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111.
日本绒螯蟹放流群体12S rRNA序列研究 总被引:1,自引:0,他引:1
参考果蝇与蚤状汊序列进行了日本绒螯蟹放流群体的线粒体DNA12S rRNA基因片段的引物设计、PCR扩增及序列测定,得到457bp的碱基序列,其A、T、G、C含量分别为158bp(34.57%)、178bp(38.95%)、51bp(11.16%)、70bp(15.32%),与果蝇与蚤状相同基因片段序列含量相似。 相似文献
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Trophic network model of the Northern Adriatic Sea: Analysis of an exploited and eutrophic ecosystem
Alberto Barausse Alessandro Duci Carlotta Mazzoldi Yuri Artioli Luca Palmeri 《Estuarine, Coastal and Shelf Science》2009,83(4):577-590
A quantitative model of the trophic network of Northern Adriatic Sea marine ecosystem during the 1990s has been constructed, with the goal of analysing its trophic structure, identifying the key trophic groups and assessing the anthropogenic impacts on the ecosystem using the Ecopath modelling protocol. The Northern Adriatic Sea is an eutrophic, shallow basin, and one of the most heavily fished areas in the Mediterranean Sea. The network aggregation into discrete trophic levels sensu Lindeman shows that low trophic levels dominate biomass and energy flows, with 40% of the total system throughput flowing out from trophic level 2. Instead, upper trophic levels appear bottom-up controlled, highly depleted and not exerting any control on the trophic network, as shown by mixed trophic impact-based analyses. Microbial loop is comparable to grazing with respect to the magnitude of flows involved, as 66% of the trophic network flows originate from detritus, which is mainly consumed by bacteria. Key trophic groups are plankton groups, macro-crustaceans and detritus, and other r-selected organisms like squids and small pelagics, which have a great influence on the ecosystem. In particular, zooplankton acts as a bottleneck for energy flows, limiting the energy from the low trophic levels effectively reaching the upper food web. The high pelagic production caused by eutrophication sustains high fishery landings and impressive discard quantities, as well as the benthic compartment. Overall, the ecosystem appears quite productive and in a stressed and developmental status. Model results and comparisons with few existing historical data suggest that the low maturity and stressed state of the Northern Adriatic Sea are not only due to natural characteristics, but mainly to anthropogenic pressures. 相似文献
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利用ITS区和12SrRNA基因对广东徐闻地区7种滨珊瑚科珊瑚的遗传多样性和系统发生关系进行了研究。结果表明:(1)基于ITS1检测到在58个样本中有48个单倍型,多样性在0.800—1.000之间,多态位点数在5—62之间,核苷酸多样性指数在0.012—0.094之间;基于ITS2检测到43个单倍型,多样性在0.742—1.000之间,多态位点数在22—75之间,核苷酸多样性指数在0.017—0.175之间。基于ITS区所得遗传分化系数在0.00409—0.12170之间(P<0.001),遗传分化不明显,7种珊瑚中,二异角孔珊瑚的遗传多样性最丰富。(2)以12SrRNA基因建立的系统发育树与传统的形态学分类系统基本吻合,7种珊瑚被分成了3个支系,滨珊瑚属3种为一个支系,二异角孔珊瑚为一个支系,其余3种角孔珊瑚为一个支系。 相似文献
115.
W. Pietsch 《Astronomische Nachrichten》2010,331(2):187-192
The first supersoft source (SSS) identification with an optical nova in M 31 was based on ROSAT observations. Twenty additional X‐ray counterparts (mostly identified as SSS by their hardness ratios) were detected using archival ROSAT, XMM‐Newton and Chandra observations obtained before July 2002. Based on these results optical novae seem to constitute the major class of SSS in M 31. An analysis of archival Chandra HRC‐I and ACIS‐I observations obtained from July 2004 to February 2005 demonstrated that M 31 nova SSS states lasted from months to about 10 years. Several novae showed short X‐ray outbursts starting within 50 d after the optical outburst and lasting only two to three months. The fraction of novae detected in soft X‐rays within a year after the optical outburst was more than 30%. Ongoing optical nova monitoring programs, optical spectral follow‐up and an up‐to‐date nova catalogue are essential for the X‐ray work. Re‐analysis of archival nova data to improve positions and find additional nova candidates are urgently needed for secure recurrent nova identifications. Dedicated XMM‐Newton/Chandra monitoring programs for X‐ray emission from optical novae covering the centre area of M 31 continue to provide interesting new results (e.g. coherent 1105 s pulsations in the SSS counterpart of nova M31N 2007‐12b). The SSS light curves of novae allow us – together with optical information – to estimate the mass of the white dwarf, of the ejecta and the burned mass in the outburst. Observations of the central area of M 31 allow us – in contrast to observations in the Galaxy – to monitor many novae simultaneously and proved to be prone to find many interesting SSS and nova types (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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新疆地质矿产勘查回顾与展望 总被引:1,自引:0,他引:1
随着地勘投入的不断增加,"十一五",尤其是新疆"358"项目启动以来,新疆地质矿产勘查取得了有史以来最为突出的成果.煤炭、铁矿、钠硝石及重要有色金属矿产成果尤为突出,水文地质勘查取得了新成果,基础地质勘查程度大幅提高,科学研究及高新技术应用推动了找矿突破进程."十二五"是实现新疆"358"目标任务的关键时期,在"十一五"成果基础上,继续按"358"总体部署,强化重要成矿带及远景区的基础地质及调查评价工作,加强找矿突破关键问题的科技攻关及高新技术方法的应用,加大重要矿集区整装勘查力度,努力实现地质找矿新突破. 相似文献
120.
以信息化带动勘察设计行业现代化,是勘察设计行业始终不渝的追求。"十一五"期间在中国勘察设计协会的领导下,行业单位的信息化工作取得了显著成绩。笔者结合近年来本单位的信息化工作实践以及行业会议和调研等行业信息化工作经历,对勘察设计单位"十一五"期间的信息化建设情况进行总结,并对"十二五"的发展思路提出相关建议。 相似文献