全文获取类型
收费全文 | 885篇 |
免费 | 27篇 |
国内免费 | 4篇 |
专业分类
化学 | 716篇 |
晶体学 | 7篇 |
力学 | 1篇 |
数学 | 60篇 |
物理学 | 87篇 |
无线电 | 45篇 |
出版年
2024年 | 1篇 |
2023年 | 14篇 |
2022年 | 86篇 |
2021年 | 97篇 |
2020年 | 38篇 |
2019年 | 29篇 |
2018年 | 29篇 |
2017年 | 31篇 |
2016年 | 36篇 |
2015年 | 31篇 |
2014年 | 36篇 |
2013年 | 66篇 |
2012年 | 44篇 |
2011年 | 65篇 |
2010年 | 28篇 |
2009年 | 42篇 |
2008年 | 52篇 |
2007年 | 39篇 |
2006年 | 33篇 |
2005年 | 28篇 |
2004年 | 22篇 |
2003年 | 8篇 |
2002年 | 9篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1991年 | 6篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1978年 | 2篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1966年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有916条查询结果,搜索用时 0 毫秒
21.
22.
23.
24.
25.
Physical, enzymatic and chemical methods were used to develop an efficient procedure for preparing gelatine hydrogels of appropriate strength and elastic properties for applications as enzyme carriers. The concentrations of the crosslinking enzyme (transglutaminase), the initial amount of gelatine, the production time and the effect of additional crosslinking with glutaraldehyde were examined. As a result, the following conditions were selected: 0.1 g cm?3 solution of gelatine, 0.01 g cm?3 of transglutaminase (mTGase), a minimum of 2 h incubation at 4°C and an additional step of crosslinking with 1.0 vol. % of glutaraldehyde. Next, the absorption properties and storage stability of hydrogels so obtained were determined. From these results, it was observed that, with the exception of the physical gel, the remaining materials presented a relatively high resistance to hydrolytic degradation and retained their original spatial structure without any visible damages. The immobilisation experiments indicated gelatine-based hydrogels crosslinked with transglutaminase as suitable for use as matrices for the entrapment of enzymes, which catalyse the conversion of low-molecular mass compounds. In addition to the potential for effective re-use in subsequent batch processes, the essential advantage of the immobilised β-galactosidase obtained in the current study is a marked reduction in its volume under storage conditions of long duration, without any significant decline in catalytic activity. 相似文献
26.
The surface activity and aggregation behaviour of two Quillaja bark saponins (QBS) are compared using surface tension, conductometry and light scattering. Despite formally of the same origin (bark of the Quillaja saponaria Molina tree), the two QBS show markedly different ionic characters and critical micelle concentrations (7.7 · 10− 6 mol·dm− 3 and 1.2 · 10− 4 mol·dm− 3). The new interpretation of the surface tension isotherms for both QBS allowed us to propose an explanation for the previous discrepancy concerning the orientation of the saponin molecules in the adsorbed layer. 相似文献
27.
28.
Roman P. Pogorilyi Inna V. Melnyk Yuriy L. Zub Guliam A. Seisenbaeva Vadim G. Kessler Mykola M. Shcherbatyik Aljoša Košak Aleksandra Lobnik 《Journal of Sol-Gel Science and Technology》2013,68(3):447-454
The surface of magnetite nanoparticles was coated with functional polysiloxane layers using reaction of hydrolytic copolycondensation of tetraethoxysilane and 3-aminopropyltriethoxysilane (or N-[3-trimethoxysilylpropyl]ethylendiamine), and also that of tetraethoxysilane, 3-aminopropyltriethoxysilane and methyltriethoxysilane (or n-propyltriethoxysilane). It was shown that these functionalized magnetically controllable particles (about 60–150 nm in size as aggregates), as opposed to magnetite, adsorb urease well from aqueous solutions (up to 1 g/g), and that the level of residual activity of adsorbed layers is up to 84 % in the case of a bifunctional sample. It was established that the activity of immobilized urease is normally gradually reduced during storage of the samples, but in the case of ethylenediamine functional group is not decreased for 45 days. The synthesized samples are promising for use as magnetically directed biocatalysts. 相似文献
29.
Aleksandra A. Chaikovskaya Radomir V. Smaliy Tamara N. Kudrya Aleksander A. Yurchenko Andrew A. Tolmachev 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1)
Abstract Isocyanatophosphoric acid dichlondes was used for introduction of phosphorus-containing groups at electron-excess heterocycles. Hetaryl containing dichlorophosphates, convenient starting material for synthesis for wide set of derivatives, were prepared by C-acylation with this reagent. 相似文献
30.
Dušan Barać Vanjica Ratković-Živanović Marijana Despotović-Zrakić Aleksandra Labus Zorica Bogdanović 《Telematics and Informatics》2017,34(1):20-29
This paper examines the possibilities of enhancing relationship management between public service broadcasters and their stakeholders by harnessing the potential of newest e-business technologies and concepts, such as: social media, digital and interactive TV, and mobile computing. In order to facilitate adoption of relationship management strategy, a framework for leveraging relationship management is proposed. Evaluation was performed within the e-business system of a public broadcaster. This empirical study explored the readiness and expected benefits of relationship management implementation. The research results have indicated that a public broadcaster could achieve a higher level of social responsibility, improve business sustainability, and empower communication and collaboration with all the stakeholders by using emerging technologies for relationship management activities. 相似文献