全文获取类型
收费全文 | 5504篇 |
免费 | 134篇 |
国内免费 | 20篇 |
专业分类
化学 | 3758篇 |
晶体学 | 37篇 |
力学 | 96篇 |
数学 | 776篇 |
物理学 | 991篇 |
出版年
2023年 | 33篇 |
2022年 | 59篇 |
2021年 | 80篇 |
2020年 | 93篇 |
2019年 | 81篇 |
2018年 | 46篇 |
2017年 | 48篇 |
2016年 | 100篇 |
2015年 | 94篇 |
2014年 | 91篇 |
2013年 | 272篇 |
2012年 | 276篇 |
2011年 | 315篇 |
2010年 | 195篇 |
2009年 | 158篇 |
2008年 | 281篇 |
2007年 | 315篇 |
2006年 | 281篇 |
2005年 | 267篇 |
2004年 | 267篇 |
2003年 | 195篇 |
2002年 | 185篇 |
2001年 | 102篇 |
2000年 | 121篇 |
1999年 | 66篇 |
1998年 | 83篇 |
1997年 | 63篇 |
1996年 | 74篇 |
1995年 | 74篇 |
1994年 | 56篇 |
1993年 | 83篇 |
1992年 | 59篇 |
1991年 | 48篇 |
1990年 | 50篇 |
1989年 | 53篇 |
1988年 | 47篇 |
1987年 | 46篇 |
1986年 | 50篇 |
1985年 | 71篇 |
1984年 | 60篇 |
1983年 | 50篇 |
1982年 | 42篇 |
1981年 | 43篇 |
1980年 | 47篇 |
1978年 | 36篇 |
1977年 | 44篇 |
1976年 | 51篇 |
1975年 | 51篇 |
1974年 | 43篇 |
1973年 | 49篇 |
排序方式: 共有5658条查询结果,搜索用时 62 毫秒
51.
A rapid, selective, sensitive and simple fluorescence method was developed for the direct determination of celecoxib in capsules. The capsules were emptied, pulverized and dissolved in either ethanol or acetonitrile, sonicated and filtered. Direct fluorescence emission was measured at 355±5 nm (exciting at 272 nm). The method was fully validated and the recoveries were excellent, even in presence of excipients. 相似文献
52.
The preferred conformations of the tripeptide glutathione have been investigated by performing quantum mechanical calculations using the PCILO method. A series of model compounds representing fragments of the tripeptide has been studied as well as the complete molecule. The results are compared with the available experimental data. 相似文献
53.
Novel proline-thiazole based cyclopeptides were produced by cyclooligomerisation of an L-proline thiazole amino acid HCl in the presence of pentafluorophenyl diphenylphosphinate (FDPP) or diphenyl phosphorazidate (DPPA). 相似文献
54.
Patricia Cava-Montesinos Agustin Pastor Miguel de la Guardia 《Analytica chimica acta》2003,481(2):291-300
A sensitive procedure has been developed for selenium and tellurium determination in milk by hydride generation atomic fluorescence spectrometry (HG-AFS) after microwave-assisted sample digestion. The method provides sensitivity values of 1591 and 997 fluorescence units ng−1 ml−1 with detection limits of 0.005 and 0.015 ng ml−1 for Se and Te, respectively. The application of the developed methodology to the analysis of cow milk samples of the Spanish market evidenced the presence of concentration ranges from 11.1 to 26.0 ng ml−1 for Se, and from 1.04 to 9.7 ng ml−1 for Te having found a good comparability with data obtained after dry-ashing of samples. 相似文献
55.
56.
57.
Simulation of aerated lagoon using artificial neural networks and multivariate regression techniques
Karla Patricia Oliveira-Esquerre Aline C. da Costa Roy Edward Bruns Milton Mori 《Applied biochemistry and biotechnology》2003,106(1-3):437-449
The aim of this study was to develop an empirical model that provides accurate predictions of the biochemical oxygen demand
of the output stream from the aerated lagoon at International Paper of Brazil, one of the major pulp and paper plants in Brazil.
Predictive models were calculated from functional link neural networks (FLNNs), multiple linear regression, principal components
regression, and partial least-squares regression (PLSR). Improvement in FLNN modeling capability was observed when the data
were preprocessed using the PLSR technique. PLSR also proved to be a powerful linear regression technique for this problem,
which presents operational data limitations. 相似文献
58.
59.
Grosnick D Wright SC Bolton RD Cooper MD Frank JS Hallin AL Heusi PA Hoffman CM Hogan GE Mariam FG Matis HS Mischke RE Piilonen LE Sandberg VD Sanders GH Sennhauser U Werbeck R Williams RA Wilson SL Hofstadter R Hughes EB Ritter MW Highland VL McDonough J 《Physical review letters》1986,57(26):3241-3244
60.