全文获取类型
收费全文 | 678篇 |
免费 | 46篇 |
出版年
2022年 | 3篇 |
2021年 | 6篇 |
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 14篇 |
2016年 | 10篇 |
2015年 | 24篇 |
2014年 | 34篇 |
2013年 | 37篇 |
2012年 | 25篇 |
2011年 | 41篇 |
2010年 | 25篇 |
2009年 | 26篇 |
2008年 | 34篇 |
2007年 | 32篇 |
2006年 | 36篇 |
2005年 | 37篇 |
2004年 | 32篇 |
2003年 | 26篇 |
2002年 | 24篇 |
2001年 | 21篇 |
2000年 | 18篇 |
1999年 | 27篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 11篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 6篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1970年 | 3篇 |
1967年 | 3篇 |
1965年 | 2篇 |
1936年 | 3篇 |
1911年 | 2篇 |
排序方式: 共有724条查询结果,搜索用时 15 毫秒
111.
Lisa J. Schulman Edward V. Sargent Bruce D. Naumann Ellen C. Faria David G. Dolan John P. Wargo 《人类与生态风险评估》2002,8(4):657-680
Analyses were conducted on four pharmaceutical compounds, representing different therapeutic classes, to evaluate the presence and potential adverse human health effects of trace levels of these substances in aqueous environmental media. Acetylsalicylic acid, clofibrate, cyclophosphamide, and indomethacin have been detected in aqueous environmental media including sewage treatment plant effluent, surface water, drinking water, and groundwater. An extensive literature search and chemical-specific risk assessments were performed to assess the potential human health significance of each compound's individual presence in environmental media. Safe water quality limits were estimated for each pharmaceutical by following the USEPA Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health and were compared to the concentrations found in the environment. The calculation of the provisional ambient water quality criteria involved estimation of human exposure to contaminated water, including intake via bioaccumulation in fish, and calculation of cancer risk and non-cancer hazard indices. Parameters detailing the toxicological and pharmacological nature, exposure assessment, and environmental fate and transport of each pharmaceutical were also considered. The overall conclusion was that based on available data, no appreciable risk to humans exists, as the detected concentrations of each of these pharmaceutical compounds found in aqueous media were far below the derived safe limits 相似文献
112.
Pathogenesis of Helicobacter pylori infection 总被引:3,自引:0,他引:3
113.
114.
Heidrun Anke Leonard B. Spector 《Biochemical and biophysical research communications》1975,67(2):767-773
Acetyl-CoA synthetase (EC 6.2.1.1) from yeast is a ligase which catalyzes the synthesis of ATP from ADP and acetyl-CoA or acetyl-dephosphoCoA. The enzyme also catalyzes the rapid and reversible transfer of an acetyl group between CoA and dephospho CoA in the absence of the other components of the total ligase reaction. Such transfer is chemically equivalent to a CoA-acetyl-CoA exchange, and points therefore to an acetyl-enzyme intermediate in the transfer (“exchange”) reaction. Since the “exchange” is an intrinsic activity of the enzyme, it seems probable that the acetyl-enzyme mediates the total ligase reaction as well. 相似文献
115.
116.
117.
Unclear or misclassified genetic background of laboratory rodents or a lack of strain awareness causes a number of difficulties in performing or reproducing scientific experiments. Until now, genetic differentiation between strains and substrains of inbred mice has been a challenge. We have developed a screening method for analyzing inbred strains regarding their genetic background. It is based on 240 highly informative short tandem repeat (STR) markers covering the 19 autosomes as well as X and Y chromosomes. Combination of analysis results for presence of known C57BL/6 substrain-specific mutations together with autosomal STR markers and the Y-chromosomal STR-haplotype provides a comprehensive snapshot of the genetic background of mice. In this study, the genetic background of 72 mouse lines obtained from 18 scientific institutions in Germany and Austria was determined. By analyzing only 3 individuals per genetically modified line it was possible to detect mixed genetic backgrounds frequently. In several lines presence of a mispairing Y chromosome was detected. At least every second genetically modified line displayed a mixed genetic background which could lead to unexpected and non-reproducible results, irrespective of the investigated gene of interest. 相似文献
118.
119.
120.
Characterization of FMR1 Promoter Elements by In Vivo-Footprinting Analysis 总被引:2,自引:0,他引:2 下载免费PDF全文