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211.
北黄海海底麻坑群形态的定量研究及控制因素 总被引:1,自引:0,他引:1
本文基于高分辨率多波束水深数据和反向散射强度数据,对北黄海海底麻坑群的形态参数进行定量研究,结合水深、地形坡度和后向散射强度的变化准确界定了麻坑的轮廓,识别出圆形、椭圆形、拉长型麻坑共282个,并在ArcGIS软件中对其形态参数进行了分析计算,麻坑的平均长轴1.36 km,短轴0.78 km,直径0.94 km,面积0.88 km2,平均周长3.82 km,长宽比1.83,深度0.3~2.5 m,平均面积密集度13%,麻坑的剖面形态有麻坑边缘凹陷、中部有明显凸起(W1型),麻坑边缘凹陷、中部略凸起(W2型),麻坑中部单纯凹陷(V型),分别集中分布在麻坑群的北部、南部、西部。麻坑的平面规模大、深度小的原因与地层中形成麻坑的游离气体浓度较小有关,也可能受到了地震、海啸等外力的诱发。麻坑的长轴优势走向为ENE-WSW、NNE-SSW,底流对其形状的塑造起了较大作用,部分麻坑成串排列,形成串珠状的麻坑链,其排列方式受到海底古河道、古潟湖等沉积地层结构的控制。海底麻坑群发育区反向散射强度为-60~-71 dB,麻坑内部较麻坑外部平均高5 dB,可能为麻坑内部气体泄漏引起海底沉积物被剥蚀后残留下的粗颗粒物质或海底生物活动留下的遗迹导致的。 相似文献
212.
The spatio-temporal patterns of macrofaunal fouling assemblages were quantitatively investigated in the nearshore waters of the South China Sea. The work was undertaken by deploying seasonal panels at two sites (H-site, L-site) for one year, and the fouling communities on the panels were examined and analyzed. The results indicated that species composition of assemblages was obviously different between the two sites. At both sites the assemblages were characteristic with solitary dominant species throughout the year, with Amphibalanus reticulates dominating at H-site and Hydroides elegans at L-site. Shannon index and biomass of the assemblages varied with depth and season at both sites. At H-site the total biomass in summer and autumn were significantly higher than those in spring and winter, while at L-site the assemblage biomass also differed significantly among the four seasons, and the greatest biomass occurred at the depth of 2.0 m in winter. The abundance of all seasonal samples in non-metric multidimensional scaling was clustered as one group at L-site and three groups at H-site. The environmental factors were more likely to be related to the variation of fouling assemblages. Furthermore, it also suggests that in tropical seas the integrated adaptability would qualify a species for dominating a fouling assemblage despite its short life cycle, rather than the usually assumed only species with long life span. This study reveals the complexity and characteristic dynamics of macrofaunal fouling assemblages in the tropical habitats, and the results would provide valuable knowledge for biodiversity and antifouling research. 相似文献
213.
Cobetia marina is a model proteobacteria in researches on marine biofouling. Its taxonomic nomenclature has been revised many times over the past few decades. ~To better understand the role of the surface-associated lifestyle of C. marina and the phylogeny of the family Halomonadaceae, we sequenced the entire genome of C. marina JCM 21022 ~T using single molecule real-time sequencing technology(SMR~T) and performed comparative genomics and phylogenomics analyses. ~The circular chromosome was 4 176 300 bp with an average GC content of 62.44% and contained 3 611 predicted coding sequences, 72 t RNA genes, and 21 r RNA genes. ~The C. marina JCM 21022 ~T genome contained a set of crucial genes involved in surface colonization processes. ~The comparative genome analysis indicated the significant diff erences between C. marina JCM 21022 ~T and Cobetia amphilecti KMM 296(formerly named C. marina KMM 296) resulted from sequence insertions or deletions and chromosomal recombination. Despite these diff erences, pan and core genome analysis showed similar gene functions between the two strains. ~The phylogenomic study of the family Halomonadaceae is reported here for the first time. We found that the relationships were well resolved among every genera tested, including Chromohalobacter, Halomonas, Cobetia, Kushneria, Zymobacter, and Halotalea. 相似文献
214.
Humans and livestock have always dwelling together, especially in rural areas. Based on a multi-method approach of ethnographic fieldwork, grounded theory and one-way multivariate analysis of variance, this paper explores human and livestock dwelling. The findings show that human and livestock dwelling form a special type of human dwelling place, with forms defined as co-, mix- and dis-dwelling. Then, from co-, mix- to dis-dwelling constructed a story line to the evolution of human and livestock dwelling forms, which further explains the entire dwelling situation of humans and livestock, including the dimensions of human dweller, livestock dweller, the rural environment and special events. Among co-, mix- and dis-dwelling significant differences existed between human and livestock individuals, the nature of rural environment, vernacularity and rural tourism development. Between co- and dis-dwelling, significant differences existed in seventeen aspects; between mix- and dis-dwelling, significant differences existed in eleven aspects; meanwhile, no significant differences existed between co- and mix-dwelling. Accordingly, this suggested that human and livestock dwelling forms can be divided into mix- and dis-dwelling. This study on humans and livestock dwelling relationship offer a new perspective on rural and animal geography. This paper is an exploratory foray into rural dwelling geography as part of the Anthrozoology study and broadens the scope of extant scholarship on human dwelling morphology, as well as analyses the spatial relationships between human and livestock dwelling. 相似文献
215.
216.
本实验选用ZLI-3654型铁电液晶(FLC)以及SE-3140型取向剂制备FLC器件样品,通过改变FLC相变过程中的降温速率以及相变前的热力学平衡态来研究FLC相变前的热力学平衡态对FLC排列的影响,共进行了十组实验.实验后,将FLC器件静态对比度进行比较,得出手性向列相到近晶A相(N*-SmA)相变前的热力学平衡态对FLC实现均匀排列起着极其重要的作用的结论.实验结果表明:器件的静态对比度可高达620 ∶1, N*-SmA相变前的热力学平衡态有利于形成高对比 相似文献
217.
利用Nd:YAG纳秒激光(波长为532和355 nm)对单晶硅在真空中进行了累积脉冲辐照,研究了表面微结构的演化情况.在激光辐照的初始阶段,532和355 nm激光脉冲均在硅表面诱导出了波纹结构,后者辐照硅表面后形成了近似同心但稍显混乱的环形波纹结构.随着脉冲数的增加,波纹结构逐渐演化为一种类似珠形的凹凸结构,最后形成准规则排列的微米量级锥形结构,该微结构的生长依赖于表面张力波和结构自组织.分析发现,形成的交叉环形结构主要是在355 nm激光辐照硅的过程中,表面张力波导致波纹结构部分叠加的结果. 相似文献
218.
219.
Jian Cao Zhijun Jin Wenxuan Hu Yijie Zhang Suping Yao Xulong Wang Yueqian Zhang Yong Tang 《Marine and Petroleum Geology》2010
Calcite veins and cements occur widely in Carboniferous and Permian reservoirs of the Hongche fault zone, northwestern Junggar Basin in northwest China. The calcites were investigated by fluid inclusion and trace-element analyses, providing an improved understanding of the petroleum migration history. It is indicated that the Hongche fault behaved as a migration pathway before the Early Cretaceous, allowing two oil charges to migrate into the hanging-wall, fault-core and footwall reservoirs across the fault. Since the Late Cretaceous, the Hongche fault has been sealed. As a consequence, meteoric water flowed down only into the hanging-wall and fault-core reservoirs. The meteoric-water incursion is likely an important cause for degradation of reservoir oils. In contrast, the footwall reservoirs received gas charge (the third hydrocarbon event) following the Late Cretaceous. This helps explain the distribution of petroleum across the fault. This study provides an example of how a fault may evolve as pathway and seal over time, and how reservoir diagenetic minerals can provide clues to complex petroleum migration histories. 相似文献
220.