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71.
多物种集合的种-多度关系模型研究进展   总被引:17,自引:3,他引:17  
彭少麟  殷祚云  任海  郭勤峰 《生态学报》2003,23(8):1590-1605
种 -多度关系是群落结构研究最基本的方面之一。Preston最早描述的物种“常见性和罕见性的分布”是群落中种 -多度关系的一般特性。自从 Motomura开创性地提出一个几何序列模型用于描述这种特性后 ,生态学家已建立了许多拟合种 -多度关系的经验模型和理论模型 ,主要包括对数序列分布、对数正态分布等统计模型 ,几何序列模型、分割线段模型等生态位模型以及反映群落动态和环境制约作用的动态模型 ,还有其中一些模型的扩展模型。近年来 ,种 -多度关系研究领域已大大拓宽 ,如“群落”的内涵已延伸为“多物种集合”,物种“多度”的测度推广到“广义多度”。尽管种 -多度关系研究已取得很大进展 ,仍有一些问题尚待解决 ,诸如多度指标选择、种 -多度分布时空变化规律及其机制以及种 -多度关系模型的选择、检验、解释与应用。  相似文献   
72.
葡萄种质资源初级核心群的构建   总被引:3,自引:0,他引:3  
以国家果树种质郑州葡萄圃保存的867份栽培种质为材料,对47项表型性状进行了主成分分析。采用欧氏遗传距离、离差平方和法进行种质初选。采用分组和逐步聚类法,分别以15%、20%、25%和30%的比例抽样,依次获得124、170、205和252份种质。通过对初选种质的遗传多样性指数、表型保留比例的分析,检验初级核心群的构建效果。结果表明,按种质类型分组,组内采用平方根策略、15%抽样比例获得的124份初选种质的表型保留比例和遗传多样性代表性均达到96%,表明构建的初级核心群对原始种质具有很好的代表性。  相似文献   
73.
甜菜种质资源遗传多样性研究与利用   总被引:2,自引:0,他引:2  
通过多年对中国甜菜种质资源搜集、整理、繁种、鉴定及编目入库等方面进行科技攻关研究,弄清了目前我国甜菜中期库保存种质资源源遗传多样性的丰富程度,根据对已经编目入国家种质长期库的1382份甜菜种质资源材料的主要经济性状鉴定试验结果,证实了我国甜菜种质资源的块根产量、含糖率和产糖量均以西北生态区最高,华北生态区次之,东北生态区最低,同时其变异幅度也比较大。由此表明我国甜菜不同生态区保存的甜菜种质资源材料具有相当高的异质性和丰富的遗传基础,这将有利于推动我国甜菜科研及育种事业的可持续发展。  相似文献   
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75.
Three species of the arcto-boreal, large gastropod Neptunea , described by Linnaeus in 1758 and 1771, occur in large numbers over wide areas of the inshore North Atlantic and adjacent Arctic seas and are conspicuous among Pliocene and Pleistocene molluscs in the Icelandic, North Sea, and western Mediterranean basins. Selections of lectotypes for these species from shells in the collection of the Linnean Society of London, and designations of their type localities, establish the identity of Linnaeus' neptunes and more accurately determine their geographic and geologic distribution. The geographic range of Neptunea (Neptunea) antiqua (L.), the type species, now extends from southern Norway to the northern Biscay coast of France and from the westernmost Baltic Sea to southwestern Ireland; this species also occurs in Pliocene-Holocene marine deposits in West and East Germany, Sweden, the Netherlands, England and France. Its type locality is determined to be the North Sea. N. (Neptunea) despecta (L.) lives in the eastern Canadian Arctic, off southern Greenland, the Barents Sea, and North Atlantic as far south as Massachusetts and Portugal; it also occurs in Pliocene-Holocene strata of eastern Canada, east-central Greenland, Norway (including Svalbard), the Soviet Union, Sweden and England. Its type locality is determined to be the postglacial deposits at Uddevalla in southwestern Sweden. N. (Sulcosipho) contraria (L.) now extends from the southern Biscay coast of France to Cape Spartel, Morocco; this species also occurs in Pleistocene and lower Holocene sequences of the western Mediterranean. Its type locality is determined to be Vigo Bay, Spain. A closely related fossil species, N. (S.) angulata (S. V. Wood), occurs in Pliocene and Pleistocene deposits of the North Sea basin.  相似文献   
76.
An algorithm of automatic classification is proposed and applied to a large collection of perennial ryegrass wild populations from France. This method is based on an ascendant hierarchical clustering using the Euclidian distance from the principal components extracted from the variance-covariance matrix between 28 agronomic traits. A contiguity constraint is imposed: only those pairs of populations which are defined as contiguous are grouped together into a cluster. The definition of contiguity is based on a geostatistical parameter: the range of the variogramme, i.e. the largest distance above which the variance between pairs of population no longer increases. This method yields clusters that are generally more compact than those obtained without constraint. In most cases the contours of these clusters fit well with known ecogeographic regions, namely, for macroclimatic homogeneous conditions. This suggests that selective factors exert a major influence in the genetic differentiation of ryegrass populations for quantitatively inherited adaptive traits. It is proposed that such a method could provide useful genetic and ecogeographic bases for sampling a core collection in widespread wild species such as forage grasses.Institut National de la Recherche Agrononique  相似文献   
77.
EPA Method 1615 was developed with a goal of providing a standard method for measuring enteroviruses and noroviruses in environmental and drinking waters. The standardized sampling component of the method concentrates viruses that may be present in water by passage of a minimum specified volume of water through an electropositive cartridge filter. The minimum specified volumes for surface and finished/ground water are 300 L and 1,500 L, respectively. A major method limitation is the tendency for the filters to clog before meeting the sample volume requirement. Studies using two different, but equivalent, cartridge filter options showed that filter clogging was a problem with 10% of the samples with one of the filter types compared to 6% with the other filter type. Clogging tends to increase with turbidity, but cannot be predicted based on turbidity measurements only. From a cost standpoint one of the filter options is preferable over the other, but the water quality and experience with the water system to be sampled should be taken into consideration in making filter selections.  相似文献   
78.
陈涛   《广西植物》1996,16(1):95-98
本文讨论了主要用以印制标本采集记录标签的数据系统及其数据库建库方案与编程原理。该系统可在IBM及其兼容系列个人计算机上使用,适合用于个人或科研与教学机构中小型标本采集信息管理;可用以数据的检索、标本标签的印制和植物名录的打印;也可用以地区性的植物区系与生态学研究。  相似文献   
79.
竹类植物是美国采集者在我国采集和引种的一类主要植物。在众多的竹类植物采集者中, 莫古礼(Floyd Alonzo McClure)是最具代表性的一位, 他于1919-1940年在岭南大学开展竹类植物研究, 在此期间多次采集竹类植物标本并引种竹类植物到美国。本研究通过大量文献研究、档案查阅以及实地调研, 整理了莫古礼采集竹类植物的路线和采集地, 并对竹类植物学名进行校对, 分析了莫古礼在华研究、采集和引种竹类植物的历史及其影响。经统计, 莫古礼在华期间竹类植物标本采集地涉及12个省级行政区39个地级市, 主要集中在广东、海南、香港等地; 引种地涉及9个省级行政区的25个地级市; 共采集竹类植物标本727号1,840份, 隶属20属93种(含种下单位, 下同), 分别占我国竹类植物属和种的58.8%和17.4%; 共引种竹类植物255份, 隶属于17属77种, 分别占我国竹类植物属和种的50.0%和14.4%。莫古礼在华采集和引种竹类植物极大地发展了竹类植物分类学, 所采集的竹类植物标本为后人竹类植物研究提供了极大的帮助, 所引种的竹类植物极大丰富了美国竹类植物种类, 也促进了竹类植物在美国的应用。  相似文献   
80.
ObjectiveThe objective of this study is to explore the construction of a digital three-dimensional model of virtual technology that plays an auxiliary role in orthopedic treatment.MethodsThree fracture patients were selected, with no abnormality was observed in bone examination, no musculoskeletal disease in the past; and spiral CT scan of the spine and pelvis, upper limbs, and lower limbs was performed. The virtual technology was used to build a digital 3D model, mainly using the editing software Mimics10.0 software. In addition, the virtual three-dimensional model was verified by virtual surgery, data storage security, work efficiency of the model, model validity, three-dimensional characteristics of the model, the interaction mode of the model, and the data accuracy of the model were studied.ResultsThe digital 3D model was successfully established by Mimics10.0 software. The data fitting efficiency was very high. The data storage security of the 3D model was greatly improved compared with the 2D model, and the work efficiency was improved by at least 50%. There was also a significant change in the accuracy and interaction of data acquisition. Therefore, the detection of digital 3D model work through virtual surgery simulation fully demonstrated the positive auxiliary role of 3D model in orthopedic treatment.ConclusionThe digital 3D model based on Mimics10.0 software is efficient and accurate in obtaining data. It is very effective for subsequent adjuvant therapy in the field of orthopedics, reducing the probability of misdiagnosis by doctors, saving time and improving efficiency, reducing patient's physical pain and unnecessary economic expenses.  相似文献   
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