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101.
The phylogenetic position of the Pedetidae, represented by a single species
Pedetes capensis, is controversial, reflecting in part the retention of
both Hystricomorphous and Sciurognathous characteristics in this rodent. In
an attempt to clarify the species evolutionary relationships, mtDNA gene
sequences from 10 rodent species (representing seven families) were
analyzed using phenetic, parsimony, and maximum-likelihood methods of
phylogenetic inference; the rabbit, Oryctolagus cuniculus (Order
Lagomorpha), and cow, Bos taurus (Order Artiodactyla), were used as
outgroups. Investigation of 714 base pairs of the protein-coding cytochrome
b gene indicate strong base bias at the third codon position with
significant rate heterogeneity evident between the three structural domains
of this gene. Similar analyses conducted on 816 base pairs of the 12S rRNA
gene revealed a transversion bias in the loop sections of all taxa. The
cytochrome b gene sequences proved useful in resolving associations between
closely related species but failed to produce consistent tree topologies at
the family level. In contrast, phylogenetic analysis of the 12S rRNA gene
resulted in strong support for the clustering of
Pedetidae/Heteromyidae/Geomyidae and Muridae in one clade to the exclusion
of the Hystricidae/Thryonomyidae and Sciuridae, a finding which is
concordant with studies of rodent fetal membranes as well as reproductive
and other anatomical features.
相似文献
102.
Influence of Ammonium Salts and Cane Molasses on Growth of Alcaligenes eutrophus and Production of Polyhydroxybutyrate 总被引:1,自引:0,他引:1
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The production of polyhydroxybutyrate (PHB) by Alcaligenes eutrophus DSM 545 was studied in a synthetic medium with 3% glucose at pH 7.0 supplemented with several ammonium substrates and cane molasses. Growth was measured by dry cell weight, and the PHB content was measured by gas chromatography. The effects of ammonium sources such as sulfate, nitrate, phosphate, and chloride salts and those of different ammonium sulfate concentrations were evaluated. The best growth and PHB production were obtained with ammonium sulfate; however, NH(inf4)(sup+) concentrations between 0.5 and 1.5 g/liter showed no significant difference. Ammonium sulfate was therefore used as the sole source of NH(inf4)(sup+) for experiments with cane molasses as the growth activator. Optimal growth and PHB production were obtained with 0.3% molasses. However, the yields of biomass (39 to 48%) and PHB (17 to 26%) varied significantly among the different ammonium substrates and cane molasses concentrations. 相似文献
103.
T. Jegajothivel Pandian 《Helgoland Marine Research》1967,15(1-4):637-647
Summary 1. In the fishOphiocephalus striatus
Bloch feeding rate increased 2 to 3 times, when feeding was resumed after less than 20 days fasting; fasting periods of more than 20 days result in resumption-feeding rates that were only slightly higher (0.5 to 0.8 times) than the controls.2. Although feeding rates were very high after resumption of feeding following different periods of starvation (10 to 40 days) absorption efficiency remained practically identical to that of controls.3. Following a period of less than 20 days fasting resumption of feeding led conversion efficiencies almost twice as high as the normal values, showing over-compensation. Fish fed after a period of more than 20 days fasting showed a decrease in conversion efficiency resulting in partial compensatory growth.4. Responses to resumption of feeding following different periods of starvation may be of two types: (a) Rates of metabolism and feeding are restored to pre-starvation rates and conversion efficiency increases due to corresponding increase in feeding rates, e. g. O.striatus, and (b) rates of metabolism and feeding continue to remain low and the increase in conversion efficiency is due to a corresponding decrease in energy expended on metabolism e. g.,E. lucius.
Part of a Ph. D. Thesis, University of Madras, India. 相似文献
Nahrungsaufnahme, Absorption und Konversion bei dem FischOphiocephalus striatus
Kurzfassung Individuen vonOphiocephalus striatus Bloch wurden nach verschieden langen Hungerzeiten gefüttert, um Aufschlüsse über Aufnahme, Absorption und Konversion der Nahrung zu erhalten. Nach einer Hungerperiode von weniger als 20 Tagen nahm die Nahrungsaufnahme um das Dreifache zu. Hungerten die Tiere länger als 20 Tage, so steigerte sich die Nahrungsaufnahme hingegen nur geringfügig. Trotz der erhöhten Nahrungsaufnahme war der Absorptions-Nutzeffekt dem der Kontrolltiere gleich. Der Konversions-Nutzeffekt verdoppelte sich bei Individuen, die weniger als 20 Tage gehungert hatten; daraus resultierte eine Überkompensation des Wachstums. Bei Tieren, die nach einer Hungerperiode von mehr als 20 Tagen wieder gefüttert wurden, konnte eine gewisse Verringerung des Konversions-Nutzeffektes sowie eine teilweise Kompensation festgestellt werden. Diese Ergebnisse werden im Hinblick auf ähnliche Versuche beiEsox lucius (Ivlev 1939) diskutiert. Es wird die Schlußfolgerung gezogen, daß sich bei Fischen, die nach verschieden langen Hungerzeiten erneut gefüttert werden, zwei Typen unterscheiden lassen: beim ersten Typ ist die Nahrungsaufnahme geringer als vor der Hungerzeit, der Konversions-Nutzeffekt jedoch durch Erniedrigung der für den Stoffwechsel aufgebrachten Energie erhöht; beim zweiten Typ erreichen Nahrungsaufnahme und Stoffwechselintensität sofort die Werte vor der Hungerzeit oder übertreffen diese sogar. Hierbei wird die Erhöhung der Nahrungsaufnahme von einer entsprechenden Vergrößerung des Konversions-Nutzeffektes begleitet.
Part of a Ph. D. Thesis, University of Madras, India. 相似文献
104.
Production and characterization of anti-DNA-RNA monoclonal antibodies and their application in Listeria detection. 总被引:5,自引:2,他引:3
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I Fliss M St Laurent E Emond R Lemieux R E Simard A Ettriki S Pandian 《Applied microbiology》1993,59(8):2698-2705
Murine monoclonal antibodies (MAbs) specific for DNA-RNA hybrids were successfully produced with two different heteropolymers as antigens, cDNA-mRNA and phi X174 DNA-RNA heteroduplexes. The former was simpler to prepare. Both had shown similar immunogenicities. Two different immunoglobulin M MAbs were isolated. The 20D3 MAb, generated with the phi X174 DNA-RNA hybrid, showed association constants of 1.05 x 10(12), 2.12 x 10(10), and 1.68 x 10(7) for the antigens phi X174 DNA-RNA, cDNA-mRNA, and poly(rA)-poly(dT), respectively. The 6B5 MAb, obtained with the cDNA-mRNA hybrid, showed association constants of 1.59 x 10(5), 5 x 10(12), and 7.1 x 10(8) for the above-described antigens, respectively. With the 20D3 MAb, an immunoassay was developed for the detection of Listeria DNA-RNA hybrids. In brief, a biotinylated rRNA gene probe specific for the genus Listeria was hybridized with rRNA in the solution phase. The hybrids thus formed were then captured in microtiter plate wells precoated with the purified 20D3 MAb, and the probe-target hybrids were detected with a streptavidin-alkaline phosphatase conjugate. This assay was shown to be specific for the genus Listeria and highly sensitive, allowing the detection of as little as 2.5 pg of target rRNA. 相似文献
105.
I. Fliss M. St-Laurent E. Emond R. E. Simard R. Lemieux A. Ettriki S. Pandian 《Applied microbiology and biotechnology》1995,43(4):717-724
This study was undertaken to evaluate the potential of a new approach using anti-DNA · RNA monoclonal antibodies to detect Listeria in both pure culture and inoculated meat and meat products. A sensitive liquid-phase assay was first developed, based on the formation in solution of a hybrid between a 784-bp DNA probe, specific for the genus Listeria, and target rRNA. Monoclonal antibody and antisera raised against hybrid nucleic acids were then used in various immunoenzymatic assays to detect specific hybrids formed in solution. System 2, using a double sandwich enzyme-linked immunosorbent assay, and system 1, using a biotinylated probe, proved to be very effective. The method using biotin-streptavidin complex, however, resulted in a higher background signal. System 2 described here, using unlabeled probe, was more effective. This strategy allowed the detection of as little as 2.5 pg target RNA from pure culture and 500 cells from inoculated meat homogenate, even in the presence of other contaminating bacteria. The assay was more sensitive and could be completed within 3 h, as opposed to several days when conventional culture methods were used. 相似文献
106.
107.
Duy Duc Nguyen Ramesh Pandian Doyoun Kim Sung Chul Ha Hye-Jin Yoon Kap Sun Kim Kyung Hee Yun Jin-Hahn Kim Kyeong Kyu Kim 《Biochemical and biophysical research communications》2014
The peptidases in clan MH are known as cocatalytic zinc peptidases that have two zinc ions in the active site, but their metal preference has not been rigorously investigated. In this study, the molecular basis for metal preference is provided from the structural and biochemical analyses. Kinetic studies of Pseudomonas aeruginosa aspartyl aminopeptidase (PaAP) which belongs to peptidase family M18 in clan MH revealed that its peptidase activity is dependent on Co2+ rather than Zn2+: the kcat (s−1) values of PaAP were 0.006, 5.10 and 0.43 in no-metal, Co2+, and Zn2+ conditions, respectively. Consistently, addition of low concentrations of Co2+ to PaAP previously saturated with Zn2+ greatly enhanced the enzymatic activity, suggesting that Co2+ may be the physiologically relevant cocatalytic metal ion of PaAP. The crystal structures of PaAP complexes with Co2+ or Zn2+ commonly showed two metal ions in the active site coordinated with three conserved residues and a bicarbonate ion in a tetragonal geometry. However, Co2+- and Zn2+-bound structures showed no noticeable alterations relevant to differential effects of metal species, except the relative orientation of Glu-265, a general base in the active site. The characterization of mutant PaAP revealed that the first metal binding site is primarily responsible for metal preference. Similar to PaAP, Streptococcus pneumonia glutamyl aminopeptidase (SpGP), belonging to aminopeptidase family M42 in clan MH, also showed requirement for Co2+ for maximum activity. These results proposed that clan MH peptidases might be a cocatalytic cobalt peptidase rather than a zinc-dependent peptidase. 相似文献
108.
109.
Marleen TJ van Ampting Arjan J Schonewille Carolien Vink Robert Jan M Brummer van der Roelof Meer Ingeborg MJ Bovee-Oudenhoven 《BMC physiology》2009,9(1):6-9
Background
Glutathione, the main antioxidant of intestinal epithelial cells, is suggested to play an important role in gut barrier function and prevention of inflammation-related oxidative damage as induced by acute bacterial infection. Most studies on intestinal glutathione focus on oxidative stress reduction without considering functional disease outcome. Our aim was to determine whether depletion or maintenance of intestinal glutathione changes susceptibility of rats to Salmonella infection and associated inflammation. 相似文献110.
Chari Nithya Mansur Farzana Begum Shunmugiah Karutha Pandian 《Applied microbiology and biotechnology》2010,88(1):341-358
According to the Centers for Disease Control and Prevention, biofilms cause 65% of infections in developed countries. Pseudomonas aeruginosa biofilm cause life threatening infections in cystic fibrosis infection and they are 1,000 times more tolerant to antibiotic
than the planktonic cells. As quorum sensing, hydrophobicity index and extracellular polysaccharide play a crucial role in
biofilm formation, extracts from 46 marine bacterial isolates were screened against these factors in P. aeruginosa. Eleven extracts showed antibiofilm activity. Extracts of S6-01 (Bacillus indicus = MTCC 5559) and S6-15 (Bacillus pumilus = MTCC 5560) inhibited the formation of PAO1 biofilm up to 95% in their Biofilm Inhibitory Concentration(BIC) of 50 and 60 μg/ml
and 85% and 64% in the subinhibitory concentrations (1/4 and 1/8 of the BIC, respectively). Furthermore, the mature biofilm
was disrupted to 70–74% in their BIC. The antibiofilm compound from S6-15 was partially purified using solvent extraction
followed by TLC and silica column and further characterized by IR analysis. Current study for the first time reveals the antibiofilm
and antiquorum-sensing activity of B. pumilus, B. indicus, Bacillus arsenicus, Halobacillus trueperi, Ferrimonas balearica, and Marinobacter hydrocarbonoclasticus from marine habitat. 相似文献