关于中学美术课堂教学中存在的几个问题

在初中美术教学中存在教师方面的问题,也存在着学生方面的问题,对这些问题要认真分析,找出解决办法,使学生素质得到全面发展。     

肩负重托 开创未来——纪念《中国图书馆学报》复刊20周年

1 概况[1,2] 《中国图书馆学报》(简称《学报》)是中国图书馆学会会刊,由中国图书馆学会和国家图书馆联合主办.其前身是1957年创刊的《图书馆学通讯》(简称《通讯》),1979年复刊至今已20周年.1979～1990年刊名为《通讯》,1991年起更名为《学报》.1979～1993年为季刊,1994年起改为双月刊.20年来,共出版94期9024页,发文1907篇.期均发文20.3篇,篇均4.7页.     

A Novel Electrmagnetic Bandgap Structure for Filer

Electromagnetic bandgap (EBG) materials are periodic structures capable of prohibiting the propagation of electromagnetic waves within a certain band of frequencies. This cheracteristic of EBG has wide application. The structures to be studied here are mainly planar EBG materials of two dimensions, which are periodic arrays of holes etched in the ground plane of a conventional microstrip line. EBG structures are calculated with finite-difference time-domain (FDTD) method in this paper. Technique of the perfectly matched layer is used for the absorption of electromagnetic waves in FDTD. The FDTD method is programmed with the blend of C + +and Matlab languages, which makes the program beth simple and fast computing. A kind of new EBG structure is brought out through a lot of experiments and analyses. A filter with wide stop-band and another filter with two stop-bands are designed.     

高考电学实验复习

电学实验是高中物理的重点和难点,突出能力考查,题型变化多样,对学生综合水平有很高的选拔性,想掌握电学实验要从基础入手,则必须掌握下面五个问题.一、电表的改装常用的电压表和电流表都是由小量程的电流表G改装而成的.G的满偏电压和满偏电流一般都较小,在测量较大电压时需要串联一个大电阻将其改装为电压表,测量较大的电流时需要并联一个小电阻将其改装为大量程的电流表.