全文获取类型
收费全文 | 4899篇 |
免费 | 554篇 |
国内免费 | 331篇 |
专业分类
化学 | 216篇 |
晶体学 | 1篇 |
力学 | 957篇 |
综合类 | 110篇 |
数学 | 3556篇 |
物理学 | 944篇 |
出版年
2024年 | 5篇 |
2023年 | 63篇 |
2022年 | 84篇 |
2021年 | 119篇 |
2020年 | 173篇 |
2019年 | 145篇 |
2018年 | 138篇 |
2017年 | 178篇 |
2016年 | 202篇 |
2015年 | 149篇 |
2014年 | 239篇 |
2013年 | 378篇 |
2012年 | 244篇 |
2011年 | 284篇 |
2010年 | 240篇 |
2009年 | 301篇 |
2008年 | 310篇 |
2007年 | 297篇 |
2006年 | 269篇 |
2005年 | 255篇 |
2004年 | 219篇 |
2003年 | 212篇 |
2002年 | 175篇 |
2001年 | 168篇 |
2000年 | 150篇 |
1999年 | 135篇 |
1998年 | 122篇 |
1997年 | 90篇 |
1996年 | 80篇 |
1995年 | 46篇 |
1994年 | 64篇 |
1993年 | 32篇 |
1992年 | 40篇 |
1991年 | 39篇 |
1990年 | 23篇 |
1989年 | 26篇 |
1988年 | 6篇 |
1987年 | 20篇 |
1986年 | 6篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 7篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1957年 | 1篇 |
1936年 | 3篇 |
排序方式: 共有5784条查询结果,搜索用时 15 毫秒
11.
We consider some Sobolev-type spaces and obtain a necessary and sufficient condition for their embedding in a Lebesgue space. 相似文献
12.
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
13.
Let
d−1{(x1,…,xd)
d:x21+···+x2d=1} be the unit sphere of the d-dimensional Euclidean space
d. For r>0, we denote by Brp (1p∞) the class of functions f on
d−1 representable in the formwhere dσ(y) denotes the usual Lebesgue measure on
d−1,
and Pλk(t) is the ultraspherical polynomial.For 1p,q∞, the Kolmogorov N-width of Brp in Lq(
d−1) is given bythe left-most infimum being taken over all N-dimensional subspaces XN of Lq(
d−1).The main result in this paper is that for r2(d−1)2,where ANBN means that there exists a positive constant C, independent of N, such that C−1ANBNCAN.This extends the well-known Kashin theorem on the asymptotic order of the Kolmogorov widths of the Sobolev class of the periodic functions. 相似文献
14.
考虑一个奇异摄动罗宾问题在Bakhvalov-Shishkin网格上的迎风差分策略,得到在改进的Shishkin网格上迎风策略是关于ε一致的一阶L∞模收敛的.数值实验证实了此理论结果,显示估计是稳健的. 相似文献
15.
In this paper, we use weighted modules ω(?)(f,t)w to study the pointwise approximation on Szasz-type operators, and obtain the direct and converse theorem, as well as characterizations of the pointwise approximation of Jacobi-weighted Szasz-type operators. 相似文献
16.
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
17.
18.
YaoKui ChenZhixiang 《分析论及其应用》2003,19(2):115-120
This paper gives the weighted Lp convergence rate estimations of the Gruenwald interpolatory polynomials based on the zeros of Chebyshev polymomials of the first kind,and proves that the order of the estimations is optimal for p≥1. 相似文献
19.
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
20.
Viviane Van Hoof Hugo Cluckers Vera Verhaeghe An Hennebel Marleen Truyens Edith Van Loock Pierre Rombouts Dirk Maes Jan Van Elven Katrien Lesage Mark Flothmann Lieve Nijs Filip Colpaert Werner Vercammen Dominique Bolain 《Accreditation and quality assurance》2004,10(1-2):55-59
In response to a change of the Belgian National Directives whereby hospital laboratories became responsible for all point-of-care testing (POCT) performed within hospital walls a standardized and automated POC glucose-testing system was implemented in our hospital. The system consists of 50 AccuCheck Inform instruments (Roche Diagnostics, Vilvoorde, Belgium), 50 docking stations, a DataCare Server, and connections to the medical laboratory information system (MOLIS, Sysmex, Barchon, Belgium) and to the hospital information system. Implementation involved many parties and extensive preparation and communication. Key issues were bar-coded patient and user identification, training, and responsibilities. One year after the hospital wide implementation of this system the quality of POC glucose testing has significantly increased, thereby improving patient safety. This study describes a stepwise change over involving the medical laboratory and with a focus on hands-on quality.Presented at the ninth conference on Quality in the Spotlight, 18–19 March 2004, Antwerp, Belgium. 相似文献