果蝇DNA和基因间序列的两个信息参数沿染色体分布     

解廷月 《雁北师范学院学报》2007,(6)

以果蝇染色体的全序列和基因间序列作为研究对象.分别用描述序列构成的两个信息参数X和F分析两类序列沿着染色体分布特征,并着重讨论染色体着丝粒及其周围区域的分布规律,用线性拟合和多项式拟合分析染色体各类序列沿染色体的统计分布特征(学生t检验),分析各个参数的平均值在染色体不同区域的分布.  相似文献   

罗斯308肉鸡Gompertz生长模型的建立     

马发顺  景园园  宋玉伟  张明亮  李进萍 《安阳工学院学报》2019,18(2):89-91,99

为掌握罗斯308肉鸡生长发育的特点和规律,测量了0～5周龄罗斯308肉鸡的体重,计算了标准差、变异系数和均匀度等指标,建立了Gompertz生长模型,获得了生长发育参数和生长发育指标。结果表明:Gompertz生长模型能很好地模拟罗斯308肉鸡的生长过程,模型参数A、B、k分别为6 098.92、4.68、0.26,R^2为0.999 5;根据该模型计算的拐点周龄为5.94周,拐点日龄为41.55 d,拐点体重为2 243.67 g,最大周增重为583.35g,最大日增重为83.34 g;累积生长、绝对生长和相对生长都符合肉鸡生长发育的一般规律。此研究结果可以作为合理饲养和优化管理的重要参考。  相似文献   

Estimating Standardized SEM Parameters Given Nonnormal Data and Incorrect Model: Methods and Comparison     

Keke Lai 《Structural equation modeling》2018,25(4):600-620

When both model misspecifications and nonnormal data are present, it is unknown how trustworthy various point estimates, standard errors (SEs), and confidence intervals (CIs) are for standardized structural equation modeling parameters. We conducted simulations to evaluate maximum likelihood (ML), conventional robust SE estimator (MLM), Huber–White robust SE estimator (MLR), and the bootstrap (BS). We found (a) ML point estimates can sometimes be quite biased at finite sample sizes if misfit and nonnormality are serious; (b) ML and MLM generally give egregiously biased SEs and CIs regardless of the degree of misfit and nonnormality; (c) MLR and BS provide trustworthy SEs and CIs given medium misfit and nonnormality, but BS is better; and (d) given severe misfit and nonnormality, MLR tends to break down and BS begins to struggle.  相似文献   

A genetic algorithm for dynamic parameters reverse deduction of integrated anchorage system     

ZHANG Yong-xing DING Yu-qin SONG Jing 《重庆大学学报(英文版)》2006,5(1):46-49

1 Introduction The widely used detection methods of anchorage quality in China are mainly on the local anti-pull tests. In recent twenty years, the studies for the non-destructive detection of anchor bar are well developed because of the compactness combi…  相似文献   

土的结构性损伤与损伤模型问题探讨   总被引：3，自引：0，他引：3  

吴能森  侯伟生  赵尘 《福建工程学院学报》2005,3(1):21-23,37

阐述土的结构性变化与损伤的关系，指出软粘土的结构性损伤包括应力损伤和扰动损伤，并在e-log曲线上探讨峰值损伤应力的合理取值和扰动损伤的定量评价。介绍复合体损伤模型，基于软粘土结构性损伤的含义。重点引荐修正损伤变量演化函数式(5a)，并从复合体概念出发，对损伤参数的合理确定提出了探讨意见与建议。  相似文献   

Between-School Variation in Students' Achievement,Motivation, Affect,and Learning Strategies: Results from 81 Countries for Planning Group-Randomized Trials in Education     

Martin Brunner  Ulrich Keller  Marina Wenger  Antoine Fischbach  Oliver Lüdtke 《Journal of research on educational effectiveness》2018,11(3):452-478

To plan group-randomized trials where treatment conditions are assigned to schools, researchers need design parameters that provide information about between-school differences in outcomes as well as the amount of variance that can be explained by covariates at the student (L1) and school (L2) levels. Most previous research has offered these parameters for U.S. samples and for achievement as the outcome. This paper and the online supplementary materials provide design parameters for 81 countries in three broad outcome categories (achievement, affect and motivation, and learning strategies) for domain-general and domain-specific (mathematics, reading, and science) measures. Sociodemographic characteristics were used as covariates. Data from representative samples of 15-year-old students stemmed from five cycles of the Programme for International Student Assessment (PISA; total number of students/schools: 1,905,147/70,098). Between-school differences as well as the amount of variance explained at L1 and L2 varied widely across countries and educational outcomes, demonstrating the limited generalizability of design parameters across these dimensions. The use of the design parameters to plan group-randomized trials is illustrated.  相似文献   

己烯雌酚对泥鳅红细胞的诱导作用     

叶盛群  唐正义 《内江师范学院学报》2006,21(6):52-54

用不同浓度的己烯雌酚饲喂泥鳅,6d后取血制片,显微镜观察,以探讨不同浓度的己烯雌酚对泥鳅红细胞形成的影响。结果表明,己烯雌酚能诱导泥鳅红细胞产生异形细胞、异常核和微核;异形细胞率、微核率及异常核率与对照组比较,差异极显著(p<0.01),说明己烯雌酚对泥鳅红细胞的形成有明显的致突变作用。  相似文献   

牛磺酸对大鼠运动时血液流变性的影响     

陈伟华 《广东教育学院学报》2005,25(3):83-86

将SD大鼠分为安静对照组、中等强度长时间运动组、中等强度长时间用药组、中等强度超长时间运动组和中等强度超长时间用药组，观察牛磺酸对运动时血液流变性以及红细胞变形性和聚集性的变化．结果表明，超长时间运动用药组大鼠全血粘度、红细胞刚性指数、聚集指数、红细胞电泳时间与安静对照组比较均有所升高，但没有显差异；与中等强度超长时间运动组比较，具有显性差异．提示，牛磺酸可缓解超长时间运动对血液流变性的影响，延缓疲劳的产生，提高运动能力．  相似文献   

垃圾渗滤液对泥鳅红细胞的诱变效应     

罗敏  胡蓉  王芳 《内江师范学院学报》2006,21(6):55-57

通过不同浓度垃圾渗滤液对泥鳅红细胞微核、核异常及异形细胞影响的研究,以监测垃圾渗滤液中有害物质的诱变性。结果表明:垃圾渗滤液能诱导泥鳅红细胞产生微核,异常核和异形细胞。在处理浓度范围内,随着处理液浓度的增高,泥鳅红细胞微核率,核异常率和异形细胞率均升高,并且呈现一定的剂量效应关系。用蒸馏水作对照处理,经t检验,差异显著(p<0.05)或极显著,说明垃圾渗滤液对泥鳅红细胞有很强的致畸作用。  相似文献   

群力水库帷幕灌浆试验及效果分析     

高应利 《杨凌职业技术学院学报》2004,3(4):11-13

帷幕灌浆是进行水库防渗处理的常用方法．但工程大都按规范和经验进行设计和施工，笔者结合凤翔群力水库帷幕灌浆进行了灌浆试验．研究了灌浆工艺和灌浆过程中几种技术参数的影响因素及对工程效果的影响，取得了一些有用的技术参数和质量控制指标．对类似工程的施工设计和施工技术及灌浆效果分析具有一定参考价值和工程意义。  相似文献