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61.
A phylogenetic analysis of the genus Leuconostoc based on reverse transcriptase sequencing of 16 S rRNA 总被引:10,自引:0,他引:10
The phylogenetic interrelationships of members of the genus Leuconostoc and some heterofermentative lactobacilli, which phenotypically resemble leuconostocs, were investigated by comparative analysis of their 16 S rRNA sequences. The six species, Leuconostoc mesenteroides, Leu. carnosum, Leu. citreum, Leu. gelidum, Leu. lactis and Leu. pseudomesenteroides exhibited a high degree of sequence similarity with each other and formed a phylogenetically coherent group, quite separate from all other lactic acid bacteria investigated. The species Leu. paramesenteroides was found to be phylogenetically distinct from the Leu. mesenteroides group of species and formed a natural grouping with the heterofermentative lactobacilli, Lb. confusus, Lb. kandleri, Lb. minor and Lb. viridescens. The rRNA sequence of the acidophilic species, Leu. oenos, displayed exceptionally low levels of homology with all of the other taxa examined. The 16 S sequence of Leu. oenos showed major nucleotide differences in relatively highly conserved positions of the molecule indicating this species is phylogenetically distinct and warrants a separate genus. 相似文献
62.
M R Smith J C Zahnley R Y Wong R E Lundin J A Ahlgren 《Journal of industrial microbiology & biotechnology》1998,21(1-2):37-45
A mutant strain (R1510) of Leuconostoc mesenteroides B-1355 was isolated which synthesized primarily an insoluble polysaccharide and little soluble polysaccharide when grown
in sucrose-containing medium. Glucose or sucrose cultures of this strain produced a single intense band of GTF-1 activity
of 240 kDa on SDS gels, and a number of faint, smaller bands. Oligosaccharides synthesized by strain R1510 from methyl-α-D-glucoside
and sucrose included a trisaccharide whose structure contained an α(1→2) glucosidic linkage. This type of linkage has not
been seen before in any products from strain B-1355 or its mutant derivatives. The structure of the purified trisaccharide
was confirmed by 13C-nuclear magnetic resonance. The insoluble polysaccharide also contained α(1→2) branch linkages, as determined by methylation
analysis, showing that synthesis of the linkages was not peculiar to methyl-α-D-glucoside. GTF-1, which had been excised with
a razor blade from an SDS gel of a culture of the parent strain B-1355, produced the same trisaccharides as strain R1510,
showing that GTF-1 from the wild-type strain was the same as GTF-1 from strain R1510. Mutant strains resembling strain R1510,
but producing a single intense band of alternansucrase (200 kDa) instead of GTF-1 were also isolated, suggesting that mutations
may be generated which diminished the activities for any two of the three GTFs of strain B1355 relative to the third. Strain
R1554 produced a soluble form of alternansucrase, while strain R1588 produced a cell-associated form. The mechanism(s) by
which specific GTFs become associated with the cells of L. mesenteroides was not explored.
Received 12 May 1998/ Accepted in revised form 16 July 1998 相似文献
63.
Arvanitis Nikolaos Kotzamanidis Charalambos Z. Skaracis George N. Karagouni Amalia D. 《World journal of microbiology & biotechnology》2004,20(3):291-296
The antimicrobial activities of five commercial disinfectants containing quaternary ammonium compound-isopropanol (D1), sodium
methyl dithiocarbamate (D2), sodium thiocarbamate (D3), sodium dimethyl dithiocarbamate (D4) and formaldehyde (D5) were studied
against three main saccharolytic indigenous isolates (Bacillus cereus, Lactobacillus plantarum and Leuconostoc mesenteroides) from a beet sugar extraction line. Preliminary studies suggested that although all the disinfectants were effective against
those isolates, the high economic cost in combination with large amounts of the disinfectants D2, D3 and D4 weaken their possibility
for industrial use. Therefore, the minimum inhibitory concentration (MIC) of the other two examined disinfectants D1 and D5
was determined and survivor curves were obtained, for a period of 7 days. Bacterial counts against time (h) suggested that
D1 was more effective than D5 against the microbial population. In particular, D1 was bacteriolytic above 7 mg/l for B. cereus and bactericidal above 80 mg/l for Lc. mesenteroides and above 100 mg/l for L. plantarum. The disinfectant D5 was bacteriolytic above 25 mg/l for B. cereus and bactericidal above 500 mg/l for Lc. mesenteroides and L. plantarum. Taking into consideration both features, i.e. high concentration and very low cost, the use of D5 (formaldehyde) appeared
more suitable to the concerned beet sugar processor.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
64.
von Weymarn N Kiviharju K Leisola M 《Journal of industrial microbiology & biotechnology》2002,29(1):44-49
Ten heterofermentative lactic acid bacteria were compared in their ability to produce D-mannitol from D-fructose in a resting state. The best strain, Leuconostoc mesenteroides ATCC-9135, was examined in high cell density membrane cell-recycle cultures. High volumetric mannitol productivity (26.2
g l−1 h−1) and mannitol yield (97 mol%) were achieved. Using the same initial biomass, a stable high-level production of mannitol was
maintained for 14 successive bioconversion batches. Applying response surface methodology, the temperature and pH were studied
with respect to specific mannitol productivity and yield. Moreover, increasing the initial fructose concentration from 100
to 120 and 140 g l−1 resulted in decreased productivities due to both substrate and end-product inhibition of the key enzyme, mannitol dehydrogenase
(MDH). Nitrogen gas flushing of the bioconversion media was unnecessary, since it did not change the essential process parameters.
Journal of Industrial Microbiology & Biotechnology (2002) 29, 44–49 doi:10.1038/sj.jim.7000262
Received 12 November 2001/ Accepted in revised form 30 March 2002 相似文献
65.
Quantification of Leuconostoc populations in mixed dairy starter cultures using fluorescence in situ hybridization 总被引:1,自引:0,他引:1
AIMS: Development of a rapid method to identify and quantify Leuconostoc populations in mesophilic starter cultures. METHODS AND RESULTS: 16S rRNA-targeted oligonucleotide probes were used in a whole cell in situ hybridization assay for the identification of the genus Leuconostoc and an undescribed Leuconostoc ribospecies. The probes were fluorescently labelled and used to quantify the Leuconostoc populations in five different mixed starter cultures. CONCLUSIONS: There was a good correlation between the results obtained using fluorescence in situ hybridization (FISH) with that of standard plate counting methods. SIGNIFICANCE AND IMPACT OF THE STUDY: To develop a FISH method capable of identifying and quantifying the Leuconostoc population in starter cultures within 1 day. 相似文献
66.
G L Cote J A Ahlgren M R Smith 《Journal of industrial microbiology & biotechnology》1999,23(1):656-660
Leuconostoc mesenteroides strain NRRL B-1355 produces two soluble extracellular α-D-glucans from sucrose: alternan and dextran. An unusual mutant strain derived from NRRL B-1355 has recently been isolated
which produces practically no soluble polysaccharide, but significant amounts of an insoluble D-glucan. Methylation analysis shows it contains linear (1→3) and (1→6) linkages as well as (1→2) and (1→3) branch linkages.
The insoluble glucan was partially digestible by endodextranase, giving rise to a series of oligosaccharides, a high-molecular
weight soluble fraction and an insoluble residue. Treatment of the soluble dextranase-limit fraction with an α(1→2) debranching
enzyme led to further dextranase susceptibility. Methylation, FTIR and NMR analyses of the dextranase-treated fractions indicate
a non-uniform structure with domains bearing similarities to L. mesenteroides strain NRRL B-1299 dextran and to insoluble streptococcal D-glucans.
Received 05 November 1998/ Accepted in revised form 31 March 1999 相似文献
67.
Leuconostoc mesenteroides NRRL B512F is the main strain used in industrial fermentations to produce dextransucrase and dextran. This process has been studied since the Second World War, when it was used as blood plasma expander. A study about the effect of phosphate concentration on cell propagation in a semicontinuous shake-flask culture is described in this work. Dextransucrase is obtained by fermentation of the Leuconostoc mesenteroides NRRL B512F in the presence of sucrose as substrate, a nitrogen source (corn liquor or yeast extract) and minerals. Phosphate is currently used in order to buffer the culture medium. Cell propagation can be done through a repeated batch culture, where dilution in a fresh medium is made with relatively short periods. The standard medium for dextransucrase production is prepared using 0.1 M of K2HPO4. In this work the level of phosphate was increased to 0.3 M, and an increase on biomass and on the enzyme activity was found when phosphate enriched medium was used. Higher phosphate buffer concentration was also able to keep the pH values above 5.0 during the entire process, avoiding enzyme denaturation. 相似文献
68.
N. Sawa K. Okamura T. Zendo K. Himeno J. Nakayama K. Sonomoto 《Journal of applied microbiology》2010,109(1):282-291
Aim: To characterize novel multiple bacteriocins produced by Leuconostoc pseudomesenteroides QU 15. Methods and Results: Leuconostoc pseudomesenteroides QU 15 isolated from Nukadoko (rice bran bed) produced novel bacteriocins. By using three purification steps, four antimicrobial peptides termed leucocin A (ΔC7), leucocin A‐QU 15, leucocin Q and leucocin N were purified from the culture supernatant. The amino acid sequences of leucocin A (ΔC7) and leucocin A‐QU 15 were identical to that of leucocin A‐UAL 187 belonging to class IIa bacteriocins, but leucocin A (ΔC7) was deficient in seven C‐terminal residues. Leucocin Q and leucocin N are novel class IId bacteriocins. Moreover, the DNA sequences encoding three bacteriocins, leucocin A‐QU 15, leucocin Q and leucocin N were obtained. Conclusions: These bacteriocins including two novel bacteriocins were identified from Leuc. pseudomesenteroides QU 15. They showed similar antimicrobial spectra, but their intensities differed. The C‐terminal region of leucocin A‐QU 15 was important for its antimicrobial activity. Leucocins Q and N were encoded by adjacent open reading frames (ORFs) in the same operon, but leucocin A‐QU 15 was not. Significance and Impact of Study: These leucocins were produced concomitantly by the same strain. Although the two novel bacteriocins were encoded by adjacent ORFs, a characteristic of class IIb bacteriocins, they did not show synergistic activity. 相似文献
69.
A lactic acid bacteria Leuconostoc paramesenteroides was isolated and characterized from cheddar cheese and was adapted to grow at low pH (2.0) and high bile salt concentration
(2%) by sequential sub-culturing so that it can survive the extreme environmental condition of gut. Cell hydrophobicity assay
shows the maximum adherence of the culture to toluene (46.11%). Adhesion ability was confirmed by in vitro assay using rat
intestinal epithelial layer. The culture has an antimicrobial activity against food borne pathogens and is vancomycin sensitive.
The culture shows a β-galactosidase activity of 3.42 μM/mg protein, which indicates the ability of the culture to hydrolyze
lactose for easy absorption. All these properties determine the ability of the culture to be used as a probiotic. 相似文献
70.
研究L·sp.HXQ001菌株对小鼠的有益作用。通过对口服该菌液使之定植于小鼠肠道,分离小鼠粪便、肠段匀浆中该菌菌落及作肠段切片HE染色,肠道的正常防御机制不能杀灭该菌,并能在小鼠肠道定植,且以结肠为主。该菌定植肠段有淋巴细胞浸润,但无变性坏死等变化,显示生理性炎症反应。L.sp.HXQ001菌株不是小鼠肠道正常菌群但仍可定植于肠道、激发机体免疫应答。有望成为新的肠道微生态调节剂。 相似文献