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1.
IntroductionSweetpotato(Ipomoeabatatas(L.)Lam.)isanimportantcrop.Ithasthreestrikingcharacters,i.e,outbred,incompatibilityandvegetativepropagation[1].Plantincompatibilityisakindofpropertywhichisaccumulatedoveralongperiodoftimeinthecourseofevolutionund…  相似文献   

2.
LetXbeaseparated,locallyconvexspaceoverthecomplexfieldC,C∞theRiemannsphere,i.e.,theonepointcompactificationofC,L(X)thealgebraofallcontinuouslinearoperatorsofXintoitself.ThetopologyofboundedconvergencemakesL(X)alocallyconvexalgebra.Theresolventsetρ(…  相似文献   

3.
Ourlanguageisinextricablyboundupwithourhu manity.Tobehumanistouselanguageandtotalkistobeaperson.Languageuse,andthewordswhicharein troducedintoalanguage,reflecttheviewsandvaluesofsociety.Alanguageorwordsofalanguagecannotbeeithergoodorbadbutcanonlyviewe…  相似文献   

4.
Ultrasoundtransducerisoneoftheimportantdevicesinmedicalultrasonicimagingsystem.Usuallythepiezoelectricmaterials,suchasPZTorPVDF,aretobeusedinanultrasoundtransducer.ThetransducermadeofPZThashighsensitivitywhilethebandwidthFig.1Constructionofcomplextr…  相似文献   

5.
Theissueofoptimaleconomicgrowthistheproblemofoptimalratioinaccumulationandconsumption.Ifthepresentconsumptionistoohigh,theaccumulationwillbelowandthatwilleffecttherapidincreaseoffutureconsumption.Ontheotherhand,ifthepresentaccumulationistoohigh,thep…  相似文献   

6.
报道中国裸藻门新记录7种3变种,即囊状裸藻EuglenasacculiformisSchiller,刺毛扁裸藻PhacushystrixPochm.,环纹囊裸藻TrachelomonasanuliferaHuber-Pestalozzi,球状囊裸藻巨大变种T.globularisvar.gigasDrez.,形囊裸藻肥壮变种T.mirabilisvar.obesa(Messik.)Conr.,卵形  相似文献   

7.
AnoldChinesemythsaysthereusedtobeahorribleperiodwhentenwickedsunscameouttogetherandburntoutallcrops.Thencamethegreathero,HouYi,whokillednineofthesunswithhispowerfulbowandarrows.Ofcoursethesuninthismythisahostileimage.Itissincethetimethestorycameintob…  相似文献   

8.
PavlovicJ.SchultzJ.PetrzilkaD.SchuhT.MoelingK.InstituteofMedicalVirology,UniversityofZurich,Gloriastrase30,CH-8028Zurich,Schw...  相似文献   

9.
记述麦蛾科3新种,园特麦蛾Teleiodes hortensis sp.nov.。和西宁平麦蛾Parachronistis xiningensis sp.nov.分布于青海,双突盖麦蛾Stegasta dicondylica sp.nov.采自云南,其中平麦蛾属Parachronistis Meyrick是中国新纪录属。  相似文献   

10.
MicrobialDiversityandResourcesLiuZhiheng(InstituteofMicrobioly,ChineseAcademyofSciences,P.R.C.)MichaelGoodfelow(Universityof...  相似文献   

11.
虚拟学习社区作为网络教育的一种新兴模式,越来越受到人们的关注.如何为不同的学习者提供良好的个性化教学服务是虚拟学习社区研究的重要问题,而学习者的学习特征的提取与分析是个性化教学的基础.以虚拟学习社区为背景,从学习者的学习过程和学习特征入手,运用模糊c均值聚类算法(FCM)挖掘并分析学习过程中学习者的学习特征,进而根据学习者的知识水平、自主学习和协作学习积极性等学习特征进行精确分组划分,以达有针对性的教学指导,实现个性化教学,提高学习者学习效率.  相似文献   

12.
为帮助学习者掌握自适应学习系统为学习者所定义的个性特征和学习信息,设计并开发了开放性学习者模型MindOLM。MindOLM 采用思维导图可视化形式将学习者模型中课程知识状态呈现给学习者,帮助学习者了解、查看自己的学习进展,以及章、节、知识点之间的关联关系,并引发学习者元认知学习体验。在实证研究方面,通过实验研究法、问卷调查和面对面访谈等方式收集数据,结果表明: MindOLM 能引发学习者在学习规划和自我反思两个方面的元认知学习体验; MindOLM 能很好地表示学习者学习进展和知识水平; 学习者对MindOLM 在有用性、易用性和满意度3 个方面都表现出较高的认可度。  相似文献   

13.
自主学习,是指自我导向、自我激励、自我监控的学习;是学习者自己对学习负责,具有明确的学习目标和积极主动的学习态度,具备参与学习所需元认知策略和认知策略能力的学习。对大学新生英语自主学习状况进行调查并提出相应的对策,将有助于培养学生英语自主学习能力和大学英语教学。  相似文献   

14.
自主学习是一个全新的教学模式,它提倡学习者全面参与学习过程,强调学习者在学习中的重要作用。英语专业教师的指导和支持对培养学习者自主性学习起着重要的作用。教师要帮助学生改变学习观念;要根据学习者的实际情况,为学生自主学习创造条件;要指导学生了解掌握各种学习策略;要利用形式多样的教学手段来激发、培养英语专业学生自主学习能力。  相似文献   

15.
随着计算机和网络技术的日益发展,如何充分发挥二者优势并将其与自主学习相结合建立新型自主学习模式成为近10年第二语言教育研究领域的一个热点课题.作为学习行为发生的推动力,学习意愿一直被认为是自主学习过程中不可或缺的主观因素.通过对60名非英语专业学生1.5a时间的跟踪调研,证明网络依托型自主学习模式下学生的学习动机和英语学习中自我及教师角色认知状况、自主学习水平都要优于常规大学英语教学模式中的学生.研究结果还显示网络依托型自主学习模式对于学习意愿产生的积极影响可以一直延续到"后大学英语学习时代".  相似文献   

16.
An intelligent agent is any program that can be considered by the user to be acting as an assistant or helper, rather than as a tool in the manner of a conventional direct-manipulation interface. An agent should as well display some, but perhaps not all, of the characteristics that are associated with human intelligence: learning, inference, adaptability,independence, creativity, etc.. In order to make webbased education (WBE) more vividly and instructionally with learner's independence at the same time, the intelligent agent can act as a learning pet, which is affiliated with learner's score or grades and will grow up with learner's achievement. And during the course of study, the learning pet can provides any information required by the learner, gives hints if necessary when the learner doing his/her assignment, offers instructional guide for further study etc..  相似文献   

17.
大学体验英语听说自主学习软件是我国目前通过人机对话进行听说训练的先进的电脑软件。该软件以自主学习理论为指导,应用于大学英语听说教学,是提高学生英语综合能力,特别是听说能力以及促进自主学习的有效途径。该软件为学习者提供了理想的自主学习环境,对于大学英语教学具有现实意义。  相似文献   

18.
远程开放教育的教学是一种与传统教学有很大差别的全新的教学模式。文章从学习动机、性格特征、认知风格三个方面对远程英语学习者的个别差异及对策进行了分析,旨在找出学习者具备什么样的条件和素质才能在英语学习中取得更大的成功,同时教师在教学中需要相应地采取不同的教学策略和教学方式以适应不同类型学生的特点,充分发挥每个学生的学习潜能。  相似文献   

19.
形成性评价是在教学过程中对学生学习效果的动态评价,通过对学习过程的及时反馈调整教学,挖掘学生的潜能,发展学生的学习能力,提高学生学习的积极性和自主性。将形成性评价运用到大学英语写作教学实践中,不仅能够促进学生写作,关注写作学习的过程,也有助于教师改革写作教学的思路,提高写作教学质量。  相似文献   

20.
《清华大学学报》2020,25(3):336-347
Recently, Massive Open Online Courses(MOOCs) have become a major online learning methodology for millions of people worldwide. However, the dropout rates from several current MOOCs are high. Usually, dropout prediction aims to predict whether a learner will exhibit learning behaviors during several consecutive days in the future. Therefore, the information related to the learning behaviors of a learner in several consecutive days should be considered. After in-depth analysis of the learning behavior patterns of the MOOC learners, this study reports that learners often exhibit similar learning behaviors on several consecutive days, i.e., the learning status of a learner for the subsequent day is likely to be similar to that for the previous day. Based on this characteristic of MOOC learning,this study proposes a new simple feature matrix for keeping information related to the local correlation of learning behaviors and a new Convolutional Neural Network(CNN) model for predicting the dropout. Extensive experimental validations illustrate that the local correlation of learning behaviors should not be neglected. The proposed CNN model considers this characteristic and improves the dropout prediction accuracy. Furthermore, the proposed model can be used to predict dropout temporally and early when sufficient data are collected.  相似文献   

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