金属粉末烧结材料泊松比模型的探讨

分析了粉末烧结材料泊松比与屈服准则的关系 ,指出了泊松比Kuhn模型的等价假设 ,比较了几种泊松比模型的特点 ,提出了一种能反映致密过程中密度较大时泊松比增长率减缓的特点的箕舌线函数型泊松比模型。     

我国几种白羽乌鸡品种资源的血型分析及其开发利用

前言 生物资源是自然资源的重要组成部分,它不但是人类赖以生存的物质基础,也在自然界良性生态循环中扮演着重要的角色。地方品种资源则是人们在自然和经济条件制约下长期劳动的结晶,是庞大的种质基因库。长期以来,我国对品种资源的研究还比较落后,手段较少,新技术应用不多,本实验室利用遗传标记性状(红细胞抗原)对我国的地方鸡种     

1420铝锂合金模锻件锻造工艺的研究

利用高温变形实验 ,研究了 14 2 0铝锂合金在不同变形条件下的变形行为 ,获得合金的塑性图、变形抗力图、晶粒尺寸 变形程度关系图 ,确定出合金的锻造工艺参数 :锻造温度为 35 0～4 2 0℃ ,临界变形程度为 8%～ 10 % ,变形速率以低速为宜。结合实际情况 ,制定出合理的、经济的14 2 0铝锂合金模锻件成形工艺 ,即 6 0 0 0t水压机上多方锻开坯→车成锥体→ 80 0 0t卧式挤压机上终压模成形。生产出的 14 2 0合金模锻件尺寸精度高 ,综合性能优良。     

Evaluation of a prenatal screening procedure for β-thalassaemia carriers in a chinese populationbased on the mean corpuscular volume (MCV)

Haemoglobin A₂ (HbA₂) levels were determined on 25 β-thalassaemia carriers by the microcolumn method and were found to range from 4.5–7.2 per cent (mean 5.2±0.82 S.D.). The haemoglobin level (Hb), mean corpuscular volume (MCV), plasma ferritin and HbA₂ levels were measured on a further 299 cconsecutive Chinese pregnant women at a gestation of less than 24 weeks. 18 patients (6 per cent) had HbA₂ level greater than 4.5 per cent and were diagnosed to be β-thalassaemic carriers. It was observed that all these patients had a MCV below 75 fl. If this level is selected in a screening procedure based on measurement of MCV alone all β-thalassaemia carriers could be detected and 11 per cent of the population screened would require HbA₂ estimation. At a lower cut-off level of 70 fl, 8 per cent of the population screened wouid require HbA₂ measurement (a decrease of 27 per cent) but the detection rate will be lowered considerably (83 per cent). The high false positive rate at all cut-off levels of MCV was largely due to the prevalence of iron deficiency anaemia in the population. Estimation of plasma ferritin level in patients with low MCV will reduce this false positive rate, but there will be a considerable delay in diagnosis in patients with concomitant iron deficiency and β-thalassaemia. The presence of iron deficiency in β-thalassaemia carriers did not reduce their HbA₂ level below the diagnostic range in this study. Measurement of Hb level did not appear to be useful as a screening method since one third of the β-thalassaemia carriers had a Hb level over 11 g/dl. The validity of the MCV cut-off levels derived from the first part of the study was assessed in screening a larger population. 61 β-thalassaemia carriers (6 per cent) were detected out of 1166 patients screened. This incidence was not significantly different from the first part of the study. All these 61 patients had a MCV less than 75 ml. It was concluded that a two-step screening policy, based on MCV measurement followed by HbA₂ estimation when the MCV value is less than 75 fl, is suitable for our population. It is efficient, straight forward with excellent sensitivity and required less time and effort for both laboratory staff and clinicians.     

模糊综合评价法在鄱阳湖水质评价中的应用

应用模糊综合评价法对鄱阳湖各重要断面的水质进行了综合评价。根据鄱阳湖10个重要断面的水质特点，确定了5个指标（DO，CODMn，NH3-N，N，P）作为评价因子，建立评价矩阵，计算出影响因子的权重，最后评价出水质级别。结果发现，鄱阳湖10个断面中，6个断面水质达Ⅱ级以上，2个为Ⅳ级，2个为V级。鄱阳湖的水质总体上还比较好，但不能过于乐观，值得警惕。通过鄱阳湖水质评价表明，模糊综合评价法由于考虑到了水质分级界限的模糊性和污染因素的权重，能够比较客观地反映水体的水质现状，且操作简单、实用性强，是1种较为科学而有效的水质定量评价方法。     

交通噪声污染经济损失估算方法比较研究

目前闷内外对于噪声污染经济损失的研究还相当有限，且采用的方法也存在很大的差别。运用环境经济学的观点和方法，提出了估算噪声污染损失的3种常用方法；损害费用法、意愿型调查评估法和防护费用法，并对其进行了比较研究。     

PCR-RFLP技术在环境地球化学研究中的应用及展望

PCR—RFLP技术为环境地球化学提供了一种新的研究方法和实验设计的新的思维方式。该方法具有所需样品量低、快速简便及特征性强等优点 ,可广泛应用于物质的生物地球化学循环、环境过程的生物作用、生物多样性及有机物源判断等方面的研究。利用PCR—RFLP技术 ,以环境中存在的 16SrRNA为对象 ,对环境生物的研究已广泛开展并取得了许多成果。展望未来研究成果 ,将会在海洋及湖泊沉积物等自然环境中发现更多的、新的微生物种类 ;将进一步阐明生物作用和物质循环的机理和过程 ;进一步阐明自然环境中生物大分子的变化机理及其环境效应并找到判断沉积物有机物源的新方法     

医疗废物集中处置项目环评应重点关注的问题

根据医疗废物集中处置项目的建设特点,对其不同处理工艺的优缺点进行辨析,归纳并阐述了该类项目环境影响评价中应重点关注的几个问题,以避免在处置过程中对环境和人体造成二次污染。     

苏南志留—第三系岩石力学性质及节理形成机制探讨

对苏南地区志留—第三系进行了系统的岩石力学性质测试,包括岩石抗压强度、抗张强度、抗剪切强度、弹性模量和泊松比值。测试结果表明,苏南存在多个岩石力学突变层;影响岩石力学性质的因素主要为岩石类型、组构、结晶程度和受力方向等。本文还讨论了在区域应力场作用下,节理形成机制和应力转化过程。节理形成通常与岩石中各种缺陷有关,在缺陷处应力易于集中。节理具有多种成因机制。     

锦州市大型公共场所室内空气质量状况与问题分析

通过对锦州市大型公共场所室内空气质量近一年的监测与分析，找出了锦州市大型公共场所室内空气的首要污染物为甲醛和二氧化碳，揭示了影响锦州市大型公共场所室内空气质量状况的因素，并提出了具体的解决办法和措施。