葛洲坝产卵场中华鲟繁殖群体数量与繁殖规模估算及其变动趋势分析

采用声学探测的方法,进行中华鲟(Acipenser sinensis)繁殖群体数量的估算。2005～2007年,第1次产卵前的资源量分别为235尾、217尾和203尾;第1次产卵后的资源量分别为157尾、157尾和102尾。采用食卵鱼解剖统计和股分析的方法对中华鲟的自然繁殖规模进行估算,其结果为,2005～2007年间中华鲟的产卵量分别为356万粒、119.6万粒和238.6万粒。结合历史相关研究数据,对近10年的中华鲟繁殖群体数量和繁殖规模的变动趋势进行分析,结果显示,在20世纪90年代中期,第1次产卵

A classification of data quality assessment methods

Data quality (DQ) assessment can be significantly enhanced with the use of the right DQ assessment methods, which provide automated solutions to assess DQ. The range of DQ assessment methods is very broad: from data profiling and semantic profiling to data matching and data validation. This paper gives an overview of current methods for DQ assessment and classifies the DQ assessment methods into an existing taxonomy of DQ problems. Specific examples of the placement of each DQ method in the taxonomy are provided and illustrate why the method is relevant to the particular taxonomy position. The gaps in the taxonomy, where no current DQ methods exist, show where new methods are required and can guide future research and DQ tool development.

栉江珧同工酶多态性的分析

采用垂直板聚丙烯酰胺梯度凝胶电泳对栉江珧(Atrina pectinata Linnaeus)消化盲囊进行了5 种酶(SOD、EST、MDH、ME、LDH) 的同工酶分析。结果表明不同个体的同工酶表达呈现多态现象,个体间酶带带型既有相一致的共同特征谱带,又有较多的变异,5种酶均可把样品大致区分为差异明显的2 种或3 种类型,而且酶谱类型与形态类型基本对应,同工酶表达上的多样性表明栉江珧种内在生化遗传上存在较大的变异, 具有较丰富的遗传多态性。

Seismic triggering of submarine slides in soft cohesive soil deposits

The geological profile of many submerged slopes on the continental shelf consists of normally to lightly overconsolidated clays with depths ranging from a few meters to hundreds of meters. For these soils, earthquake loading can generate significant excess pore water pressures at depth, which can bring the slope to a state of instability during the event or at a later time as a result of pore pressure redistribution within the soil profile. Seismic triggering mechanisms of landslide initiation for these soils are analyzed with the use of a new simplified model for clays which predicts realistic variations of the stress-strain-strength relationships as well as pore pressure generation during dynamic loading in simple shear. The proposed model is implemented in a finite element program to analyze the seismic response of submarine slopes. These analyses provide an assessment of the critical depth and estimated displacements of the mobilized materials and thus are important components for the estimation of submarine landslide-induced tsunamis. © 2003 Elsevier B.V. All rights reserved.

三峡库区汞污染的化学生态效应

测定长江三峡库区江段鲤、铜鱼、鲇、长吻中的砷、镉、铜、汞、铅、硒、锌等元素的含量。比例匹配分析表明，样品或元素间无显著相关。铜鱼、鲤、鲇及长吻对汞的富集系数分别为8．0×103、1．5×104、3．3×104、8．4×104（L／kg）。这表明鱼体汞元素含量与鱼类在食物链营养级的位置密切相关，食物链越长，汞的富集系数越高。鲤、鲇及长吻的肌肉、肝、肾和牌间的汞含量比值约为6：2：1，而铜鱼为1：1：2．5。三峡库区降低鲤、鲇及长吻的肌肉有机汞含量占总汞含量的84％－92％，肝、肾和脾的有机汞占总汞的55％－

A comparative study of transistors based on wurtzite and zincblende InAs nanowires

We report a comparative study of the electronic properties of nominally identical nanowire field-effect transistor (NW-FET) devices produced using 50 nm diameter InAs nanowires that differ only in phase: ZB on the one hand, and WZ on the other. We find much higher current densities in the ZB NW-FETs, and on/off ratios of up to 100. © 2010 IEEE.

鳗鲡爱德华氏病的研究

本文记述了在我国新发现的鳗鲡爱德华氏病的症状和病原菌的特征。病鱼的症状表现为两大类型,以肾脏病变为主的肾脏型和以肝脏病变为主的肝脏型。从病鱼的内脏分离到7株菌,用其中的E86～205进行人工感染,100％的鳗鲡死亡,与自然发病的症状相似,从感染的鳗鲡上又重新分离到菌株E86-203。E86-203与E86-205以及其他菌株的特征也都一致。均为革兰氏阴性杆菌。菌体直,两端圆形,单个,大小为0.6—0.8×0.8—2.4微米。周鞭毛,运动,兼性厌氧,发酵葡萄糖产酸产气。氧化酶阴性,过氧化氢酶阳性,产生硫化氢

固氮鱼腥藻的蛋白水解酶及其部分性质的研究

应用溶菌酶处理,超声破碎细胞,通过差异离心和解离剂处理,将细胞的不同部分分开。以水解α-酪蛋白反应检测蛋白水解酶活性,结果表明,在细胞的可溶部分、内细胞质膜、外膜及胞浆周围区均存在蛋白水解酶活性。异形胞可溶部分的蛋白酶活比营养细胞可溶的蛋白酶活高4—5倍。在固氮条件下,营养细胞可溶性蛋白酶反应最适温度为50—55℃,65℃时,酶活迅速下降。有Ca~(2+)5mmol/l时,蛋白酶在60℃稳定,无Ca~(2+)存在下,酶液在60℃预处理10分钟,酶活性丧失80%以上。酶反应的最适pH为8—10。而且氮饥饿之

What kind of friction model is needed to predict brake squeal?

Predictive models of friction-induced vibration have proved elusive despite decades of research. There are many mechanisms that can cause brake squeal; friction coupled systems can be highly sensitive to small perturbations; and the dynamic properties of friction at the contact zone seem to be poorly understood. This paper describes experimental and theoretical work aimed at identifying the key ingredients of a predictive model. A large-scale experiment was carried out to identify squeal initiations using a pin-on-disc test rig: approximately 30,000 squeal initiations were recorded, covering a very wide range of frequencies. The theoretical model allows for completely general linear systems coupled at a single sliding point by friction: squeal is predicted using a linearised stability analysis. Results will be presented that show that almost all observed squeal events can be predicted within this model framework, but that some subsets require innovative friction modelling: predictions are highly dependent on the particular choice of friction model and its associated parameters. Copyright © 2012 by ASME.

雌核发育银鲫卵抑制异源精子原核化的作用模式初探

雌核发育银鲫卵能抑制异源精子原核化,其个体发育完全由雌核控制。本实验通过去核、卵质转移和去除卵膜等手段,初步揭示了银鲫卵抑制异源精子原核化的作用,提出了双重控制的假说,即银鲫卵对异源精子具有初级控制和次级控制功能。初级控制可能是由于在精子进入卵子深部的通道上存在着某种特殊的抑制物的缘故,而次级控制的产生则可能是因为银鲫卵质中缺少某种两性融合生殖鱼类卵质所具有的促精子核化物质。

鲮鱼混精授精的育种试验

1979至1982年间,用瓦氏雅罗鱼、草鱼、链鱼、鲤鱼中的一种或多种精液同鲮鱼新鲜精液混合对鲮鱼成熟卵授精,使其发育成苗,并培育成鱼种。经养殖表明,有几组混精授精得到的鲮鱼,其抗寒性能比不混精授精的鲮鱼强;其中以四种混合精液授精以得混精鲮的耐寒能力最高。现将耐寒能力低达 5.5℃的混精鲮鱼选出,供进一步选育用。最后,根据各组试验结果,提出进一步工作的意见。

白暨豚上呼吸道的解剖和组织学的研究

白鱀豚上呼吸道具有前庭囊、鼻额囊及前颌囊三对气囊,没有副囊和连接囊。三对囊均右大于左,其中又以前庭囊最为显著。喉由甲状软骨、环状软骨、会厌软骨及一对杓状软骨组成,从喉腔壁的组织学观察发现有室皱襞(假声带)的存在。

中国胭脂鱼的骨骼形态和胭脂鱼科的分类位置

<正> 中国胭脂鱼Myxocyprinus asiaticus(Bleeker)是迄今知道胭脂鱼科(Catostomidae)分布于我国的一个种,而该科的大多数种属分布于北美洲,总计有14个现存属,大约80个种(Miller,1958)。 方炳文(Fang,1934)对中国胭脂鱼除了发表一个头骨及下咽齿的照片外,主要是阐明这种鱼的体形随不同体长(实际是不同龄期)而改变的事实。Nelson(1948)作了胭脂鱼韦氏器的比较解剖,他提到中国胭脂鱼第二和第三脊椎具有分离的椎体和第一脊椎存在一对横突之外,只简单地