鳖类疾病及其防治对策(九)

<正> 鳖体受伤是毛霉菌动胞子有机会入侵,毛霉病一年四季均可发生,而以4～6月上旬,9～10月最流行。在流水池、水质清洁且透明度较高的池中,白斑病的发病率有增高的倾向。相反肉眼看来不很清洁,水中藻类大量繁殖时,毛霉菌的生长却受到抑制,发病率下降。全国各地都有此病流行。

龟类、鳖类的寄生水蛭及其防治技术

<正> 蛭类俗称蚂蟥,属于环节动物门(Annelida)中的蛭纲(Hirudinea)。蛭类多数种类营自由生活,分布在淡水、海洋、土壤和陆地上;少数种类营寄生生活,寄生在无脊椎动物和脊椎动物体内或体表,吸取宿主的血液或体液为食。对宿主造成不同程度的危害。

碳酸氢钠、硼砂在水产养殖业的应用

<正> 众所周知,不论是饲养中华鳖,还是饲养金鱼和热带观赏鱼类,对水质都有一定的要求。水质包含的内容颇多,但其中主要有酸碱度(即pH值)和硬度。中华鳖适宜弱碱性水pH7.2—8.0,经过养鳖生产实践,在这样的水中饲养,生长快、产量高而疾病少。金鱼最适宜的水是弱碱性pH7.5—8.0。热带观赏鱼由于种类繁多,习性有所不同,多数种类适宜

太平湖水库藻类及适度产鱼潜力探讨

太平湖水库藻类的群落结构仍以绿藻为主，硅藻和蓝藻次之，其他藻类所占比例较小。在敞水区，藻类的生长丰度显示从上游至下游逐渐递减的趋势，且明显低于库湾区。藻细胞密度和生物量均在夏季出现高峰，冬季最低。和８年前的结果相比，藻类多样性下降，总种类数减少了３６％，细胞数量大幅度上升，小型种类密度增加。提出了一种藻类适度产鱼潜力的新概念和依据藻类现存生物量计算藻类适度产鱼潜力的方法。计算表明，全库藻类每年的适度产鱼潜力约为４５４万ｋｇ。

一种用来可同时测定氮及其它金属元素的新型延长炬管的设计

本文介绍了一种新型延长炬管的设计。该炬管使在电感耦合等离子体原子发射光谱仪（ＩＣＰ－ＡＥＳ）上同时测定氮及其它金属元素成为可能，并且在不同程度上改善了一些金属元素的检测限。本文利用该炬管，在ＡＲＬ３５２０光谱仪上同时测定了生物标准样品中的氮及Ｆｅ、Ｍｎ、ＣｕＺｎ等四种金属元素。结果与定值吻合，相对标准偏差均小于５％。

澳洲红螺的饲养方法

<正> 澳洲红螺(Bulinus australianus)又称红螺或澳洲水泡螺、是一种淡水观赏螺,原产澳洲淡水中,其颜色为红色而鲜艳,可供观赏。螺肉营养价值高,容易大量饲养繁殖,还可作为肉食性热带鱼和绿毛龟的补充食料。现将红螺的生活习性及饲养方法简述如下。

鸭儿湖污染治理研究

鸭儿湖污染是通过氧化塘系统控制的。氧化塘系统,由四个串联氧化塘组成,总面积为2800亩,塘深3米,当废水量为7万吨/天时停留时间为80天。并利用净化后的废水培育鱼种(鱼种塘),通过菌—藻—浮游动物—鱼的相互作用,以鱼种形式回收部分营养元素。以解决在氧化塘沿岸的东西排灌渠12.8公里两岸人民的灌溉水和饮用水的污染问题。从1976年底氧化塘初步建成,四年运转结果表明:COD、有机磷、对硝基酚、对硫磷、马拉硫磷、乐果和六六六处理效果分别为77.3、82.5、99.3、98.7、98.4、92.9和86.2%。每

武汉东湖湖区降水中的氮含量及其变化的研究

<正> 东湖位于长江中游的湖北省武汉市市区,其北面为重工业区。在水位高程为20.5m时,湖的面积为27.899km~2(合41,850亩)。总汇水面积为187km~2。根据东湖蒸发实验站提供的资料,1962—1980年的平均年降水量为1182mm,主要集中在4—9月。年平均气温约为16.9℃。降水不仅影响东湖水位的变化,降水中所含的化学组成,特别是氮化合物对于东湖湖水的化学组成、水体生物生产力以及水生态系统中氮的平衡都有一定的影响。为了研究

Rapid growth cost in “all-fish” growth hormone gene transgenic carp: Reduced critical swimming speed

Evidence has accumulated that there is a trade-off between benefits and costs associated with rapid growth. A trade-off between growth rates and critical. swimming speed (U-crit) had been also reported to be common in teleost fish. We hypothesize that growth acceleration in the F-3 generation of "all-fish" growth hormone gene (GH) transgenic common carp (Cyprinus carpio L.) would reduce the swimming abilities. Growth and swimming performance between transgenic fish and non-transgenic controls were) compared. The results showed that transgenic fish had a mean body weight 1.4-1.9-fold heavier, and a mean specific growth rate (SGR) value 6%-10% higher than the controls. Transgenic fish, however, had a mean absolute U-crit (cm/s) value 22% or mean relative Ucrit (BL/s) value 24% lower than the controls. It suggested that fast-growing "all-fish" GH-transgenic carp were inferior swimmers. It is also supported that there was a trade-off between growth rates and swimming performance, i.e. faster-growing individuals had lower critical swimming speed.

Freshwater testate amoebae of nine Yunnan Plateau lakes, China

The testate amoebae from nine major lakes in the Yunnan Plateau, southwest China were investigated from August to October 2003. Ninety-four species and subspecies belonging to 21 genera were found, and six species were new to the testate amoebae fauna of China. The most diverse genera were Difflugia (28 species), Centropyxis (22 species), Arcella (12 species), and Euglypha (seven species), while the predominant genera were Centropyxis (42.0%), Difflugia (21.4%), Arcella (9.7%), and Euglypha (8.2%). The most diverse testate amoebae fauna was found in a mesotrophic lake, Lake Yilong (57 species). The lowest species richness was recorded in the two hypereutrophic lakes, Lake Dianchi (7 species) and Lake Xingyun (11 species). The results suggest that the lake trophic status plays an important role in shaping community structure and in determining species diversity of testate amoebae.

The algae-lytic ability of bacterium DC10 and the influence of environmental factors on the ability

A lysing-bacterium DC10, isolated from Dianchi Lake of Yunnan Province, was characterized to be Pseudomonas sp. It was able to lyse some algae well, such as Microcystis viridis, Selenastrum capricomutum, and so on. In this study, it was shown that the bacterium lysed the algae by releasing a substance; the best lytic effects were achieved at low temperatures and in the dark. Different concentrations of CaCl2 and NaNO3 influenced the lytic effects; the ability to lyse algae decreased in the following order: pH 4 > pH 9 > pH 7 > pH 5.5. It was significant to develop a special technology with this kind of bacterium for controlling the bloom-forming planktonic microalgae.

纳米半导体技术

本书介绍了纳米半导体材料的定义、性质及其在未来信息技术中的地位的同时，主要介绍了纳米半导体材料制备的方法和共性关键技术，几种常用的纳米半导体材料的评价技术和应变自组装半导体量子点(线)的尺寸、密度分布、形貌、组分及结构特性的实验研究，纳米半导体材料的电子结构、光学和电学性质，基于子带跃迁的量子级联激光器的工作原理、特性和它的发展现状及其应用前景分析，最后重点介绍了纳米半导体器件及应用。本书适合于从事或对纳米半导体科学技术有兴趣的科研工作者、教师、研究生、本科生和工程技术人员阅读，有些章节可作为科普读物。

低轮FOX分组密码的碰撞-积分攻击

FOX是最近推出的系列分组密码，它的设计思想基于可证安全的研究结果，且在各种平台上的性能优良．本文利用碰撞攻击和积分攻击相结合的技术分析FOX的安全性，结果显示碰撞-积分攻击比积分攻击有效，攻击对4轮FOX64的计算复杂度是2^45.4，对5轮FOX64的计算复杂度是2^109.4，对6轮FOX64的计算复杂度是2^173.4，对7轮FOX64的计算复杂度是2^237.4，且攻击所需数据量均为2^9；也就是说4轮FOX64／64、5轮FOX64／128、6轮FOX64／192和7轮FOX64／256对本文攻击是不免疫的．