全文获取类型
收费全文 | 6093篇 |
免费 | 319篇 |
国内免费 | 153篇 |
专业分类
化学 | 1646篇 |
晶体学 | 3篇 |
力学 | 940篇 |
综合类 | 69篇 |
数学 | 2481篇 |
物理学 | 1426篇 |
出版年
2024年 | 6篇 |
2023年 | 102篇 |
2022年 | 274篇 |
2021年 | 276篇 |
2020年 | 388篇 |
2019年 | 299篇 |
2018年 | 256篇 |
2017年 | 263篇 |
2016年 | 311篇 |
2015年 | 252篇 |
2014年 | 284篇 |
2013年 | 378篇 |
2012年 | 229篇 |
2011年 | 294篇 |
2010年 | 218篇 |
2009年 | 269篇 |
2008年 | 246篇 |
2007年 | 277篇 |
2006年 | 242篇 |
2005年 | 241篇 |
2004年 | 219篇 |
2003年 | 199篇 |
2002年 | 155篇 |
2001年 | 143篇 |
2000年 | 113篇 |
1999年 | 103篇 |
1998年 | 111篇 |
1997年 | 67篇 |
1996年 | 63篇 |
1995年 | 29篇 |
1994年 | 51篇 |
1993年 | 26篇 |
1992年 | 30篇 |
1991年 | 29篇 |
1990年 | 15篇 |
1989年 | 16篇 |
1988年 | 4篇 |
1987年 | 9篇 |
1986年 | 33篇 |
1985年 | 9篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1980年 | 2篇 |
1979年 | 13篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1957年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有6565条查询结果,搜索用时 15 毫秒
1.
2.
本文以一道题为例对研究性教学中的习题环节进行了实例研究.大致按照事件发生的顺序叙述以再现现场情景. 相似文献
3.
Josep Maria Izquierdo 《TOP》2006,14(2):375-398
The paper introduces a refinement of the notion of population monotonic allocation scheme, called regular population monotonic
allocation scheme (regularpmas). This refinement is based on economic situations in which players may have to select new partners from a set of potential
players and in which there exist certain capacity constraints. A sufficient condition for the existence of a regularpmas is given. For the class of games with regularpmas, we prove that the core coincides with the Davis and Maschler and the Mas-Colell bargaining sets. 相似文献
4.
An implicit quasi-monotone second-order accurate method is proposed for analyzing the spiral Couette flow of a rarefied gas between coaxial cylinders. The basic advantages of the method over the conventional method of stationry iterations are that the former is conservative with respect to the collision integral, has a simple software implementation for any types of boundary conditions, and applies to a wide range of Knudsen numbers. 相似文献
5.
ZHANG LUMING 《应用数学学报》2005,(1)
本文首先分析线性Schrodinger方程一种高阶差分格式的构造方法,得到方程的耗散项.在此基础上对三次非线性Schrodinger方程,提出了一种精度为O(r2 h2)的差分格式,证明了该格式保持了连续方程的两个守恒量,且是收敛的与稳定的.并通过数值例子与已有隐格式进行了比较,结果表明,本文格式在计算量类似的情况下,提高了数值精度. 相似文献
6.
A parallel DSMC method based on a cell‐based data structure is developed for the efficient simulation of rarefied gas flows on PC‐clusters. Parallel computation is made by decomposing the computational domain into several subdomains. Dynamic load balancing between processors is achieved based on the number of simulation particles and the number of cells allocated in each subdomain. Adjustment of cell size is also made through mesh adaptation for the improvement of solution accuracy and the efficient usage of meshes. Applications were made for a two‐dimensional supersonic leading‐edge flow, the axi‐symmetric Rothe's nozzle, and the open hollow cylinder flare flow for validation. It was found that the present method is an efficient tool for the simulation of rarefied gas flows on PC‐based parallel machines. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
7.
In this paper, a generalized anti–maximum principle for the second order differential operator with potentials is proved. As an application, we will give a monotone iterative scheme for periodic solutions of nonlinear second order equations. Such a scheme involves the Lp norms of the growth, 1 ≤ p ≤ ∞, while the usual one is just the case p = ∞. 相似文献
8.
We consider a splitting finite-difference scheme for an initial-boundary value problem for a two-dimensional nonlinear evolutionary
equation. The problem is split into nonlinear and linear parts. The linear part is also split into locally one-dimensional
equations. We prove the convergence and stability of the scheme in L
2 and C norms.
Printed in Lietuvos Matematikos Rinkinys, Vol. 45, No. 3, pp. 413–434, July–September, 2005. 相似文献
9.
In this paper we consider the (t, n)-threshold visual secret sharing scheme (VSSS) in which black pixels in a secret black-white images is reproduced perfectly
as black pixels when we stack arbitrary t shares. This paper provides a new characterization of the (t, n)-threshold visual secret sharing scheme with such a property (hereafter, we call such a VSSS the (t, n)-PBVSSS for short). We use an algebraic method to characterize basis matrices of the (t, n)-PBVSSS in a certain class of matrices. We show that the set of all homogeneous polynomials each element of which yields
basis matrices of the (t, n)-PBVSSS becomes a set of lattice points in an (n−t+1)-dimensional linear space. In addition, we prove that the optimal basis matrices in the sense of maximizing the relative
difference among all the basis matrices in the class coincides with the basis matrices given by Blundo, Bonis and De Santis
[3] for all n≥ t ≥ 2. 相似文献
10.
抓好数学建模竞赛 推动数学教学改革 总被引:5,自引:0,他引:5
本文通过近几年组织数学建模教学和指导学生参加竞赛的实践 ,探索抓好数学建模竞赛 ,促进数学教学改革 ,推动数学素质教育 ,提高人才培养质量的途径、措施和方法 相似文献