The role of repair in radiobiology

Summary Apart from cancer and mutation induction, radiobiological effects on mammals are mostly attributable to cell death, defined as loss of proliferative capacity. Survival curves relate retention of that capacity to radiation dose, and often manifest a quasi-threshold (shoulder). The shoulder is attributable to an initial mechanism of repair (Q-repair) which is gradually depleted as dose increases. Another form of repair, which is not depleted (P-repair), increases the dose required to deliver an average of one lethal event per cell (dose D₀). Neither form of repair can unambiguously be linked with repair of defects in isolated DNA. An important initial lesion may well be disruption of the complex structural relationship between the DNA, nuclear membrane and associated proteins. One form of P-repair may be restoration of that structural relationship.     

The melatonin rhythm: both a clock and a calendar

The paper briefly reviews the data which shows that the circadian production and secretion of melatonin by the pineal gland can impart both daily, i.e., clock, and seasonal, i.e., calendar, information to the organism. The paper summarizes the 3 patterns of nocturnal melatonin production that have been described. Clearly, regardless of the pattern of nocturnal melatonin production a particular species normally displays, the duration of nightime elevated melatonin is proportional to the duration of the night length. Since daylength under natural conditions changes daily the melatonin rhythm, which adjusts to the photoperiod sends time of year information to the organism. The melatonin receptors which subserve the clock message sent by the pineal gland in the form of a melatonin cycle may reside in the biological clock itself, namely, the suprachiasmatic nuclei (SCN). The melatonin receptors that mediate seasonal changes in reproductive physiology are presumably those that are located on the pars tuberalis cells of the anterior pituitary gland. Besides these receptors which likely mediate clock and calendar information, melatonin receptors have been described in other organs. Interestingly, the distribution of melatonin receptors is highly species-specific. Whereas the clock and calendar information that the melatonin cycle imparts to the organism relies on cell membrane receptors, a fact that is of some interest considering the high lipophilicity of melatonin, recent studies indicate that other functions of melatonin may require no receptor whatsoever.     

用流媒体技术制作流式PPT课件

运用流媒体技术把PFT文件转化为远程教育课件的方法,可以很方便地将高校教师在平时教学中积累的大量教学课件资源转换成远程教育课件,从而提高工作效率。     

生物教学论课程中设置实验教学的研究

生物教学论谭程没有设置实验教学的内容，根据本课的特点及高师学生面临的教育实习及毕业后所从事的职业性质，提出了在生物教学论课程中设置实验教学内容的必要性及具体实施方法。     

中国古典诗歌对美国现代诗歌的影响

中国古典诗歌对美国现代诗的影响，是中国文化西传产生的重要成果之一，是中西比较文学研究中一个重要的课题，它足足影响了欧美三代诗人的诗歌创作，本文试举例说明这些跨越时空的对话的主要模式和媒介，以及这种双向文化交流的现实意义。     

多媒体教学前瞻

本从多媒体教育和传统教学之间的对比看比媒体教学的先进性。多媒体教学以其多媒共生性，交互性，个别辅导性，以及互联网络资源的丰富和快捷性将成为未来教学发展的方向。     

大众传媒对大学生环保观念的影响调查报告

文章以南京高校为例,论述了调查的背景、目的及方法,指出调查结果对其进行分析,最后总结出经验,并对存在的问题提出一些建议。     

“铁道线路情况演播室”的设计与实现

“铁道线路情况演播室”为“铁道线路灾害和事故抢修方案决策支持系统”的子系统，是运用计算机的多媒体技术开发的图像演播系统．它可将线路的具体情况直观地呈现在用户面前，帮助对现场上报的情况进行有效的资料核对，节省了人力、物力，使决策者能了解线路的状况及周围环境，从而作出更为明智的选择与决定，为及时抢修线路，减少经济损失起到一定的辅助作用．本文介绍了“铁道线路情况演播室”的设计方法与实现技术     

论高校体育网络学习系统的运用

对大学体育交互式多媒体网络教学平台构建的理论依据、系统功能与制作流程等进行了概述。这有助于学生自主、协作和探究性地掌握体育知识与技能,提高体育学习质量和效率。建议从高校体育教学实际出发,不断推进优质体育网络资源建设,促进信息技术与大学体育课程更深层次的整合。     

大气臭氧层变化、太阳活动与中国流脑及人间鼠疫流地特征的关系研究

通过以1950－1989年有关的资料系列进行分析后，首次研究和报道了中国大气臭层变化、太阳活动与流行性脑脊髓膜炎（ECM）及人间鼠疫（HP）两类传染病发病率流行周期特征之间的关系，研究结果表明：①由较长时段看，自氧层变化／太阳活动与ECM及HP年发病率间存在着较为密切的相关；②从较短时段看，发病率的季节变化与某些气象因子的变化有一定的关系，最后，提出了一个解释这两类疾病周期流行机制的简单模型。