The predictive value of cytogenetic diagnosis after CVS based on 4860 cases with both direct and culture methods

Cytogenetic analysis was performed in 4860 chorionic villus samples by means of both direct preparation and long-term culture. The results of the analysis were compared with a classification including all theoretical types of combinations between the chromosomal constitution of the cytotrophoblast, extraembryonal mesoderm, and fetus, with the aim of evaluating the cytogenetic variability along the trophoblast—embryo axis. Eighteen of 29 possible combinations were found demonstrating a considerable heterogeneity. A mosaic conceptus was found in 1·5 per cent of cases, with generalized mosaicisms and confined mosaicisms in 0·2 and 1·3 per cent, respectively. Cytogenetic variability along the trophoblast—embryo axis was found in 1·42 per cent of cases. Results possibly leading to diagnostic errors (false-positive and false-negative results) were found in only 1·38 per cent. False-positive results of direct preparation were the most commonly observed discrepancy (0·8 per cent), while the incidence of false-positive results of the culture method and of both methods was 0·31 and 0·16 per cent respectively. The incidence of false-negative results was 0·1 per cent, with false-negative results of direct preparation 0·08 per cent and false-negative results of both methods 0·02 per cent. False-negative results of the culture method were not found. Our data confirm the high diagnostic accuracy of chorionic villus sampling and the utility of the combined use of the two methods in minimizing diagnostic errors and in reducing the need for follow-up amniocentesis.     

整地施肥对尾叶桉生长及土壤性状的影响

整地施肥试验结果表明，全垦、带垦和穴垦三种整地方式以及施肥对尾叶按造林成活率和保存率均无明显的影响，成活率在９５％－９８．８％之间，保存率在９２．１％－９７．７％之间．整地能改变土壤性状，如土壤孔隙度全垦为５７．８８％。穴垦为４９．４２％；对林木生长有促进作用，但作用效果很快减少，如造林３年后的林木材积全垦、带垦分别为穴垦的１３６．４％和１２０．０％，５年后却分别下降到１１６．５％和１０８．３％．施肥可提高土壤养分，促进林木生长．造林５年后的调查结果，穴垦施肥林地的土壤有机质、速效Ｎ分别为１５．４４７ｇ／ｋｇ和４９．２３０ｍｇ／ｋｇ，林木年均树高生长为１．２５ｍ；不施肥处理的有机质、速效Ｎ分别为１０．３８８ｇ／ｋｇ和３５．７１５ｍｇ／ｋｇ，林木年平均生长量为０．３５ｍ；林木材积施肥处理的为不施肥的９．８倍．整地施肥还可提高林木叶片的养分含量．     

多氯二苯并-对-二噁英(PCDDs)半定量标准的制备

以热聚法合成,柱色谱纯化,配制了几种PCDDs的半定量标准,并对其进行了评价。     

微波法制取锯末活性炭及其吸附Cr~(6 )性能的研究

介绍了微波照射—氯化锌法(ZCMR)制取锯末活性炭的方法。用该法所制锯末活性炭处理含铬废水的结果表明,该锯末活性炭具有吸附容量大、过滤速度快、操作控制方便等优点,活性炭对铬的吸附容量是市售一级粉末活性炭的1.72倍,极限吸附量达21.5mg/g,过滤速度为市售活性炭的1.64倍。     

稻壳吸附剂净化水中有机污染物的研究

以酸处理稻壳为原料，研究了稻壳吸附剂的活化工艺，所制备的吸附剂对水中芳香化合物和杂环染料均有较大的吸附能力。通过试验得出了吸附剂净化水中芳香化合物及染料的最佳条件     

电磁屏蔽织物的制备及应用

本文介绍了电磁屏蔽织物的制备技术和国外电磁屏蔽织物的产品开发概况。     

云南省土壤污染状况调查中土壤样品制备

主要介绍了土壤采集后的混合样品和单独样品制备过程，并根据不同的分析项目采用不同粒径的过筛样品。统一规范操作，确保数据的准确性和可比性。     

用生产草酸产生的废草酸泥渣制备铬酸铅的工艺研究

用生产草酸产生的废草酸泥渣,通过采用以加热转化,硝酸溶解提取,重铬酸钠合成为主要步骤的制备新工艺,用草酸泥渣制得了铬酸铅.对用草酸泥渣制备铬酸铅的工艺原理进行了分析.本文着重研究了原料粒度、反应温度、反应时间和硝酸用量等因素对产品产量和铬酸铅含量的影响.     

用三聚氰胺生产中排放的固体废物制备三聚氰酸

对三聚氰胺生产企业产生的固体废物利用进行了研究。研究发现 ,在自生压力下可以由三聚氰胺生产过程中排放出的固体废弃物酸解制备三聚氰酸 ;添加酸式硫酸盐在低硫酸浓度下水解几乎能达到高硫酸浓度下水解的效果 ;固体废弃物酸解时 ,反应温度升高、反应时间延长和NaHSO4用量增加都会提高三聚氰酸的收率 ;酸解过程中 ,反应温度对收率有显著影响 ,而反应时间、硫酸氢钠的用量对收率影响不显著 ;在 160℃、NaHSO4用量为 10 0g时反应 4h ,三聚氰酸的收率可达 67%     

铝质固体废料制取聚合氯化铝及絮凝脱色性能

采用酸溶一步法利用三种铝质固体废料制取了聚合氯化铝。实验表明 :该法生产聚合氯化铝 ,工艺可行 ,产品主要指标满足国家标准 (GB1 5892 95)的要求 ,所制的PAC对模拟染料废水的絮凝效果与用AlCl3.6H2 O制成的聚合氯化铝的相当。