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Echinocystis Torr. et Gray of the Cucurbitaceae is reported as a naturalized genus in China. 相似文献
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溥发鼎 《中国科学院研究生院学报》1991,29(5):385-393
藁本属Ligusticum L.属伞形科Umbelliferae芹亚科Apioideae Drude阿米芹族Ammineae
Koch。它在阿米芹族中，是一个较进化的类群，是介于阿米芹族与前胡族Peucedaneae DC．之间的一个过渡类型。藁本属全世界60余种。我国现知有34种，占该属种数的二分之一，其中28种及2个栽培变种为我国所特有。本文比较分析藁本属的形态学性状和孢粉学性状，以小总苞片及其相关特征作为该属次级划分的主要依据，将藁本属分为两个类群，并对该属的种类作了增补，对一些种的名称、分布作了补充修订。文中还记载了4个新种。喜马拉雅藁本L．elatum(Edgew.)C.B．Clarke和开展藁本L. thomsonii C. B. Clarke var．evolutior C. B．Clarke，系我国首次记录。 相似文献
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报道了蔷薇科李亚科两个种的改隶新组合,将广义李属中的背毛樱Prunus hypotrichodes改隶为杏属中的背毛杏Armeniaca hypotrichides;疏花稠李Prunus laxiflora改隶为疏花樱Cerasus laxifiora。进一步研究的结果,同意前苏联学者G．V．Eremin et V．S．Simagin的意见,将稠李属中的种斑叶稠李Padus maackii改隶为樱属中的斑叶樱Cerasus maackii。 相似文献
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综合研究凤头黍属与其邻近属的叶片表皮微形态、颖片及内、外稃等特征后，发表禾本科一新属——刺毛头黍属。 相似文献
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蔡联炳 《中国科学院研究生院学报》1997,35(2):148-177
本文对中国鹅观草属Roegneria进行了分类修订，提出了一个新的分类系统。新系统包括19个新组合或新等级，并按照颖分组、芒分系的原则确认了中国该属植物4组、18系、79种、22变种，其中包括7新系、5新种和1新变种。此外，一些类群的省级分布新记录也在本文作了报道。 相似文献
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本文对国产7种甘草属植物的核型进行了研究，其结果为：乌拉尔甘草2n＝16＝
6m+10sm；黄甘草2n＝16=8m+6sm十2st；光果甘草2n＝16=14m+2sm；胀果甘
草2n＝16＝6m十10sm；粗毛甘草2n=16=12m十4sm；云南甘草20＝16=12m十
4sm；刺果甘草2n＝16＝12m十4sm。基于对现有资料的分析，确认该属的染色体基数为
x=8， 且核型对称性程度较高。 通过对不同种核型进行比较，发现刺果甘草是本文所研究
7个种中最原始的，而黄甘草的进化程度相对较高。 相似文献
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中国萱草属数量分类研究 总被引：1，自引：0，他引：1
用聚类分析和主成分分析研究了国产萱草属11个类群的分类。结果发现这些类群形成4簇。第一簇：北黄花菜、黄花菜、小黄花菜和多花萱草。第二簇：小萱草和大苞萱草。第三簇：折叶萱草，西南萱草和矮萱草。第四簇：萱草及其三倍体类型。各簇都有其区别特征。讨论了簇内各类群之间的亲缘关系及属下分组问题。 相似文献
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《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
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Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
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《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
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A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
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Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
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Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
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Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献
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Milton Mueller 《The Information Society》2001,17(3):151-163
Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP. 相似文献
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Prof. Raymond C.K. Chen a neuropsychologist with the CAS Institute of Psychology has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.…… 《中国科学院院刊(英文版)》2008,22(1):15-15
Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology. 相似文献
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Prof. SUN Changpu from the CAS Institute of Theoretical Physics coworkers from University of Basel in Switzerland have worked out a way - at least in theory - to split a beam of molecules according to their chirality. The technique involves passing the molecules through three different laser beams is similar to the famous Stern-Gerlach effect whereby a beam of atoms passing through a magnetic field is split in two according to the atoms' spin states 《中国科学院院刊(英文版)》2008,22(1):23-23
Prof. SUN Changpu from the CAS Institute of Theoretical Physics and coworkers from University of Basel in Switzerland have worked out a way --at least in theory --to split a beam of molecules according to their chirality. The technique involves passing the molecules through three different laser beams and is similar to the famous Stern-Gerlach effect, whereby a beam of atoms passing through a magnetic field is split in two according to the atoms＇ spin states （Phys. Rev. Lett. 99 130403）. 相似文献