美国运营商 财报很体面——全美主要运营商06首季财报分析

截止到五月初,美国主要电信及有线运营商第一季度的财务报告陆续发布,有线运营商的势头强劲,电信运营商的业绩亦可圈可点。     

基于工作流的签字管理系统分析

签字是办公系统中的一个重要内容，本文在分析了签字工作流特点的基础上，重点分析了签字软件需要解决的几个关键问题。     

高重复频率脉冲染料激光器激发的半导体时间分辨荧光光谱

采用带有宽带前置放大器的Boxcar接收系统,我们研究了掺氢非晶硅(a-Si:H)和Ⅲ-Ⅴ族化合物的时间分辨光谱和瞬态过程。     

光纤检测技术的应用

具有低损耗、宽带、无感应等多种优良特性的光纤正在公共通信和工厂、大型建筑和电力设施等的通信控制电路等广泛的领域中获得应用。光纤在检测技术方面也有很宽的应用范围,例如,利用其低损耗、无感应性进行检测数据传送和以前的光检测,利用光纤的细线径、柔软性、电绝缘性等特长的检测,以及用光纤做传感器的检测等。本文介绍这些光纤检测技术的一个侧面。     

二氧化碳激光治疗尖锐湿疣

尖锐湿疣也称生殖道或性病性疣，发病率正在不断增加。近20年来，电子显微镜鉴定出生殖道下段疣的感染因子是病毒，即乳头状病毒，属Papova组的含小量DNA抗醚致瘤病毒。     

GaAs-Ga_(1-x)Al_xAs双异质结激光器的深能级荧光

测量了垂直于结平面各空间位置的荧光光谱和某些特定波长的空间分布.实验结果表明在 n-GaAs衬底、n-GaAs缓冲层和 P-GaAs有源层都存在着峰值波长为 1.03 μm和 1.09μm的深能级辐射.这些辐射在热处理和小电流密度老化下有着不同的行为. 另外在N-Ga_(1-x)Al_xAs层的荧光谱中还可以看到一个波长比有源区带到带的辐射还短的辐射.可以认为这是由于在N-P异质界面存在着电子势垒从而导致在N-Ga(1-x)AlxAs层中导带的非平衡电子与在Sn深受主能级上的非平衡空穴复合产生的辐射.     

专家数据库系统的设计与实现

分析、比较了专家系统与数据库管理系统中的搜索功能和库处理能力，采用两有效结合的方法建立了一个专家数据库系统模型，从而提出了开发信息系统的一种有效途径。     

Improving the precision of fluorescence lifetime measurement using a streak camera

Streak camera has high temporal resolution and high sensitivity, and is a powerful tool in biomedical study to measure fluorescence lifetime and perform fluorescence lifetime imaging. However, nonuniformity of the gain in the streak tube and nonlinearity of the sweeping speed limit the precision of fluorescence lifetime measurement, particularly when fluorescence lifetimes are short. We have constructed a two-photon excitation fluorescence lifetime measurement system that is based on a synchroscan streak camera and have developed accordingly a method to correct the effect of gain nonuniformity and nonlinearity of sweeping speed on the measurement precision. A continuous-wave laser of high stability is used to calibrate the gain of the streak camera, and a Fabry-Perot etalon is used to calibrate the nonlinearity of the sweeping speed. Fitting algorithms are used to correct the gain of the streak camera and nonlinearity of the sweeping speed respectively, which significantly improves the measurement precision of the system, as characterized through the fluorescence lifetime of the short-lived fluorescence dye, Rose Bengal. Experimental results show that the measurement fluctuation of the lifetime has been improved from more than 10% to 2% after correcting the effects of gain nonuniformity and sweeping speed nonlinearity.     

Calculation of equation of state of QCD at zero temperature and finite chemical potential

In this paper we calculate the equation of state （EOS） of QCD at zero temperature and finite chemical potential by using several models of quark propagators including the Dyson-Schwinger equations （DSEs） model,the hard-dense-loop （HDL） approximation and the quasi-particle model.The results are analyzed and compared with the known results in the literature.