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排序方式: 共有229条查询结果,搜索用时 187 毫秒
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RAYMOND IGNAR DONALD ENGLISH LUIS JIMENEZ 《Journal of Rapid Methods and Automation in Microbiology》1998,6(1):51-58
Abstract The Celsis ATP Bioluminescence method was optimized and validated to detect the presence of microbial contamination in High Fluoride and Triclosan dentifrice formulations. Several enrichment broths were evaluated by using a 24–27 h incubation period. The ATP concentrations of the enrichment broths were found to a range from 0.012 to 0.040 nM. None of the tested enrichment broths were found to exhibit any sample inhibition/enhancement effects on the ATP Bioluminescence reaction. Dentifrice suspensions were inoculated with bacteria, yeast, and mold. All test microorganisms (ca. 1–15 CFU/g) were detected within a 24–27 h incubation period by using TAT Broth Base enrichment broths containing different concentrations of the following ingredients: Tween 20, Neopeptone, Dextrose, Triton X-100, Thiosulfate, Sodium Dibasic Phosphate, and Glycine. Negative ATP response after 24–27 h of incubation at 35C indicates the absence of contamination from these products. 相似文献
3.
THE DEVELOPMENT OF CHLOROPLASTS IN ROOT MERISTEMATIC TISSUE OF SECALE CEREALE L. SEEDLINGS 总被引:1,自引:1,他引:0
LUIS OLIVEIRA 《The New phytologist》1982,91(2):263-275
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JUAN CARLOS ALONSO LUIS MARIANO GONZALEZ† BORJA HEREDIA† JOSE LUIS GONZALEZ‡ 《Ibis》1987,129(S1):212-224
The behaviour of five broods of radio-tagged Spanish Imperial Eagles Aquila heliaca adalberti was studied in Doñana National Park, Spain during the post-fledging period. The distance between perching sites and nest, the mean flight duration and distance, the percentage of time spent flying and the home range all increased exponentially with age. As the young got older, the parents spent less time in their vicinity. Young were not seen hunting, but depended on their parents for food. They begged and chased their parents throughout the post-fledging period, with higher intensity at the end. Nevertheless, the adults became progressively more reluctant to feed them, as reflected in the decrease in feeding frequency and in the number of approaching flights towards the young. At the end of the post-fledging period, adults often performed aerial displays and frequently chased their offspring. The age of independence of the different young studied varied between 123 and 145 days. The correlations between individual independence and the dates when the young were last fed by their parents, and when the highest intensity of parental aggressive behaviour occurred, were higher than correlations with the variables related to the maturation of flying. Therefore, it is suggested that parental 'meanness' and aggressive behaviour may be the factors determining the date of juvenile independence and dispersal from the home territory. 相似文献
5.
PILAR DELGADO PURIFICACION CALVO ANTONIO TORRES 《The Journal of eukaryotic microbiology》1988,35(3):393-399
The Euplotes cytoskeleton obtained by treatment with Triton X-100 in a microtubule-stabilizing buffer has been studied by electron microscopy and SDS-polyacrylamide electrophoresis. An antiserum has been prepared using the tubulin band from preparative gels of Euplotes cytoskeletons as an antigen. This antiserum reacts with the tubulin from different ciliated protozoa but fails to recognize the vertebrate tubulin by immunoblotting. Immunoblotting studies have demonstrated a slower electrophoretic mobility for the α-tubulin of Euplotes and Oxytricha than that of Paramecium and Tetrahymena. A cytoplasmic microtubular network in Euplotes has been revealed by indirect immunoftuorescence using both an anti-α-tubulin monoclonal antibody directed against chick brain tubulin and an antiserum raised against the tubulin of Euplotes. 相似文献
6.
Macaca mulatta with multilead electrodes permanently implantedin the brain were electrically stimulated, either under restraint,or by radio while moving freely as part of a colony, in whichcase individual and social behavior were recorded, analyzed,and quantified with the aid of time-lapse photography. Somecerebral radio stimulations evoked complex sequences of wellorganized responses. Increase in running and in offensive behaviorwas produced by excitation of midline thalamus, while even fasterrunning without changes in aggressiveness was produced by stimulationof the fimbria of the fornix. Conditioning was absent in thefirst case, but it was easily established in the latter. Increasein aggressive behavior was also produced by stimulation of Forel'sfield, the nucleus ventralis posterior lateralis of the thalamus,and the central gray matter. Increase in aggressiveness wasoriented by the animal according to past experience, likes anddislikes, and was adapted to the changing strategies of itsopponent, indicating an excellent processing of sensory information,and demonstrating that brain stimulation had induced a "drive"and not a stereotyped motor response. As a working hypothesis it is proposed that cerebral mechanismsfor perception of pain and for aggressive behavior have differentanatomical and physiological systems closely interrelated byuse, disuse, and conditioning. 相似文献
7.
Macrophytes from lakes in the eastern Pyrenees: community composition and ordination in relation to environmental factors 总被引:2,自引:0,他引:2
ESPERANÇA GACIA†‡ ENRIC BALLESTEROS† LLUIS CAMARERO†§ OLGA DELGADO ANTONI PALAU† JOAN LLUIS RIERA§ JORDI CATALAN†§ 《Freshwater Biology》1994,32(1):73-81
1. Thirty-six species of macrophytes (fourteen flowering plants, two quillworts, sixteen mosses and liverworts, and two algae) were collected in an extensive survey of 116 high mountain lakes in the eastern Pyrenees. Seventy per cent of the lakes showed macrophyte development. 2. The isoetids (Isoetes lacusiris, Isoetes setacea and Subularia aquatica) were the dominant growth form, although the natopotamid Sparganium angusifolium was the most widespread species. Potamids (Potamogeton spp., Ranunculus spp.), the alga Nitella gr. opaca and some mosses (Warnstorfia exannulata, Sphagnum denticulatum) were often present. 3. A multivariate ordination analysis (RDA-redundancy analysis) revealed that water chemistry, altitude and vegetation cover of the catchment, and nutrient availability are major environmental factors associated with macrophyte distribution along the eastern Pyrenean lakes. Isoetids prevailed in softwater oligotrophic lakes, potamids in relatively hardwater oligotrophic lakes, and Potamogeton natans and Callitriche palustris in small and eutrophic water bodies affected by the presence of cattle. 相似文献
8.
Species-specific phytoplankton responses to nutrients and zooplankton manipulations in enclosure experiments 总被引:2,自引:0,他引:2
1. In situ enclosure experiments were performed in the mesotrophic Bermejales reservoir to evaluate the algal response to changes in the nutrient supply and in the zooplankton size structure and density in a 2 × 2 factorial design. The experiments were conducted during the spring bloom of nanoplanktonic diatoms in 1989. 2. Nutrient enrichment promoted a great increase of phytoplankton biomass indicating a strong nutrient limitation on phytoplankton growth. Total phytoplankton biomass was significantly lower in the Daphina-added enclosures at a given nutrient level and strong direct an indirect effect of zooplankton on phytoplankton community structure and nutrient availability were observed. 3. Most of the nanoplanktonic species were effectively grazed but species with protective coverings and large size colonies were favoured by grazers and small chlorococcales were unaffected probably because of their compensatory high growth rates. The decrease in total biomass imposed by grazers is attributable mainly to the decrease of Cyclotella ocellata, the most abundant species. This taxon suffers two net effects of zooplankton: direct grazing and the indirect decrease of Si availability caused by the growth of C. ocellata which was promoted by P excretion by zooplankton. Indirect effects of grazers on Si availability should, therefore, be taken into account in explaining phytoplankton succession and community structure. 4. In this experiment grazers affected considerably the nanoplanktonic community in Bermejales reservoir. The extent which they were affected, however, depended not only on the algal size as a determinant of edibility but also greatly on the specific nutrient requirements and taxonomic features of the algal species. 相似文献
9.
The Little Bustard is suffering a widespread population decline mainly due to agricultural intensification. This study evaluates the effects of intensification level, habitat availability and rainfall on the population dynamics of this species. The population density of males was monitored for 7 years (2002–2008) at 184 points located within three sites with contrasting levels of agricultural intensification in southern Portugal. Densities decreased along the intensification gradient from 8.2 to 2.3 males / km2. Overall, there was an approximately 50% population decline during the period 2002–2008, driven by a decline observed in one of the less intensive sites, whereas in the other two sites densities remained fairly constant. Yearly variations in male densities were influenced by intensification level, amount of grassland habitat and rainfall patterns. Thus, agricultural intensification is having a negative effect on population densities of this threatened species, particularly through the loss of grasslands (fallow fields and pastures) suitable for displaying males. The results also suggest a positive impact of rainfall on male densities, although this is more likely in grasslands within less intensive agricultural regions of poorer soil quality, where higher breeding male densities occur. Grassland habitat quality, driven by both climate and human management, probably plays a major role in the population dynamics of this threatened steppe bird in its strongholds. 相似文献
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