇 |
1987年 | 42篇 |
1986年 | 35篇 |
1985年 | 46篇 |
1984年 | 42篇 |
1983年 | 23篇 |
1982年 | 28篇 |
1981年 | 32篇 |
1980年 | 20篇 |
1979年 | 21篇 |
1978年 | 18篇 |
1977年 | 21篇 |
1976年 | 12篇 |
1973年 | 15篇 |
排序方式: 共有8011条查询结果,搜索用时 0 毫秒
1.
Lisa Lorentzen 《Numerical Algorithms》1995,10(1):69-111
Over the last 20 years a large number of algorithms has been published to improve the speed and domain of convergence of continued fractions. In this survey we show that these algorithms are strongly related. Actually, they essentially boil down to two main principles.We also prove some results on asymptotic expansions of tail values of limit periodic continued fractions.Dedicated to Luigi Gatteschi on his seventieth birthdayThis research was partially supported by The Norwegian Research Council and by the HMC project ROLLS, under contract CHRX-CT93-0416. 相似文献
2.
LIU Jixue ZHANG Sanguo & CHEN Xiru Department of Statistics Finance University of Science Technology of China Hefei China Department of Mathematics Graduate School of Chinese Academy of Sciences Beijing China 《中国科学A辑(英文版)》2006,49(6):752-769
This paper studies the linear EV model when replicate observations are made only on independent variables. We construct the estimates of regression coefficients and prove the consistency and asymptotic normality under some proper conditions. Results obtained reveal the difference between the case where the independent and dependent variables are observed repeatedly and simultaneously and the case studied in this article. 相似文献
3.
Given a principal value convolution on the Heisenberg group Hn = Cn×R, we study the relation between its Laguerre expansion and the Fourier-Bessel expansion of its limit on Cn. We also calculate the Dirichlet kernel for the Laguerre expansion on the group Hn. 相似文献
4.
D. Yafaev 《Proceedings Mathematical Sciences》2002,112(1):245-255
We find an explicit function approximating at high energies the kernel of the scattering matrix with arbitrary accuracy. Moreover,
the same function gives all diagonal singularities of the kernel of the scattering matrix in the angular variables.
This paper is dedicated to Jean-Michel Combes on the occasion of his sixtieth birthday. 相似文献
5.
Belov V. V. Dobrokhotov S. Yu. Maksimov V. A. 《Theoretical and Mathematical Physics》2003,135(3):765-791
Different versions of the Darboux–Weinstein theorem guarantee the existence of action–angle-type variables and the harmonic-oscillator variables in a neighborhood of isotropic tori in the phase space. The procedure for constructing these variables is reduced to solving a rather complicated system of partial differential equations. We show that this system can be integrated in quadratures, which permits reducing the problem of constructing these variables to solving a system of quadratic equations. We discuss several applications of this purely geometric fact in problems of classical and quantum mechanics. 相似文献
6.
The semi‐iterative method (SIM) is applied to the hyper‐power (HP) iteration, and necessary and sufficient conditions are given for the convergence of the semi‐iterative–hyper‐power (SIM–HP) iteration. The root convergence rate is computed for both the HP and SIM–HP methods, and the quotient convergence rate is given for the HP iteration. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
7.
乌桕类可可脂结晶过程中表现体积变化 总被引:1,自引:0,他引:1
为了解乌桕类可可脂(CTCBE)缓冷结晶横向胀罐爆裂原因,研究CTCBE结晶过程中的膨胀特性,采用流体静力法测试了不同等温结晶条件下CTCBE结晶形成的表观密度和表观体积及其横纵向膨胀状况。结果表明,CTCBE缓冷结晶后形成外部和中部两个晶区。在5-25℃的各等温结晶范围内,当结晶温度增加时,外部结晶区域减小、表观密度变化不大;中部结晶区域增大、表观密度明显减小,CTCBE的表观体积、横向、纵向膨胀率均增大,膨胀横向大于纵向。进一步表明CTCBE在自然缓冷固化的表观体积根本上由其结晶温度决定。为有效防止横向胀罐,自然缓冷固化温度应低于10℃。 相似文献
8.
给出引理解决了方程非振动解与其各阶导数的符号关系,并由此得到了若干判别准则,用于判别三阶线性脉冲微分方程解的振动性与渐近性,举例说明了准则的有效性。本文推广了相关文献的结果。 相似文献
9.
V.I. Kushch I. Sevostianov L. Mishnaevsky Jr 《International Journal of Solids and Structures》2008,45(18-19):5103-5117
The paper addresses the problem of calculation of the local stress field and effective elastic properties of a unidirectional fiber reinforced composite with anisotropic constituents. For this aim, the representative unit cell approach has been utilized. The micro geometry of the composite is modeled by a periodic structure with a unit cell containing multiple circular fibers. The number of fibers is sufficient to account for the micro structure statistics of composite. A new method based on the multipole expansion technique is developed to obtain the exact series solution for the micro stress field. The method combines the principle of superposition, technique of complex potentials and some new results in the theory of special functions. A proper choice of potentials and new results for their series expansions allow one to reduce the boundary-value problem for the multiple-connected domain to an ordinary, well-posed set of linear algebraic equations. This reduction provides high numerical efficiency of the developed method. Exact expressions for the components of the effective stiffness tensor have been obtained by analytical averaging of the strain and stress fields. 相似文献
10.
We obtain exponential upper bounds for tails of distributions of generalized L-statistics based on a sample from an exponential distribution. We prove the asymptotic normality of generalized L-statistics based on a sample from the uniform distribution on [0,1] and of L-statistics with decomposed kernels (without any restrictions on the sample distribution type). 相似文献