禾本科植物幼苗性状的聚类分析

本文用201种禾本科植物幼苗的60个形态和解剖性状进行了聚类分析，将禾本科植物分为四个大类(一级聚合单位)—狐茅类(Festucoid)、黍类(Panicoid)，竹类(Bambusoid)和画眉草类(Eragrostidoid)。这四类基本上与分类系统中的亚科相吻合，只是芦竹亚科植物的幼苗分散聚到了其它类中。推测芦竹亚科是一个比较原始的类群，狐茅亚科、黍亚科和画眉草亚科可能是在芦竹亚科的基础上进化而来的。  除个别种外，大多数同属的种在较低的聚合水平上聚在一起，超族在亚聚合单位中基本上能够反映出来。  研究证明禾本科植物的幼苗性状在禾本科植物分类中具有重要的分类学意义。     

Learning from education to communicate science as a good story

Science communicators must learn from science educators in their crusade to counteract the traditional boring and inefficient approaches to convey science. Educators encounter a need for methods of teaching that portray science as 'hard fun' and resources that encourage students' minds to burst into action. Narratives are considered by several authors as highly valuable resources for science education. However, little research has been undertaken to measure the efficiency of narratives in the context of science communication to the general public. Recent work however, suggests that narratives are indeed an alternative and an important means for science communication to convey information in an accurate, attractive, imaginative and memorable way. To present scientific information through stories, novels, comics and plays should be regarded as an important means to transmit information in the repertoire of both science teachers and science communicators.     

Alfred Russel Wallace's North American tour: transatlantic evolutionism

Evolutionary theory aroused vigorous debate in the late-19th century, regarding both its scientific status and its sociocultural implications. Alfred Russel Wallace's lecture tour of North America, during 1886-1887, affords a striking insight into his particular interpretation of evolution and reveals the depth of his conviction that science was inseparable from ethical and political realities. Wallace's views on matters scientific and cultural were as controversial and significant in North America as they were in Great Britain and Europe.     

小屋子

从前,乡间有一间小屋子。它是一间漂亮的小屋子,建造得很结实。有个人把它造好后说:"这座小屋子金不换,银不换,它是属于孩子们的,无数的孩子们将住进去。"小屋子很快活,它坐在小山上,观看着周围的景色:早晨太阳升起,傍晚太阳下山,一天跟着一天,每天的景色各不相同。夜晚,它看着月亮。一钩弯弯的新月,渐渐变成一轮圆圆的满月,接着又变成     

优秀的标准

在马萨诸塞州北安普敦市的一家出售二手服装的店里,我和我14岁的儿子约翰同时盯上了那件大衣。它就挂在衣架上,夹在劣质的军用风衣和各式各样寒酸的羊毛大衣当中,然而它却像荆棘丛中的一朵玫瑰。其他的大衣都显得没精打采,唯独这件衣服趾高气扬。厚厚的黑色羊绒柔软而蓬松,这件     

我为什么要写作

大约在我很小,也许是五六岁的时候,我就知道了我在长大以后要当一个作家。在大约十七到二十四岁之间,我曾经想放弃这个念头,但是我心里很明白:我这么做有违我的天性,或迟或早,我会安下心来写作的。