结构群

During the postgenomics era the information about genomic sequence and gene functions provides a new foundation for evolutionary biology and ecology As the first whole-genome sequenced plant Arabidopsis thaliana and its wild relatives have played a critical role in understanding the evolution of genomics and speciation Both A halleri and A lyrata are closely related to the model species A thaliana A halleri ssp gemmifera occurs in northeastern China Japan and Taiwan; while its sister A halleri ssp halleri is mainly distributed in Europe Geographical barriers such as Tienshan Mountain Range isolate these intraspecific sisters Likewise A lyrata ssp kamchatica and ssp lyrata occur in East Asia and North America respectively Such distribution patterns seem to be consistent with allopartic speciation The comparison between ancestral and extant polymorphism by multilocus can be informative about the population genetics of speciation In this study we collected and analyzed DNA sequences of 98 genes from four wild relatives of A thaliana A halleri ssp gemmifera A halleri ssp halleri A lyrata ssp kamchatica and A lyrata ssp lyrata The ancestral states of these four species were compared to each other in terms of level of genetic variation However the ancestral species at the time of speciation were substantially more polymorphic than the extant geographical populations The observations are not fully compatible with speciation by strict allopatry At some species pairs parapatric speciation seems more reasonable in speciation of Arabidopsis The 98 gene sequences are also used for the congruence test between gene genealogy and species phylogeny Only 28 genes support the species phylogeny but there are 23 genes supports another major genealogy { lyrata} thaliana Based on the phylogenetic position change of A lyrata ssp kamchatica and Ks value for each species pair suggested the recent directional gene flow between A halleri ssp gemmifera and A lyrata ssp kamchatica

阿拉伯芥是第一个完成基因体定序的开花植物，其基因体资讯提供植物学研究的重要依据；在解析阿拉伯芥属物种的亲缘关系以及种化机制等重要的演化议题时，阿拉伯芥近缘的野生物种自然成了不可或缺的关键；跟阿拉伯芥近缘的物种包括A halleri及A lyrata，其中A halleri ssp gemmifera主要分布於中国东北、日本以及台湾，与近缘的A halleri ssp halleri其分布於欧洲隔著天山及大陆的障蔽，而A lyrata ssp kamchatica主要分布於东北亚及台湾，与分布於北美五大湖的A lyrata ssp lyrata被北极圈所分隔，这样的分布模式暗示异域种化的可能。藉由多基因分析比较祖先物种与现生物种遗传歧异度的相关可提供讯息探讨种化时期的族群遗传结构，本研究针对A halleri ssp gemmifera、A halleri ssp halleri及A lyrata ssp kamchatica、A lyrata ssp lyrata四个物种，两对互为亚种的姊妹群，以阿拉伯芥为外群进行研究，在四个物种完成98个同源基因的分子序列，利用套装软体MCMCcoal来估算祖先物种的遗传变异，亦估算现生物种的核苷酸歧异度，观察到？多物种配对中祖先物种遗传多型性大於现生物种DNA歧异度，显示异域种化模型并无法完全解释阿拉伯芥属物种的种化模式，在某些物种配对间邻域种化模式应比异域种化更为可能；在基因树与物种树的比较，98个基因片段的亲缘模式只有28个是与已知物种树一致的，有23个基因其树状图支持{ lyrata} thaliana的型式，藉由kamchatica位置的变化以及估算各物种配对间的平均同义置换率，推测在A halleri ssp gemmifera与A lyrata ssp kamchatica间具有近代的单方向基因交流。

Epigyny The type of flower structure in which the perianth and androecium are inserted above the gynoecium, giving an inferior ovary, fused with the receptacle.

上位式：指花被和雄蕊群着生于雌蕊群之上的花的结构类型。子房在下方，与花托融合。

At first,This thesis determines the full automorphism group s of connected Cayley graphs of valency 4 of .

首先，本文决定了3p(p＞3为素数)阶亚循环群的连通4度Cayleyr图的全自同构群结构，并由此得到这类图的CI性，正规性和弧传递性。

Human gut microbiota plays an essential role in the physiology, nutrition and immunity of human hosts and it may be closely related with the pathogenesis of many intestinal diseases.

肠道菌群在宿主的营养、代谢以及保护宿主免受外界侵袭等方面都起到非常重要的作用，而很多肠道疾病的发生、发展也与肠道菌群结构的变化有着密切的联系。

The course contains four sections as follows: mathematical logic (including basic concepts of propositional logic and predicate logic, propositional calculuses and inference theories), set theory (including set algebras, relations, functions and cardinal numbers), algebraic structure (including algebraic systems, semigroups and groups, rings and fields, lattices and Boolean algebras), graph theory (including basic concepts of graph, Euler graphs and Hamiltonian graphs, trees, planar graphs and coloring graphs, some special vertex subsets and edge subsets).

本课程包含四部分内容：数理逻辑（包含命题逻辑与一阶逻辑的基本概念、等值演算以及推理理论），集合论（包含集合代数、二元关系、函数和基数），代数结构（包含代数系统、半群与群、环与域、格与布尔代数），图论（包含图的基本概念、欧拉图与哈密顿图、树、平面图及图的着色、图的某些特殊的顶点子集与边子集）。

Biology A chromatically, structurally, or functionally differentiated strip or stripe in or on an organism.

群；组：生物体内或生物体上在染色质、结构或功能上不同的群

With the popularization of cluster system,the management of cluster system becomes more important.

受集群系统结构的固有特性的影响，集群系统的管理问题日益突出。

Based on the analysis of the formation pattern and the convergency structure of enterprise cluster,as well as the development situation and the feature of tourism industry in China,.

通过对产业集群形成模式、集聚结构及我国旅游业的发展现状和特征的分析，指出我国旅游业应在市场核心导向、政府积极参与的模式下积极培育"龙头+网络"式的旅游企业集群，以提高我国旅游产业的国际竞争能力。

With regard to the section of coset in algebraic structure, a series of well-mastered concepts including equivalent relationship and division are applied, and typical examples are cited to introduce the conception of equivalent relationship-coset relationship defined through subgroup.

对于其中代数结构部分的陪集一节，应用已经熟知的等价关系和划分的概念，通过引例导出由子群定义的等价关系―陪集关系，进而得到群的划分―陪集，再研究陪集的性质。

According to the data of the analyses,revealed the population of Cryptomeria fortunei exhibited clump distribution pattern,single-dominant community type,sporadic type population structure and is able to natural regenerate...

柳杉种群呈典型的集群分布，并随个体的增大，由集群分布向随机分布发展的趋势，为间歇型的种群结构。通过对天目山柳杉的起源及其更新类型的探讨表明：天目山柳杉林属天然林与人工林共存状态，并可通过幼苗库进行天然更新，但具有机会性和波动性，需林窗和林内倒木等条件。图3表2参25

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。