基于FPGA的一种直接序列扩频信号接收技术

在介绍了一种基于FPGA大规模可编程芯片的数字直接序列扩频接收技术的基础上,着重阐述了其数字接收机模型、PN码捕获及PN码同步技术,给出了该数字接收机的实际测量结果。     

ELISA技术在饲料安全检测中的应用

近年来随着兽药在饲料中的使用日益广泛,饲料安全检测工作在畜牧生产中更加重要,具有高选择性、高灵敏度、高分析效率、低成本、低环境污染特点的ELISA技术成为当今饲料安全检测工作中应用日益广泛的测定技术之一．ELISA技术在饲料安全检测中的运用及其试验条件的要求就显得非常重要．     

中国经济的直接物质投入与物质减量分析

一个国家的经济发展需要物质投入,投入的物质量越大,对自然资源的消耗越多,排放的废弃物也越多,因此造成的环境压力也就越大.降低环境压力实现可持续发展的根本途径在于减少经济系统运行所需的物质量.本文以德国Wuppertal气候、能源、环境研究所提出的物质流账户系统为基础,计算了1990年～2002年中国经济系统的直接物质投入,并对其进行了减量化分析和国际比较.结果表明:中国直接物质投入(Direct Material InputDMI)为27×108t～42×108t,DMI中90%以上是国内物质,这一比例比日本高约20个百分点,比荷兰高约40个百分点,说明我国经济发展主要依赖自身资源的支撑;中国的人均DMI量为3t左右,约为英国的1/5、荷兰的1/9;中国的DMI使用效率(单位DMI创造的GDP)也比发达国家低很多,1996年只有不到200美元/t,约为同年荷兰的1/5、日本的1/11;但中国的DMI使用效率在升高,过去8年的平均年增长率约为6%,说明我国经济实现了一定程度的物质减量;通过对未来50年中国人均GDP增长率的估计以及国家计划生育委员会对2050年中国人口的预测得出,若保持经济增长的同时实现DMI使用量的零增长,2050年中国的DMI使用效率应是现在的5倍或10倍,即年增长率达到3.35%或4.85%,实现这一目标是完全可能的.     

Diagnostic role of the antibody response to the 38kDa, 16kDa proteins and lipoarabinomannan of mycobacterium tuberculosis

The antibody response to the 38kDa, 16kDa and Lipoarabinomannan (LAM) antigens ofMycobacterium tuberculosis was evaluated using three different ELISAs based on these antigens. The study group included tuberculosis patients (n=52), patients with HIV and TB co-infection (n=10), other chest symptomatics (n=5), HIV infected individuals (n=10), leprosy cases (n=7) and healthy controls (n=75). The results indicate that the 38kDa and LAM based ELISA for IgM/IgG has a low specificity (ranging from 69–85%) and sensitivity (ranging from 55–78%). When three ELISAs are carried out on a single patient the probability of detection of tuberculosis was significantly increased to 95.2% indicating that a single ELISA test is of low sensitivity and that a combination of ELISA’s may be needed to be of any value as a diagnostic test for tuberculosis. Additionally, a western blot assay of the serum antibody response to protein fraction ofM. tuberculosis was analysed in 15 tuberculosis patients and five healthy controls. A multiple antibody response to various M.tuberculosis proteins was observed which varied from patient to patient as compared to controls who showed a single 38–39 kDa protein band positivity. These finding suggest that a western blot assay which determines the antibody response to a set of antigenic components ofM. tuberculosis could be a better serological test for the diagnosis of tuberculosis in our population.     

The differential influence of instructional context on the academic engagement of students with behavior problems

The teacher–student interactions of 39 students exhibiting high externalizing behavior problems and 59 students exhibiting average behavioral adjustment from urban elementary schools were directly observed. Comparisons between these students within four different instructional contexts indicated that levels of student engagement were significantly related to both behavior and classroom context. Although teachers’ use of behavioral management strategies was minimal, it was significantly related to the type of instructional context in which it occurred. Findings are discussed in terms of how different instructional contexts place unique demands and offer distinct affordances for students with behavior problems. A more comprehensive understanding of the influence of these environmental contexts can allow teachers to scaffold task demands to bring them within the domains of the student's ability.     

Design of ERT system

INTRODUCTION Electrical resistance tomography (ERT) is a technique producing images based upon variations in conductivity, and has great potential in process ap- plications (Tapp et al., 2003). In an ERT system, current is injected to a pair of drive electrodes and voltage measurements are taken between sense elec- trode pairs, yielding resistance information for image reconstruction (Cilliers et al., 2001). Traditional ERT systems usually use high fre- quency sinusoidal waveforms as …     

ELISA法检测三种类型的类风湿因子

用ELISA法建立了检测IgM、IgG、IgA三种类风湿因子。在类风湿关节炎(RA)中IgM-RF,IgG-RF,IgA-RF的阳性率分别为67.1％,58.6％,42.8％,明显高于其他结缔组织病,且OD值也高。ELISA法检测IgM-RF的阳性率明显高于乳胶凝集法检测的阳性率,但特异性一样为2.3％,但弥补了乳胶凝集法只能检测IgM-RF的不足,尤其是建立了IgG-RF和IgA-RF的检测,对临床诊断有很大帮助,我们还发现IgA-RF和SS有一定关系。     

论责任保险第三人直接请求权在我国的确立

责任保险是指以被保险人的民事损害赔偿责任作为保险标的的保险,它具有保护被保险人和受害第三人的双重功能。经过多年发展,我国的责任保险制度取得了长足的进步,但第三人直接请求权却一直未被明确承认。本文对责任保险第三人直接请求权的性质、立法现状及其可行性进行了探讨,并提出了相应的立法建议。     

浅谈伪随机序列在直接序列扩频通信中的应用

伪随机序列具有良好的随机性与相关性,直接序列扩频系统正是采用了序列的良好特性,才大大提升了通信系统的整体性能。本文介绍了伪随机序列的特性,并详细地阐述了序列在直扩系统中不同的应用于作用。