全文获取类型
收费全文 | 98224篇 |
免费 | 1116篇 |
国内免费 | 270篇 |
专业分类
化学 | 55218篇 |
晶体学 | 1535篇 |
力学 | 3807篇 |
综合类 | 2篇 |
数学 | 11560篇 |
物理学 | 27488篇 |
出版年
2022年 | 921篇 |
2021年 | 1194篇 |
2020年 | 1262篇 |
2019年 | 1406篇 |
2018年 | 1858篇 |
2017年 | 1917篇 |
2016年 | 2713篇 |
2015年 | 1481篇 |
2014年 | 2221篇 |
2013年 | 4330篇 |
2012年 | 4032篇 |
2011年 | 4562篇 |
2010年 | 3385篇 |
2009年 | 3324篇 |
2008年 | 4165篇 |
2007年 | 4022篇 |
2006年 | 3879篇 |
2005年 | 3433篇 |
2004年 | 3118篇 |
2003年 | 2763篇 |
2002年 | 2887篇 |
2001年 | 2463篇 |
2000年 | 1836篇 |
1999年 | 1456篇 |
1998年 | 1336篇 |
1997年 | 1283篇 |
1996年 | 1194篇 |
1995年 | 1021篇 |
1994年 | 1018篇 |
1993年 | 991篇 |
1992年 | 1065篇 |
1991年 | 1088篇 |
1990年 | 1061篇 |
1989年 | 1064篇 |
1988年 | 966篇 |
1987年 | 900篇 |
1986年 | 867篇 |
1985年 | 1085篇 |
1984年 | 1209篇 |
1983年 | 1003篇 |
1982年 | 1102篇 |
1981年 | 969篇 |
1980年 | 904篇 |
1979年 | 953篇 |
1978年 | 1066篇 |
1977年 | 1076篇 |
1976年 | 969篇 |
1975年 | 911篇 |
1974年 | 954篇 |
1973年 | 901篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
21.
22.
23.
Dr. Antonio M. Rodríguez Dr. Pilar Prieto Prof. Antonio de la Hoz Prof. Ángel Díaz-Ortiz D. Raúl Martín Prof. José I. García 《ChemistryOpen》2015,4(3):308-317
The aim of this work was to determine the parameters that have decisive roles in microwave-assisted reactions and to develop a model, using computational chemistry, to predict a priori the type of reactions that can be improved under microwaves. For this purpose, a computational study was carried out on a variety of reactions, which have been reported to be improved under microwave irradiation. This comprises six types of reactions. The outcomes obtained in this study indicate that the most influential parameters are activation energy, enthalpy, and the polarity of all the species that participate. In addition to this, in most cases, slower reacting systems observe a much greater improvement under microwave irradiation. Furthermore, for these reactions, the presence of a polar component in the reaction (solvent, reagent, susceptor, etc.) is necessary for strong coupling with the electromagnetic radiation. We also quantified that an activation energy of 20–30 kcal mol−1 and a polarity (μ) between 7–20 D of the species involved in the process is required to obtain significant improvements under microwave irradiation. 相似文献
24.
Antonio R. Montoro Bustos Marta Garcia-Cortes Hector González-Iglesias Jorge Ruiz Encinar José M. Costa-Fernández Miguel Coca-Prados Alfredo Sanz-Medel 《Analytica chimica acta》2015
A generic strategy based on the use of CdSe/ZnS Quantum Dots (QDs) as elemental labels for protein quantification, using immunoassays with elemental mass spectrometry (ICP-MS), detection is presented. In this strategy, streptavidin modified QDs (QDs-SA) are bioconjugated to a biotinylated secondary antibody (b-Ab2). After a multi-technique characterization of the synthesized generic platform (QDs-SA-b-Ab2) it was applied to the sequential quantification of five proteins (transferrin, complement C3, apolipoprotein A1, transthyretin and apolipoprotein A4) at different concentration levels in human serum samples. It is shown how this generic strategy does only require the appropriate unlabeled primary antibody for each protein to be detected. Therefore, it introduces a way out to the need for the cumbersome and specific bioconjugation of the QDs to the corresponding specific recognition antibody for every target analyte (protein). Results obtained were validated with those obtained using UV–vis spectrophotometry and commercial ELISA Kits. 相似文献
25.
Novikova D. A. Flisyuk O. M. Martsulevich N. A. Garabadzhiu A. V. 《Russian Journal of General Chemistry》2021,91(7):1387-1392
Russian Journal of General Chemistry - The main sources of emissions of industrial nitrogen oxides have been reviewed. A promising method for the absorption of nitrogen monoxide by a reusable... 相似文献
26.
27.
28.
Development of biocompatible porous supports is a promising strategy in the field of tissue engineering for the repair and regeneration of bone tissues with severe damage. Graphene oxide aerogels (GOAs) are excellent candidates for the manufacture of these systems due to their porosity, ability to imitate bone structure, and mechanical resistance, and according to their surface chemical reactivity, they can facilitate osseointegration, osteogenesis, osteoinduction and osteoconduction. In this review, synthesis of GOAs from the most primary source is described, and recent studies on the use of these functionalized carbonaceous foams as scaffolding for bone tissue regeneration are presented. 相似文献
29.
Guizellini Filipe Corrêa Franzin Bruno Trevizan da Silva Matheus Antonio Abra Luciana Mazotti Hojo Ossamu Pastre Iêda Aparecida Ribeiro Clóvis Augusto Paiva-Santos Carlos de Oliveira Fertonani Fernando Luis 《Journal of Thermal Analysis and Calorimetry》2021,143(1):47-60
Journal of Thermal Analysis and Calorimetry - The aim of this work is to synthesize and characterize a new structured silver–clay dried, calcined or sintered at different temperatures... 相似文献
30.
Journal of Experimental and Theoretical Physics - We suggest that the principle of holographic duality be extended beyond conformal invariance and AdS isometry. Such an extension is based on a... 相似文献