全文获取类型
收费全文 | 498252篇 |
免费 | 4519篇 |
国内免费 | 1685篇 |
专业分类
化学 | 231152篇 |
晶体学 | 7098篇 |
力学 | 27071篇 |
综合类 | 11篇 |
数学 | 87521篇 |
物理学 | 151603篇 |
出版年
2021年 | 2589篇 |
2020年 | 2878篇 |
2019年 | 3074篇 |
2018年 | 19436篇 |
2017年 | 19880篇 |
2016年 | 13994篇 |
2015年 | 5486篇 |
2014年 | 6287篇 |
2013年 | 16383篇 |
2012年 | 19204篇 |
2011年 | 33982篇 |
2010年 | 20915篇 |
2009年 | 21289篇 |
2008年 | 28310篇 |
2007年 | 33000篇 |
2006年 | 14192篇 |
2005年 | 19793篇 |
2004年 | 15841篇 |
2003年 | 14627篇 |
2002年 | 11818篇 |
2001年 | 11637篇 |
2000年 | 9212篇 |
1999年 | 6857篇 |
1998年 | 5490篇 |
1997年 | 5456篇 |
1996年 | 5354篇 |
1995年 | 4815篇 |
1994年 | 4508篇 |
1993年 | 4378篇 |
1992年 | 4854篇 |
1991年 | 4843篇 |
1990年 | 4444篇 |
1989年 | 4302篇 |
1988年 | 4352篇 |
1987年 | 4305篇 |
1986年 | 4050篇 |
1985年 | 5514篇 |
1984年 | 5723篇 |
1983年 | 4652篇 |
1982年 | 4969篇 |
1981年 | 4846篇 |
1980年 | 4709篇 |
1979年 | 4735篇 |
1978年 | 4892篇 |
1977年 | 4770篇 |
1976年 | 4822篇 |
1975年 | 4569篇 |
1974年 | 4466篇 |
1973年 | 4648篇 |
1972年 | 2879篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Periodica Mathematica Hungarica - We present a tight parametrical Hermite–Hadamard type inequality with probability measure, which yields a considerably closer upper bound for the mean value... 相似文献
102.
Mathematical Notes - It is proved that the lattice of all Fitting classes of finite groups is not distributive, and conditions under which Fitting classes satisfy the distributive and modular laws... 相似文献
103.
Ding Q. Yao M. Wu Sh. Zeng M. Xue N. Wu D. Xu J. 《Journal of Applied Spectroscopy》2022,89(4):712-718
Journal of Applied Spectroscopy - Based on partial least squares (PLS) analysis, the effects of different smoothing points and different preprocessing methods on the accuracy and precision of the... 相似文献
104.
Stolpovskaya N. V. Kruzhilin A. A. Zorina A. V. Shikhaliev Kh. S. Ledeneva I. V. Kosheleva E. A. Vandyshev D. Yu. 《Russian Journal of Organic Chemistry》2019,55(9):1322-1328
Russian Journal of Organic Chemistry - A procedure has been proposed for the synthesis of a series of substituted N-(1,3-thiazol-2-yl)-pyrimidin-2-amines and N-(pyrimidin-2-yl)thioureas by... 相似文献
105.
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
106.
A protocol to correct for intra‐ and interspecific variation in tail hair growth to align isotope signatures of segmentally cut tail hair to a common time line
下载免费PDF全文
![点击此处可从《Rapid communications in mass spectrometry : RCM》网站下载免费的PDF全文](/ch/ext_images/free.gif)
107.
108.
109.
110.
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