前车之鉴--访美国环保协会首席经济学家杜丹德先生

上世纪六七十年代，美国发生过不少环境重大事故，有的造成了较大的人员伤亡，有的还是发生在国外。但如今，美国在应对环境危机的各个方面，如立法、机构、人员培训、行政程序、信息披露等方面都走在了世界的前面。那么，过去的几十年，美国又是走过了一条什么样的路程？他们遇到了怎样的困境？社会对此又有什么反应？近日，我刊对美国环保协会中国项目首席经济学家杜丹德（Daniel J．Dudek）博士进行了采访。[编者按]     

腕足类生物壳体在沉积、成岩过程中同位素平衡问题研究

综合分析了现代腕足类生物壳体方解石中的C、O同位素特征，以及有关古生代腕足类生物壳体方解石构造和地球化学研究成果，分析结果证明：只有那些无发光性特点、无胶结和溶蚀构造特点、有较好纤维构造特点、含高Sr、Na和低Mn、Fe（Mg）的第二层腕足类生物壳体方解石的δ18O值不受成岩作用影响；而原始层和壳体中的特殊部位如铰合轴、腕骨、茎孔、交互面、肌痕等在沉积、成岩过程中与海水处于非同位素平衡状态。     

Genetic amniocentesis in biamniotic twin pregnancies by a single transabdominal insertion of the needle

We present a technique to aspirate amniotic fluid from both sacs in biamniotic twin pregnancies using a single abdominal insertion with a spinal needle. It was successful in 48 out of 55 cases of biamniotic twin pregnancies referred to our perinatal unit between 1985 and 1994. The single insertion technique was used when the inter-amniotic membrane was clearly evident and two separate free amniotic fluid pools could be reached by the operator with a single puncture. An adequate amount of amniotic fluid was sampled from both sacs to make a cytogenetic diagnosis in all cases. There were four fetuses with trisomy 21 in three twin pregnancies. In two cases, only one twin was affected whilst the co-twin was normal, so that a selective feticide was performed. No miscarriages due to genetic amniocentesis were reported. After 1990, all genetic amniocenteses in biamniotic twin pregnancies (except for one case due to late booking) were performed between 14 and 15 weeks of gestation and with all cases except one, it was possible to sample both twins by a single puncture. We suggest that early amniocentesis (14–15 weeks) by a single abdominal puncture could be a reliable and safe alternative to first-trimester chorionic villus sampling in twin pregnancies.     

A／O工艺处理石油化工废水试验研究

本文介绍了采用Ａ／Ｏ新工艺组合处理高浓度的炼油、化工混合废水中试情况，试验结果表明；Ａ／Ｏ新工艺组合具有抗冲击性能好，产泥量少，在一定条件下，出水各项指标达标排放，还就填料选择、含氮化合物的消化反应、污泥生物相和各池工艺参数相互关系进行了讨论。     

Genetic amniocentesis following multifetal pregnancy reduction to twins: Assessing the risk

Fifty-three patients who elected to reduce their pregnancies to a twin gestation in our centre are known to have subsequently undergone genetic amniocentesis. Five of these patients lost their entire pregnancy following the genetic amniocentesis procedure. This is equivalent to a 9·4 per cent pregnancy loss rate for reduced twin gestations in comparison with an expected loss rate of 2 per cent for non-reduced twin gestations.     

Internal circulating fluidized bed incineration system and design algorithm

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Prevention of debris flow disasters on Chengdu-Kunming Railway

ＩｎｔｒｏｄｕｃｔｉｏｎＣｈｅｎｇｄｕ ＫｕｎｍｉｎｇＲａｉｌｗａｙＬｉｎｅｉｓｌｏｃａｔｅｄｏｎｔｈｅｍｏｕｎｔａｉｎｒｅｇｉｏｎｏｆｓｏｕｔｈｗｅｓｔｅｒｎＣｈｉｎａ .Ｔｈｅｒｅａｒｅａｌｏｔｏｆｄｅｂｒｉｓｆｌｏｗｇｕｌｌｉｅｓｓｐｒｅａｄｉｎｇｂｅｓｉｄｅｔｈｉｓｒａｉｌｗａｙｌｉｎｅ .Ｏｎｓｕｍｍｅｒ,ｔｈｅｄｅｂｒｉｓｆｌｏｗｏｆｔｅｎｂｕｒｓｔｓａｎｄｔｈｒｅａｔｅｎｓｔｈｅｓａｆｅｔｙｏｆｔｈｅｒａｉｌｗａｙｔｒａｎｓｐｏｒｔａｔｉｏｎ.Ｉｎ 1981,ａｌａｒｇｅ ｓｃａｌｅｄｅｂｒｉｓ…     

First-trimester prenatal diagnosis in quintuplets: A practical approach using step-by-step embryo reduction

A multiple pregnancy of high rank may occur in a couple at risk for a Mendelian disorder. Prenatal diagnosis is hampered by the difficulty of (1) obtaining chorionic villi from each zygote arid (2) unequivocally relating each sample to the corresponding embryo. The calculation of the genetic risk according to the number of zygotes led us to propose a diagnostic strategy based on embryo reduction, a technique initially designed to improve the perinatal outcome of multiple pregnancies with normal embryos. We report a case in which this approach allowed rational use of first-trimester chorionic villus sampling in a quintuplet pregnancy at risk for non-ketotic hyperglycinaemia, resulting in the selective birth of unaffected twins.