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台湾海峡金色小沙丁鱼幼鱼索饵群体研究 总被引：2，自引：1，他引：2
本文研究了台湾海峡南部和北部的金色小沙丁鱼当年生幼鱼计数性状和量度性状特征差异,并结合其生物学特性、产卵场、洄游及海区环境特征进行综合分析。结果表明,台湾海峡南部和北部的索饵幼鱼仍属于同一地方种群:闽南-台湾浅滩语地方种群。根据其索饵洄游特点,可分为台湾海峡南部和北部两个索饵群体. 相似文献
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南沙群岛西南陆架区条尾鲱鲤资源状况研究 总被引：1，自引：0，他引：1
根据2003年南沙群岛西南陆架区春秋两季调查资料,分析南沙群岛西南陆架区条尾鲱鲤的资源现状.结果表明,渔获率有明显的季节变动,秋季（1.76kg/h）高于春季（0.08kg/h）,春季密集分布于91～100m水深,秋季密集分布于71～80m水深.其群体组成也有季节差异,春季的平均体长、平均体重大于秋季,春季优势体长组为101～110mm,秋季优势体长组为91～100mm,渔获中不足1龄鱼占多数,其资源密度及现存资源量分别为12.02kg/km^2 和880.82t,现存资源量只有原始资源量的54.92%,该鱼种资源已接近衰退状态.文中并讨论合理利用该资源的措施. 相似文献
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Regional variation in maturation of sandeels in the North Sea 总被引：1，自引：0，他引：1
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Abstract. Benthic metabolism and standing stocks were investigated in the deep Red Sea between 21o and 27o N, Activity was assessed by the determination of respiration rates with a shipboard method and by calculating oxygen consumption from the activity in the electron transport system. We attempted to compare results from different latitudes within the warm Red Sea and with data from cold Atlantic environments. Our investigations were part of an environmental risk assessment to evaluate future mining of metalliferous sediments from the Atlantis II Deep. 相似文献
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Potential of High-Resolution Satellite Data in the Context of Vulnerability of Buildings 总被引：1，自引：2，他引：1
High-resolution space-borne remote sensing data are investigated for their potential to extract relevant parameters for a
vulnerability analysis of buildings in European countries. For an evaluation of large earthquake scenarios, the number of
parameters in models for vulnerability is reduced to a minimum of relevant information such as the type of building (age,
material, number of storeys) and the geological and spatial context. Building-related parameters can be derived from remote
sensing data either directly (e.g. height) or indirectly based on the recognition of the urban structure type in which the
buildings are located. With the potential of a fully- or semi-automatic inventory of the buildings and their parameters, high-resolution
satellite data and techniques for their processing are a useful supporting tool for the assessment of vulnerability. 相似文献
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Observations show that the sequences of microsecond-scale pulses are produced in cloud flashdischarge processes.In the present work we report on measurements of larger bipolar pulses(LBP)of the radiation fields which are classified into four types according to their waveshapes andpolarities of initial peak.Either positive or negative pulse contains two kinds of waveshapes:onewith a smooth rise and the other with 2 or 3 fast-rising pulse superimposed on the initial half cycle.The pulse waveshape characteristics in both time and frequency domains are as follows.Among2908 samples there are 45% of the positive polarity and 55% of the negative polarity.The positivepulses tend to have distinctly smaller values than negative pulses in rise time,half width and zero-crossing time of the initial peak.The peaks of positive pulse spectra tend to occur at a higherfrequency than those of negative pulses.Despite differences above,positive and negative pulseshave a similar total duration. 相似文献