全文获取类型
收费全文 | 832篇 |
免费 | 122篇 |
国内免费 | 40篇 |
专业分类
化学 | 346篇 |
晶体学 | 3篇 |
力学 | 90篇 |
综合类 | 7篇 |
数学 | 48篇 |
物理学 | 500篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 11篇 |
2020年 | 15篇 |
2019年 | 8篇 |
2018年 | 11篇 |
2017年 | 20篇 |
2016年 | 18篇 |
2015年 | 15篇 |
2014年 | 26篇 |
2013年 | 55篇 |
2012年 | 21篇 |
2011年 | 63篇 |
2010年 | 47篇 |
2009年 | 47篇 |
2008年 | 67篇 |
2007年 | 60篇 |
2006年 | 65篇 |
2005年 | 43篇 |
2004年 | 32篇 |
2003年 | 38篇 |
2002年 | 29篇 |
2001年 | 39篇 |
2000年 | 23篇 |
1999年 | 32篇 |
1998年 | 27篇 |
1997年 | 30篇 |
1996年 | 22篇 |
1995年 | 16篇 |
1994年 | 21篇 |
1993年 | 18篇 |
1992年 | 10篇 |
1991年 | 4篇 |
1990年 | 13篇 |
1989年 | 10篇 |
1988年 | 1篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1980年 | 1篇 |
排序方式: 共有994条查询结果,搜索用时 15 毫秒
111.
The stability characteristics of an ultra-thin layer of a viscous liquid flowing down a cylindrical fibre are investigated by a linear theory. The film with the thickness less than 100 nm is driven by an external force and under the influence of the van der Waals forces. The results show that, when the relative film thickness decreases, the curvature of the fibre depresses the development of the linear perturbations, whereas the van der Waals forces promote the instabilities. This competition results in a non-monotonous dependence of the growth rate on the relative film thickness. The critical curves are also obtained to describe the transition from the absolute instability to the convective instability, indicating that the van der Waals forces can enlarge the absolutely unstable region. Furthermore, the surface tension can cause the development of the absolute instability, whereas the external force has an opposite effect. 相似文献
112.
113.
《Composite Interfaces》2013,20(8):529-541
Glycidoxypropyltrimethoxysilane (GPS) and γ-aminopropyltrimethoxysilane (APS) were used to modify the surface chemistry of polyamide fibre. The surface chemistry was characterised using X-ray photoelectron spectroscopy. The silanol functional group was designed to be introduced on the surface of polyamide fibre to increase its chemical activity by N-alkylation of GPS and hydrolysis of APS, and to improve the poor interfacial adhesion between a polyamide 66 fibre and an aqueous polyurethane polymer adhesive. The microbond test was used to measure the interfacial shear strength between the waterborne PU adhesive and the polyamide fibre. It has been found that APS hydrolysis and GPS-alkylated fibre surface can be used to improve the interfacial adhesion of polyamide fibre to PU. The IFSS can be improved by N-alkylation of GPS from 5.0 to 8.4?MPa. After water immersion at 50?°C for 48?h, then drying, the IFSS increased to 8.8?MPa due to the plasticisation of PU in water. Better interfacial adhesion was also observed by the hydrolysis of APS, but not significantly improved by this method due to the relatively weak hydrogen bond at the interface between APS and polyamide fibre. 相似文献
114.
《Composite Interfaces》2013,20(2):101-119
The interphase in polyethylene fibre/epoxy matrix composites is studied with FT-IR microspectroscopy using a set-up to investigate the matrix as close to the fibre as a few μm or less. It is shown that moisture present on the fibre surface is able to influence the polymerization reaction of the epoxy/anhydride matrix in an irreversible manner. This effect is enhanced for composites from the more hydrophilic polyvinylalcohol fibre. The fibre/matrix interaction in these thermoplastic fibre composites is also studied with DSC through the characterization of the fibre melting. A decreased 'DSC interaction parameter' is found if the composition of the interphase is changed by moisture. For a composite with an epoxy/amine matrix, on the other hand, the DSC interaction parameter is unaffected by moisture from the fibre surface. 相似文献
115.
116.
Markus Schlicht 《Annals of Global Analysis and Geometry》1995,13(1):19-22
In this paper we relate the group of automorphisms of a principal fibre bundle with the (second) Bianchi identity generalizing a result of Kazdan.During the preparation of this paper the author was supported by a fellowship of theGraduiertenkolleg Geometrie und Mathematische Physik at the Ruhr-Universität Bochum. 相似文献
117.
118.
This paper explored the technical feasibility of surgical calcium alginate stanch fibre steriliged by radiation. By detecting the biological load before and after irridiation the optimum sterilized dose is 10–12KGY. By determing the Ca++ content, a linear regression equation relative to adsorbed dose and Ca++ content percentage is given out. lgD=0.13449+7.966x10-3N(r=0.9935) The result of biological studies of radio sterilized stanch fibre to be applied on adult rabbits and NIH mice by biologic test was performed that the γ-ray sterilized stanchfibre had no irritant effect on both the health and the wound skin, crust formation rate was better than of the check. The total and partial irritation intensity and the allergization rate became zero. 相似文献
119.
The process of casting occupies an important place in the metallurgical industry, and the entire world of the metal user. In the past, the ingot casting–rolling (slabbing, blooming, or billeting) process was commonly used. The continuous casting process has largely replaced this earlier method because of the inherent advantages of energy savings, enhanced productivity, higher yield and reduced costs. However, continuous casting process is not without of its problems. Considerable effort has been made by many researches to establish adequate design, operation and maintenance of continuous casting machine to ensure metallurgical quality of the final product. One of the most severe defects in continuous casting products is concerned with the cracks provoked by improper design of the spray cooling system. The aim of this work is to develop a two dimensional heat transfer model based on the finite difference method in order to calculate the strand temperatures and the solid shell profile along the machine. An Artificial Intelligence heuristic search procedure interacts with the numerical model to determine the improved cooling conditions for the sprays zones of a real continuous caster for the production of quality billets. 相似文献
120.