Isolation and identification of Sclerotinia stem rot causal pathogen in Arabidopsis thaliana     

Wang AR  Lin WW  Chen XT  Lu GD  Zhou J  Wang ZH 《Journal of Zhejiang University. Science. B》2008,9(10):818-822

A new stem rot disease is found to occur naturally on Arabidopsis plants in greenhouses of Fuzhou, China. In order to identify its pathogen, we conducted a series of fimgal isolation and purification, plant reinoculation, and ascus and ascospore induction from the sclerotia. The isolate caused typical water-soaked lesions after reinoeulation and produced sclerotia both on Arabidopsis plants and culture medium plates, and the sclerotia could be induced to produce discal apothecia and 8 binucleate ascospores per ascus. These disease symptom and fungal morphology data revealed that the fungus Sclerotinia sclerotiorum (Lib.) de Bary was the pathogen for Arabidopsis stem rot. To confirm this, we further amplified its large subunit ribosomal DNA (LSU rDNA) by polymerase chain reaction (PCR), and compared the sequence with the known LSU rDNA sequences in GenBank. The results show that the sequence shares the highest identities with the LSU rDNAs of different S. sclerotiorum strains. Taking all these data together, we concluded that the fungus that caused the Arabidopsis stem rot is S. sclerotiorum (Lib.) de Bary. This is the first report that Arabidopsis is naturally infected by S. sclerotiorum.  相似文献   

Rapid Feedback Assessment Methods: Can We Improve Engagement and Preparation for Exams in Large-enrollment Courses?   总被引：1，自引：0，他引：1  

Sehoya H. Cotner  Bruce A. Fall  Susan M. Wick  J. D. Walker  Paul M. Baepler 《Journal of Science Education and Technology》2008,17(5):437-443

Scratch-off immediate feedback assessment technique (IF-AT) forms and classroom response systems (clickers) can increase student engagement and interaction and help students prepare for exams by indicating the type and level of questions they will encounter. We used the IF-AT throughout the semester in three sections of a lower-division biology class; in two, students worked on IF-AT questions in small permanent groups, and in one, students alternated between IF-AT and clickers each week. At the end of the semester, students answered surveys about instant feedback techniques. Students appreciated prompt feedback on their understanding of course material, enjoyed the group interaction and opportunities to learn from each other, and continued to have positive perceptions of instant feedback activities and to take them seriously throughout the semester. While appreciating the versatility of clicker questions, we find that the ease of use, low cost, effectiveness, and improved classroom climate of the IF-AT method are particularly commendable.  相似文献   

套料钻在大直径深孔加工中的应用     

王莹 《洛阳工业高等专科学校学报》2007,17(5):23-24

通过实例对套料钻的结构、套料加工工艺进行阐述,并与传统的扁钻对比,说明套料加工对于大直径深孔加工是一种高效率、低成本的加工方法.  相似文献   

论英语大班教学的困境及对策   总被引：3，自引：0，他引：3  

李枫 《宁波广播电视大学学报》2005,3(1):58-60

针对目前外语大班教学的现状和触及的种种难题,本文提出了“小班大班化”、“教学手段多样化”和“大班作业合理化”等策略,并对其具体的应用进行阐述,对其可能达到的效果进行评估,从而帮助那些从事大班英语教学的教师达到教学目的,提升教学效果,减轻教学负荷。  相似文献   

Large eddy simulation of the gas-particle turbulent wake flow     

罗坤  金晗辉  樊建人  岑可法 《浙江大学学报(A卷英文版)》2004,5(1):106-110

To find out the detailed characteristics of the coherent structures and associated particle dispersion in free shear flow, large eddy simulation method was adopted to investigate a two-dimensional particle-laden wake flow. The well-known Sub-grid Scale mode introduced by Smagorinsky was employed to simulate the gas flow field and Lagrangian approach was used to trace the particles. The results showed that the typical large-scale vortex structures exhibit a stable counter rotating arrangement of opposite sign, and alternately form from the near wall region, shed and move towards the downstream positions of the wake with the development of the flow. For particle dispersion, the Stokes number of particles is a key parameter. At the Stokes numbers of 1.4 and 3.8 the particles concentrate highly in the outer boundary regions. While the particles congregate densely in the vortex core regions at the Stokes number of 0.15, and the particles at Stokes number of 15 assemble in the vortex braid regions and the rib regions between the adjoining vortex structures.  相似文献   

Student evaluation of audience response technology in large lecture classes   总被引：2，自引：0，他引：2  

Erina L. MacGeorge  Scott R. Homan  John B. Dunning Jr.  David Elmore  Graham D. Bodie  Ed Evans  Sangeetha Khichadia  Steven M. Lichti  Bo Feng  Brian Geddes 《Educational technology research and development : ETR & D》2008,56(2):125-145

In the past few years, audience response technology (ART) has been widely adopted on college campuses, and is especially popular among instructors of large lecture classes. Claims regarding ART’s benefits to students have received only limited empirical evaluation, and prior studies exhibit methodological limitations. The current study provides a multi-dimensional evaluation, utilizing a newly-developed measure, the Audience Response Technology Questionnaire (ART-Q). Data were provided at three points during a semester by undergraduate students (n = 854) who used ART in three large lecture university courses. Results indicate moderately positive evaluations of ART on some dimensions (e.g., ease of use, impact on attendance), with less positive evaluations on others (e.g., influence on preparation for class). These evaluations showed some variability across time of semester and course, but were not substantially affected by gender, ethnicity, or year in school. Findings are discussed with respect to the need for future research on instructors’ techniques for using ART and their influence on student perceptions and outcomes.

Erina L. MacGeorgeEmail:

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苏南大型集镇空间规划与土地利用结构模式研究   总被引：3，自引：2，他引：3  

冯建 《资源科学》2002,24(5):39-45

90年代以来 ,苏南的集镇规划达到高潮。大型集镇 ,作为苏南一种较为普遍的集镇类型 ,其规划的功能布局与土地利用结构模式相对复杂 ,客观上需要从理论上进行总结。该文选取苏、锡、常地区的 6个集镇规划样本 ,从集镇性质、规模定位和主导产业选择、路网设计和交通规划、公共用地布局以及功能布局与集镇土地利用结构模式等方面对苏南大型集镇的空间规划进行系统的理论总结。最后 ,就规划实践中的若干共性问题和新的尝试展开讨论。  相似文献   

基于5W1H分析的公共图书馆大字本图书阅读推广服务探究     

叶静 《河北科技图苑》2020,33(2):68-71

大字本图书是低视力人群重要的信息来源和学习资源,公共图书馆作为大字本图书主要的馆藏地,肩负着大字本图书阅读推广服务的重要职责。通过5W1H分析法,提出公共图书馆大字本图书阅读推广服务对策,包括服务时间、地点的选择、服务团队的建设以及服务方法等,以期对公共图书馆开展大字本图书阅读推广服务有所帮助。  相似文献   

老铁山—长兴岛VLCC外海航路安全水深的确定     

李连博  刘德新  尹建川  戴冉 《上海海事大学学报》2016,37(2):1-6

为确保长兴岛北港区30万吨级油船泊位正常营运，科学合理地规划老铁山水道至长兴岛北港区的外海航路，对国内外关于航道水深的标准、规范和影响船舶富余水深的要素进行对比分析.基于MATLAB 8.0平台，利用芳村公式、Eryuzlu（1994）修正公式和Norbin公式计算船舶在开敞水域航行时的下沉量、富余水深和安全水深，并画出满载VLCC在开敞水域航行时的下沉量、富余水深、安全水深在不同航速情况下随水深与吃水比值变化的曲线.根据《海港总体设计规范》、芳村公式、Eryuzlu(1994)修正公式和Norbin公式，计算出在开敞水域航行的满载VLCC在不同航速下所需的下沉量和外海航路安全水深.运用该方法提出老铁山水道至长兴岛北港区外海航路的安全水深建议值.该方法可为渤海湾其他有VLCC码头的外海航路设计提供一定的参考.  相似文献   

基于大数据的旅游市场研究综述     

雷可为  王小辉  豆晓宁 《环球赛鸽科技》2015,(14)

互联网技术的兴起及大数据概念应运而生使得旅游信息的传播不再受时空的限制,本文分析了用户对旅游的网络关注度和实际旅游市场需求的关系的研究现状,梳理了其研究内容、思路及发展趋势,期望整合有利因素,为旅游部门做出科学、合理的决策提供有力借鉴。  相似文献