内螺纹变截面铜管拉伸工艺的研究

此文提出了内螺纹变截面铜管分段拉仲一次成形新工艺,并就工艺因素对该管拉伸成形的影响进行了试验研究,从而为合理制订成形工艺提供了依据。     

固相萃取气相色谱法测定地表水中有机磷农药

建立了固相萃取(SPE)气相色谱火焰光度(GC-FPD)检测方法,并且检测了地表水中8种有机磷农药,检测限在0.09～0.26μg/L之间,相对标准偏差为3.1%～9.7%(n=8),加标回收率达到61.3%～103.2%,与传统的气相色谱法相比,该方法具有比较高的重现性和选择性,在地表水有机磷农药的测定中具有很好的应用前景.     

污染物在地下水毛细饱水带的运移规律浅释

分析了毛细饱水带的水动力学特性，指出在地下水污染研究中，污染物在毛细饱和水带和潜水怪具有相同的水平运动规律，并以实例分析说明该带对污染物运移的重要性。建议在研究和一非饱和条件地下水及污染物运动问题时把毛细饱水带与潜水含水层统一为饱马毛细饱水带顶面作为饱水面。     

石墨管连续涂覆结合基体改进测定地表水中的铅

尝试了使用5%钼酸铵-5%磷酸二氢铵溶液组成石墨管连续涂覆结合基体改进剂的方法,应用于地表水Pb的测量中。实验表明,本法具有提高石墨管在使用过程中的稳定性,消除基体效应的作用。     

助催化无汞盐快速测定水中化学需氧量

在ψ（Ｈ２ＳＯ４）＝５６％硫酸介质，重铬酸钾的氧化体系中，以钼权铵，硫酸铝钾为助催化剂，可减少量化剂硫酸银的用量，消解１５ｍｉｎ即可测定水中化学需氧量，用硝酸银溶液代替硫酸汞去除水氯离子，避免了汞盐的污染，工业废水回收率在９７％～１０１％之间，有较好的准确度。     

开口圆管非对称弯曲的一种方法

开口圆管非对称弯曲时,在尺寸、形状均有较高精度要求的情况下弯曲有一定的难度。此文介绍了一种成功的开口圆管非对称弯曲冷态成形方法。     

Detecting neural tube defects by amniocentesis between 11 and 15 weeks' gestation

Forty-two open neural tube defects (NTDs) were identified in our series of 7440 amniocenteses tested between 11 and 15 weeks of gestation. Using a cut-off of ≥2.0 MOM, the detection rate for open NTDs was 95 per cent; 100 per cent each for anencephaly and spina bifida; and 78 per cent for encephalocele. Two encephaloceles had AFP levels less than 2.0 MOM and negative AChEs. Thirty-four (81 per cent) of these NTDs were tested between 13 and 15 weeks and 8 (19 per cent) before 13 weeks. There were 0.6 per cent false positives by AFP (excluding serious abnormalities and fetal death) and 0.1 per cent after AChE. The likelihood of an open NTD after an elevated AFP (≥2.0 MOM) was 24 and 77 per cent for any serious abnormality. These results, when combined with an earlier study, indicate that amniotic fluid AFP appears to be as sensitive a test for open NTDs between 13 and 15 weeks as between 16 and 20 weeks. Additional experience is necessary to determine this before 13 weeks.     

毛细管气相色谱法分析1,3—丁二烯中炔烃杂质含量

介绍了一种毛细管毛相谱法测定１，３－丁烯中炔烃质含量的新试验方法，该方法以氮气为载气，采用氢火焰离子化检测器，样品经分离后，采用外标法定量，操作简便，准确。该方法还可用于１，３－丁二烯纯度分析 。     

Serum alpha-fetoprotein and neural tube defects in the first trimester of pregnancy

As part of the Medical Research Council randomized trial of vitamin supplementation in the prevention of neural tube defects (NTDs), maternal serum alpha-fetoprotein (AFP) was available for 19 NTD pregnancies. Each of these was matched with four unaffected controls, by maternal age, participating centre, and duration of sample storage. The samples came from women whose gestational age ranged from 6 to 14 completed weeks. The median AFP level in the affected pregnancies was 1·2 multiples of the median value in unaffected pregnancies of the same gestational age (95 per cent confidence interval (CI) 0·83–1·59). This confirmed the view that serum AFP measurement is of no practical value in the detection of NTDs in the first trimester of pregnancy. The study also showed that folic acid supplementation, used as a method of preventing NTDs, had no effect on the concentrations of maternal serum AFP up to 14 weeks of pregnancy.     

Amniotic fluid fibrinolytic system in fetal neural tube defects

Second trimester amniotic fluid fibrinolytic system was examined in normal pregnancies and those complicated by anencephaly, spina bifida and fetal chromosome abnormalities. No significant difference was demonstrated between the fibrinolytic systems from normal pregnancies and those complicated by fetal chromosome abnormalities. In pregnancies complicated with anencephaly and spina bifida no significant difference was demonstrated for alpha-1-antitrypsin, alpha-1-antichymotrypsin and urokinase. Plasminogen was significantly lower (p < 0.02) and plasmin significantly higher (p < 0.001) than levels from normal amniotic fluid. Alpha-2-macroglobulin, fibrinogen, FDP-D and FDP-E were detected only in pregnancies complicated with anencephaly and spina bifida.