全文获取类型
收费全文 | 4670篇 |
免费 | 358篇 |
国内免费 | 368篇 |
专业分类
化学 | 235篇 |
晶体学 | 6篇 |
力学 | 425篇 |
综合类 | 61篇 |
数学 | 4070篇 |
物理学 | 599篇 |
出版年
2024年 | 7篇 |
2023年 | 54篇 |
2022年 | 66篇 |
2021年 | 66篇 |
2020年 | 131篇 |
2019年 | 108篇 |
2018年 | 101篇 |
2017年 | 118篇 |
2016年 | 117篇 |
2015年 | 112篇 |
2014年 | 219篇 |
2013年 | 401篇 |
2012年 | 172篇 |
2011年 | 231篇 |
2010年 | 203篇 |
2009年 | 304篇 |
2008年 | 325篇 |
2007年 | 312篇 |
2006年 | 306篇 |
2005年 | 260篇 |
2004年 | 215篇 |
2003年 | 225篇 |
2002年 | 200篇 |
2001年 | 157篇 |
2000年 | 175篇 |
1999年 | 131篇 |
1998年 | 147篇 |
1997年 | 117篇 |
1996年 | 80篇 |
1995年 | 59篇 |
1994年 | 49篇 |
1993年 | 28篇 |
1992年 | 29篇 |
1991年 | 34篇 |
1990年 | 18篇 |
1989年 | 15篇 |
1988年 | 6篇 |
1987年 | 12篇 |
1986年 | 4篇 |
1985年 | 14篇 |
1984年 | 17篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1981年 | 11篇 |
1980年 | 10篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 2篇 |
1974年 | 2篇 |
排序方式: 共有5396条查询结果,搜索用时 15 毫秒
1.
2.
Lu Chuanrong 《数学年刊B辑(英文版)》1997,18(1):71-78
Let $\{\xi_{\bold t}, {\bold t}
\in {\bold Z}^d\}$ be a nonuniform $\varphi$-mixing strictly stationary
real random field with
$E\xi_{\bold 0}=0, E|\xi_{\bold 0}|^{2+\delta}<\infty$ for some
$0<\delta<1$. A sufficient
condition is given for the sequence of partial sum set-indexed process
$\{Z_n(A),\ A\in \Cal A\}$ to converge to Brownian motion. By a direct
calculation, the author shows
that the result holds for a more general class of set index ${\Cal A}$, where
${\Cal A}$ is assumed only to have the metric entropy exponent $r, 0相似文献
3.
对由一类非线性抛物型变分不等方程所描述的无穷维动力系统,给出了存在全局吸引子及弱近似惯性流形的充分条件. 相似文献
4.
Summary This paper is concerned with the problem of developing numerical integration algorithms for differential equations that, when
viewed as equations in some Euclidean space, naturally evolve on some embedded submanifold. It is desired to construct algorithms
whose iterates also evolve on the same manifold. These algorithms can therefore be viewed as integrating ordinary differential
equations on manifolds. The basic method “decouples” the computation of flows on the submanifold from the numerical integration
process. It is shown that two classes of single-step and multistep algorithms can be posed and analyzed theoretically, using
the concept of “freezing” the coefficients of differential operators obtained from the defining vector field. Explicit third-order
algorithms are derived, with additional equations augmenting those of their classical counterparts, obtained from “obstructions”
defined by nonvanishing Lie brackets. 相似文献
5.
WANG Libin 《数学年刊B辑(英文版)》2002,23(4):439-454
The author gets a blow-up result of C1 solution to the Cauchy problem for a first order quasilinear non-strictly hyperbolic system in one space dimension. 相似文献
6.
7.
非光滑非凸多目标规划解的充分条件 总被引:4,自引:0,他引:4
Kuhn-Tucker型条件的充分性一直是最优化理论中引人注意的一个问题.本文对非光滑函数提出了几个非凸概念,然后,讨论了非光滑非凸多目标规划中Kuhn-Tucker型条件和Fritz John型条件的充分性,在很弱的条件下,建立了一系列充分条件. 相似文献
8.
S. K. Godunov V. T. Zhukov O. B. Feodoritova 《Computational Mathematics and Mathematical Physics》2006,46(6):971-982
An algorithm is constructed for calculating invariant subspaces of symmetric hyperbolic systems arising in electromagnetic, acoustic, and elasticity problems. Discrete approximations are calculated for subspaces that correspond to minimal eigenvalues and smooth eigenfunctions. Difficulties related to the presence of an infinite-dimensional kernel in the differential operator are successfully handled. The efficiency of the algorithm is demonstrated using acoustics equations. 相似文献
9.
ON THE UNIQUENESS OF THE WEAK SOLUTIONS OF A QUASILINEAR HYPERBOLIC SYSTEM WITH A SINGULAR SOURCE TERM
下载免费PDF全文
![点击此处可从《数学年刊B辑(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper is a continuation of the authors'previous paper[1].In this paper the authorsprove,assuming additional conditions on the initial data,some results about the existence anduniqueness of the entropy weak solutions of the Cauchy problem for the singular hyperbolicsystem a_t+(au)_x_2au/x=0,u_t+1/2(a~2+u~2)_x=0,x>0,t≥0. 相似文献
10.
ON HYPERBOLIC TIME DISCOUNTING IN EXHAUSTIBLE RESOURCE MODELS: AN APPLICATION TO WORLD OIL RESOURCES
JOHN ROWSE 《Natural Resource Modeling》2006,19(2):243-277
ABSTRACT. Recent research on discounting in long term economic models involves hyperbolic discounting, in which the marginal discount rate shrinks as time passes. To investigate hyperbolic discounting and exhaustible resource allocation, this work develops a discrete‐time world oil model and model solution procedure, then uses the model to examine the consequences of adopting conventional (constant annual) discounting when hyperbolic discounting is appropriate, of adopting one hyperbolic discount rate path when a different hyperbolic path is appropriate, and of adopting hyperbolic discounting when conventional discounting is appropriate. Five conventional and two hyperbolic discount rate paths are considered. One hyperbolic path is that used by Nordhaus and Boyer [2000]; the other is that recommended by Weitzman [2001]. The generality of the findings is also assessed. 相似文献