如何选择和应用ADSL技术

本文首先比较了采用两种不同的线路编码和调制技术的ＡＤＳＬ产品的优缺点 ，介绍了一种组网方式，讨论了ＡＤＳＬ技术在实际应用推广中所需解决的了后比较了两种不同网络结构的ＡＤＳＬ宽带接入技术。     

玉米多糖的抗衰老作用

本试验探讨了玉米活性多糖的抗衰老作用。未配对的雌雄小鼠被随机分成五组:衰老模型组,正常对照组,低剂量组,中剂量组和高剂量组,除正常对照组外均为D-半乳糖致衰老模型小鼠。五周后将实验小鼠处死,取其血清,大脑,肝脏和肾脏分别测得超氧化物歧化酶(SOD)、谷光甘肽过氧化物酶(GSH-PX)、过氧化氢酶(CAT)的活性和丙二醛(MDA)等相关指标。结果表明:①从衰老模型组、空白组、低剂量组、中剂量组到高剂量组,SOD,GSH-PX和CAT活力均呈上升趋势,3个剂量组血清及各脏器中的SOD、GSH-PX活力与衰老模型组均存在显著性差异(P0.05),量效关系呈正相关趋势;②各剂量组与衰老组相比血清和各脏器中的MDA含量均显著下降(P0.05),且量效关系呈负相关趋势。而高剂量组小鼠的SOD、GSH-PX和CAT活力增加比其他各组更显著,MDA含量更低。所以,玉米多糖可以提高D-半乳糖致衰老小鼠的SOD、GSH-PX和CAT活性,降低MDA含量,从而具有抗衰老作用。     

Upland landscapes in Britain and the 1992 CAP reforms

The impact of the Common Agricultural Policy (CAP) on the uplands of Great Britain is examined, with particular emphasis on open land characterized by large expanses of rough pasture and heath. Following much concern in the immediate post-war period about the incomes of hill farmers, the paper outlines how the upland problem has been redefined in recent years as an environmental concern. The evolution of agricultural policy for the uplands is examined. In particular, the paper explores the impact of the 1992 reforms on upland management, drawing on a recent empirical study of the countryside impact of the CAP. It is shown that the environmental problem of overgrazing has not been seriously tackled by CAP reforms with extensification payments, cross-compliance and agri-environmental policies all too weak to tackle fully the underlying problem of high densities of sheep in the uplands. The problem is compounded by the decline of the beef sector in the hills. The paper concludes by speculating on the likely impact of the CAP reforms proposed under Agenda 2000 and suggests that the moves towards a new policy are encouraging but will need very careful drafting to ensure maximum environmental benefit.     

蛋白芯片法快速测定食品中氯霉素和磺胺二甲嘧啶残留

人们对食品中药物残留检测方法提出了快速检测、准确定量的要求。本文研究了蛋白芯片法快速定量检测食品中氯霉素和磺胺二甲嘧啶残留。芯片上固定氯霉素和磺胺二甲嘧啶人工抗原,芯片反应区内加入氯霉素和磺胺二甲嘧啶单克隆抗体和其标准品或待测样品混合物,待抗原抗体完全反应后加入荧光标记二抗示踪。不同浓度的竞争标准品与检测荧光强度作标准曲线,然后通过标准曲线对待检试样中氯霉素和磺胺二甲嘧啶残留量进行定量分析,并同现行的免疫学测定方法进行了比较。     

Mechanical and thermal properties of LDPE‐cellulose acetate phthalate blends—Effect of maleic anhydride‐grafted LDPE compatibilizer

Biodegradable blends of LDPE and cellulose acetate phthalate have been prepared. Maleic anhydride‐grafted LDPE has been added as a compatibilizer to this blend. The elastic modulus and tensile strength has been considerably improved by adding LDPE‐g‐maleic anhydride compatibilizer. Scanning electron microscope micrographs reflected the observed results for the increase in mechanical properties of the blend. Further blend morphology exhibited a deformed matrix for the compatibilized blends. Thermogravimetric analysis studies showed two‐stage degradation for the blends. Differential scanning calorimetry thermograms showed a loss of crystallinity for the LDPE phase. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

小分子双水相浮选高效液相色谱法测定污水中痕量氯霉素

用乙醇/磷酸氢二钾双水相体系浮选污水中的氯霉素,通过对盐的质量分数、有机溶剂的体积、气体流速和浮选时间的选择和优化,在理想条件下,氯霉素的平均浮选效率可以达到94%。该方法用于河水和鱼塘水样品中氯霉素的检测,检出限为0.5 ng/mL,加标回收率为89.44%～100.16%,相对标准偏差RSD为1.1%～2.1%,适用于污水中痕量氯霉素的分离/富集及分析测定。     

CAP1400核电站钢制安全壳焊后热处理

基于ASME锅炉及压力容器规范第Ⅲ卷第1册NE分卷对焊后热处理的规定,结合CAP1400钢制安全壳结构形式、材质要求,确定需进行焊后热处理的焊缝范围。结合工程建造特点,对贯穿件套筒与补强板焊缝进行炉内整体热处理,筒体纵焊缝、环焊缝、补强板与筒体焊缝进行局部焊后热处理。为控制焊后热处理的变形,筒体纵焊缝采用单条或多条对称加热、筒体环焊缝及设备闸门补强板焊缝采用分段加热方式,通过试验确定局部焊后热处理的加热带宽度、隔热带宽度和厚度,保证均温带温度达到595℃~620℃的设计要求。     

CAP1400示范电厂气载放射性流出物模拟计算

CAP1400为我国自行研发的装机容量为140万kW的先进非能动三代核电机组。本文以高斯烟羽模型为基础,介绍了我国自行设计的CAP1400核电站正常运行工况下气载排出物的弥散模式。针对实际情况,计算中对模型进行了相关修正,如有效源高、干湿沉积、放射性衰减等,结合示范电厂石岛湾厂址的气象数据,采用C-AIRDOS程序对气载放射性核素的大气弥散因子、年均浓度分布和部分核素的地面沉积浓度进行了模拟计算。为了解CAP1400示范核电厂运行后对周边地区的辐射环境影响提供了参考信息。     

CAP1400主管道用112t电渣锭研制

利用自主研发的大型电渣技术,生产出CAP1400主管道用超低碳控氮不锈钢SA376 TP316LN 112 t电渣锭。电渣重熔的关键则是有效保证超低碳氮含量、高纯净度和高均匀性。     

Evaluation of CIM technologies in Saudi industries using AHP

Successful implementation of computer integrated manufacturing (CIM) technologies offers manufacturing organizations numerous benefits (both tangible and intangible). The evaluation and selection process of these technologies is a very complex task due to the many parameters involved that should be taken into consideration during the selection process. In this research, a number of Saudi industries were surveyed to evaluate their current CIM technologies. Future plans regarding the implementation of such technologies are also investigated. This research also presents a decision support system (DSS) for the evolution and selection of CIM technologies, taking into consideration the requirements of manufacturing industries. This is done to ensure that the selected technologies comply with the objectives of these companies. Depending on the emerged results, a multi-attribute decision-making approach (analytical hierarchy process - AHP) is used. A computerized tool CIMAHP (selection of CIM technologies using AHP) is developed to simplify the application of the suggested DSS. Developed tools are tested and demonstrated using a real case study.