Mass mortalities associated with viral nervous necrosis (VNN) disease in two species of hatchery-reared grouper, Epinephelus fuscogutatus and Epinephelus akaara (Temminck & Schlegel)     

S C Chi  C F Lo  G H Kou  P S Chang  S E Peng  & S N Chen 《Journal of fish diseases》1997,20(3):185-193

Mass mortalities of hatchery-reared juvenile groupers have occurred in southern Taiwan. The diseased fish swam in a darting, corkscrew fashion. Light microscopy revealed vacuolation in the brain tissue. Electron microscopy showed numerous non-enveloped, cytoplasmic viral particles (20–25 nm in diameter) in the brain cells, and many virions were enclosed in the membrane-bound organelles of the cells. Two structural proteins of the purified grouper virus, with molecular weights of 44 and 43 kDa, were revealed by SDS-PAGE. Moreover, the results of RT-PCR and nested PCR diagnosis using primers specific to the T2 and T4 target segments of striped jack nervous necrosis virus (SJNNV) RNA2 genes suggest that this virus is a fish nodavirus, and is designated as GNNV 9410 strain (grouper nervous necrosis virus strain 9410). This is the first case report of viral nervous necrosis among marine fish in Taiwan.  相似文献   

威提特东非狼尾草种子生产技术的研究     

匡崇义  王勃  徐驰  薛世明 《云南农业大学学报(自然科学版)》2008,23(4)

比较了4种土壤类型和3种留茬高度对威提特东非狼尾草(Pennisetum clandestinum cv. Whittet)种子产量和质量的影响。结果表明:以单因素而言,生土处理和0.05 m留茬高度处理所获得的平均种子产量最高;两因素处理的结果表明,以生土和0.05 m留茬高度互作后所获得的种子产量最高,其种子产量达447kg/hm2;各土壤类型和不同留茬高度的处理对种子的质量影响差异不显著。  相似文献   

How much variation can be explained by seasonal,spatial and environmental effects in nekton assemblages of the Terminos Lagoon?     

Julia Ramos Miranda  David Mouillot  Atahualpa Sosa Lopez  Thang Do Chi  Domingo Flores Hernández 《水产资源保护:海洋与淡水生态系统》2008,18(5):508-517

• 1. The coastline is very sensitive to both climatic and human influences but also provides essential goods and services upon which human welfare depends. Species inhabiting these coastal areas provide valuable resources and enhance ecosystem functioning: it is therefore essential to understand the main factors influencing species abundance patterns. The aim of this study is to estimate the amount of variation in nekton coastal assemblages explained by spatial, temporal and environmental variables.
• 2. Nekton sampling was carried out over 17 months in the Terminos Lagoon, a reserve area situated in the Gulf of Mexico, using a shrimp trawl. At each station, 11 environmental variables were recorded. The influence of seasonal, spatial and environmental variables on nekton species abundance was analysed using Partial Canonical Correspondence Analysis (PCCA).
• 3. The explanatory variables explained only 19.7% of the total observed variation in the nekton community for the Terminos Lagoon. The major part of the explained variation was due to the spatial effect (9.2%), while environmental variables and seasonality explained only 3.6% and 0.8%, respectively, suggesting the necessity to consider experimental fishing design in such artisanal fisheries.
• 4. Results also suggest focusing on more integrative indicators of community structure such as measures of taxonomic diversity based on presence/absence or on measures related to functional attributes of communities rather than using species abundance patterns to predict changes in coastal ecosystems.

Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

汇率预测的理论与方法及其最新进展     

谢赤  杨小帆 《湖南农业大学学报(自然科学版)》2004,(5)

总结了众多国内外学者在汇率预测方面的理论及其研究方法。通过对传统的统计方法与非参数方法的比较分析,得出结论:大多数传统的时间序列模型是线性的,不能抓住非线性时间序列数据的内在特征。而相对于传统的预测模型而言,非参数方法能发现观察结果和输入数据的关系,不需要事先确定模型,其拟合结果能更好的捕捉汇率的动态特征与走势。  相似文献   

四川乐山市竹林主要病虫害调查初报   总被引：1，自引：0，他引：1  

杨瑶君  汪淑芳  牟翅 《四川林业科技》2009,30(1)

将乐山竹林区分为5个不同的生态区域.2006年～2008年3年的时间调查研究了乐山竹林的主要病虫害及其发生特点.调查结果表明,乐山竹林区主要虫害10种,以长足大竹象危害最为严重,主要病害4种,以竹基腐病危害最重,且面积逐年增加.随着竹林面积的增加,竹类病虫害呈现上升趋势,防治-虫(长足大竹象)-病(竹基腐病)并加强竹林病虫的预测预报,对提高竹林产量、促进竹产业发展具有十分重要的作用.  相似文献   

浙粤两省六个杉木种子园施肥技术和效应研究^*   总被引：3，自引：0，他引：3       下载免费PDF全文

迟健  胡德活  谢正成  王嫩良  李锦清 《林业科学研究》1993,6(1):19-26

  相似文献   

海南北部地区热带雨林的组成特征   总被引：11，自引：2，他引：11  

杨小波  吴庆书  李跃烈  吴小毅  池清湖  王生年 《林业科学》2005,41(3):19-24

在海南东北部农村周边植物调查过程中,发现了分布在这一区域的青梅林。基于与海南其他热带雨林的植物区系成分和群落结构的比较,认为此青梅林是海南东北部原有森林的幸存者,与海南现有的典型热带雨林属一个类型,是海南北部地区热带雨林幸存的活证据,所不同的是次生性强,优势种明显。  相似文献   

燃油锅炉房设计的探讨     

陈赤  杨基春 《林业科技情报》2002,34(3):48-49

本文介绍了燃油锅炉的自身特点,替代燃煤锅炉的优越性,探讨了燃油锅炉设计中应严格执行规范规定以及应注意的几个问题,阐明燃油锅炉设计将为暖通设计开辟新的领域。  相似文献   

STUDY ON BIOLOGICAL CHARACTERISTICS OF HENDERSORNIA ACICOLA     

何秉章  迟玉杰  齐国信  杨立新 《林业研究》1994,(4)

ThediseasedyellowneedlesofPinusrylvestrisvar.mongoliaLitvinwerecollec-tCdinAershanForestBureau,theNeiMonggolAutonomousRegionandintheforestareasofHeilongiiangProvince.Theseneedleswereculturedundercertainrelativehumidityandtemperatureinroom,andconidiaandcirrhiwereproduced.ThefungiwasidentifiedasDeuteromycotina,Coelomycetes,Sphaeropsidales,Hender-sonia.Basedonthereport(Wehmeyer,l946),therearetwospeciesofHendersorniaonpinesandaccompaniedbyLoPhodermelIa.Thesetwofungicansup-presstheapotheci…  相似文献   

RELATIONSHIP BETWEEN SCOTCH PINE NEEDLE RUST AND HOST CHLOROPHYLL CONTENT     

薛煜  池玉杰  李继君 《林业研究》1996,7(1):32-35

PhotoSynthe3isisaprocessofaccumulat-ingorganicmaterialsinthylakoidmembranesofgreenplantchloroplast.Whentheleavesofgreenplantaredestroyedbysomefactor,chlo-rophyllcontentwillchange,whichcanaffeetorganicmaterialsaccumulatonandharmtreegrowth.TherearesomerePortsonrelationshipbetWeentreechlorophyllcontentanddifferentstandsmictUre,differentsiteconditionanddifferentgrowthperiod,buttherePOrtsontreedisease,especiallytheeffectsofneedlesrustonchlorophyllcontCnthavenotbeenseen.lntl1isstUd3,thechlorophyl…  相似文献