全文获取类型
收费全文 | 5089篇 |
免费 | 694篇 |
国内免费 | 298篇 |
专业分类
化学 | 924篇 |
晶体学 | 6篇 |
力学 | 295篇 |
综合类 | 66篇 |
数学 | 2598篇 |
物理学 | 2192篇 |
出版年
2023年 | 45篇 |
2022年 | 103篇 |
2021年 | 90篇 |
2020年 | 133篇 |
2019年 | 134篇 |
2018年 | 118篇 |
2017年 | 154篇 |
2016年 | 162篇 |
2015年 | 146篇 |
2014年 | 267篇 |
2013年 | 405篇 |
2012年 | 250篇 |
2011年 | 299篇 |
2010年 | 240篇 |
2009年 | 313篇 |
2008年 | 366篇 |
2007年 | 339篇 |
2006年 | 295篇 |
2005年 | 272篇 |
2004年 | 213篇 |
2003年 | 218篇 |
2002年 | 196篇 |
2001年 | 183篇 |
2000年 | 162篇 |
1999年 | 149篇 |
1998年 | 161篇 |
1997年 | 96篇 |
1996年 | 83篇 |
1995年 | 54篇 |
1994年 | 57篇 |
1993年 | 41篇 |
1992年 | 31篇 |
1991年 | 30篇 |
1990年 | 17篇 |
1989年 | 23篇 |
1988年 | 23篇 |
1987年 | 22篇 |
1986年 | 22篇 |
1985年 | 14篇 |
1984年 | 19篇 |
1983年 | 11篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1980年 | 17篇 |
1979年 | 19篇 |
1978年 | 20篇 |
1977年 | 10篇 |
1976年 | 6篇 |
1974年 | 7篇 |
1973年 | 9篇 |
排序方式: 共有6081条查询结果,搜索用时 31 毫秒
1.
2.
Recent Progress in the $L_p$ Theory for Elliptic and Parabolic Equations with Discontinuous Coefficients
下载免费PDF全文
![点击此处可从《分析论及其应用》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hongjie Dong 《分析论及其应用》2020,36(2):161-199
In this paper, we review some results over the last 10-15 years on elliptic and parabolic equations with discontinuous coefficients. We begin with an approach given by N. V. Krylov to parabolic equations in the whole space with $\rm{VMO}_x$ coefficients. We then discuss some subsequent development including elliptic and parabolic equations with coefficients which are allowed to be merely measurable in one or two space directions, weighted $L_p$estimates with Muckenhoupt ($A_p$) weights, non-local elliptic and parabolic equations, as well as fully nonlinear elliptic and parabolic equations. 相似文献
3.
4.
Gauss periods give an exponentiation algorithm that is fast for many finite fields but slow for many other fields. The current paper presents a different method for construction of elements that yield a fast exponentiation algorithm for finite fields where the Gauss period method is slow or does not work. The basic idea is to use elements of low multiplicative order and search for primitive elements that are binomial or trinomial of these elements. Computational experiments indicate that such primitive elements exist, and it is shown that they can be exponentiated fast. 相似文献
5.
Rakhim Aitbayev 《Numerical Methods for Partial Differential Equations》2006,22(4):847-866
Efficient multilevel preconditioners are developed and analyzed for the quadrature finite element Galerkin approximation of the biharmonic Dirichlet problem. The quadrature scheme is formulated using the Bogner–Fox–Schmit rectangular element and the product two‐point Gaussian quadrature. The proposed additive and multiplicative preconditioners are uniformly spectrally equivalent to the operator of the quadrature scheme. The preconditioners are implemented by optimal algorithms, and they are used to accelerate convergence of the preconditioned conjugate gradient method. Numerical results are presented demonstrating efficiency of the preconditioners. © 2005 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2006 相似文献
6.
最速下降规则不失为一可用规则 总被引:5,自引:4,他引:1
本从统计意义上平均迭代次数的观点出发,指出求解线性规划的最速下降规则是可取的,好用的。 相似文献
7.
陈泽乾 《数学物理学报(B辑英文版)》2002,22(3)
A new framework of Gaussian white noise calculus is established, in line with generalized expansion in [3, 4, 7]. A suitable frame of Fock expansion is presented on Gaussian generalized expansion functionals being introduced here, which provides the integral kernel operator decomposition of the second quantization of Koopman operators for chaotic dynamical systems, in terms of annihilation operators dt and its dual, creation operators t*. 相似文献
8.
非傍轴平顶高斯光束M2因子两种定义的比较研究 总被引:3,自引:2,他引:1
基于功率密度的二阶矩方法,推导出了非傍轴平顶高斯(FG)光束束宽和远场发散角的解析表达式·研究表明,当w0/λ→0时,远场发散角趋于渐近值θmax=63.435°,与阶数无关·使用非傍轴高斯光束代替傍轴高斯光束作为理想光束,研究了非傍轴FG光束的M2因子,并与传统定义的M2因子作了比较·在非傍轴范畴,非傍轴FG光束的M2因子不仅与阶数N有关,而且与w0/λ有关·按照定义,当w0/λ→0时,非傍轴FG光束的M2因子不等于0,对阶数N=1,2,3时,M2因子分别趋于0.913,0.882和0.886·当N→∞时,M2因子取最小值M2min=0.816· 相似文献
9.
非傍轴平顶高斯光束M2因子两种定义的比较研究 总被引:1,自引:1,他引:0
基于功率密度的二阶矩方法,推导出了非傍轴平顶高斯(FG)光束束宽和远场发散角的解析表达式.研究表明,当w0/λ→0时,远场发散角趋于渐近值θmax=63.435°,与阶数无关.使用非傍轴高斯光束代替傍轴高斯光束作为理想光束,研究了非傍轴FG光束的M2因子,并与传统定义的M2因子作了比较.在非傍轴范畴,非傍轴FG光束的M2因子不仅与阶数N有关,而且与w0/λ有关.按照定义,当w0/λ→0时,非傍轴FG光束的M2因子不等于0,对阶数N=1, 2, 3时,M2因子分别趋于0.913,0.882和0.886.当N→∞时,M2因子取最小值M2min=0.816. 相似文献
10.
Propagation of the Hermite–Gaussian beams through misaligned optical system with a circular aperture
By means of expanding a hard-edged aperture into a finite sum of complex Gaussian functions, the approximate analytical formula of one kind of higher-order Gaussian beams called the Hermite–Gaussian beams (HGBs) passing through circular apertured and misaligned optical system is obtained in this paper. The result provides more convenience for studying its propagation than the usual way by using diffraction integral directly. Some numerical simulations are also given for illustrating the propagation properties of the HGBs through the circular apertured optical systems. 相似文献