全文获取类型
收费全文 | 519篇 |
免费 | 51篇 |
国内免费 | 54篇 |
专业分类
624篇 |
出版年
2023年 | 6篇 |
2022年 | 7篇 |
2021年 | 15篇 |
2020年 | 12篇 |
2019年 | 17篇 |
2018年 | 15篇 |
2017年 | 17篇 |
2016年 | 13篇 |
2015年 | 20篇 |
2014年 | 34篇 |
2013年 | 32篇 |
2012年 | 33篇 |
2011年 | 38篇 |
2010年 | 25篇 |
2009年 | 18篇 |
2008年 | 24篇 |
2007年 | 21篇 |
2006年 | 31篇 |
2005年 | 25篇 |
2004年 | 27篇 |
2003年 | 23篇 |
2002年 | 29篇 |
2001年 | 24篇 |
2000年 | 14篇 |
1999年 | 27篇 |
1998年 | 17篇 |
1997年 | 10篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 7篇 |
1993年 | 1篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1970年 | 1篇 |
1965年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有624条查询结果,搜索用时 0 毫秒
621.
622.
Dimethyl sulfide protects against oxidative stress and extends lifespan via a methionine sulfoxide reductase A‐dependent catalytic mechanism
下载免费PDF全文
![点击此处可从《Aging cell》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Xin‐Lei Guan Peng‐Fei Wu Sheng Wang Juan‐Juan Zhang Zu‐Cheng Shen Han Luo Hao Chen Li‐Hong Long Jian‐Guo Chen Fang Wang 《Aging cell》2017,16(2):226-236
Methionine (Met) sulfoxide reductase A (MsrA) is a key endogenous antioxidative enzyme with longevity benefits in animals. Only very few approaches have been reported to enhance MsrA function. Recent reports have indicated that the antioxidant capability of MsrA may involve a Met oxidase activity that facilities the reaction of Met with reactive oxygen species (ROS). Herein, we used a homology modeling approach to search the substrates for the oxidase activity of MsrA. We found that dimethyl sulfide (DMS), a main metabolite that produced by marine algae, emerged as a good substrate for MsrA‐catalytic antioxidation. MsrA bounds to DMS and promoted its antioxidant capacity via facilitating the reaction of DMS with ROS through a sulfonium intermediate at residues Cys72, Tyr103, and Glu115, followed by the release of dimethyl sulfoxide (DMSO). DMS reduced the antimycin A‐induced ROS generation in cultured PC12 cells and alleviated oxidative stress. Supplement of DMS exhibited cytoprotection and extended longevity in both Caenorhabditis elegans and Drosophila. MsrA knockdown abolished the cytoprotective effect and the longevity benefits of DMS. Furthermore, we found that the level of physiologic DMS was at the low micromolar range in different tissues of mammals and its level decreased after aging. This study opened a new window to elucidate the biological role of DMS and other low‐molecular sulfides in the cytoprotection and aging. 相似文献
623.
The authors studied the antigenic composition of 105 Sh. sonnei strains freshly isolated from patients suffering from acute dysentery and carriers. Immunophoregrams of pure S-and R-forms species were obtained. Up to 13 antigens differing by electrophoretic and diffusion mobility and immunological specificity were revealed among soluble Sh. sonnei antigens The position of common and specific antigens was determined on the immunophoregram. Along with the thermostable somatic O-antigen detected at the I phase of the S-forms, and two thermolabile O-antigen components at the II phase, and the R-forms, there was revealed a surface, relatively thermolabile, K-antigen of A-type capable of agglutinating live bacteria in the O-antiserum; position of the latter on the immunophoregram was also determined. 相似文献
624.
Shungang Wan Guiying Li Taicheng An Bin Guo Lei Sun Lei Zu Ailing Ren 《Biodegradation》2010,21(6):1057-1066
In the present study, a new bacterial strain isolated from activated sludge has been identified as Lysinibacillus sphaericus based on its morphology, physiochemical properties, and the results of 16S ribosomal RNA (rRNA) gene sequence analysis. This
new bacterial strain uses ethanethiol as both carbon source and energy source. The key factors for controlling the degradation
efficiency of ethanethiol by this strain were found to be initial ethanethiol concentration, temperature, and pH value of
solutions. Under the optimized conditions, as well as 4 mg l−1 ethanethiol, 30°C, and pH = 7.0, almost 100% ethanethiol can be degraded within 96 h and sulfate as a final product was detected
in aqueous medium. The degradation reaction of ethanethiol over this newly isolated strain can be described by pseudo first-order
equation in which the maximum degradation rate constant K and the minimum half-life were respectively calculated to be 0.0308 h−1 and 22.5 h under the optimal conditions. 相似文献