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81.
Bandwidth capabilities of next generation networks have turned interactive multimedia services to a cost effective reality, targeting not only large companies, but SMEs and individual users as well. An application with direct social impact is tele-teaching and in the broader sense distance learning. A large numbers of colleges, universities, and other higher education institutions already offer online courses to their local and remote students, via new methods of education. In this paper, combining the WWW, the H.323/MPEG-4 protocol family and the CORBA model, we specify an open system and network architecture towards the Virtual Classroom realisation. Over this architecture an educational process is described using formal Object Modelling Technique (OMT) rules, while educational services are provided as methods of distributed objects. In this way, a framework is proposed in order to allow educational institutes to publish content in an abstract object-oriented manner, so as to become widely available via the well-known WWW interface. 相似文献
82.
研究了Fe(Ⅲ)在酸性介质中催化双氧水甲基紫体系的氧化褪色反应,提出一种测定痕量Fe(Ⅲ)的新方法,体系的最大吸收波长为566nm,Fe(Ⅲ)含量在4~12μg*ml-1符合朗伯-比耳定律,回归方程为ΔA=0.00775C+0.05,相关系数γ=0.9930,最低检出限为2.75×10-7g*ml-1,相对标准偏差为1.83%,结果令人满意. 相似文献
83.
Jessica H. Daniel Ph.D. 《Child abuse & neglect》1978,2(4):247-259
The predictive value of a child abuse screening instrument on unselected populations is illustrated for varying hypothesized levels of child abuse prevalence in order to demonstrate outcome of a hypothetical national screening program. At any level of application, the prediction of false positives and false negatives suggests a low practical utility for an unacceptably high social cost. 相似文献
84.
Roger H. Bruning John K. Burton Michele Ballering 《Contemporary educational psychology》1978,3(4):340-351
In two experiments, visual and auditory memory was tested for good and for poor readers from the upper elementary grades. Under experimenter-blind conditions, no reading group differences existed for single mode presentation in recognition frequency or recognition latency. With a multimodal presentation, latencies for poor readers were similar to those for the single mode presentation. Good readers, however, had significantly faster latencies with multiple input. Generally, results supported dual coding and self-terminating memory search hypotheses for previously encoded stimuli. Implications of the latency differences between reader groups were discussed with respect to the reading process and reading theory. 相似文献
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古汉语谦敬称谓词类的词性探讨 总被引:1,自引:0,他引:1
李冬香 《广东技术师范学院学报》2003,(3):53-56
古汉语谦敬称谓词类的词性,有两种不同的看法:代词说和名词说。通过全面考察,我们发现它们的语法功能、语义演变、代替作用等,都同名词基本相同,而与代词相距较远。因此,它们应该归属于名词。仅仅因为其代替作用就把它们归为代词是不恰当的,我们应该考虑其整体特点。 相似文献
88.
The name Hydrocotyle chinensis (Dunn) Craib (Apiaceae) used in 《Flora Reipub-
licae Popularis Sinicae》 has had a confused history and is also a later homonym of H. chinesis
L. Hydrocotyle shanii is proposed as a new name for this species to commemorate ProfessorRen-hwa Shan's lifelong study of the Apiaceae. 相似文献
89.