994 resultados para 187-1155A
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采用曝气-混凝一体法处理碱性含砷废水。氧化方式研究表明,以曝气替代混凝机械搅拌过程,既起到氧化作用,又完成了混合作用,同时具有较好的处理效果;采用该法结合二次混凝工艺处理高浓度碱性含砷废水(砷浓度达414.94mg/L),聚合铁为絮凝剂,总Fe/As=3.0,砷去除率99.92%,出水中砷浓度0.33mg/L;在所选用的三种混凝剂中,聚合铁处理效果最佳。
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我国对虾暴发性流行病病因初探江育林,张奇亚,刘荭,李彦,李正秋(中国科学院水生生物研究所武汉430072)关键词杆状病毒、对虾病毒病、中国对虾、日本对虾STUDYONCAUSEOFINFECTIONSDISEAESOFPENAEIDSHRIMPINC...
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We have investigated the structural and optical properties of III-V nanowires grown by metalorganic chemical vapour deposition. Binary GaAs, InAs and InP nanowires, and ternary InGaAs and AlGaAs nanowires, have been fabricated and characterised. A variety of axial and radial heterostructures have also been fabricated, including GaAs/AlGaAs core-multishell and GaAs/InGaAs superlattice nanowires. GaAs/AlGaAs core-shell nanowires exhibit strong photoluminescence as the AlGaAs shell passivates the GaAs nanowire surface reducing the surface nonradiative recombination. © 2007 IEEE.
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在水质酸化和模拟酸雨试验中,共出现浮游动物17种,其中包括轮虫9种、枝角类6种和桡足类2种。在pH5.0—8.3各试验组出现种类数(10—13种)和个体数(223.0—334.5个·L~(-1))较多,而在pH3.0和4.5试验组出现种类数(5—9种)和个体数(16.8—182.0个·L~(-1))较少,表明pH5.0以下对浮游动物群落有明显的影响。从不同类群出现所占比例看,在pH5.5以下,随着pH的下降,存在着轮虫逐渐取代桡足类的趋势。
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<正> 银鲫是行天然雌核发育生殖的鱼类。以往对其繁殖生物学的研究一般都认为:异源父本的性状不能或仅能少量地在子代群体中得到表达。但桂建芳等(1991)在人工繁育的异育银鲫群体中发现了具有一整套父本染色体组的复合四倍体鱼,其出现率为0.2%左右。此外,Kobayasi
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<正> 在现代生物数学中,常常需要对数据的分布类型作正态性检验。然而,在常用的分布类型检验方法中,由于各方法的侧重点不同,应用条件也不尽相同,因而对于某一类具体问题,各检验方法的检验效率也不同。因此,有必要对常用的几种分布类型检验方法的检验效率和应用条件进行讨论,以便能在实际应用中有选择地使用这些方法。
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采用武汉地区胆石症患者胆囊或胆管中的胆石、胆汁及对照组的胆汁,通过原子吸收光谱等方法测定其中18种微量元素的含量。结果发现不同部位结石中的这些微量元素平均含量除铬外均无显著性差异,结石中12种微量元素的含量高于其胆汁中的含量;7种微量元素(铅、钙、砷。、铬、锰、铁、铝)高于对照组中的含量(P均<0.05)。胆石症患者胆汁中钠、钾、铜、铝、镁的平均含量均低于对照组(P<0.05),其它微量元素平均含量与对照组比较差异无显著性意义,本结果对进一步研究结石形成机理与防治措施提供了依据。
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<正> 1986年6月,作者在四川涪陵的中华倒刺鲃(Barbodes sinensis Bleeker)后肠检获一种纤毛虫,根据虫体的特征及前人的分类方法,鉴定为斜口科(Plagiotomidae),肠肾虫属(Nyctotherus)一新种,定名为长江肠肾虫(Nyctotherus changjiangensis sp.nov.) 寄生虫的形态研究,除活体观察外,均采用纤毛虫常规涂片染色方法观察。测量了10个以上标本,测量单位为微米。模式标本保存于中国科学院水生生物研究所鱼病室。长江肠肾虫(新种)Nyct
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<正> 白鱀豚是我国特有的稀珍水生哺乳动物。仅分布于长江的中、下游干流之中。关于如何饲养白鱀豚没有可借鉴的资料。在没有水净化装置和流水系统的条件下,为了既能节省人力和财力,又能保证豚体的健康,我们对白鱀豚饲养池的理化和微生物因子进行了系统、全面的测定和研究。
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1.汉江产漂流性卵的鱼类至少有25种,其中经济鱼类有草鱼、青鱼、鲢、鳙、鯮、鳤、鳡、长春鳊、赤眼鳟、铜鱼、吻鮈、鳜以及三种红鲌属鱼类。2.产漂流性卵鱼类开始产卵的水温分别在16—20℃之间,经济鱼类多在18℃上下。产卵时需要有江河的涨水过程。在河流涨水的诸水文要素中,流速的增大,对促使产卵起着主要作用。不同的鱼类产卵时对流水的要求是有差异的。鱼类的产卵规模与江水的流速增大紧密相关。3.丹江水库建成后,上游的产卵场有前房、天河口和安康等10处。中游有钟祥和马良等7处,支流唐河、白河也有产卵场。就总产卵量来看
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<正> 东湖位于武汉市武昌区东北,形若一斜放的等腰三角形,面积在水位20.5米时为27.899平方公里,平均水深2.21米,流域面积187平方公里。东湖是长江中下游的一个中型浅水湖泊。 湖之南,两列东西向残丘(以瑜家山最高,151.84米),互相平行,断续相连。这两列残丘皆为泥盆系石英砂岩所组成的向斜山,它们之间为志留系页岩所组成的背斜谷地,表
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We investigated the macroinvertebrate community structure in Three-Gorges Reservoir during a three-year period after the reservoir became operational. Comparison with data of previous authors obtained before the damming showed that the benthic community changed drastically in the reservoir. Oligochaetes and chironomids dominate the present community. An apparent annual cycle in the benthic community (expressed as richness, density and community type) was found in the second year, lagging one year behind the annual cycle of transparency. After the second year, a Nais-Polypedilum community type, occurring in winter and spring with low inflow discharge and high transparency, was followed by a Limnodrilus community type that occurred in autumn and summer under contrasting conditions. Despite river regulation and damming, it appeared that macroinvertebrates in subtropical canyon-shaped reservoirs remained influenced by floods.
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The environmental impact of diesel-fueled buses can potentially be reduced by the adoption of alternative propulsion technologies such as lean-burn compressed natural gas (LB-CNG) or hybrid electric buses (HEB), and emissions control strategies such as a continuously regenerating trap (CRT), exhaust gas recirculation (EGR), or selective catalytic reduction with trap (SCRT). This study assessed the environmental costs and benefits of these bus technologies in Greater London relative to the existing fleet and characterized emissions changes due to alternative technologies. We found a >30% increase in CO2 equivalent (CO2e) emissions for CNG buses, a <5% change for exhaust treatment scenarios, and a 13% (90% confidence interval 3.8-20.9%) reduction for HEB relative to baseline CO2e emissions. A multiscale regional chemistry-transport model quantified the impact of alternative bus technologies on air quality, which was then related to premature mortality risk. We found the largest decrease in population exposure (about 83%) to particulate matter (PM2.5) occurred with LB-CNG buses. Monetized environmental and investment costs relative to the baseline gave estimated net present cost of LB-CNG or HEB conversion to be $187 million ($73 million to $301 million) or $36 million ($-25 million to $102 million), respectively, while EGR or SCRT estimated net present costs were $19 million ($7 million to $32 million) or $15 million ($8 million to $23 million), respectively.
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Prenatal exposures to persistent organic pollutants were assessed using the levels of PCBs and organochlorine pesticides (OCPs) measured in cord blood and meconium samples from Luqiao and two other localities of the Zhejiang province in China. Luqiao is a town with the largest site for disassembly of PCB-containing obsolete transformers and electrical waste in China. The other two localities Pingqiao (100 km NW of Luqiao) and Lin'an (500 km NW of Luqiao) are towns without known electronic or electrical waste sites. A total of 23 PCB congeners (including 12 dioxin-like) and 6 OCPs were measured using the traditional GC-mu ECD technique. Micro-EROD bioassay was additionally used to measure TCDD-based TEQ levels of the 12 dioxin-like PCBs. Significant correlations were found between the TEQs measured by the two methods, supporting the application of micro-EROD as a practical toot for complementing the chemical analysis. The data showed that beta-HCH, p,p'-DDE, and 6 PCB congeners (101, 138 153, 180, 183, and 187) were the predominant pollutants, with PCB 138 being the best indicator (predictor) for total PCB levels. Cord blood and meconium from Luqiao have higher levels of PCBs than those from the other two localities, suggesting that a disassembly site for electronic and electric waste would provide an environment for greater exposure to these chemicals. The cord blood or meconium levels of beta-HCH, though likewise considerably high, were comparable in the three localities. Similar findings were observed for p,p'-DDE. Pollution by these OCPs might have come from past use of agricultural pesticides in the three localities. (c) 2007 Published by Elsevier B.V.
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Poyang Lake (Poyang Hu) is located at the junction of the middle and lower reaches of the Yangtze (Changjiang) River, covering an area of 3283 km(2). As one of the few lakes that are still freely connected with the river, it plays an important role in the maintenance of the unique biota of the Yangtze floodplain ecosystem. To promote the conservation of Poyang Lake, an investigation of the macrobenthos in the lake itself and adjoining Yangtze mainstream was conducted in 1997-1999. Altogether 58 benthic taxa, including, 22 annelids, 8 mollusks, 26 arthropods, and 2 miscellaneous animals, were identified from quantitative samples. The benthic fauna shows a high diversity and a marine affinity. The standing crops of benthos in the lake were much higher than those in the river, being 659 individuals/m(2) and 187.3g/m(2) (wet mass) in the main lake, and 549 individuals/m(2) and 116.6 g/m(2) in the lake outlet, but only 129 individuals/m(2) and 0.4g/m(2) in the river. The dominant roup in the lake was Mollusca, comprising 63.4% of the total in density and 99.5% in biomass. An analysis of the functional feeding structure indicated that collector-filterers and scrapers were predominant in the lake, up to 42.2% and 24.7% in density and 70.2% and 29.2% in biomass, respectively, while shredders and collector-gatherers were relatively common in the river. The present study was restricted to the northern outlet and the northeast part of Poyang Lake. A scrutiny is required for the remaining areas.