基于壳板和齿舌形态对中国沿岸几种常见多板纲软体动物的分类研究   总被引：1，自引：1，他引：0  

张均龙  史振平  王承  张树乾  张素萍 《海洋科学》2015,39(11):96-107

多板纲软体动物统称石鳖,是软体动物门较为低等的一个类群,在软体动物的系统进化中占有重要的地位。但有关我国沿海多板纲软体动物的调查研究十分欠缺,而且对中国沿海多板纲的分布状况和区系特点尚不明确,并存在着一些鉴定错误和分类混乱现象。本研究利用10%Na OH溶液处理齿舌部获取齿舌带和壳板的方法,通过扫描电镜和显微镜观察拍照,对我国沿岸常见多板纲软体动物中5科7属13种的齿舌和壳板形态结构进行了描述,并进行了比较研究。  相似文献   

Using SPOT 5 fusion-ready imagery to detect Chinese tamarisk (saltcedar) with mathematical morphological method     

《International Journal of Digital Earth》2013,6(3):217-228

Chinese tamarisk (saltcedar) is a deciduous shrub that occurs widely across the Yellow River Delta in China. The spatial structure of Chinese tamarisk is believed to have an influence on the landscape and habitats of rare birds. In this study, first, Chinese tamarisk is detected using Canny edge detector and mathematical morphological operators based on SPOT 5 fusion-ready imagery. Then the numbers, areas, locations, and patch spacing of Chinese tamarisk patches are calculated. The experiments show that the detection accuracy of Chinese tamarisk patches is about 93.4% after the disconnection of connected patches. The distribution orientation of about 70% of the patches is approximately south–north. About 91% of the minimum distances among the patches are between 12.5 and 57.5 m. The rose graph indicates that the main azimuth between patches is north–northwest, and the second is northeast and southeast. The present study indicates that the integrating Canny edge detector with the algorithms for extracting circular and elliptical objects based on mathematical morphology is simple and effective for detecting Chinese tamarisk patches and is easy to identify the spatial structure of Chinese tamarisk patches, which reduces the time and labor for the visual interpretation of Chinese tamarisk patches.  相似文献   

Burrowing and burying by the crab Macrophthalmus hirtipes     

Pauline A. Nye 《新西兰海洋与淡水研究杂志》2013,47(2):243-254

Macrophthalmus hirtipes (Jacquinot, 1853) excavates burrows under water in soft, muddy sand that remains waterlogged at low tide. The crabs are immersed for at least 4 h in every tide. The burrows are usually single, blind‐ending, slightly curved passages; their openings do not appear to be deliberately closed by the crabs. Excavation is effected by using one set of walking legs as a scoop while the other set provides sideways traction.

Burrow openings are readily obscured by water movement, so that apparent burrow density does not give a true indication of the number of crabs in an area, but only indicates how many have been active recently; the true density may be found by sieving.

The burrowing activity of M. hirtipes is compared with that of other ocypodid crabs, and the functions of burrows are discussed. A distinction is made between excavating a burrow and rapid burying, because the two behaviours are very different, and must involve different adaptations and selection pressures.  相似文献   

Morphology and Histology of Lattice-like Ossified Epaxial Tendons in Psittacosaurus (Dinosauria: Ceratopsia)     

ZHOU Chang-Fu  GAO Ke-Qin  and Richard C. FOX 《《地质学报》英文版》2010,84(3):463-471

<正>Epaxial tendons play an important role in the study of the musculoskeletal system and locomotory style of dinosaurs.Although the ossified epaxial tendon lattice is fairly well known in Iguanodontoidea,only recently has knowledge of this complex been extended to ceratopsians.This study concerns the gross morphology and microstructure of the tendon lattice in Psittacosaurus,a basal ceratopsian.As in the neoceratopsian Chasmosaurus,the ossified tendons of Psittacosaurus form a three-layered, lattice-like structure.The microstructure of the tendons in large psittacosaur individuals retains an early stage of ossification,as in juvenile birds and nestling hadrosaurs,suggesting a slow developmental rate of ossification of the tendons in psittacosaur ontogeny.Comparative study indicates that a lattice-like arrangement of three-layered epaxial tendons is widely distributed in Cerapoda.This pattern also extends to Ankylosauria,implying a similar pattern of the epaxial muscles through the ornithischian clade.In addition,comparison with crocodiles implies that the different morphology of ossified tendons in dinosaurs may be associated with adaptive aspects of their paleobiology,not simply a side effect of skeletal ossification.In contrast to the short tendons in quadrupedal Chasmosaurus and Protoceratops,the elongated tendons in Psittacosaurus may be related to the bipedal locomotion characteristic of this taxon.  相似文献   

云南孟连芒信金矿成因探讨   总被引：1，自引：0，他引：1  

唐治安  张贵华  和松文 《云南地质》2010,29(3):269-270,261

芒信金矿脉状、透镜状、串球状金矿体,赋存于石炭系碳酸盐岩破碎带中。以裂隙金、晶隙金、固溶金、吸附金状存在。经历沉积—变质—岩浆活动等阶段。  相似文献   

Modelling tidal current‐induced bed shear stress and palaeocirculation in an epicontinental seaway: the Bohemian Cretaceous Basin,Central Europe     

ANDREW J. MITCHELL  DAVID ULIČNÝ  GARY J. HAMPSON  PETER A. ALLISON  GERARD J. GORMAN  MATTHEW D. PIGGOTT  MARTIN R. WELLS  CHRISTOPHER C. PAIN 《Sedimentology》2010,57(2):359-388

Lower to Middle Turonian deposits within the Bohemian Cretaceous Basin (Central Europe) consist of coarse‐grained deltaic sandstones passing distally into fine‐grained offshore sediments. Dune‐scale cross‐beds superimposed on delta‐front clinoforms indicate a vigorous basinal palaeocirculation capable of transporting coarse‐grained sand across the entire depth range of the clinoforms (ca 35 m). Bi‐directional, alongshore‐oriented, trough cross‐set axes, silt drapes and reactivation surfaces indicate tidal activity. However, the Bohemian Cretaceous Basin at this time was over a thousand kilometres from the shelf break and separated from the open ocean by a series of small islands. The presence of tidally‐influenced deposits in a setting where co‐oscillating tides are likely to have been damped down by seabed friction and blocked by emergent land masses is problematic. The Imperial College Ocean Model, a fully hydrodynamic, unstructured mesh finite element model, is used to test the hypothesis that tidal circulation in this isolated region was capable of generating the observed grain‐size distributions, bedform types and palaeocurrent orientations. The model is first validated for the prediction of bed shear stress magnitudes and sediment transport pathways against the present‐day North European shelf seas that surround the British Isles. The model predicts a microtidal to mesotidal regime for the Bohemian Cretaceous Basin across a range of sensitivity tests with elevated tidal ranges in local embayments. Funnelling associated with straits increases tidal current velocities, generating bed shear stresses that were capable of forming the sedimentary structures observed in the field. The model also predicts instantaneous bi‐directional currents with orientations comparable with those measured in the field. Overall, the Imperial College Ocean Model predicts a vigorous tide‐driven palaeocirculation within the Bohemian Cretaceous Basin that would indisputably have influenced sediment dispersal and facies distributions. Palaeocurrent vectors and sediment transport pathways however vary markedly in the different sensitivity tests. Accurate modelling of these parameters, in this instance, requires greater palaeogeographic certainty than can be extracted from the available rock record.  相似文献   

The interaction of fluid inclusions and migrating grain boundaries in a rock analogue: deformation and annealing of polycrystalline camphor–ethanol mixtures     

J. SCHMATZ  J. L. URAI 《Journal of Metamorphic Geology》2010,28(1):1-18

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冀东平原土壤重金属元素的存在形态及有效性分析   总被引：3，自引：0，他引：3       下载免费PDF全文

栾文楼刘洪微  温小亚杜 俊李振宁  陈志贤谷海峰 《中国地质》2010,37(2):508-514

通过对冀东平原根系土中8种重金属元素形态含量的统计与分析,总结出其形态组成特征,初步分析了各重金属元素在土壤中的地球化学行为。笔者运用相关性分析方法,对重金属元素有效态含量与全量及土壤pH、TOC的相关性进行分析,从而得出重金属元素有效态含量的高低不仅受其全量的影响,而且与土壤pH、TOC亦有密切关系,这为表层土壤重金属元素污染程度的科学合理评价提供了理论依据。  相似文献   

南海3种小型砗磲的外壳形态差异分析     

钞琪琪  杨毅  顾志峰  王爱民  L&#;PEZ Violet  刘春胜 《海洋科学》2022,46(10):24-31

本研究对中国南海3种小型砗磲(Tridacnaspp.)[番红砗磲(Tridacnacrocea,包括2种外壳形态)、长砗磲(Tridacna maxima)和诺亚砗磲(Tridacna noae)]的外壳形态性状进行生物统计学差异分析。研究表明,4组砗磲外壳存在显著形态学差异。单因素方差分析发现9个外壳比例性状能够较好区分3种砗磲,且2种不同外壳形态的番红砗磲在壳宽/壳长、足丝孔宽/壳长、壳质量/壳长和左右壳厚比壳长存在显著性差异(P<0.05);在基于欧氏距离Ward法且指定聚类数k=4的条件下,4组砗磲层次聚类效果较好;主成分分析提取3个主成分建立散点图,累计主成分贡献率73.85%,各主成分贡献率依次为50.47%,13.78%和9.60%;线性判别分析得出3个判别函数,方差解释率依次为70.13%、20.97%和8.90%。3种多元统计方法从不同角度解释各组砗磲的外壳形态差异,结果均显示两组番红砗磲的外壳形态更为接近,同时长砗磲与诺亚砗磲的外壳形态较为接近。  相似文献   

腾格里沙漠南部格状沙丘的形态演变及移动特征     

杨馥宁  吕萍  马芳  曹敏  肖南  顾立霞  杨迎 《中国沙漠》2023,43(1):107-115

沙丘的形态变化与移动蕴含区域风沙环境和地貌演化的关键信息,是风沙地貌研究的重要内容。以腾格里沙漠南缘的长格状和方格状沙丘为研究对象,利用风况资料和Google Earth卫星影像,监测2009—2020年两种格状沙丘的形态变化并分析其移动特征。结果表明：(1)腾格里沙漠西南缘和东南缘的主风向均为西北风,长格状沙丘分布区的次风向为东南风,方格状沙丘分布区次风向为东风和东南风,都属于低风能环境、中变率风况。西南部风能环境大于东南部,研究区近10年风动力呈衰减趋势。(2)格状沙丘的主副梁长度和间距在增加,其中,长格状沙丘高度增加,方格状沙丘高度在降低。沙丘主梁向东偏移,副梁向南偏移,形态整体保持稳定。(3)长格状沙丘平均移动速率为1.57～1.71 m·a^-1,方格状沙丘平均移动速率为1.63～2.01 m·a^-1,沙丘平均移动方向与合成输沙方向基本一致,沙丘的体积是造成移动速率差异的主因。  相似文献