全文获取类型
收费全文 | 733篇 |
免费 | 22篇 |
国内免费 | 6篇 |
专业分类
化学 | 382篇 |
晶体学 | 7篇 |
力学 | 45篇 |
数学 | 162篇 |
物理学 | 165篇 |
出版年
2023年 | 4篇 |
2022年 | 18篇 |
2021年 | 18篇 |
2020年 | 28篇 |
2019年 | 22篇 |
2018年 | 29篇 |
2017年 | 18篇 |
2016年 | 31篇 |
2015年 | 18篇 |
2014年 | 23篇 |
2013年 | 65篇 |
2012年 | 48篇 |
2011年 | 50篇 |
2010年 | 37篇 |
2009年 | 37篇 |
2008年 | 31篇 |
2007年 | 28篇 |
2006年 | 26篇 |
2005年 | 18篇 |
2004年 | 23篇 |
2003年 | 19篇 |
2002年 | 9篇 |
2001年 | 10篇 |
2000年 | 6篇 |
1999年 | 10篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 12篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 8篇 |
1990年 | 8篇 |
1989年 | 9篇 |
1988年 | 9篇 |
1987年 | 9篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1967年 | 2篇 |
1956年 | 2篇 |
1955年 | 2篇 |
排序方式: 共有761条查询结果,搜索用时 15 毫秒
91.
n-Type indium antimonide-Au hybrid macro-structure was successfully fabricated on p-GaAs substrate by a simple and economic
flash evaporation technique. The elemental composition of the prepared InSb film was confirmed by energy dispersive X-ray
spectroscopy microanalysis (EDX). The surface topography and crystal structure of the InSb film was characterized by scanning
electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The magnetoresistance of the prepared hybrid macro-structure
was measured and discussed in terms of the model of current redistribution. 相似文献
92.
93.
Mansour Hashemi 《代数通讯》2018,46(9):4104-4119
94.
95.
Let K be a noncyclotomic CM field. We show that the field has a reciprocal unit-primitive element when K does. Also, we prove some related conditions that make the converse of this assertion true. 相似文献
96.
We count derangements, involutions and unimodal elements in the wreath product C
r
≀ S
n
by the numbers of excedances, fixed points and 2-cycles. Properties of the generating functions, including combinatorial
formulas, recurrence relations and real-rootedness are studied. The results obtained specialize to those on the symmetric
group S
n
and on the hyperoctahedral group B
n
when r = 1, 2, respectively. 相似文献
97.
Toufik Zaimi 《Archiv der Mathematik》2006,87(2):124-128
Let N be a positive rational integer and let P be the set of powers of a Salem number of degree d. We prove that for any α∈P the fractional parts of the numbers
, when n runs through the set of positive rational integers, are dense in the unit interval if and only if N≦ 2d − 4. We also show that for any α∈P the integer parts of the numbers αn are divisible by N for infinitely many n if and only if N≦ 2d − 3.
Received: 27 April 2005 相似文献
98.
99.
Noura Beji Bassem Jarboui Mansour Eddaly Habib Chabchoub 《Journal of computational science》2010,1(3):159-167
The Redundancy Allocation Problem generally involves the selection of components with multiple choices and redundancy levels that produce maximum system reliability given various system level constraints as cost and weight. In this paper we investigate the series–parallel redundant reliability problems, when a mixing of components was considered. In this type of problem both the number of redundancy components and the corresponding component reliability in each subsystem are to be decided simultaneously so as to maximise the reliability of system. A hybrid algorithm is based on particle swarm optimization and local search algorithm. In addition, we propose an adaptive penalty function which encourages our algorithm to explore within the feasible region and near feasible region, and discourage search beyond that threshold. The effectiveness of our proposed hybrid PSO algorithm is proved on numerous variations of three different problems and compared to Tabu Search and Multiple Weighted Objectives solutions. 相似文献
100.
M. B. A. Mansour 《Acta Appl Math》2010,109(3):939-947
This paper concerns with the traveling wave solutions of a nonlinear reaction-diffusion-advection model for describing the
spatiotemporal evolution of bacterial colony pattern. We use different methods for computing the traveling wave fronts of
the model equations. One of the methods involves the traveling wave equations. Numerical solutions of these equations as an
initial-value problem lead to accurate computations of the wave profiles and speeds. The second method is to construct the
time-dependent solutions by solving an initial-moving boundary-value problem for the PDE system, showing an approximation
for such wave fronts, in particular, the minimum speed traveling wave. 相似文献