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81.
Yang H Wan L Li X Cai H Chen L Li S Li Y Cheng J Lu X 《Protein expression and purification》2007,54(2):309-317
Since antibiotics with a broad spectrum of activity would select for resistance among the normal flora, colicins having a narrow spectrum of activity can potentially be developed as novel antibiotics. Colicin-based bactericidal proteins with modified spectra of activity might also be developed by further gene fusion or gene modification. To achieve these goals, it is necessary to first build an efficient system to produce large amounts of colicin. In the presence of an immunity gene, we successfully constructed an expression vector pQE30-cfa-cfi producing high levels of His-tagged colicin 5 (60-80 mg/L). We found that the purified His-tagged colicin 5 possesses narrow-spectrum bactericidal activity against nonimmune Escherichia coli cells. It is highly toxic to sensitive E. coli cells at a low concentration of 0.01 microg/ml, while it is nontoxic to other tested gram-negative bacteria, gram-positive bacteria and yeast at a high concentration of 1000 microg/ml. His-tagged colicin 5 kills sensitive cells by permeabilizing their cell membranes. It is not hemolytic to rabbit erythrocytes and has no obvious cytotoxicity to other nucleated mammalian cells at a high concentration of 500 microg/ml. The His-tagged colicin 5 is similar to wild-type colicin 5 in spectrum and bactericidal activity against E. coli. It is a potential novel antibiotic particularly for treating human and animal infections caused by pathogenic E. coli. Besides producing high level of colicin 5, the highly efficient expression vector constructed here might also be a useful tool to develop colicin-based artificial bactericidal proteins. 相似文献
82.
Jos M.B.M. van der Vossen Marcel H.M. van Herwijnen Rob J. Leer Bart ten Brink Peter H. Pouwels Jos H.J. Huis in `t Veld 《FEMS microbiology letters》1994,116(3):333-340
Abstract Plasmid-curing studies suggest that acidocin B production is encoded by the 14-kb plasmid pCV461 in Lactobacillus acidophilus M46. Loss of pCV461 from the original producer strain M46 did not coincide with loss of immunity to acidocin B. Bacteriocin activity determination after SDS-PAGE showed that a substance of 2.4 kDa, absent in the culture supernatant of the mutant strain M46A2, lacking pCV461, represented acidocin B activity. In order to introduce a positive selection criterion, pCV461 was marked in vivo by the erythromycin resistance marker of pE194, present on pUC19 containing a 1.4-kb Hin dIII fragment of pCV461, after plasmid integration. Introduction of this recombinant plasmid into the mutant strain M46A2 or Lactobacillus plantarum resulted in erythromycin-resistant, acidocin B-producing transformants, showing unambiguously that acidocin B is encoded by pCV461. 相似文献
83.
Linear DNA plasmids of yeasts 总被引:2,自引:0,他引:2
Hiroshi Fukuhara 《FEMS microbiology letters》1995,131(1):1-9
Abstract Proteinaceous antimicrobial compounds are produced by a diversity of species ranging from bacteria to humans. This review focuses on the mode of action of pore-forming bacteriocins produced by Gram-positive bacteria. The mechanism of action of specific immunity proteins, which protect the producer strains from the lethal action of their own products (producer self-protection), are also discussed. 相似文献
84.
S. V. N. Vijayendra K. Rajashree Prakash M. Halami 《Indian journal of microbiology》2010,50(2):243-246
Lactic acid bacteria (LAB) are known to produce various types of bacteriocins, ribosomally synthesized polypeptides, which
have antibacterial spectrum against many food borne pathogens. Listeria monocytogenes, a pathogenic bacterium, is of particular concern to the food industry because of its ability to grow even at refrigeration
temperatures and its tolerance to preservative agents. Some of the bacteriocins of LAB are known to have anti-listerial property.
In the present study, the bacteriocin produced by vancomycin sensitive Enterococcus faecium El and J4 isolated from idli batter samples was characterized. The isolates were found to tolerate high temperatures of 60°C for 15 and 30 min and 70°C
for 15 min. The bacteriocin was found to be heat stable and had anti-listerial activity. The bacteriocin did not lost anti-listerial
activity when treated at 100°C for 30 min or at 121°C for 15 min. The bacteriocin lost its antimicrobial activity after treating
with trypsin, protinase-K, protease and peptidase. 相似文献
85.
Hua Ling 《FEBS letters》2010,584(15):3354-3358
The nucleic acid sequence at the positions 1067817-1066321 of Pseudomonas aeruginosa PAO1 genome was predicted to encode a novel S-type pyocin, designated S5, based on the genome sequence. However, its antimicrobial spectrum, activity and mechanism have not been investigated. Herein, we report that pyocin S5 has an antimicrobial activity against seven clinical P. aeruginosa isolates (DWW3, InA, InB, In3, In4, In7, and In8). Among them, DWW3 is most sensitive with a minimum inhibitory concentration of 12.6 μg/ml and a killing percentage of 95.7 at 225 μg/ml. Further, we demonstrated that the antimicrobial mechanism of pyocin S5 is membrane damage, evidenced by the leakage of intracellular materials, the increase of membrane permeability, and cell surface disruption. 相似文献
86.
Jun Kurushima Ikue Hayashi Motoyuki Sugai Haruyoshi Tomita 《The Journal of biological chemistry》2013,288(52):36915-36925
Enterococcus faecalis strains are commensal bacteria in humans and other animals, and they are also the causative agent of opportunistic infectious diseases. Bacteriocin 41 (Bac41) is produced by certain E. faecalis clinical isolates, and it is active against other E. faecalis strains. Our genetic analyses demonstrated that the extracellular products of the bacL1 and bacA genes, which are encoded in the Bac41 operon, coordinately express the bacteriocin activity against E. faecalis. In this study, we investigated the molecular functions of the BacL1 and BacA proteins. Immunoblotting and N-terminal amino acid sequence analysis revealed that BacL1 and BacA are secreted without any processing. The coincidental treatment with the recombinant BacL1 and BacA showed complete bacteriocin activity against E. faecalis, but neither BacL1 nor BacA protein alone showed the bacteriocin activity. Interestingly, BacL1 alone demonstrated substantial degrading activity against the cell wall fraction of E. faecalis in the absence of BacA. Furthermore, MALDI-TOF MS analysis revealed that BacL1 has a peptidoglycan d-isoglutamyl-l-lysine endopeptidase activity via a NlpC/P60 homology domain. These results collectively suggest that BacL1 serves as a peptidoglycan hydrolase and, when BacA is present, results in the lysis of viable E. faecalis cells. 相似文献
87.
Sten Ståhl 《Archives of microbiology》1989,151(2):159-165
Mesophilic strains producing a new bacteriocin: Megacin BII, have been isolated from strains of Bacillus megaterium. Facultatively thermophilic strains producing Megacin BI were less sensitive to this new activity than nonproducing mesophiles and strains producing Megacin BII were also also more resistant to Megacin BI. Strains producing Megacin BII contained a large plasmid of 36·106:pSE 203. This plasmid was introduced into non-megacinogenic acceptor strains by protoplast transformation, they then became megacin producers and immune to Megacin BII. Plasmid pSE 203 has been mapped with endonucleases. No similarity to the Megacin A plasmids pBM 309 [Rostás et al. (1980) and pBM 113 (von Tersch and Carlton (1983b)] was evident.Abbreviations CFU
colony forming units
- CCO
covalently closed circular
- OC
open circular
- LIN
linear
- EB
ethidium bromide
- Meg
megacin
- Tris
tris (hydroxyl methyl) amino methane
- Ot
obligately thermophilic
- Ft
facultatively thermophilic
- Sm
streptomycin
- Trim
trimethoprim
- Rif
rifampicin
- Thy
thymine
- Tc
tetracycline 相似文献
88.
The objective of this study was to investigate the mode of action of BLS P34, a bacteriocin-like substance (BLS) produced
by a novel Bacillus sp. strain P34 isolated from the Amazon basin. The effect of the BLS was tested against Listeria monocytogenes, showing a bactericidal effect at 200 AU (activity units) ml−1, while no inhibition of spore outgrowth of Bacillus cereus was observed with a dose of 1,600 AU ml−1. Growth of Escherichia coli and Salmonella Enteritidis was inhibited, but only when the chelating agent EDTA was co-added with the BLS. The effect of BLS P34 on L. monocytogenes was also investigated by Fourier transform infrared spectroscopy. Treated cells showed an important frequency increase in
1,452 and 1,397 cm−1 and decrease in 1,217 and 1,058 cm−1, corresponding assignments of fatty acids and phospholipids. Transmission electron microscopy showed damaged cell envelope
and loss of protoplasmic material. BLS P34 was bactericidal to Gram-positive, and also showed inhibitory effect against Gram-negative
bacteria. There is evidence that its mode of action corresponds to that of a membrane-active substance. The knowledge about
the mode of action of this BLS is essential to determine its effective application as an antimicrobial agent. 相似文献
89.
Summary Bacteriocin ST33LD, produced by Leuconostoc mesenteroides subsp. mesenteroides, is approximately 2.7 kDa in size and inhibits Enterococcus faecalis, Escherichia coli, Lactobacillus casei and Pseudomonas aeruginosa. Good growth was recorded in the presence of 10% (w/v) soy milk or 10% (w/v) molasses, but there was no bacteriocin production.
Growth in MRS broth adjusted to pH 4.5 yielded low bacteriocin levels (800 AU/ml). However, the same medium adjusted to pH
5.0, 5.5 and 6.5, respectively, yielded 3200 AU/ml. Tween 80 decreased bacteriocin production by more than 50%. Growth in
the presence of tryptone yielded maximal activity (12,800 AU/ml), whereas different combinations of tryptone, meat extract
and yeast extract produced activity levels of 1600 AU/ml and less. Growth in the presence of 2.0% (w/v) sucrose, or maltose,
yielded much higher levels of bacteriocin activity (12,800 AU/ml) compared to growth in the presence of 2.0% (w/v) glucose
or lactose (6400 AU/ml). Lower yields were also recorded in the presence of fructose and mannose. KH2PO4 at 10.0% (w/v) stimulated bacteriocin production. Glycerol concentrations of 0.5% (w/v) and higher (up to 5.0%, w/v) repressed
bacteriocin production by 50%. The addition of cyanocobalamin, thiamine and L-ascorbic acid to MRS broth (1.0 ppm) yielded
12,800 AU/ml bacteriocin, whereas the addition of DL-6,8-thioctic acid yielded only 6 400 AU/ml. 相似文献
90.