Genomic and genic sequence variation in synthetic hexaploid wheat （AABBDD） as compared to their parental species

In order to understand the genomic changes during the evolution of hexaploid wheat, two sets of synthetic hexaploid wheat from hybridization between maternal tetraploid wheat （AABB） and paternal diploid goat grass （DD） were used for DNA-AFLP and single strand conformation polymorphism （SSCP） analysis to determine the genomic and genic variation in the synthetic hexaploid wheat. Results indicated that more DNA sequences from paternal diploid species were eliminated in the synthetic hexaploid wheat than from maternal tetraploid wheat, suggesting that genome from parental species of lower ploidity tends to be eliminated preferentially. However, sequence variation detected by SSCP procedure was much lower than those detected by DNA-AFLP, which indicated that much less variation in the genic regions occurred in the synthetic hexaploid wheat, and sequence variations detected by DNA-AFLP could be derived mostly from non-coding regions and repetitive sequences. Our results also indicated that sequence variation in 4 genes can be detected in hybrid F1, which suggested that this type of sequence variation could be resulted from distant hybridization. It was interesting to note that 3 out of the 4 genes were mapped and clustered on the long arm of chromosome 2D, which indicated that variation in genic sequences in synthetic hexaploid wheat might not be a randomized process.     

大学的绿色意识与使命

面对生态环境危机的逼压，具有化先导作用的大学必须承担新的历史使命：面向整个社会模范地构建绿色意识和积极传播绿色思想，调适自己的功能观和专业观。     

以多媒体效果体现VB的图形,声音功能

ＶＢ是近年推出的一种面向对象的，可视化的编程语言 ，本文论述了利用ＶＢ的图形，声音功能产生多媒体效果的方法。     

对单摆实验中计时周期的误差分析

对单摆法测重力加速度ｇ的误差主要来源－－周期的测量误差进行分析，并结合实验给出了周期测量计时误差的主要来源及最大计时误差随周期变化的范围。     

水流量远程智能监测系统的设计与实现

介绍了水流量远程智能监测系统,阐述了系统的设计思路、逻辑架构、创新技术、功能组成等部分关键技术。系统设计严密、操作方便,具有通用性,适用各地水务部门,有利于提高水务行业的信息化水平。     

HDLC/SDLC协议帧校验序列的计算方法

HDLC/SDLC 数据通信链路规程是目前广泛采用的串行通信规程,但当前大多数文献资料就HDLC/SDLC 规程帧校验序列的生成都未给出准确的定义,因而常常给用户造成一些概念上的模糊或误解。该文依据 HDLC 规程的原始定义给出了 HDLC 帧校验序列 FCS 的计算方法及硬件实现系统码字编码的方案。     

Ni2B分子结构及成键特性的abinitio计算研究

本文用ＤＦＴ方法对Ｎｉ２Ｂ分子双重态和四重态两种多重度进行高水平的ａｂｉｎｉｔｉｏ计算，结果发现Ｂ以ｓｐ，ｓｐ＾２两种杂化方式同Ｎｉ成键，并且Ｂ带有相反的电荷；体系存在多个区域极小点。     

关于一元线性回归简化计算公式的注记

本文用初等变换方法，给出了一元线性回归预测公式ｙ∧＝ａ＋ｂｘ中参数ａ和ｂ的简化计算公式．     

有限二尺度方程的讨论

以 B 样条为例讨论了有限二尺度方程两方面的应用,特别从另一角度推导了 B 样条二尺度方程。     

Distribution of some similarity coefficients for dyadic binary data in the case of associated attributes

Parameters are derived of distributions of three coefficients of similarity between pairs (dyads) of operational taxonomic units for multivariate binary data (presence/absence of attributes) under statistical independence. These are applied to test independence for dyadic data. Association among attributes within operational taxonomic units is allowed. It is also permissible for the two units in the dyad to be drawn from different populations having different presence probabilities of attributes. The variance of the distribution of the similarity coefficients under statistical independence is shown to be relatively large in many empirical situations. This result implies that the practical interpretation of these coefficients requires much care. An application using the Jaccard index is given for the assessment of consensus between psychotherapists and their clients.

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La distribution des coefficients de similarité pour les données binaires et les attributs associés

Résumé Les paramètres de la distribution de trois coefficients de similarité entre paires d'éléments taxinomiques opérationels de données multivariables binaires (présence/absence) ont été dérivés dans l'hypothèse d'indépendance statistique. Ces paramètres sont utilisés dans un test d'indépendance pour les données dyadiques. L'existence est autorisée, dans la population d'éléments, d'une association entre plusieurs attributs. Il est également permis que les deux éléments de la dyade soient tirés de deux populations différentes, ayant différentes probabilit és quant à la présence des attributs. Dans beaucoup de situations empiriques, la variance des coefficients de similarité peut être relativement élevée dans le cas d'indépendance statistique. Par conséquence, ces coefficients doivent être interprétés avec précaution. Un exemple est donné pour le coefficient de Jaccard, qui a été employé dans une recherche sur la concordance entre des psychothérapeutes et leurs clients.