Evaluation of genetic diversity and relationships within and between two breeds of duck based on microsatellite markers

The genetic diversity of two natural populations (M, N) of Beijing duck (Anas platyrhynchos) and 11 artificially selected lines of Beijing duck (A, B, E-L, O) from China Gold Star Duck Production Ltd., along with two Cherry Valley duck lines (C and D) from the British Cherry Valley Livestock Division, was evaluated using 18 microsatellite markers covering 16 linkage groups. A phylogenetic tree of the 15 populations of duck, formed of four main branches, was constructed from Nei’s D_A genetic distance. The mean genetic differentiation index (F_ST) in all loci, Nei’s standard genetic distance (Ds), and the genetic distance D_A between the Beijing duck and the Cherry Valley duck were 0.075, 0.143 and 0.142, respectively. These results demonstrated a high degree of genetic similarity between the two breeds and supported the hypothesis that the Cherry Valley duck was derived from the Beijing duck. The F_ST matrix of seven clusters of Beijing duck suggested that the efficiency of selection was not significant to some extent and should be supplemented by marker-assisted selection.     

黑板条干检测仪器化的一种方法

本文讨论了一种把表示纱线不匀信号转变为黑板模型的方法及该模型的建立。按照黑板法检测的标准,拟出了13个能体现模型特征的特征参数;并讨论了对该模型进行识别和评级的方法。提出了这种方法能用在所有检测纱线不匀的仪器上,经作者在研制的仪器上实验,表明是可行的。     

赤霉素对山楂叶片发育及光合速率的影响

山楂盛花期喷布50—70ppm赤霉素溶液,能增加叶面积和比叶重,但叶片内叶绿素含量略低于对照。赤霉素处理能提高山楂叶片的光合速率,对提高山楂座果率、提高产量有一定作用。     

抽象微分—积分方程解的混合单调迭代求法

首次应用混合单调方法,研究了Banach空间中二阶微分-积分方程边值问题u~n(t)=-f(t,u(t),Tu(t)),t∈I=[a,b]u(a)=u(b)=0解的存在与唯一性,获得了新的结果.     

轻型电视天线塔桅结构的探讨

本文讨论安装开路和闭路电视系统所用发射与接收天线的支承物——轻型电视天线塔桅结构的外型设计,及其截面选择的理论计算方法,并用有限元法计算塔身在风载作用下杆件内力及结点位移的方法.     

织物风格评价中的客观尺度问题

本文提出了利用Karhunen-Loéve展开定理和主成分分析法解决变量权数确定问题,并对一般欧氏距离进行改进以作为织物风格的客观量度。文中还介绍了改进后的欧氏距离的特点,并给出与织物风格感官评价结果的对应关系。     

98男排世锦赛前、后排进攻的分析研究

采用文献资料法、数理统计法、录像观察法对第 14届男排世锦中外球队的进攻能力、手段、效果进行分析 ,以找出中国同欧美强队的差距     

线性综合评价模型参数的专家评定方法

基于层次分析法(AHP),对一类线性综合评价模型参数的确定给出了三种有效的专家评定方法:专家评定法,综合专家评定法,修正专家评定法。     

更新会计观念适应改革形势

会计要由过去那种单纯报帐型向开拓理财、经营管理型转变，以适应改革形势。     

Morita Context理论的对偶

对任意有限维Ｈｏｐｆ代数讨论它所诱导的ＭｏｒｉｔａＣｏｎｔｅｘｔ理论的对偶，即ｐｒｅｅｑｕｉｖａｌｅｎｃｅｄａｔｅ的理论，并进而建立Ｈ余模余代数的ＣｏＧａｌｏｉｓ余扩张理论．