全文获取类型
收费全文 | 282570篇 |
免费 | 3203篇 |
国内免费 | 1016篇 |
专业分类
化学 | 147498篇 |
晶体学 | 4204篇 |
力学 | 13132篇 |
综合类 | 64篇 |
数学 | 32582篇 |
物理学 | 89309篇 |
出版年
2020年 | 2269篇 |
2019年 | 2472篇 |
2018年 | 4109篇 |
2017年 | 4182篇 |
2016年 | 5102篇 |
2015年 | 3123篇 |
2014年 | 4716篇 |
2013年 | 11244篇 |
2012年 | 9202篇 |
2011年 | 10666篇 |
2010年 | 7618篇 |
2009年 | 7406篇 |
2008年 | 9620篇 |
2007年 | 9786篇 |
2006年 | 9117篇 |
2005年 | 10912篇 |
2004年 | 10161篇 |
2003年 | 8269篇 |
2002年 | 6811篇 |
2001年 | 7416篇 |
2000年 | 5743篇 |
1999年 | 4481篇 |
1998年 | 3935篇 |
1997年 | 3926篇 |
1996年 | 3649篇 |
1995年 | 3395篇 |
1994年 | 3538篇 |
1993年 | 3233篇 |
1992年 | 3690篇 |
1991年 | 3692篇 |
1990年 | 3617篇 |
1989年 | 3464篇 |
1988年 | 3572篇 |
1987年 | 3467篇 |
1986年 | 3298篇 |
1985年 | 4365篇 |
1984年 | 4632篇 |
1983年 | 3873篇 |
1982年 | 4005篇 |
1981年 | 3935篇 |
1980年 | 3908篇 |
1979年 | 3876篇 |
1978年 | 4190篇 |
1977年 | 4107篇 |
1976年 | 4173篇 |
1975年 | 3849篇 |
1974年 | 3861篇 |
1973年 | 4004篇 |
1972年 | 2822篇 |
1971年 | 2349篇 |
排序方式: 共有10000条查询结果,搜索用时 125 毫秒
71.
随着经济的飞速发展,社会对能源的需求日益扩大,对工业废水的无害化处理也提出了更高的要求。光催化燃料电池 (photocatalytic fuel cell, PFC) 在燃料电池中引入半导体光催化材料作为电极,实现了有机污染物高效降解和同步对外产电的双重功能,在废水无害化与资源化利用方面具有潜在的应用价值。半导体光催化电极是PFC系统高效运行的核心组件,增强其可见光响应和光生载流子分离是提高PFC性能的关键策略。反应器结构设计和运行参数优化也有利于改善PFC性能。本文从PFC基本原理和应用入手,综述了PFC在环境污染物资源化处理中的研究进展,并详细阐述了提高PFC的污染控制性能和产电效率的优化手段,为进一步设计高效稳定的PFC系统并实现其在水污染控制和清洁能源生产中的应用提供理论指导。 相似文献
72.
Manjumol K. A. Jayasankar M. Vidya K. Mohamed A. Peer Nair Balagopal N. Warrier K. G. K. 《Journal of Sol-Gel Science and Technology》2015,74(1):161-167
Journal of Sol-Gel Science and Technology - High temperature stable brookite rich titanium dioxide of average crystallite size 20&;nbsp;nm has been prepared by a novel aqueous sol–gel... 相似文献
73.
Saleh Z. M. Nasser H. Özkol E. Günöven M. Abak K. Canli S. Bek A. Turan R. 《Journal of nanoparticle research》2015,17(10):1-12
Journal of Nanoparticle Research - Plasmonic interfaces consisting of silver nanoparticles of different sizes (50–100&;nbsp;nm) have been processed by the self-assembled dewetting... 相似文献
74.
E. V. Shadrina O. N. Malinkina T. G. Khonina A. B. Shipovskaya V. I. Fomina E. Yu. Larchenko N. A. Popova I. G. Zyryanova L. P. Larionov 《Russian Chemical Bulletin》2015,64(7):1633-1639
The biomimetic sol—gel synthesis of silicon—chitosan-containing glycerohydrogels was carried out using silicon tetraglycerolate as a precursor. It was found that chitosan accelerates gel formation in weakly acidic media. In more acidic media, the kinetics of the process changes according to the curve with a maximum, which can be attributed to different mechanisms of silanol condensation before and after the isoelectric point. The investigated silicon—chitosan-containing glycerohydrogels exhibit antibacterial, anti-inflammatory, and wound healing activity. The synthesized hybrid glycerohydrogels are promising materials for biomedical applications. 相似文献
75.
76.
77.
78.
João Marcos G. Barbosa Milenna K. Fernandes Rodrigues Lurian C. David Taynara C. e Silva Danielly A. Fortuna Lima Naiara Z. Pereira Emmanuel B. D'Alessandro Anselmo E. de Oliveira Paulo H. Jorge da Cunha Maria Clorinda S. Fioravanti Nelson R. Antoniosi Filho 《Biomedical chromatography : BMC》2020,34(11):e4935
An innovative volatolomic approach employs the detection of biomarkers present in cerumen (earwax) to identify cattle intoxication by Stryphnodendron rotundifolium Mart., Fabaceae (popularly known as barbatimão). S. rotundifolium is a poisonous plant with the toxic compound undefined and widely distributed throughout the Brazilian territory. Cerumen samples from cattle of two local Brazilian breeds (‘Curraleiro Pé-Duro’ and ‘Pantaneiro’) were collected during an experimental intoxication protocol and analyzed using headspace (HS)/GC–MS followed by multivariate analysis (genetic algorithm for a partial least squares, cluster analysis, and classification and regression trees). A total of 106 volatile organic metabolites were identified in the cerumen samples of bovines. The intoxication by S. rotundifolium influenced the cerumen volatolomic profile of the bovines throughout the intoxication protocol. In this way, it was possible to detect biomarkers for cattle intoxication. Among the biomarkers, 2-octyldecanol and 9-tetradecen-1-ol were able to discriminate all samples between intoxicated and nonintoxicated bovines. The cattle intoxication diagnosis by S. rotundifolium was accomplished by applying the cerumen analysis using HS/GC–MS, in an easy, accurate, and noninvasive way. Thus, the proposed bioanalytical chromatography protocol is a useful tool in veterinary applications to determine this kind of intoxication. 相似文献
79.
Chandrachood Pranav S. Jadhav Amol R. Garud Dinesh R. Deshpande Nirmala R. Puranik Vedavati G. Kashalkar Rajashree V. 《Research on Chemical Intermediates》2020,46(12):5219-5230
Research on Chemical Intermediates - A series of quinoxaline derivatives were efficiently synthesized by convenient and simple procedure in excellent yields using 1 wt.% of titanium silicate (TS-1)... 相似文献
80.