宝石的清洗与保护

宝石的清洗与保护ＭｅｍｏｔｙＳｔａｔｈｅｒ，Ｆ．Ｇ．Ａ宝石作为昂贵装饰物品，需要精心的保护、清洗，并且有其独特的保养方法，目的是为了使宝石免受损伤或变色，洗涤方法主要有二种：手工洗涤、机械洗涤。下面分别对这两种方法的原理及其注意事项作一介绍。在方便的...     

降低厚板钢材的非金属夹杂含量

钢水的纯净度即非金属夹杂含量是钢材产品的质量指标之一。订户对钢材纯净度其中包括非金属夹杂的要求加严：产品应符合SEL072标准的2-3类，全苏国家标准22727的0-1类，EN160-85标准的A类等。     

内燃机车柴油机缸内摩擦副与节能降耗

阐述了铁道内燃机车柴油机汽缸内摩擦副的摩擦磨损状况，以及采用适当的新材料、新工艺、新技术之后，在节能降耗方面可以产生的效益。     

悬挂式转鼓的传动装置

这种传动装置为:电动机4的皮带轮3用三角皮带与减速器5轴上的皮带轮2联接,减速器的转矩则借链传动装置而传到转鼓1上。链传动装置包括减速器出轴上的小链轮6,装在张紧装置的轴11上的链轮12和链条7,链条的上段(如图)从外面包在鼓底13的大链轮10上。大链轮做成四个弓形段,其圆周直径为#2792mm;小链轮直径为327mm,齿数13:传动链为     

Comparing frozen saphenous vein with Gore-tex in vascular access for chronic hemodialysis

Performing chronic hemodialysis in patients suffering from end‐stage renal disease needs a suitable vascular access like arteriovenous fistula in the upper limbs and bridge fistula in the upper or lower limbs, and also use of permanent and temporary catheters. The purpose of this study is to compare frozen saphenous vein versus using synthetic Gore‐tex vascular graft for A–V fistula. In the prospective randomized study, 70 patients needing for dialysis access were randomly divided into two groups. We performed the frozen saphenous vein A–V fistula in the test group and the Gore‐tex fistula in the control group. An assessment included function criteria (fistula thrill and murmur) and complications (infection and thrombosis) in planned intervals. At the end of the follow‐up period, the flow rates of all fistulas were assessed by Doppler sonography. The data were compared. Comparing the function criteria (fistula murmur and thrill) and the flow rate of the test group (frozen saphenous A–V fistula) and the control group (Gore‐tex method) showed no significant difference and also no significant difference between two groups in thrombosis. Infection rate of the Gore‐tex method was significantly high (p < 0.05). Arteriovenous fistula was an acceptable alternative in chronic hemodialysis, and frozen saphenous vein arteriovenous fistula was superior to Gore‐tex arteriovenous graft in some aspects.     

铁道机车车辆轮轨的摩擦磨损与节能降耗

阐述了铁道机车车辆轮轨摩擦磨损的现状;研究了内燃机车车轮、闸瓦和钢轨的消耗数量及相应的维修费用;指出了采用适当的新技术之后,在节能降耗方面会产生显著的经济效益。     

电刷镀在矿山设备修理中的应用

作者缍可以向读者介绍金属电刷镀技术的一个极其重要的应用领域。这就是采矿工业中常用的矿石振筛机轴的电刷镀修复。