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221.
LIHUA RAN HUI JIANG KAREN LUISE KNUDSEN JÓN EIRÍKSSON 《Boreas: An International Journal of Quaternary Research》2008,37(3):399-413
A high-resolution diatom record from core MD99-2275 reveals a series of palaeoceanographic changes on the North Icelandic shelf since about 9000 cal. yr BP. The influence of relatively warm high-salinity Atlantic water-masses of the IC was strong in the study area during the Holocene Climate Optimum (8760 (base of record) to c . 5300 cal. yr BP) and peaked between c . 8000 and 7000 cal. yr BP. There is a general cooling trend from c . 7000 cal. yr BP to the present, which is indicated by an increase in the influence of cold Polar water-masses from the EGC and the EIC and a decrease in the influence of the IC. A major change in diatom assemblages at around 5300 cal. yr BP indicates a palaeoceanographic shift on the North Icelandic shelf in the mid-Holocene. In addition, several abrupt palaeoceanographic changes are distinguished. Enhanced influence of Polar waters is reflected during the intervals 8120–8000, 6650–6100, 4300–4100, 3000–2700, 1300–1100 and 600–200 cal. yr BP. The palaeoceanographic indication of the diatom record of core MD99-2275 is consistent with the indication of other environmental parameters from the same core, such as benthic and planktonic foraminifera as well as magnetic properties, and the results are also consistent with palaeoclimatic records from adjacent areas around Iceland and in the North Atlantic region. 相似文献
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223.
面对规模日益庞大的影像数据集合,提供一个高效的数据管理模式或配置一个高效的数据库管理系统,能够向用户提供影像可视化和快速查询功能,是影像数据管理中需要着重解决的问题。本文通过简介ArcGIS海量影像管理的方法,分析镶嵌数据集影像数据管理模型特点,从而提出高效管理海量影像数据的方法。 相似文献
224.
使用中国及邻区的18个数字化地震台的宽频带三分向远震记录图,筛选计算得到了263条径向接收函数,并拾取了在41Okm和660km间断面上的透射转换震相P4S、P660S与P波的到时差.通过调整各台站之下的速度模型中这两个间断面的深度,使理论接收函数的P4S、P660S与P波的到时差与观测值相符,最终确定这两个间断面的实际埋藏深度.结果表明,各台站之下4km间断面的平均深度为403km,具有明显的横向不均匀性和区域性,其中北京台、西安台、兰州台和恩施台等的埋藏深度较浅,琼中台、CHTO等台较深.660km间断面的平均埋藏深度为663km,也存在明显的横向不均匀性,其中牡丹江台和MAJO台的较深,琼中台和HYB台的较浅. 相似文献
225.
区域构造和微构造分析表明,新生代藏东地区构造应力场自印支燕山期的NE-SW向挤压向喜马拉雅山期的NNE-SSW向压扭性转变,表现在:(1)沿昌都地块两侧及古生代一中生代形成的深大断裂带发生了大规模的右旋走滑活动,伴重型较强的碎裂岩化、拉伸线埂和剑鞘褶皱等,沿主断裂两侧叠加一系列NW、NNW及NE向雁行式排列的褶皱和张扭性断裂;(2)在区域上,沿大规模右旋走滑断裂两侧形成一系列雁行式排列的第三系走滑拉分盆地;(3)新生代岩浆活动沿走滑断裂两侧的张扭性次级断裂有规律分布,新生代构造体制的转变造成大规模成矿流体与富集,使新生代成为本区最重要的成矿时期,而北澜沧江,妥坝、温泉断裂带及车所乡断裂带北段是该期矿产最有利的富集部位。 相似文献
226.
This paper deals with the saltation of bed-load solid grains in flowing water. Experiments have been carried out by means of high-speed photographing and advanced data processing techniques while the analysis is made by combined method of mechani- cal and statistical theories. Experiments reveal that saltation is the main form of the bed-load transport under ordinary flow conditions. Taking successive saltation as the model of bed-load transport, systematic analysis has been made with regard to the forces acting on grains and the variation of their magnitudes along the saltation trajec- tories to obtain the kinematic and dynamic properties of these grains. The statistical analysis shows that the probability density functions of the relative height and length of saltation are in conformity with distribution, while the probability density functions of the relative velocities of saltation are in conformity with the Gaussian distribution. 相似文献
227.
The genome size(C-value) of an organism is referring to the DNA content of its non-replicated haploid chromosome complement,generally deduced from measuring somatic diploid nuclei.We presented genome size(C-value) data obtained by flow cytometry for four commercially important crabs(Portunus trituberculatus,Charybdis japonica,Scylla paramamosain,and Eriocheir sinensis) common in the coast of China.Gallus domesticus(2C=2.5 pg) was used as the internal standard.The results showed that the C-value for P.trituberculatus,C.japonica,S.paramamosain,and E.sinensis were(2.31±0.01) pg,(2.33±0.03) pg,(1.64±0.02) pg,and(2.29±0.03) pg,respectively.The C-value of P.trituberculatus,C.japonica and S.paramamosain were reported for the first time.The data represented by the four species indicated that they had lower DNA contents than average DNA values in crustaceans((4.99±0.48) pg),and three of the four values were very similar if not identical.The results provide useful data for future studies in the fields of biodiversity,species conservation,and phylogeny of these commercial crabs.They will also be helpful in instructing the hybridization breeding program and estimating the cost of the whole genome sequencing project. 相似文献
228.
1 .Introduction Underwater acoustic (UWA) communicationis a fast developingfield,and its applicationis notlimitedto military affairs ,but is also extendinginto commercial fields .Catipovic (1990) ,Stojanovic(1996) and Kilfoyle and Baggeroer (2000) pointed… 相似文献
229.
南海海面温度的年际模态及其与季风强迫的关系 总被引:1,自引:0,他引:1
通过对COADS和OISST海洋气象资料的分析,以南海的海面温度异常(SSTA)为指示因子,在研究年际尺度上的南海与大尺度ENSO关系的基础上,进一步探讨了季风强迫下Ekman抽吸对SSTA年际变化的贡献。研究发现,南海SSTA滞后5个月时与:Nifio 3的SSTA相关系数最大,且其年际变化依方差贡献大小,分别有42.7月、25.6月及36.6个月的周期,这3个年际模态基本上能够描述海面温度的年际变异,为南海在大尺度ENSO背景下存在区域响应提供了重要的证据;应用Krause—Turner混合层温度方程对南海异常暖事件的研究表明,除了经向风应力异常,Ekman抽吸也是影响SSTA年际变异的主要因素,在某些异常年份甚至是主导因素,为南海SSTA年际变化的研究提供了重要的补充。 相似文献
230.