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71.
为了解南沙群岛海域春、秋季浮游介形类生态学特征,根据2013年春季(3月中旬至4月初)及秋季(9月)在南沙群岛开展的两个航次生态环境综合调查资料,对该海域浮游介形类生态学特征进行分析研究。结果显示:(1)南沙群岛海域浮游介形类物种组成较为丰富,记录 45种隶属于2科、4亚科、19属。其中,春季有21种,秋季38种,两季均出现的共有种有14个;(2)春、秋两季浮游介形类优势种差异明显,春季优势种组成较为单一,数量低,主要生态类群为外海暖水类群和广温暖水类群,秋季优势种组成较为复杂,数量多,主要为外海暖水类群。春季优势种由后圆真浮萤、葱萤、尖头毛浮萤组成,秋季由纳米海萤、双叉真浮萤、刺喙葱萤、短形小浮萤、粗大后浮萤组成。研究表明:(1)春秋两季浮游介形类密度差异显著,密度分布不均,局部区域密度较高,与该海域局部环流密切相关;(2)浮游介形类两季平均丰富度、多样性指数和均匀度分别为0.59、1.37和0.55,秋季高于春季;(3)春季及秋季均分为岛礁群落和外海群落,群落分布随洋流改变呈季节性变化;(4)受季风影响的大环流及局部环流是浮游介形类种类组成、数量分布及多样性呈明显季节差异的主要因素。 相似文献
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73.
Shingo Mitsui Sueo Aso Kiyoshi Tensho Kikuo Kumazawa 《Soil Science and Plant Nutrition》2013,59(1):17-18
The Foliar Uptake by Squash Plant The radioactive ash for experimental use, hereafter referred to as “Bikini ash”, was prepared by igniting the heavily contaminated substances on board No. 5 Fukuryu Maru at about 650°C, followed by sifting through a 100 mesh sieve. On ignition some parts of the fission products, particularly iodine, ruthenium and tellurium would have possibly been lost to the air. 相似文献
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75.
Acute laminitis has been associated with the release of compounds, as yet unidentified, produced by hindgut fermentation which affect blood flow to the digit. The objectives of this study were to identify amine compounds in equine caecal and colonic contents, some of which are known to have vasoactive properties. In addition, the concentrations of amines in caecal contents of horses fed either grass or hay diets were compared. Fifteen amines were identified in equine hindgut contents in concentrations greater than 1 microM. The caecal concentrations of phenylethylamine, isoamylamine, cadaverine, diaminoheptane and spermidine were significantly higher in horses on spring/summer grass compared with those on winter grass or hay. These data show that many amines are present in the equine hindgut, some of which may have the potential to cause peripheral vasoconstriction if released into the circulation from the gastrointestinal tract. 相似文献
76.
Brucella organisms are pathogens that ultimate goal is to propagate in their preferred niche, the cell. Upon cell contact the bacteria is internalized via receptor molecules by activating small GTPases of the Rho subfamily and by a moderate recruitment of actin filaments. Once inside cells, Brucella localizes in early phagosomes, where it avoids fusion with late endosomes and lysosomes. These early events require the control of Rab small GTPases, and cytokines such as the G-CSF. Then, the bacterium redirects its trafficking to autophagosomes and finally reaches the endoplasmic reticulum, where it extensively replicates. Some of the bacterial molecular determinants involved in the internalization and early events after ingestion are controlled by the BvrS/BvrR two component regulatory system, whereas the intracellular trafficking beyond this early compartments are controlled by the VirB type IV secretion system. Once inside the endoplasmic reticulum, Brucella extensively replicates without restricting basic cellular functions or inducing obvious damage to cells. The integrity of Brucella LPS on the bacterial surface is one of the required factors for Brucella intracellular survival, and therefore for virulence. 相似文献
77.
对四个香菇开放式接种场所内不同时间点环境中霉菌和细菌的数量、温度和湿度进行测定,结果表明,在同一测试场所,不同测试时间点环境中霉菌和细菌的数量有所变化。总体上,消毒前和接种结束时环境中霉菌和细菌的数量相对较多,接种开始和接种进行一半时环境中霉菌和细菌的数量较少。各场所环境中的温度、湿度与霉菌和细菌的数量无相关性。消毒前环境中霉菌、细菌数量与菌棒污染率成正相关,相关系数分别为0.83和0.96;接种开始时环境中霉菌、细菌数量与菌棒污染率的相关系数分别为0.64和0.94;接种进行一半和接种结束时环境中的霉菌数量与菌棒污染率无相关性,而这两个时间点细菌数量与菌棒污染率的相关系数分别为0.62和0.88。 相似文献
78.
79.
While several studies have demonstrated that roads can act as barriers to small mammal movement, the relationship between
road density and small mammal abundance has not yet been investigated. In southeastern Ontario, Peromyscus leucopus (white-footed mice) suffer high over-winter mortality rates, resulting in small springtime populations and frequent local
extinctions. Peromyscus leucopus movement is known to be inhibited by roads, which should result in lower rates of immigration into and recolonization of
habitats in landscapes with high road density. We tested two predictions: (1) Forest sites situated in landscapes with high
road densities have a higher chance of P. leucopus being absent during the early spring than forest sites situated in landscapes with low road densities and (2) P. leucopus populations during the summer are smaller in forest sites situated in landscapes with high road densities than in landscapes
with low road densities. We sampled P. leucopus in focal patches within nineteen landscapes (7 rural, low-road-density landscapes; 7 rural, high-road-density landscapes;
5 urban landscapes). There was no significant relationship between road density and the presence/absence of P. leucopus during the early spring. We found a significant positive effect of road density on P. leucopus relative abundance during the summer, even when we excluded the urban landscapes and based the analysis on only the 14 rural
landscapes. Our results suggest that any negative effect of roads on P. leucopus populations, created by their inhibition to moving across roads, is far outweighed by some positive effect of roads on P. leucopus abundance. We suggest that the two most likely explanations are that roads are positively correlated with an important as-yet-undetermined
component of habitat quality, or that roads positively affect P. leucopus by negatively affecting their predators. 相似文献
80.
高蛋白日粮对家兔的危害 总被引:3,自引:0,他引:3
陈凤虎 《黑龙江农垦师专学报》1999,(3)
蛋白质含量超过营养需要的日粮,不仅造成浪费,更重要的是直接引起蛋白质消化、吸收和代谢障碍;间接地引起肝肾疾病和全身中毒,诱发传染病和其它疾病。 相似文献