豆科黄华属的植物地理研究     

萨仁  陈家瑞  李沛琼 《中国科学院研究生院学报》2000,38(2):148-166

首次全面论述了全世界黄华属(豆科)植物地理。黄华属是豆科少数几个东亚-北美间断分布属之一。对黄华属5组21种的分布进行了分析,发现本属4个频度分布中心依次是：东亚地区(8种／3组,其中特有种4种),伊朗-土兰地区(7种／3组,其中特有种3种),落基山地区(7种／2组,均为特有种)及大西洋北美地区(3种／1组,均为特有种)。基于以下事实：在东亚地区存在本属最多的组与种;在此区可以见到黄华属系统发育系列;该属最原始的组种及最进化的组种也在该区出现等,可以认为东亚地区是该属的现代分布中心及分化中心。伊朗-土兰地区(中亚东部至喜马拉雅)及落基山地区所含种、组数仅次于东亚地区,而且多倍体现象多发生于这两区,因此可认为是本属的次生分布中心及分化中心。在此二地区,物种分化较活跃且复杂,先后描述了很多新种和变种,也曾进行过较多的归并处理。最近的分子生物学证据不断揭示,在这地区曾被归并的一些分类群存在着较大不同,从而提醒分类学家对年轻区系中物种分化较活跃的类群进行分类处理时,无论是建新分类群还是对某些类群进行归并,应持谨慎态度。作者根据黄华属植物的现代地理分布、形态演化趋势、现有的化石及地质历史资料,推测黄华属植物在中新世之前早已形成,并且在晚第三纪欧亚大陆与北美大陆失去陆地连接之前在两大陆已经存在,很可能是于早第三纪或晚白垩纪在劳亚古陆上起源于一个含羽扇豆生物碱的古槐成员。两大陆分离后,在不同的成种因子的影响下,形成了各自的演化格局：在亚洲,晚第三纪的喜马拉雅造山运动、古地中海消失及第四纪冰川作用引起的旱化、寒化,促进了该属植物的强烈分化;而在北美,第四纪的冰川作用及局部的山体隆起,可能是促进该属植物演化的主要动力。根据黄华属植物的系统演化趋势及原始类群的分布式样分析,东亚地区的中国-日本亚区可能是本属植物的原始类型中心。  相似文献   

Outlines of physical chemistry: By George Senter,D.Sc. (Lond.), Birkbeck College (University of London). Fourteenth edition,xx–421 pages, 13 x 19 cm., 46 illustrations in text. New York,D. Van Nostrand Company, 1926. Price, $3     

George Wesley Perkins 《Journal of The Franklin Institute》1927,203(5):732-733

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Measures of cognitive structure: Do they assess learning at the level of comprehension?     

Marcy Perkins Driscoll 《Contemporary educational psychology》1985,10(1):38-51

One purpose of this study was to determine whether cognitive structure, assessed by psychometric measures of concept interrelatedness, can be developed when the students initially do not know what concept relationships exist and what they mean. The second purpose was to apply those measures to a learning situation that has produced a nonspecific transfer effect, i.e., the facilitative effect of concrete examples on learning abstract passages, to attempt to explain this effect more completely. Five groups of 20 students each read two prose passages and took recall and structure assessment tests on the second passage. Results (1) indicated that the nonspecific facilitative transfer effect was replicated and (2) offered some support for the contention that the cognitive structure which proximity measures assess can be trained to correspond to content structure, but that related recall remains low. With resolution of some of the methodological issues surrounding these measures, however, clearer explanation of transfer effects and assessment of higher order learning may be facilitated.  相似文献   

Storage Techniques for Art,Science and History Collections (STASHc.com): An Online Resource for Collection Storage     

Rachael Perkins Arenstein  Lisa Goldberg  Bonnie Naugle 《文物保护研究》2018,63(5):316-319

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Globetrotting Students and Faculty: Adapting Library Instruction to Global Sites     

Eimmy Solis  Dan Perkins 《Journal of Library & Information Services in Distance Learning》2017,11(1-2):123-139

ABSTRACT

As e-resources become more ubiquitous, and the technologies available to access them more sophisticated, libraries have greater opportunities to reach out to global users. However, this same distance means that some users never even set foot in a physical library. This case study will describe how one large academic library started a business, economics, and marketing library online instruction pilot for global users in an effort to replicate library instruction offered at the home institution. Librarians assessed global library use and research needs; prepared unique lesson plans for each global site; and created digital learning objects using synchronous and asynchronous methods to establish an instruction strategy for Business and Economics courses. The goal was to test instruction practices and develop an online instruction template that would be replicable and sustainable for library instruction in other subject areas in New York University Libraries and other institutions.  相似文献   

信息技术下的平面构成教学方法探讨     

洒玉波 《唐山师范学院学报》2008,30(4)

信息技术改变了人们的生活方式,同时也改变了教育的方式.计算机辅助教学可以帮助教师更好地拓展学生的创造性思维.教学方法应紧跟时代步伐,不断创新.  相似文献   

Let’s Build Something Together     

Ross Perkins 《TechTrends》2010,54(4):12-13

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International Contributions to e-Learning Literature from 2000 to 2008     

Andy Hung  Ross Perkins 《TechTrends》2012,56(4):9-10

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Evaluating a Multidimensional Reading Comprehension Program and Reconsidering the Lowly Reputation of Tests of Near‐Transfer          下载免费PDF全文

Douglas Fuchs  Emma Hendricks  Meagan E. Walsh  Lynn S. Fuchs  Jennifer K. Gilbert  Wen Zhang Tracy  Samuel Patton III  Nicole Davis‐Perkins  Wooliya Kim  Amy M. Elleman  Peng Peng 《Learning disabilities research & practice》2018,33(1):11-23

We conducted a 14‐week experimental study of 2 versions of a relatively comprehensive RC intervention that involved 50 classroom teachers, 15 tutors, and 116 children drawn in equal proportions from grades 3 and 5 in 13 schools in a large urban school district. Students were randomly assigned in equal numbers to the two tutoring conditions and a control group. Results indicated that students in the two tutored groups tended to perform comparably on all tests and to outperform controls (more so in grade 5 than grade 3) on near‐transfer but not far‐transfer measures of RC. This differential pattern of program effects for near‐ versus far‐transfer measures raises questions about how tests of near‐transfer and far‐transfer are conventionally understood.  相似文献   

On a screw-joint for water-pipes, &c.     

A.M. Perkins 《Journal of The Franklin Institute》1844,37(3):200-201

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