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281.
A marine bacterium, Pseudoalteromonas sp. BC228 was supplemented to feed in a feeding experiment aiming to determine its ability of enhancing the digestive enzyme activity and immune response of juvenile Apostichopus japonicus. Sea cucumber individuals were fed with the diets containing 0(control), 105, 107 and 109 CFU g-1 diet of BC228 for 45 days. Results showed that intestinal trypsin and lipase activities were significantly enhanced by 107 and 109 CFU g-1 diet of BC228 in comparison with control(P 0.01). The phagocytic activity in the coelomocytes of sea cucumber fed the diet supplemented with 107 CFU g-1 diet of BC228 was significantly higher than that of those fed control diet(P 0.05). In addition, 105 and 107 CFU g-1 diet of BC228 significantly enhanced lysozyme and phenoloxidase activities in the coelomic fluid of sea cucumber, respectively, in comparison with other diets(P 0.01). Sea cucumbers, 10 each diet, were challenged with Vibrio splendidus NB13 after 45 days of feeding. It was found that the cumulative incidence and mortality of sea cucumber fed with BC228 containing diets were lower than those of animals fed control diet. Our findings evidenced that BC228 supplemented in diets improved the digestive enzyme activity of juvenile sea cucumber, stimulated its immune response and enhanced its resistance to the infection of V. splendidus.  相似文献   
282.
Abstract Zinc (Zn) and copper (Cu) concentrations were determined in the tissues (muscle, stomach, liver, gills, skin, and gonads) of five commercial fish species (mullet Liza haematocheilus, flathead Platycephalus indicus, mackerel Scomberomorus niphonius, silver pomfret Pampus argenteus, and sea bass Lateolabrax japonicus) from Laizhou Bay in the Bohai Sea. Metal bioaccumulation was highest in the metabolically active tissues of the gonads and liver. Bioconcentration factors for Zn were higher in all tissues (gonads 44.35, stomach 7.73, gills 7.72, liver 5.61, skin 4.88, and muscle 1.63) than the corresponding values for Cu (gonads 3.50, stomach 3.00, gills 1.60, liver 5.43, skin 1.50, and muscle 0.93). Mackerel tissues accumulated metal to higher concentrations than did other fish species, but bioaccumulation levels were not significantly correlated with the trophic levels of the fish. Zn and Cu concentrations in the tissues were generally negatively correlated with fish length, except for a few tissues of sea bass. Risk assessment based on national and international permissible limits and provisional tolerances for weekly intake of Zn and Cu revealed that the concentrations of these two metals in muscle were relatively low and would not pose hazards to human health.  相似文献   
283.
为了解北部湾北部海区浮游动物数量分布规律及优势种组成,2006—2007年对北部湾进行4个航次的综合性调查。根据浮游动物样品分析结果,研究了北部湾北部浮游动物的丰度、生物量和优势种组成,并利用Spearman等级相关法分析丰度与环境因子间的关系。研究结果表明,北部湾北部浮游动物丰度年均值(183.5±142.9)ind/m3,丰度的季节分布由高到低依次为秋季、夏季、冬季、春季;生物量年均值(139.5±116.8)mg/m3,由高到低依次为春季、秋季、冬季、夏季特征。平面分布上,春、秋两季丰度分布呈远岸高近岸低的趋势,而夏、冬两季则在近岸海域形成高丰度区。生物量的平面分布趋势与丰度的分布趋势基本一致。丰度变化与环境因子的相关性显著,水深、温度及叶绿素a浓度是影响丰度分布的主要因素。肥胖软箭虫Flaccisagitta enflata、亚强次真哲水蚤Subeucalanus subcrassus和间型莹虾Lucifer intermedius在北部湾北部的优势地位显著,优势种演替具有明显的季节性。  相似文献   
284.
A sediment sample was collected from a deep-sea hydrothermal vent field located at a depth of 2 951 m on the Southwest Indian Ridge. Phylogenetic analyses were performed on the prokaryotic community using polymerase chain reaction(PCR) amplification of the 16 S rRNA and nifH genes. Within the Archaea, the dominant clones were from marine benthic group E(MBGE) and marine group I(MGI) belonging to the phyla Euryarchaeota and Thaumarchaeota, respectively. More than half of the bacterial clones belonged to the Proteobacteria, and most fell within the Gammaproteobacteria. No epsilonproteobacterial sequence was observed. Additional phyla were detected including the Actinobacteria, Bacteroidetes, Planctomycetes, Acidobacteria, Nitrospirae, Chloroflexi, Chlorobi, Chlamydiae, Verrucomicrobia, and candidate divisions OD1, OP11, WS3 and TM6, confirming their existence in hydrothermal vent environments. The detection of nifH gene suggests that biological nitrogen fixation may occur in the hydrothermal vent field of the Southwest Indian Ridge. Phylogenetic analysis indicated that only Clusters I and III NifH were present. This is consistent with the phylogenetic analysis of the microbial 16 S rRNA genes, indicating that Bacteria play the main role in nitrogen fixation in this hydrothermal vent environment.  相似文献   
285.
传统的海冰检测手段都存在着受天气影响或实时检测成本太高的缺点,为了更实时有效的检测海冰,减轻海冰灾害对于我国的影响,并达到防灾减灾的目的,本文研究了GPS反射信号(GPS-R)技术检测海冰的可能性。通过对2013年2月下旬在中国天津渤海湾的岸基架设GPS信号接收机所接收的观测数据进行分析,使用不同特性的反射海域(几乎全为海水或是海冰)的数据进行比对分析,其结果显示极化比值(反射左旋信号与直射右旋信号的比值)能够明显反演海冰密集度。本文首次将GPS-R技术应用于国内自主设计的渤海海冰检测实验中。  相似文献   
286.
为满足气象实时资料传输中大量气象数据小文件的高时效传输需求,对其中的数据传输服务进行优化,提出一种基于实时网络状况的自适应数据传输优化方法。该方法采用优化网络传输协议并使用文件压缩技术,通过获取网络传输线路上的实时参数,实时调整压缩参数和网络传输参数以优化传输性能。在自适应压缩时,通过试验分析和归纳,确立了气象数据小文件标准为文件小于50 KB;根据网络实时状况,设计了基于实时网络状况自适应调整压缩等级的算法。在自适应传输参数调优中,研究了TCP缓冲区大小和TCP并发连接数在GridFTP协议中的重要性,针对实时网络状况,分别设计了自适应调整TCP缓冲区大小和TCP并发连接数的算法,算法提升传输性能65%。对以上提出各自适应参数调整算法进行试验验证表明,融合压缩和网络传输的自适应调优方法能显著提升气象小数据文件的传输性能近500倍。  相似文献   
287.
This paper presents a novel approach for assessing the precision of the wet refractivity field using BDS (BeiDou navigation satellite system) simulations only,GPS,and BDS+GPS for the Shenzhen and Hongkong GNSS network.The simulations are carried out by adding artificial noise to a real observation dataset.Instead of using the δ and σ parameters computed from slant wet delay,as in previous studies,we employ the Bias and RMS parameters,computed from the tomography results of total voxels,in order to obtain a more direct and comprehensive evaluation of the precision of the refractivity field determination.The results show that:(1) the precision of tropospheric wet refractivity estimated using BDS alone (only 9 satellites used) is basically comparable to that of GPS; (2) BDS+GPS (as of current operation) may not be able to significantly improve the data's spatial density for the application of refractivity tomography; and (3) any slight increase in the precision of refractivity tomography,particularly in the lower atmosphere,bears great significance for any applications dependent on the Chinese operational meteorological service.  相似文献   
288.
This paper reviews recent progress in the development of the Beijing Climate Center Climate System Model(BCC-CSM) and its four component models(atmosphere,land surface,ocean,and sea ice).Two recent versions are described:BCC-CSM1.1 with coarse resolution(approximately 2.8125°×2.8125°) and BCC-CSM1.1(m) with moderate resolution(approximately 1.125°×1.125°).Both versions are fully coupled climate-carbon cycle models that simulate the global terrestrial and oceanic carbon cycles and include dynamic vegetation.Both models well simulate the concentration and temporal evolution of atmospheric CO_2 during the 20th century with anthropogenic CO2 emissions prescribed.Simulations using these two versions of the BCC-CSM model have been contributed to the Coupled Model Intercomparison Project phase five(CMIP5) in support of the Intergovernmental Panel on Climate Change(IPCC) Fifth Assessment Report(AR5).These simulations are available for use by both national and international communities for investigating global climate change and for future climate projections.Simulations of the 20th century climate using BCC-CSMl.l and BCC-CSMl.l(m) are presented and validated,with particular focus on the spatial pattern and seasonal evolution of precipitation and surface air temperature on global and continental scales.Simulations of climate during the last millennium and projections of climate change during the next century are also presented and discussed.Both BCC-CSMl.l and BCC-CSMl.l(m) perform well when compared with other CMIP5 models.Preliminary analyses indicate that the higher resolution in BCC-CSM1.1(m) improves the simulation of mean climate relative to BCC-CSMl.l,particularly on regional scales.  相似文献   
289.
54个晋冀低山丘陵区人工和人工扰动植被表土花粉样品分析表明:花粉组合以草本植物花粉(74.5%)为主,乔木花粉含量低于20%。人类活动较强的农田以谷物禾本科、蒿属和藜科花粉为主,人类活动较弱的荒地以蒿属、藜科和杂草禾本科花粉为主。人类活动强度不同,指示种不同,孢粉浓度亦不同;农田指示种为谷物禾本科、葡萄科和胡桃科,孢粉浓度约4380粒/g;而蒿属、蓼科和蔷薇科则为荒地指示种,孢粉浓度约10983粒/g。农作物种植方式不同,谷物禾本科花粉含量不同,单一禾本科作物种植区谷物禾本科花粉含量(40.2%)高于多种作物混作区(18.8%)和荒地(3.8%)的含量。谷物禾本科含量的变化可以为利用化石花粉提取和检测人类活动信息提供依据,也可为利用地层中谷物禾本科花粉判断古代农业活动提供依据。  相似文献   
290.
银都矿床位于内蒙古大兴安岭西坡,为受断裂控制的银多金属矿床。该矿床的岩体主要为石英闪长岩。该岩体中的锆石分为岩浆锆石和热液锆石两类:岩浆锆石无色透明,自形长柱状,具有典型的振荡环带特征;而热液锆石呈浅褐色,半透明—不透明,等轴状,其暗色增生边明显切过了核部岩浆锆石结构。热液锆石相对岩浆锆石具有低Th/U和LREE,高Hf和HREE的特征。银都岩体岩浆锆石的206Pb/238 U加权平均年龄为(451.8±7.8)Ma,属加里东期,为岩体的结晶年龄;热液锆石的206 Pb/238 U加权平均年龄为(337.0±7.7)Ma,属中石炭世,代表了热液作用的年龄。热液锆石年龄表明,该区在337Ma左右经历了一次强烈的热液作用,该期热液作用可能与该区造山峰期的变质作用有关。本区的地质特征和流体包裹体特征表明,本区银矿的形成很可能与这期热液活动密切相关。  相似文献   
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