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关键词： COELICOLOR A3(2)   ESCHERICHIA-COLI   PLASMID   MICROORGANISMS   SURVIVAL   PHI-C31   MODEL  

摘要： We observed the infection cycle of the temperate actinophage KC301 in relation to the growth of its host Streptomyces lividans TK24 in sterile soil microcosms. Despite a large increase in phage population following germination of host spores, there,vas no observable impact on host population numbers as measured by direct plate counts. The only change in the host population following infection aas the establishment of a small subpopulation of KC301 lysogens, The interaction of S. lividans and KC301 in soil was analyzed with a population-dynamic mathematical model to determine the underlying mechanisms of this low susceptibility to phage attack relative to aquatic environments, This analysis suggests that the soil environment is a highly significant component of the phage-host interaction, an idea consistent with earlier observations on the importance of the environment in determining host growth and phage-host dynamics, Our results demonstrate that the accepted phage-host interaction and host Life cycle, as determined from agar plate studies and liquid culture, is sufficient for quantitative agreement with observations in soil, using soil-determined rates. There are four significant effects of the soil environment: (i) newly germinated spores are more susceptible to phage lysis than are hyphae of developed mycelia, (ii) substrate mycelia in mature colonies adsorb about 98% of the total phage protecting susceptible young hyphae from infection, (iii) the burst size of KC301 is large in soil (>150, 90% confidence) relative to that observed in liquid culture (120, standard error of the mean [SEM], 6), and (iv) there is no measurable impact on the host in terms of reduced growth by the phage, We hypothesize that spatial heterogeneity is the principal cause of these effects and is the primary determinant in bacterial escape of phage lysis in soil.

关键词： 行列式   Rolle定理   高阶微分中值定理   数学分析  

摘要： 利用行列式的有关结论 ,把一阶微分中值定理推广到高阶微分中值定理 。

关键词： 创造性思维   过渡期   数学分析   数学教学   大学  

摘要： 本文对大一“数学分析”

关键词： 极限法   稳定不变   动   静  

摘要： 本文通过生动、形象的例子阐述了从极限法中引申出来的以“动”求“静”的方法 ,进行有效。

关键词： 连续函数   连续性   Lipschitz连续   数学分析   Hoder连续性   可微函数  

摘要： 本文主要介绍了函数的Lipschitz连续性，对于全面掌握数学分析的连续连数，具有指导意义。

关键词： 数学分析   教村   教法   改革  

摘要： 分析了高师《数学分析》教学改革的必要性,提出了改革的思路、内容、目标与特色,并对教材、教法改革进行了初步实践与尝试,在此基础上提出了继续改革的设想与打算。

关键词： 数学分析   教学   思维能力   训练  

摘要： 本文通过丰富实例说明数学分析的教学中注重从数学分析学科的内在规律性、教学方法、几何直观教学等方面训练学生应用已有知识获取新知识的能力、探索问题的能力、类比推理的能力等,能有效地促进学生思维能力的发展,提高学生分析问题、解决问题的能力。

关键词： 数学分析   特点   基本线索   矛盾   教学   知识结构  

摘要： 对数学分析教学方法进行探讨和研究 。

关键词： 数学分析   中值定理  

摘要： 本文介绍数学分析中两类命题证明的入手思路,利用微分中值定理和积分中值定理先进行处理,从而使命题证明的思路逐渐变得清晰起来。

关键词： 积分公式   牛顿-莱布尼兹公式   数学分析   高等数学