Telling the tree: Narrative representation and the study of evolutionary history

Accounts of the evolutionary past have as much in common with works of narrative history as they do with works of science. Awareness of the narrative character of evolutionary writing leads to the discovery of a host of fascinating and hitherto unrecognized problems in the representation of evolutionary history, problems associated with the writing of narrative. These problems include selective attention, narrative perspective, foregrounding and backgrounding, differential resolution, and the establishment of a canon of important events. The narrative aspects of evolutionary writing, however, which promote linearity and cohesiveness in conventional stories, conflict with the underlying chronicle of evolution, which is not linear, but branched, and which does not cohere, but diverges. The impulse to narrate is so great, however, and is so strongly reinforced by traditional schemes of taxonomic attention, that natural historians have more often abandoned the diverging tree than they have abandoned the narrative mode of representation. If we are to understand the true nature of the evolutionary past then we must adopt tree thinking, and develop new and creative ways, both narrative and non-narrative, of telling the history of life.     

基于内容分析法的中国垂直绿化研究进展

以墙面垂直绿化为研究对象,借助CNKI文献库,以垂直绿化及相关关键词检索文献。运用内容分析法,通过3个维度分析中国垂直绿化整体特征。集中分析2006—2015年文献资料,总结研究进展与研究趋势。研究目前主要探讨垂直绿化植物应用、构建技术、基质选择、灌溉技术等工程问题。植物应用贯穿整个研究过程,但主要关注植物选择,缺乏植物造景研究。新技术研究起步较晚,成果不断增加,但基质选择与灌溉技术的研究水平相对较低。此外,垂直绿化的效益研究逐渐成为热点方向,其实践应用也不断开展。为了完善垂直绿化体系,未来研究应朝学科交叉发展、系统性的理论研究及设计指导方法、景观绩效评价体系的建立3个方面继续深入进行。     

Evolution Is Linear: Debunking Life's Little Joke

Linear depictions of the evolutionary process are ubiquitous in popular culture, but linear evolutionary imagery is strongly rejected by scientists who argue that evolution branches. This point is frequently illustrated by saying that we didn't evolve from monkeys, but that we are related to them as collateral relatives. Yet, we did evolve from monkeys, but our monkey ancestors are extinct, not extant. Influential voices, such as the late Stephen Jay Gould, have misled audiences for decades by falsely portraying the linear and branching aspects of evolution to be in conflict, and by failing to distinguish between the legitimate linearity of evolutionary descent, and the branching relationships among collateral relatives that result when lineages of ancestors diverge. The purpose of this article is to correct the widespread misplaced rejection of linear evolutionary imagery, and to re‐emphasize the basic truth that the evolutionary process is fundamentally linear.     

多肉植物离体再生研究进展

通过品种、外植体类型、培养基、外源植物激素的选择等几方面对国内多肉植物的离体再生研究现状进行了综述。发现多肉植物的离体再生研究多以种子、叶片、茎段、花器官等为外植体;不定芽诱导阶段常用的培养基类型为MS培养基,不定根诱导常用1/2 MS培养基;6-苄氨基腺嘌呤(6-BA)、萘乙酸(NAA)和激动素(KT)作为常见的外源植物激素,被广泛运用于多肉植物愈伤组织诱导、不定芽诱导、不定根诱导等离体再生各阶段;分析了当前存在的问题和发展前景,以期为日后多肉植物的相关研究提供可行性建议。     

枫香树属二种香树脂类生药——苏合香与枫香脂的研究概况

本文对金缕梅科枫香树属两时树脂类生药苏合香和枫香脂的研究作了总结和比较,主要包括它们的分类学、化学成分、药理作用等,并对今后的工作提出设想。     

小麦赤霉病流行动态的控制论模型

对小麦赤霉病流行资料进行分析,给出了流行状态微分方程的预测方法．根据不同的状态微分方程,以极大值原理建立小麦赤霉病流行动态的控制论模型,得到流行动态的最优控制轨线．结果表明,气象条件有利,品种感病,药剂防效低,则防治时间应提早．要求消灭病害彻底,防治时间也应提前．药剂防效高,小麦产量高,品种感病,则防治后的净收益就大．以小偃6号为例,给出了Malthus增长型下的病害最优控制轨线和最大净收益．     

腹主动脉瘤炎症机制的研究进展

腹主动脉瘤是血管外科最高危的血管退化性疾病之一,其最严重的后果是由于薄弱的动脉管壁无法承受血流冲击,导致动脉瘤壁破裂,引起的猝死。随着我国人口老龄化形势日趋严峻,腹主动脉瘤的发病率也逐年上升,成为威胁我国人民生命健康的重要疾病之一。随着对腹主动脉瘤认识的进步,影像学检查手段的增多,该疾病的确诊率已大大提高,但其具体的发病机制仍不完全清楚。目前已知腹主动脉瘤的发生与吸烟、性别、氧化应激、基质蛋白酶、血脂等多种因素相关,最新的研究显示炎症反应在腹主动脉瘤的发生发展过程中起到重要作用,本文主要对腹主动脉瘤与白细胞相关的炎症反应机制的最新研究进展予以综述。     

植物叶片氮分配及其影响因子研究进展

氮是植物生长的基本限制性因子,它的有效利用可以增加植物的适应性。叶片氮分配是指氮在植物叶片细胞各细胞结构以及游离化合物中所分配的比例。叶片氮的分配方式决定了叶片光合作用的强弱,影响叶片的坚韧程度以及化学防御强度,因此研究氮在植物叶片内的分配方式具有重要意义。阐述了叶片氮分配的方式,分析了影响叶片氮分配的生物和非生物因子(CO2,光,土壤养分),介绍了常用的叶片氮分配的研究方法,并对未来的研究进行了展望。