227 resultados para 183-1140A
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从1998年9月至1999年9月对人工养殖湖泊——武湖日本沼虾生长特性作了研究. 以月龄来研究日本沼虾的生长,研究结果表明日本沼虾在7-1月份(1-7月龄)呈等速生长,在2-6月份(8-12月龄)呈异速生长.日本沼虾体重(W)与体长(L)呈幂函数相关,但在7-1月份时其b值接近于3,而在2-6月份时其b值明显小于3,其关系式如下: 1-7月龄:W♂=0. 0148L3. 2419(r=0. 9978,n=390),W♀=0. 0206L3. 0117(r=0. 9968,n=372); 8-12月龄:W♂
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根据1999~2001年的野外调查数据,研究了湖北梁子湖湿地浮游藻类和高等植物多样性资源.结果表明,该湿地常见浮游藻类73种,隶属于7门58属(绿藻28种,硅藻19种,蓝藻14种,金藻4种,裸藻3种,甲藻3种,隐藻2种);高等植物282种,隶属于72科183属(苔藓8种,蕨类9种,裸子植物3种,被子植物262种),其中国家重点保护野生植物5种.浮游藻类密度和生物量均值分别为(1163.79913.51)104cell/L和6.1342.737mg/L,叶绿素a含量12.754.98mg/L,浮游藻类表层日
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中国科学院知识创新工程重要方向项目专题“封闭繁育种群的遗传多样性与种群生存力” (KSCX2 -SW -118); 中国科学院水生生物研究所创新领域前沿资助项目“长江豚类保护生物学研究” (2 2 0 10 3)
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构建湿地是 2 0世纪 70年代才蓬勃兴起的一种处理污水的方式 ,由于其造价和运行费用低 ,净化效果稳定 ,越来越引起各国的兴趣和高度重视。现已广泛应用于城市生活污水、工业污水和农业污水的控制 ,有着十分广阔的应用前景。虽然关于构建湿地净化污水的研究已有不少报道 ,但关于湿地基质中的微生物类群和基质酶在污水净化中的作用仍不清楚。通过对生长在复合垂直流构建湿地和天然环境条件下菰和石菖蒲根区微生物类群数量及其根区基质酶活性的测定发现 :同种植物在复合垂直流构建湿地根区微生物的数量比天然条件下的要高 ,特别是硝
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本文记述了鲴亚科的一个化石新属新种Eoxenocyprisliui,标本产于黑龙江省桦南县附近的中新世地层中。它与现生鲴亚科鱼类的区别是:头长大于体高,口端位,鳃盖长大于高,背鳍起点至吻端距较其至尾鳍基距为大,臀鳍起点至腹鳍起点的距离小于其至尾鳍基的距离。对新生代晚期东亚淡水鱼类特征分析的结果表明,从中新世到上新世东亚大陆和日本列岛存在一个相同的淡水鱼类区系。这一区系在中国东部一直延续到现在,而在日本自更新世中期以后却发生过较大的演替。
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<正> 同工酶分析一般常用淀粉凝胶电泳进行,但它常受淀粉质量的制约,在淀粉的水解和制胶过程较难标准化,因而不易掌握,其机械强度不够也不易操作。而聚丙烯酰胺凝胶电泳具有优于淀粉凝胶电泳的一些特性,如有较高的分辨率、机械强
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<正> 人们一般认为金属钼是生物固氮必需的条件,钼是固氮酶的主要催化活性的组成部分。早先一些学者曾研究以钒、锰代替钼的氮固定作用,到1980年美国的Bishop等人首先提出棕色固氮菌(Azotobacter vinelandii)具有不含铝的第二固氮系统。通过棕色固氮菌缺失编码固氮酶蛋白基因突变株研究发现,该菌株并不失去
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<正> 从1981到1983年,作者等曾多次在湖北省宜都县和黄冈县团风镇两地,从事长江中游鱼类寄生吸虫的调查研究。在70多种鱼中,获得了一批吸虫标本,将陆续整理后发表。本文首先报告在中华鲟Acipenser sinensis Gray中发现的动殖科Zoogonidae Odhner,1911一新属、新种吸虫。动殖科吸虫在我国发现很少,迄今为止,仅顾昌栋、申纪伟(1979,1983),汪溥钦
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<正> 1981—1983年,我们在拍摄、编写《中国淡水鱼类原色图集》时,从广西采集一批鱼类标本,经鉴定其中有二新种。正模标本,编号83-IV-0388,全长183毫米,体长147毫米。副模标本7尾,编号83-IV-0008,83-IV-0085,83-IV-0384-0387,83-IV-0389,全长152一227毫米,体长121一184毫米。
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<正> 陆水系长江南岸支流之一,发源于湘、鄂、赣三省交界的幕阜山北部,流经湖北省通城、崇阳、蒲圻及嘉鱼等四县,由汉口上游157公里处的陆溪口注入长江,全长183公里。 为了探讨将来蒲圻水库中有关水生生物学及渔业生产的一些问题,我们于1961年及1962年曾组织调查队去该河中游未来水库淹没区——蒲圻至崇阳河段,以及该河上游支
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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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Systematic investigations into the temporal and spatial distribution, composition and abundance of protozoa in two regions with different trophic levels in Chaohu Lake, a large, shallow and highly eutrophic freshwater lake in China, were conducted during 2002-2003. A total of 114 species of protozoa, including phytomastigophorans, zoomastigophorans, amoebae and ciliates, were identified from 120 polyurethane foam unit (PFU) samples exposed at four stations and from various types of natural substrates. Of the 114 taxa, 36 core species were found on PFU substrates and 23 of these were found on natural ones. Protozoan abundance and chemical physical parameters at nine sampling stations, four in the western lake and five in the eastern part, indicate trophic gradient changes along the lake. Seasonal variations in the species composition of major groups at littoral PFU sampling stations illustrate the effect of a severe algal bloom on the protozoan community structure. Temporal and spatial distributions of individual abundance as functions of water temperature and trophic status were revealed. This study demonstrates again that the PFU artificial substrate method samples protozoan communities more effectively than routine natural substrate methods. (c) 2005 Elsevier GmbH. All rights reserved.
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Amplified fragment length polymorphism (AFLP) was used to analyse the genetic structure of 45 individuals of Gymnocypris przewalskii (Kessler, 1876), an endangered and state-protected rare fish species, from three areas [the Heima (HM), Buha (BH) and Shaliu rivers (SL), all draining into Qinghai Lake]. A total of 563 polymorphic loci were detected. The HM, BH and SL populations have 435, 433 and 391 loci, respectively (Zhu and Wu, 1975), which account for 77.26%, 76.91% and 69.45% of the total number of polymorphic loci of each population, respectively. The Nei indices of genetic diversities (H) of the three populations were calculated to be 0.2869 (HM), 0.2884 (BH) and 0.2663 (SL), respectively. Their Shannon informative indices are 0.4244, 0.4251 and 0.3915, respectively. Research results show that the mean genetic distance between HM and BH is the smallest (0.0511), between BH and SL is the second shortest (0.0608), and between HM and SL is the largest (0.0713), with the mean genetic distance among the three populations being over 0.05. Data mentioned above indicate that the three populations have a certain genetic differentiation. The total genetic diversity (H-t = 0.3045) and the mean value of genetic diversity within the population (H-s = 0.2786) indicate that the variations have mainly come from within the population.