全文获取类型
收费全文 | 3362篇 |
免费 | 134篇 |
国内免费 | 53篇 |
专业分类
化学 | 2027篇 |
晶体学 | 46篇 |
力学 | 103篇 |
数学 | 605篇 |
物理学 | 768篇 |
出版年
2023年 | 25篇 |
2022年 | 38篇 |
2021年 | 58篇 |
2020年 | 65篇 |
2019年 | 60篇 |
2018年 | 41篇 |
2017年 | 43篇 |
2016年 | 90篇 |
2015年 | 75篇 |
2014年 | 101篇 |
2013年 | 180篇 |
2012年 | 226篇 |
2011年 | 255篇 |
2010年 | 137篇 |
2009年 | 131篇 |
2008年 | 220篇 |
2007年 | 175篇 |
2006年 | 170篇 |
2005年 | 144篇 |
2004年 | 145篇 |
2003年 | 126篇 |
2002年 | 110篇 |
2001年 | 67篇 |
2000年 | 73篇 |
1999年 | 59篇 |
1998年 | 27篇 |
1997年 | 48篇 |
1996年 | 39篇 |
1995年 | 49篇 |
1994年 | 52篇 |
1993年 | 53篇 |
1992年 | 57篇 |
1991年 | 42篇 |
1990年 | 38篇 |
1989年 | 32篇 |
1988年 | 23篇 |
1987年 | 18篇 |
1986年 | 21篇 |
1985年 | 32篇 |
1984年 | 31篇 |
1982年 | 15篇 |
1981年 | 17篇 |
1980年 | 15篇 |
1979年 | 21篇 |
1978年 | 18篇 |
1977年 | 9篇 |
1976年 | 11篇 |
1975年 | 11篇 |
1974年 | 15篇 |
1973年 | 10篇 |
排序方式: 共有3549条查询结果,搜索用时 0 毫秒
11.
Conventionally, surface roughness is predominantly determined through the use of stylus instruments. However, there are certain limitations involved in the method, particularly when a test specimen, such as a silicon wafer, has a smooth mirror-like surface. Hence, it is necessary to explore alternative non-contact techniques. Light scattering has recently been gaining popularity as an optical technique to provide prompt and precise inspection of surface roughness. In this paper, the total integrated scattering (TIS) model is modified to retrieve parameters on surface micro-topography through light scattering. The applicability of the proposed modified TIS model is studied and compared with an atomic force microscope. Experimental results obtained show that the proposed technique is highly accurate for measuring surface roughness in the nanometer range. 相似文献
12.
Positron-Lithium Atom and Electron-Lithium Atom Scattering Systems at Intermediate and High Energies 下载免费PDF全文
K. Ratnavelu S. Y. Ng 《中国物理快报》2006,23(7):1753-1756
The coupled-channel optical method is used to study positron scattering by atomic lithium at energies ranging from the ionization threshold to 60eV, The present method simultaneously treats the target channels and the positronium (Ps) channels in the coupled-channel method together with the continuum effects via an ab-initio optical potential. Ionization, elastic and inelastic cross sections in target channels, and the total cross section are also reported and compared with other theoretical and experimental data. A comparative study with the corresponding electron-lithium data is also reported. 相似文献
13.
In 1987 the Canadian Department of National Defence enunciated the Total Force concept. The Total Force is comprised of Regular and Reserve components. The intention is to make maximum use of the Reserve to reduce defence expenditures and at the same time to ensure that military capability remains adequate to support national policy objectives. This paper discusses some of the governing parameters that affect the modelling of the composition of the Total Force and analyses the mix of regular and reserve forces. The interplay between the key factors and their marginal costs will be stressed. The models are employed to study two units in the Canadian Forces, a maintenance support unit and a tactical unit with high operational activity cost. The lessons drawn from these studies are highlighted. 相似文献
14.
Fa‐Yan Meng Xu‐Qing Liu Seik Weng Ng 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(7):m341-m342
The terephthalate dianion and the bis(imidazolyl)benzene ligand of the title compound, {[Zn(C8H4O4)(C20H14N4)]·C2H6O}n, each bridges two adjacent zinc centers, resulting in a layer‐type coordination polymer; the zinc center shows tetrahedral coordination. The disordered ethanol solvent molecules occupy the spaces between the layers and are hydrogen bonded to the layers. The two symmetry‐independent dianions lie on different inversion sites. 相似文献
15.
Chi-Keung Ng 《Proceedings of the American Mathematical Society》1998,126(12):3767-3768
We show that the Morita equivalence part of Mansfield's Imprimitivity Theory can be obtained by Green's Imprimitivity Theorem (and duality theory).
16.
17.
18.
19.
20.