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排序方式: 共有74条查询结果,搜索用时 936 毫秒
41.
Christopher Marlowe A. Caipang Ingvild Berg Monica F. Brinchmann Viswanath Kiron 《Aquaculture (Amsterdam, Netherlands)》2009,295(1-2):110-115
Considering overcrowding as a stressor, the effects of a short-term exposure on the immune responses of Atlantic cod, Gadus morhua L. were determined at 2, 24 and 72 h post-crowding. While plasma glucose and total antioxidant capacity were quantified as stress responses, immune responses were based on humoral indices. Bactericidal capacity of plasma was also assessed. There was a significant increase in plasma glucose and total antioxidant capacity at 2 h post-crowding, however the former returned to pre-stress levels 24 h later and the latter remained elevated until 72 h. The plasma protein did not reveal any significant change, but there was a transient upregulation of globulin at 24 h post-crowding. The myeloperoxidase activity increased at 2 h after the stress, but returned to its pre-stress levels at 24 h. The lysozyme activity was upregulated even from the first time point after stress, although the differences were significant only at 24 and 72 h compared to the activity prior to stress. At 72 h post-crowding there was a significant increase in alkaline phosphatase activity while haemolytic activity showed a significant decrease. An increase in the proliferation of the bacterial pathogens, Vibrio anguillarum and Aeromonas salmonicida was seen from 24 h in the plasma of the stressed fish. Thus, our finding suggests that short-term crowding stress modulates the immune responses in Atlantic cod and therefore husbandry procedures should consider these effects while addressing better management strategies. 相似文献
42.
43.
Jorunn Larsen Peter G. Appleby Guttorm N. Christensen Toril Berg Ingvar Eide 《Water, air, and soil pollution》2010,206(1-4):237-250
Sediment cores collected from 12 lakes and eight marine sites along the Norwegian and Svalbard coast as part of a project investigating polycyclic aromatic hydrocarbons (PAH) in sediments were dated radiometrically using 210Pb, 137Cs and 241Am fallout radionuclides. In all lake cores, except on Svalbard, the 137Cs activity versus depth profile appears to have been significantly modified by post-depositional migration within the sediment column. The relatively low 137Cs inventories suggest that these sites were not significantly impacted by fallout from the 1986 Chernobyl accident. All the marine cores have 137Cs inventories that are substantially lower than in lake sediments almost certainly due to leaching of 137Cs from the marine sediments due to higher solubility in the seawater. In the marine surface sediments, the unsupported 210Pb concentrations are up to an order of magnitude lower than in the corresponding lake sediments reflecting the higher (dry mass) sedimentation rate at the marine sites. Five of the cores including marine sites and lakes have unusual high 210Pb flux most likely due to sediment focusing. Most of the irregularities in the 210Pb records seem to be due to slump events but some patterns are also due to possibly increased accumulation rates. Three of the marine cores show systematic increase in their sedimentation rate from c.1960 towards the present while only one lake shows the same systematic increase. 相似文献
44.
Atkinson (Reports, 15 April 2011, p. 346) argues that the phonological complexity of languages reflects the loss of phonemic distinctions due to successive founder events during human migration (the serial founder hypothesis). Statistical simulations show that the type I error rate of Atkinson's analysis is hugely inflated. The data at best support only a weak interpretation of the serial founder hypothesis. 相似文献
45.
I J Mehlman E L Eide A C Sanders M Fishbein C C Aulisio 《Journal of the Association of Official Analytical Chemists》1977,60(3):546-562
Surveillance for dysentery-related invasive potential in bacteria using the Sereny keratoconjunctivitis test is restricted by expense, time factor, and necessity for confirmation. Primary screening of isolates in a standardized mammalian cell culture system is recommended. Bacteria are grown 20 hr in veal infusion, washed, and resuspended in 20% heat-inactivated fetal bovine serum (FBS) supplemented with 0.12% brain heart infusion and 0.1% bile salts. The HeLa culture is grown 20 hr as a monolayer in chamber slides with 90% minimal essential medium (MEM)-10% FBS. The host culture is infected at a ratio of 10 bacteria/mammalian cell for 3 hr at 35 degrees C. The infection medium is replaced with MEM-FBS supplemented with 300 microng lysozyme and 5 microng gentamycin/ml. The infected monolayer is incubated 5 hr at 35 degrees C to permit intracellular multiplication. Specimens are washed, fixed with methanol, and stained successively with May-Grunwald and Giemsa dyes. Bacteria occur within the cytoplasm if invasion has occurred. The criterion for a positive test is that 1% of the host cells possesses at least 5 bacteria in 2 of 3 trials. Invasiveness is correlated with and possibly preconditioned by cytotoxic principle(s). Infectivity rates vary from 0 to 30%. The cytopathic effect is noted in 5-50% of HeLa cells. Positive results must be confirmed by the Sereny test. 相似文献
46.
Christensen PR Wyatt MB Glotch TD Rogers AD Anwar S Arvidson RE Bandfield JL Blaney DL Budney C Calvin WM Fallacaro A Fergason RL Gorelick N Graff TG Hamilton VE Hayes AG Johnson JR Knudson AT McSween HY Mehall GL Mehall LK Moersch JE Morris RV Smith MD Squyres SW Ruff SW Wolff MJ 《Science (New York, N.Y.)》2004,306(5702):1733-1739
The Miniature Thermal Emission Spectrometer (Mini-TES) on Opportunity investigated the mineral abundances and compositions of outcrops, rocks, and soils at Meridiani Planum. Coarse crystalline hematite and olivine-rich basaltic sands were observed as predicted from orbital TES spectroscopy. Outcrops of aqueous origin are composed of 15 to 35% by volume magnesium and calcium sulfates [a high-silica component modeled as a combination of glass, feldspar, and sheet silicates (approximately 20 to 30%)], and hematite; only minor jarosite is identified in Mini-TES spectra. Mini-TES spectra show only a hematite signature in the millimeter-sized spherules. Basaltic materials have more plagioclase than pyroxene, contain olivine, and are similar in inferred mineral composition to basalt mapped from orbit. Bounce rock is dominated by clinopyroxene and is close in inferred mineral composition to the basaltic martian meteorites. Bright wind streak material matches global dust. Waterlain rocks covered by unaltered basaltic sands suggest a change from an aqueous environment to one dominated by physical weathering. 相似文献
47.
McSween HY Arvidson RE Bell JF Blaney D Cabrol NA Christensen PR Clark BC Crisp JA Crumpler LS Des Marais DJ Farmer JD Gellert R Ghosh A Gorevan S Graff T Grant J Haskin LA Herkenhoff KE Johnson JR Jolliff BL Klingelhoefer G Knudson AT McLennan S Milam KA Moersch JE Morris RV Rieder R Ruff SW De Souza PA Squyres SW Wänke H Wang A Wyatt MB Yen A Zipfel J 《Science (New York, N.Y.)》2004,305(5685):842-845
The Spirit landing site in Gusev Crater on Mars contains dark, fine-grained, vesicular rocks interpreted as lavas. Pancam and Mini-Thermal Emission Spectrometer (Mini-TES) spectra suggest that all of these rocks are similar but have variable coatings and dust mantles. Magnified images of brushed and abraded rock surfaces show alteration rinds and veins. Rock interiors contain =25% megacrysts. Chemical analyses of rocks by the Alpha Particle X-ray Spectrometer are consistent with picritic basalts, containing normative olivine, pyroxenes, plagioclase, and accessory FeTi oxides. M?ssbauer, Pancam, and Mini-TES spectra confirm the presence of olivine, magnetite, and probably pyroxene. These basalts extend the known range of rock compositions composing the martian crust. 相似文献
48.
The influence of the fauna on displacement and on homogeneity and permeability of soils The influence of the most important soil animals (mammals, ants, termites, woodlice and earthworms) on displacement and on homogeneity and permeability of soils is discussed in reference to both older and more recent literature. Nearly all soil animals cause displacement of organic and mineral soil particles. The quantity, intensity and direction of this activity depends upon the morphological characters of the species involved. The homogeneity of soils is positively influenced only by the earthworms (and related forms) whereas the activity of the other soil fauna mostly has a contrary effect as far as shorter periods are concerned. The permeability of soils increases in different dimensions due to the activity of all species discussed. Permanent vegetation and non-tilling for the most part favour the activity of the soil fauna. Recent field experiments dealing with minimum or zero tillage have made this fact fairly evident. 相似文献
49.
Yerushalmi J Kolodney M Graff RA Squires AM Harvey RD 《Science (New York, N.Y.)》1975,187(4177):646-648
In a bed of anthracite or bituminous coke fluidized by air at 10 to 15 meters per second at 1200 degrees to 1400 degrees C, molten ash forms beads on the surface of a coke particle, some exuding from its interior. The beads merge and detach them-selves to grow further as loose fluidized ash agglomerates of low carbon content. 相似文献
50.
Zoospore suspensions ofPhytophthora infestans applied to potato cultivars in the field with an exponential inoculum sprayer resulted in defoliation within a range of severity that was log-normal with respect to inoculum concentration. Regression lines for different cultivars differed in position and, depending upon moisture conditions, slope, indicating that the cultivars differed in resistance to penetration and to invasion of tissue by the pathogen. 相似文献