无线本地环路技术与竞争接入技术的比较

近年来，随着新思路和新技术（如数字用户线路、视频点播、全球化、融合、固定／移动集成、固定替代、网络电话、第三代移动、微波视频传输系统等）的不断涌现，本地环路技术成为人们的最佳选择，并且获得了迅速的发展。本文考察了不同技术及其发展趋势，并且预测了无线本地环路技术作为竞争接入技术的作用。     

在德国如何成为一名验光师(Ⅰ.从实习生到助理验光师)

对细节的重视和敏锐的观察力、感受力,这些都是成为一名验光师需要具备的素质。从事能改善人们视力和外表的视光行业,从实习生到专家,其工作的目的、性质和前景在任何国家都很相似,而过程却有所不同。 谁希望成为验光师?哪些人恰如其分地选择了这一适合自己职业?这可不是一项简单的工作,因为验光师既是眼镜商人,同时还是技     

Solvothermal Synthesis, Structure and Optical Property of Nanosized CoSb(3) Skutterudite

Binary skutterudite CoSb₃ nanoparticles were synthesized by solvothermal method. The nanostructuring of CoSb₃ material was achieved by the inclusion of various kinds of additives. X-ray diffraction examination indicated the formation of the cubic phase of CoSb₃. Structural analysis by transmission electron microscopy analysis further confirmed the formation of crystalline CoSb₃ nanoparticles with high purity. With the assistance of additives, CoSb₃ nanoparticles with size as small as 10 nm were obtained. The effect of the nanostructure of CoSb₃ on the UV–visible absorption and luminescence was studied. The nanosized CoSb₃ skutterudite may find application in developing thermoelectric devices with better efficiency.     

Temporal and Spectral Resolved Measurement of Soft X-ray From Ultrashort Pulse Laser Produced Plasma

Ultrashort laser pulse produced plasmas are powerful sources of incoherent XUV/soft X-ray radiation and have important applications range from microscopy to lithography. Adding a prepulse is one possible way to enhance soft X-ray emission. The experiment is performed on the Jena 10 TW laser system in IOQ, Germany. The main purpose is to measure the time-resolved soft X-ray spectrum, and study how a prepulse play an important role and enhance the X-ray emission as well as and pulse duration. We clarified the temporal behavior of X-ray emission from quartz plasma produced by intensive femtosecond 800 nm laser pulse, and obtained a quantitative pictures of the     

总油气系统——制约评价单元的天然流体网络

美国地质调查所的“2000年世界油气评价”总共鉴别、命名和标绘了全世界159个最大的总油气系统(TPS)。本章节的表1按已知规模大小(累积产量加剩余储量)列出了这159个系统。在这次资源评价中，总油气系统(以下用英缩略语TPS代替)是评价单元(AU)的基本制约因素。     

轻松走出好身材——纤行1100女子健身鞋

如今的女子训练鞋市场上，打着“走路就能瘦身”旗号的产品层出不穷，然而各种怪异的造型却让爱美的女士们望而却参，荀群争一双造型传统，又能轻松塑身的健身鞋呢？     

Strong Anisotropy of KTiOPO4 Crystals under an Electric Field Observed by Synchrotron Radiation Topography

In-situ white-beam synchrotron radiation topographic observations under an electric field have been made on KTiOPO4 family crystals.The investigation shows a strong enhancement of diffracted intensity of hkl reflections(l≠0) and the topographic extinction contrast,when the field is applied along the polar axis.Doped and undoped samples with grown-in defects are studied in detail.It is believed that the movement of K^ ions driven by the field leads to a local accumulation of charges and the lattice distortion.All the field-related phenomena appear to be related to the one-dimensional ionic conductance.     

展望2000年的建筑——幻灯片解说词

本文作者是西北建筑工程学院名誊教授,美国建筑师学会任命委员会主席,美国Nebraska—lincoln大学建筑学院院长。在这套幻灯片解说词中,作者没有具体介绍建筑设计方法,而是讨论了建筑师在未来世界中的地位、职责范围以及影响建筑师行为的各种主要因素。社会的变化要求建筑师必须随时调整自己的行为。在(?)驳陆离的社会现象中,建筑师如何分析社会发展趋势的各种可能性呢?如何依据这些趋势做出自己的选择呢?作者通过调查,介绍了专业人员和非专业人员对待这些问题的看法。概要地介绍了美国建筑师所面临的问题及所需作出的选择。这是一份浓缩了的调查报告,对从事建筑设计、教学人员均有参考价值。翻译过程中,有些地方作了删节,原文52幅图,我们选取了24幅。     

小型矿山的重要性

本文旨在提起人们对非大型矿山和公司的注意,并就其在均衡发展的矿物工业中引起的问题、所具有的实力和弱点及其重要性陈述几点看法。对矿物工业结构应从三个不同的方面来看,即矿床的大小、矿山的生产水平和拥有     

蒸气化学分析用传感器阵列

已经报道了一些传感器阵列,在这些阵列中,加热催化丝与随后的低温测量电流气体敏感器组合以检测电化学活性和惰性化合物及增强识别不同化合物的能力,此工作有五个目的:(i)通过催化丝温度的快速调制,从传感器阵列得到更多的信息内容;(ii)通过传感