全文获取类型
收费全文 | 250篇 |
免费 | 11篇 |
国内免费 | 1篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2014年 | 10篇 |
2013年 | 15篇 |
2012年 | 11篇 |
2011年 | 12篇 |
2010年 | 10篇 |
2009年 | 11篇 |
2008年 | 21篇 |
2007年 | 11篇 |
2006年 | 10篇 |
2005年 | 12篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 9篇 |
2001年 | 7篇 |
2000年 | 4篇 |
1999年 | 8篇 |
1998年 | 7篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
排序方式: 共有262条查询结果,搜索用时 31 毫秒
1.
Signal peptidase I overproduction results in increased efficiencies of export and maturation of hybrid secretory proteins in Escherichia coli 总被引:4,自引:0,他引:4
Jan Maarten van Dijl Anne de Jong Hilde Smith Sierd Bron Gerard Venema 《Molecular & general genetics : MGG》1991,227(1):40-48
Summary The effects of 25-fold overproduction ofEscherichia coli signal peptidase I (SPase I) on the processing kinetics of various (hybrid) secretory proteins, comprising fusions between
signal sequence functions selected from theBacillus subtilis chromosome and the mature part of TEM-β-lactamase, were studied inE. coli. One precursor (pre[A2d]-β-lactamase) showed an enhanced processing rate, and consequently, a highly improved release of
the mature enzyme into the periplasm. A minor fraction of a second hybrid precursor (pre[Al3i]-β-lactamase), which was not
processed under standard conditions of SPase I synthesis, was shown to be processed under conditions of SPase I overproduction.
However, this did not result in efficient release of the mature β-lactamase into the periplasm. In contrast, the processing
rates of wild-type pre-β-lactamase and pre(A2)-β-lactamase, already high under standard conditions, were not detectably altered
by SPase I overproduction. These results demonstrate that the availability of SPase I can be a limiting factor in protein
export inE. coli, in particular with respect to (hybrid) precursor proteins showing low (SPase I) processing efficiencies. 相似文献
2.
Nonrandom insertion of Tn5 into cloned human adenovirus DNA 总被引:4,自引:0,他引:4
3.
Gordon C. K. Roberts 《Neurochemical research》1996,21(9):1117-1124
NMR spectroscopy has proved to be a valuable tool in the study of the interactions between enzymes and their substrates. The
kinds of structural and dynamic information which can be obtained are illustrated by studies of three enzymes involved in
drug metabolism. Cytochromes P450 play a crucial role in metabolism of a wide range of exogenous chemicals. NMR has been used to measure distances from the
haem iron of the cytochrome to protons of the bound substrate, leading to detailed structural models for the enzyme-substrate
complexes. The other two enzymes, chloramphenicol acetyltransferase and β-lactamase, are responsible for bacterial resistance
to specific antibiotics. In chloramphenicol acetyltransferase, NMR has been used to determine the conformation of coenzyme
A bound to the enzyme, while in the case of β-lactamase the pK of a specific lysine residue at the active site has been determined,
providing valuable information on the catalytic mechanism.
Special issue dedicated to Dr. Herman Bachelard. 相似文献
4.
5.
The stable continuous overproduction of a plasmidencoded protein, beta-lactamase, for at least 50 days by Escherichia coli K-12, RB791(pKN), with release into the culture medium has been demonstrated in two-stage chemostats. The second-stage culture was continuously induced with 0.1 mM IPTG. Continuous expression of beta-lactamase could not be sustained with this strain in a single-stage chemostat because of cell death and selection for lac(-1) cells. beta-Lactamase production in the second stage was sensitive to the second-stage dilution rate and the distribution of the limiting substrate (i.e., glucose) between the first and second stages. The fraction of viable, excreting cells and the average copy number in the induced culture was measurably higher under those conditions of dilution rate and substrate distribution which yielded high beta-lactamase levels. The best operating conditions found at 20 degrees C were a first-stage dilution rate of 0.12 h(-1), a second-stage dilution rate of 0.03 h(-1), and equal glucose feed supplied to each stage. Enzymatically active beta-lactamase was produced at a level of 25% of total cellular protein with 90% excretion yielding 300 mg beta-lactamase/L that was 50% pure at an OD(600) < 6. (c) 1993 Wiley & Sons, Inc. 相似文献
6.
Thirty nine clinical isolates of Acinetobacter belonging to six species were tested for resistance to 20 metal ions and their ability to produce -lactamase. Fifty two percent of the strains produced -lactamase. -Lactamase producers and non-producers were almost equally distributed in the different species. A. baumannii was the predominant biotype and was found to be most resistant to metals. Resistance to mercury was prevalent in -lactamase-producing A. baumannii only. Silver resistant strains of A. baumannii produced -lactamase. Sensitivity and resistance to copper and cadium was equally distributed between -lactamase producers and non-producers. -Lactamase-producer and -non-producer strains were uniformly sensitive to cadmium except Acinetobacter genospecies 1. 相似文献
7.
X Xiao G Hintermann AL Demanin J Piret 《Journal of industrial microbiology & biotechnology》1996,16(4):261-262
Streptomyces glaucescens is shown to possess -lactamase activity which is inhibitable by clavulanate. This is important in regard to its use as a cloning host for enzymes of \-lactam biosynthesis. 相似文献
8.
A D Brabban J Littlechild R Wisdom 《Journal of industrial microbiology & biotechnology》1996,16(1):8-14
Twenty five environmental isolates enriched for their ability to grow onN-acetylphenylalanine as sole carbon source were investigated for their hydrolytic action on (+)-lactam (2-azabicyclo[2.2.1]hept-5-en-3-one). Strain CMC 3060, a mucoidal Gram-negative rod identified as a strain ofPseudomonas fluorescens, produced high levels of (+)lactamase, and was subsequently found to produce two distinct intracellular enantiomer-selective, -lactamases, one for each isomer. The (+)lactamase was produced constitutively whereas the (-lactamase was produced only in the presence of the substrate. The (+)lactamase was stable when stored as a frozen cell paste but unstable as a protein solution, losing activity during purification and storage. This enzyme was highly selective for the (+)lactam and showed no activity against a wide range of similar compounds. By use of rapid purification techniques and the inclusion of protease inhibitors and protein stabilisers, the (+)lactamase was purified to homogeneity by FPLC and found to be a monomer of molecular weight 61000 Da. 相似文献
9.
10.
The ability of Escherichia coli with different receptor specificities to interact with meconium was studied. E. coli strains expressing P-fimbriae, specific for Gal alpha 1-4Gal beta-containing receptors, were agglutinated by meconium at high titres. This reaction was inhibited by globotetraosylceramide. The attachment of P-fimbriated E. coli to human colonic epithelial cells of the HT-29 cell line was inhibited by meconium. Some type 1 fimbriated strains were agglutinated by meconium, but the agglutination was rarely blocked by methyl alpha-D-mannoside. The attachment by type 1 fimbriated strains to HT-29 cells was reduced by meconium only in some cases. These results suggest that meconium interacts with the P-fimbriae of E. coli, in a way that may influence bacterial colonization of the neonatal intestine. 相似文献