全文获取类型
收费全文 | 871篇 |
免费 | 64篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 27篇 |
2020年 | 6篇 |
2019年 | 12篇 |
2018年 | 9篇 |
2017年 | 16篇 |
2016年 | 26篇 |
2015年 | 37篇 |
2014年 | 43篇 |
2013年 | 81篇 |
2012年 | 89篇 |
2011年 | 79篇 |
2010年 | 51篇 |
2009年 | 36篇 |
2008年 | 66篇 |
2007年 | 60篇 |
2006年 | 49篇 |
2005年 | 53篇 |
2004年 | 49篇 |
2003年 | 47篇 |
2002年 | 38篇 |
2001年 | 5篇 |
2000年 | 1篇 |
1999年 | 6篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1981年 | 3篇 |
1976年 | 1篇 |
排序方式: 共有935条查询结果,搜索用时 78 毫秒
931.
932.
David Daudé Christopher M. Topham Magali Remaud‐Siméon Isabelle André 《Protein science : a publication of the Protein Society》2013,22(12):1754-1765
The amylosucrase from Neisseria polysaccharea is a transglucosidase from the GH13 family of glycoside-hydrolases that naturally catalyzes the synthesis of α-glucans from the widely available donor sucrose. Interestingly, natural molecular evolution has modeled a dense hydrogen bond network at subsite −1 responsible for the specific recognition of sucrose and conversely, it has loosened interactions at the subsite +1 creating a highly promiscuous subsite +1. The residues forming these subsites are considered to be likely involved in the activity as well as the overall stability of the enzyme. To assess their role, a structure-based approach was followed to reshape the subsite −1. A strategy based on stability change predictions, using the FoldX algorithm, was considered to identify the best candidates for site-directed mutagenesis and guide the construction of a small targeted library. A miniaturized purification protocol was developed and both mutant stability and substrate promiscuity were explored. A range of 8°C between extreme melting temperature values was observed and some variants were able to synthesize series of oligosaccharides with distributions differing from that of the parental enzyme. The crucial role of subsite −1 was thus highlighted and the biocatalysts generated can now be considered as starting points for further engineering purposes. 相似文献
933.
A putative contribution of polyamines to the control of peptidase activity expression during re-growth was studied in source organs (roots and stolons) of defoliated white clover (Trifolium repens L.). Endopeptidase activity increased in roots during the first 6 days following complete defoliation, while exopeptidase expression seemed to be restricted to the early hours of re-growth. These changes correlated with an immediate 80% decline in the content of total free polyamines, mainly represented by the diamine cadaverine. The inhibitory capacities of cadaverine and spermine were tested on enzyme activity in vitro in order to elucidate whether the endogenous polyamine level was associated with the cut-induced endopeptidase expression. Cadaverine seemed to inhibit endopeptidase activity of stolons but not root endopeptidase activity. These data support the view that polyamines may play a role in the regulation of peptidase expression in source organs of white clover during post-clipping re-growth. The existence of different endopeptidase isoforms in roots and stolons is discussed in relation to the molecular mechanisms by which polyamines may regulate their activities.Abbreviations AP
aminopeptidase
- Cad
cadaverine
- CP
carboxypeptidase
- EP
endopeptidase
- PA(s)
polyamine(s)
- Spm
spermine 相似文献
934.
Metabolic blocking of exopolysaccharides synthesis: effects on microbial adhesion and biofilm accumulation 总被引:5,自引:0,他引:5
A blocking agent of polysaccharide synthesis (5 x 10-4 M 2,4-dinitrophenol) was continuously added to a reaction system, where a heterogeneous microbial population was cultivated at a dilution rate of 0.1 h-1. The results indicate that adhesion and biofilm accumulation were severely reduced when exopolysaccharydes synthesis was blocked. 相似文献
935.
Lucie Paloque Nicolas Vidal Magali Casanova Aurélien Dumètre Pierre Verhaeghe Daniel Parzy Nadine Azas 《Journal of microbiological methods》2013
We validated a new method, based on luciferine/luciferase bioluminescence, for drug screening on promastigotes of different Leishmania species. Results obtained with this new, rapid, reproducible, and reliable method are in good accordance with results obtained by the conventional MTT assay. This bioluminescence assay has a lower detection limit. 相似文献