收费全文 | 5197篇 |
免费 | 460篇 |
国内免费 | 3篇 |
2024年 | 3篇 |
2023年 | 18篇 |
2022年 | 47篇 |
2021年 | 100篇 |
2020年 | 65篇 |
2019年 | 51篇 |
2018年 | 77篇 |
2017年 | 67篇 |
2016年 | 124篇 |
2015年 | 234篇 |
2014年 | 272篇 |
2013年 | 346篇 |
2012年 | 426篇 |
2011年 | 430篇 |
2010年 | 281篇 |
2009年 | 265篇 |
2008年 | 331篇 |
2007年 | 353篇 |
2006年 | 353篇 |
2005年 | 345篇 |
2004年 | 305篇 |
2003年 | 338篇 |
2002年 | 297篇 |
2001年 | 46篇 |
2000年 | 31篇 |
1999年 | 55篇 |
1998年 | 71篇 |
1997年 | 43篇 |
1996年 | 43篇 |
1995年 | 32篇 |
1994年 | 34篇 |
1993年 | 29篇 |
1992年 | 26篇 |
1991年 | 21篇 |
1990年 | 14篇 |
1989年 | 12篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 11篇 |
1985年 | 9篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1979年 | 5篇 |
1978年 | 6篇 |
1973年 | 4篇 |
1972年 | 1篇 |
1966年 | 1篇 |
1936年 | 1篇 |
The use of synthetic dyes for laccase induction in vivo has been scarcely explored. We characterized the effect of adding different synthetic dyes to liquid cultures of Pycnoporus sanguineus on laccase production. We found that carminic acid (CA) can induce 722 % and alizarin yellow 317 % more laccase than control does, and they promoted better fungal biomass development in liquid cultures. Aniline blue and crystal violet did not show such positive effect. CA and alizarin yellow were degraded up to 95 % during P. sanguineus culturing (12 days). With this basis, CA was selected as the best inducer and used to evaluate the induction of laccase on solid-state fermentation (SSF), using sugarcane bagasse (SCB) as substrate, in an attempt to reach selective delignification. We found that laccase induction occurred in SSF, and a slight inhibition of cellulase production was observed when CA was added to the substrate; also, a transformation of SCB under SSF was followed by the 13C cross polarization magic angle spinning (CPMAS) solid-state nuclear magnetic resonance (NMR). Results showed that P. sanguineus can selectively delignify SCB, decreasing aromatic C compounds by 32.67 % in 16 days; O-alkyl C region (polysaccharides) was degraded less than 2 %; delignification values were not correlated with laccase activities. Cellulose-crystallinity index was increased by 27.24 % in absence of CA and 15.94 % when 0.01 mM of CA was added to SCB; this dye also inhibits the production of fungal biomass in SSF (measured as alkyl C gain). We conclude that CA is a good inducer of laccase in liquid media, and that P. sanguineus is a fungus with high potential for biomass delignification.
相似文献We established an efficient fed-batch fermentation process for two novel dirigent proteins from cotton plants, GbDIR2 from Gossypium barbadense and GhDIR3 from G. hirsutum, using the engineered Pichia pastoris GlycoSwitch® SuperMan5 strain to prevent hyperglycosylation. The two (His)6-tagged proteins were purified by metal-chelate affinity chromatography and obtained in quantities of 12 and 15 mg L−1 of culture volume, respectively. Glycosylation sites were identified for the native and for the enzymatically deglycosylated proteins by mass spectrometry, confirming five to six of the seven predicted glycosylation sites in the NxS/T sequence context. The predominant glycan structure was Man5GlcNAc2 with, however, a significant contribution of Man4–10GlcNAc2. Both dirigent proteins (DIRs) mediated the formation of (+)-gossypol by atropselective coupling of hemigossypol radicals. Similar to previously characterized DIRs, GbDIR2 and GhDIR3 lacked oxidizing activity and depended on an oxidizing system (laccase/O2) for the generation of substrate radicals. In contrast to DIRs involved in the biosynthesis of lignans, glycosylation was not essential for function. Quantitative enzymatic deglycosylation yielded active GbDIR2 and GhDIR3 in excellent purity. The described fermentation process in combination with enzymatic deglycosylation will pave the way for mechanistic and structural studies and, eventually, the application of cotton DIRs in a biomimetic approach towards atropselective biaryl synthesis.
相似文献![点击此处可从《Biology of the cell / under the auspices of the European Cell Biology Organization》网站下载免费的PDF全文](/ch/ext_images/free.gif)
![点击此处可从《Journal of neurochemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
![点击此处可从《Journal of neurochemistry》网站下载免费的PDF全文](/ch/ext_images/free.gif)
![点击此处可从《Obesity (Silver Spring, Md.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)