STUDY OF PREPARATION AND PROPERTY OF YBa_2Cu_3O_(7-δ)-Ag_x COMPOSITE SUPERCONDUCTORS PREPARED BY SOL-GEL PROCESS

YBa_2Cu_3O_(7-δ)-Ag_x composite superconductorswere prepared by hybrid sintering process using YBa_2Cu_3O_(7-δ)-Ag_x ultrafine powder and AgO_2 finepower,which were pre-pared by sol-gel process and precipitation process respective-ly.The effect of the Ag content on superconducting cricticaltransition temperature of YBa_2Cu_3O_(7-δ)-Ag_x was not evident aslong as YBa_2Cu_3O_(7-δ)-Ag_x can form continuous network.ButAg can increase superconduction crictical current and densityof the composite superconductors.The normal state(i.e.non-superconducting state at room temperature)resistivity shows apercolation threshold at 20%～30% Ag,whereas the super-conduction network shows a percolationthreshold at 70%～80% Ag.     

融与合——有感于Freedom in Design：The Architectnre of JJ．Pan and Partners.2000-2006

潘冀,1966年毕业于美国莱斯大学建筑学专业,1967年获美国哥伦比亚大学城市建筑硕士学位,主攻城市设计方向。在之后的几年内,先后为菲利普·约翰逊和理查德·罗杰斯等建筑师事务所服务,1972年取得美国职业建筑师资格,并于1981     

数字系统设计的新方法及实例

介绍了一种新的数字系统设计方法（ Ｖ Ｈ Ｄ Ｌ） ,并详细介绍了用 Ｖ Ｈ Ｄ Ｌ 设计的简易频率计。     

六钛酸钾纳米线的结构分析

采用X射线粉末衍射Rietveld精修方法和高分辨电子显微方法分析了六钛酸钾纳米线的品体结构。X射线精修结果表明纳米线的晶体结构与六钛酸钾晶须结构相同。高分辨电子显微像模拟计算所得的像与高分辨像匹配良好，且与X射线结构精修所得结构模型相符。纳米线的生长方向平行于K2Ti6O13结构的[010]方向。