话说电视信号

当你坐在电视机前,电视屏幕中那五彩缤纷的世界展现在你的面前时,你知道这五彩缤纷的电视节目信号是如何传送来的吗?     

漫话E-mail

E-mail中的@ 每当你发送或接收电子邮件时,总离不开@这个字符.说起它的由来,不能不提到"电子邮件之父"雷·汤姆林森.     

HERMES上深度非弹过程中纵向自旋转移的处理方法

为了得到HERMES(德国DESY实验室)实验装置上的深度非弹散射过程中产生的A粒子的极化信息,探知核子中夸克自旋的分布及转移,建立了一种能消除对该分析结果有很大影响的接收度的不均匀性的新方法,即归一法;此外,对由匹兹堡组新提出的螺旋度平衡法作了改进并加以论证.并将两种新方法与依赖模拟的蒙特卡洛方法螺旋度平衡法作了比较.     

气溶胶对红外辐射衰减的试验与计算尝试

高温燃气红外辐射抑制的研究在国民经济和军事上都是非常有意义的，对红外热源进行红外线屏蔽的各种方法中，使用气溶胶是一种可行的方案。     

Structure characterization of melt drawn polyethylene ultrathin films

Highly oriented ultrathin polyethylene (PE) films were prepared by a melt-draw technique. Transmission electron microscopy study on the obtained ultrathin films indicates that the melt drawn PE thin films consist of highly oriented edge-on lamellae aligned perpendicular to the drawing direction. Electron diffraction confirms that the PE chains in crystal-line phase are highly oriented in film plane along the drawing direction, while only a random orientation of the crystallographic a-and b-axes can be described through electron diffraction. The IR results on the melt-drawn ultrathin PE films demonstrate that the PE molecular chains in both crystalline and amorphous phases of the melt drawn thin films are well oriented along the drawing direction. Moreover, the IR results indicate that in the crystalline phase, the crystallographic b-axis tend to lie in the thin film plane, while in the amorphous phase, the skeleton plane of some local chains prefers to parallel the film plane. The alignment of b-axis of PE crystals in ultrathin films originates from the fact that the b-axis is the fastest growth direction of the PE crystals.     

红外线下另样天空

迄今为止．斯皮策太空望远镜仍然在用人眼看不见的红外线继续观测着宇宙。它所携带的高性能的照相机拍下了大量红外线图像，把一个以前不为人知的宇宙侧面呈现在我们面前。本文介绍了斯皮策太空望远镜在近几个月里捕捉到的人眼看不观的宇宙模样。[编者按]     

宾馆应该善于运用“六化”的服务艺术

自20世纪90年代中期以来，宾馆的网络化服务逐渐成全球趋势。如自1995年开始，美国饭店目录商REED集团就在网上推出了500家饭店REED旅客网，方便客人根据自己打算停留的地点选择称心的饭店下榻。在新加坡，宾馆目录商又借助网络将城市旅游资源牢牢掌握在手中，拥有城市旅游资源的宾馆的CONCIERGE柜台都设置了卫星接收系统和互联网接口。