全文获取类型
收费全文 | 6965篇 |
免费 | 505篇 |
国内免费 | 605篇 |
专业分类
化学 | 117篇 |
晶体学 | 1篇 |
力学 | 298篇 |
综合类 | 168篇 |
数学 | 7272篇 |
物理学 | 219篇 |
出版年
2024年 | 6篇 |
2023年 | 63篇 |
2022年 | 61篇 |
2021年 | 100篇 |
2020年 | 147篇 |
2019年 | 172篇 |
2018年 | 174篇 |
2017年 | 200篇 |
2016年 | 208篇 |
2015年 | 128篇 |
2014年 | 281篇 |
2013年 | 547篇 |
2012年 | 310篇 |
2011年 | 355篇 |
2010年 | 288篇 |
2009年 | 427篇 |
2008年 | 399篇 |
2007年 | 441篇 |
2006年 | 382篇 |
2005年 | 334篇 |
2004年 | 289篇 |
2003年 | 280篇 |
2002年 | 302篇 |
2001年 | 288篇 |
2000年 | 285篇 |
1999年 | 250篇 |
1998年 | 221篇 |
1997年 | 203篇 |
1996年 | 154篇 |
1995年 | 116篇 |
1994年 | 97篇 |
1993年 | 79篇 |
1992年 | 51篇 |
1991年 | 49篇 |
1990年 | 53篇 |
1989年 | 27篇 |
1988年 | 22篇 |
1987年 | 26篇 |
1986年 | 27篇 |
1985年 | 32篇 |
1984年 | 30篇 |
1983年 | 16篇 |
1982年 | 32篇 |
1981年 | 24篇 |
1980年 | 18篇 |
1979年 | 18篇 |
1978年 | 21篇 |
1977年 | 15篇 |
1976年 | 12篇 |
1975年 | 4篇 |
排序方式: 共有8075条查询结果,搜索用时 124 毫秒
51.
求解非线性方程的一个新方法 总被引:2,自引:0,他引:2
张艺 《宁波大学学报(理工版)》2002,15(3):55-57
提出了一种求解非线性方程的数值方法,此方法不需要导数的计算,其收敛阶与抛物线法相同,但计算量要比抛物线法小得多。 相似文献
52.
Jian‐guo Tang 《Mathematical Methods in the Applied Sciences》2006,29(11):1327-1338
An implicit iterative method is applied to solving linear ill‐posed problems with perturbed operators. It is proved that the optimal convergence rate can be obtained after choosing suitable number of iterations. A generalized Morozov's discrepancy principle is proposed for the problems, and then the optimal convergence rate can also be obtained by an a posteriori strategy. The convergence results show that the algorithm is a robust regularization method. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
53.
54.
Recently, molecular imaging has been rapidly developed to studyphysiological and pathological processes in vivo at the cellularand molecular levels. Among molecular imaging modalities, opticalimaging has attracted a major attention for its unique advantages.In this paper, we establish a mathematical framework for multispectralbioluminescence tomography (BLT) that allows simultaneous studiesof multiple optical reporters. We show solution existence, uniquenessand continuous dependence on data as well as the limiting behaviourswhen the regularization parameter approaches zero or when thepenalty parameter approaches infinity. Then, we propose twonumerical schemes for multispectral BLT and derive error estimatesfor the corresponding solutions. 相似文献
55.
A. A. Maleev 《Computational Mathematics and Mathematical Physics》2006,46(12):2031-2039
Stationary and nonstationary Jacobi-like iterative processes for solving systems of linear algebraic equations are examined. For a system whose coefficient matrix A is an H-matrix, it is shown that the convergence rate of any Jacobi-like process is at least as high as that of the point Jacobi method as applied to a system with 〈A〉 as the coefficient matrix, where 〈A〉 is a comparison matrix of A. 相似文献
56.
A quasilinearization method for a class of integro-differential equations with mixed nonlinearities 总被引:2,自引:1,他引:1
We develop an extended form of the quasilinearization method for an initial value problem involving a nonlinear integro-differential equation with mixed nonlinearities, occurring in distributed-infective and distributed-contact models. In fact, a monotone sequence of iterates converging uniformly and quadratically to a solution of the problem is obtained. Some interesting observations are presented. 相似文献
57.
赵丽琴 《数学物理学报(B辑英文版)》2007,(2)
In this article, the author studies the boundedness and convergence for the non-Lienard type differential equation (x|·)=a(y)-f(x) (y|·)=b(y)β(x)-g(x) e(t) where a(y),b(y),f(x),g(x),β(x) are real continuous functions in y∈R or x∈R,β(x)≥0 for all x and e(t) is a real continuous function on R = {t: t≥0} such that the equation has a unique solution for the initial value problem. The necessary and sufficient conditions are obtained and some of the results in the literatures are improved and extended. 相似文献
58.
本文对几种模糊传递关系进行比较 ,从一个侧面说明了用于构造偏好关系的模糊关系应是互逆关系 .文中证明了对任意的 n阶互逆传递模糊关系 R,必有 Rn=Rn+1 . 相似文献
60.
The theory of monotone semiflows has been widely applied to functional differential equations (FDEs). The studies on the theory and applications of monotone semiflows for FDEs are very important and interesting. A brief des-cription of our recent works are as follows.By using general monotone semiflow theory, several results of positively invariant sets, monotone solutions and contracting rectangles of retarded functional differential equations(RFDEs) with infinite delay are gained under the assumption of quasimonotonicity; sufficient conditions for the existence, un-iqueness and global attractivity of periodic solutions are also established by combining the theory of monotone semiflows for neutral functional differential equations(NFDEs) and Krasnoselskii's fixed point theorem. 相似文献