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731.
A systematic study of microvillar enzyme activities in the amniotic fluid in correlation with their values in different fetal tissues during development has been undertaken. Microvillar enzymes appeared in the amniotic fluid at the time of disappearance of the anal membrane, 12–13 weeks, and declined from the 18th week until the 24th week. The study of fetal tissues and fluids has shown that gamma-glutamyltranspeptidase is mainly of liver origin. The significant decrease of the activities of these amniotic fluid enzymes has been the basis of prenatal diagnosis of cystic fibrosis. These assays may be useful for the diagnosis of certain digestive tract abnormalities at later stages of pregnancy. 相似文献
732.
Arthur Lau Yuk Shan Wong logy ChemistryCity University of Hong KongKowloonH.K. Zhang Tong Nora F.Y.Tam 《环境科学学报(英文版)》1998,10(4):474-478
1IntroductionIndustrialwastewaters,particularlythosedischargedfrommanufacturingofprintedcircuitboard(PCB)andelectroplatingcon... 相似文献
733.
A single umbilical artery was seen in 10 out of 117 cytogenetically abnormal pregnancies. The abnormal karyotypes found to be associated with a single umbilical artery were trisomy 18 (n = 5), monosomy X (n = 2), triploidy (n = 1), sex chromosome (47,XYY; n = 1) and translocation (46t(X,5)(q13p15); n = 1). With the exception of the translocation case, all cases with a single umbilical artery had anatomical defects which were detectable ultrasonographically. This suggests that a single umbilical artery alone is not an indication for prenatal fetal karyotyping. 相似文献
734.
735.
四川黄龙沟天然水中的深源CO_2与大规模的钙华沉积 总被引:10,自引:1,他引:10
在有大规模钙华沉积的四川黄龙沟中,使用化学成分数据以及碳氧稳定同位素组成对其水文地球化学特征进行了分析研究。研究区钙华沉积的地表溪流水质基本上受到两种水混合的制约,即断层泉水和山区的融雪(冰)水。泉水中含有高浓度的经由断层提供的CO2,结果高浓度的溶解CO2使得其溶解的碳酸盐岩比普通的岩溶泉溶解的碳酸盐岩高得多,同时也导致硅酸盐岩的溶解。黄龙沟中上游的泉水相对于方解石接近于平衡。溶解无机碳(DIC)的浓度和它们的δ13C值是大约由c=0.02mol·L1δ13C=-3‰的CO2(aq)与含有δ13C=+3‰的碳酸盐岩在封闭系统条件下反应的结果。估计这些CO2中约有70%来自上地幔。所有泉水的水化学数据均落在高岭石稳定域内,但对Na长石和Ca长石具有侵蚀性。由于这些长石矿物的溶解速率太慢,所以水中的化学成分远离长石稳定域。地表溪流的DIC种类之间达到同位素平衡,在不同观测点发现的δ13CDIC变化主要是由于从水中释放出的CO2的程度不同引起的。水样的δ18O值与其采集点的海拔高度之间存在线性关系;研究区的地表溪流的氧同位素组成受到蒸发的制约。在流经钙华沉积物的地表溪流中白天和夜晚的水化学及pH的日变化表明生物作用促进了碳酸盐的沉积,尽管作用不显著。据估计研究区碳酸钙的日沉积速率是4778kg·km2,即约1mm·a1。 相似文献
736.
Lillian Y. F. Hsu M. D. 《黑龙江环境通报》1989,9(1):31-48
A total of 54 cases with prenatal diagnosis of 45,X/46,XY mosaicism was reviewed. Of 47 cases with information on phenotypic outcome, 42 cases (89·4 percent) were reported to be associated with a grossly normal male phenotype. Three cases (6·4 percent) were diagnosed as having mixed gonadal dysgenesis with internal asymmetrical gonads. Two other cases were questionably abnormal. In 40 cases with successful cytogenetic confirmatory studies, the overall rate of cytogenetic confirmation of 45,X/46,XY from tissues derived from fetus/liveborn/placenta was 70·O per cent. This review shows a major difference in the phenotypic outcome between postnatal diagnosis and prenatal diagnosis. Due to the ascertainment bias, almost all known patients with postnatal diagnosis of 45,X/46,XY mosaicism are phenotypically abnormal. Therefore, caution must be used in translating information derived from postnatal diagnosis to prenatal diagnosis. This review calls for collection of more data on 45,X/46,XY mosaicism diagnosed prenatally, more long-term follow-up of liveborn infants, and pathological studies of all abortuses. Emphasis is placed also on the importance of genetic counselling, ultrasound examination, and cytogenetic confirmation. 相似文献
737.
ZHANG Yi-xian 《环境科学学报(英文版)》2001,13(1):69-74
IntroductionTheaccidentalriskassessmentofthechemicalsisafrontierscienceandtechnologyreferredtobothenvironmentalscienceandsafetytechnology .Inrecentyearsmanyresearchworkersinthisfieldhavedoneit.Theanalysisofchemicalaccidentsmainlyincludedthattheleakage… 相似文献
738.
B. Brambati L. Tului I. Bonacchi K. Shrimanker Y. Suzuki J. G. Grudzinskas 《黑龙江环境通报》1994,14(11):1043-1047
Serum measurements of pregnancy-associated plasma protein A (PAPP-A) and the free β-human chorionic gonadotrophin (hCG) subunit were made in 13 women with Down syndrome (DS) pregnancies and six other women with fetal aneuploidy ascertained at chorionic villus sampling (CVS), as well as 89 women with contemporaneous normal control pregnancies. Median serum PAPP-A measurements (0·31 MOM, 95 per cent confidence interval (CI) 0·22–0·65 vs. normal 1·06, 95 per cent CI 0·89–1·20) were lower and free β-hCG subunit measurements (1·13 MOM, 95 per cent CI 0·93–2·63 vs. normal 0·91, 95 per cent CI 0·79–1·03) were higher at statistically significant levels. Receiver operator characteristic (ROC) curves showed that the highest sensitivity for detection, 71·2 per cent (95 per cent CI 54·7–87·6 per cent), was for depressed PAPP-A levels; the combination of low serum PAPP-A levels, maternal age, and elevated free β-hCG levels yielded a detection rate of 78·9 per cent (95 per cent CI 64·9–92·8 per cent) of the affected pregnancies at 8–12 weeks' gestation. 相似文献
739.
One hundred and three cases with prenatal diagnosis of trisomy 20 mosaicism through amniocentesis were reviewed. Approximately 90 per cent (90/101) of the cases were associated with grossly normal phenotype. It is likely that, in the majority of cases, cells with trisomy 20 were extraembryonic in origin or largely confined to the placenta. However, in some cases, the cells with trisomy 20 were confined to certain specific fetal organs or tissues such as kidney, skin, etc. Cytogenetic follow-up studies in liveborns should include a culture from urine sediment. 相似文献
740.
Chen Zongliang Zhang Yang Wang Yubao Zhuang Yahui KazuhikoSakamoto Katsunori Kimijim Tadao Suzuki Masahiro Uchiyam Yoshikazu Hashimoto Hisao oht Yasuaki mae NobutoshiHoriuchi Shin Suzuki 《环境科学学报(英文版)》1990,2(1):41-48
The conversion rates of SO2 to SO2-4 and NO2 to HNO3+NO3- are estimated from the field-data obtained in Beijing in summer, 1988. The results show that the conversion rate of NO2 is about four times as much as that of SO2; The conversion rates have a diurnal variation in a day. On the average, the rate of SO2 is estimated to be 4.7% h-1 during the daytime and 3.4% h-1 during the nighttime. Similarly, the rate of NO2 is estimated to be 17.2% h-1 and 12% h-1 respectively. 相似文献