The land carrying capacity and environmental risk assessment of livestock and poultry breeding considering crop planting

Environmental Science and Pollution Research - At present, the contradiction between survival and ecology necessitates the integration of crop planting, chemical fertilizer application, and...     

Research progress and hot spots of hydrothermal liquefaction for bio-oil production based on bibliometric analysis

Environmental Science and Pollution Research - Hydrothermal liquefaction (HTL) of biomass used HTL reaction under high temperature and pressure to produce bio-oil. This technology is considered as...     

消防员职业健康测试项目的研究

本文从医学测试、体质测试和心理测试三个方面论述了消防员职业健康测试项目研究的重要性,以促进我国消防员职业健康研究水平的提高。     

关于长江产业带建设总体布局的初步思考

重点开发长江是90年代中国经济重大战略布署。将长江产业带建设成具有强大经济实力的国家一级经济轴线,宜采用分层次推进与中心辐射相结合的发展战略,以浦东开发和三峡建设为契机,加强基础产业,发展新兴产业和第三产业,优化产业结构,以能源和交通建设先行,改善基础设施。同时,要协调产业带建设与浦东开发、三峡工程建设的关系。     

长江三峡柑桔的冻害和热害（二）

本文从柑桔冻害和热害的危害因子和指标等级划分的研究和选取入手,着重探讨了长江三峡地区(湖北境内)两害显著的时空变化特征、差异与关联性及对柑桔生产的影响;揭示了80年代以来冬暖春热的重大气候变化是使两害向“两极分化”的根本原因;讨论了三峡水利工程对两害时空格局的可能调整及减灾原理;最后提出了可能的对策。     

三峡水库忠县至秭归县段消落带植被群落特征研究

为了研究三峡水库周期性的水位调节对消落带植被群落特征的影响，选择重庆忠县至宜昌秭归段的消落带植被群落进行研究，运用重要值和多样性指数分析不同高程的植物种类组成、生活型分布特征及物种多样性。结果表明：（1）研究区域统计植物共32科70属73种，禾本科、菊科和豆科是3个优势科，单种、属现象明显；狗牙根、苍耳、鬼针草、苘麻、鳢肠、酸模叶蓼、莲子草是3个高程的共存种，其中，狗牙根和苍耳在3个高程均为优势物种。（2）研究区域共统计11种植物生活型，在消落带下部和中部，一年生草本植物占绝对优势；在消落带上部，多年生草本植物成为优势生活型，生活型类型多样化，蕨类、藤本、灌木以及乔木植物开始出现。（3）消落带植物群落的丰富度、多样性、均匀度指数均随海拔变化表现出显著差异，并且随海拔升高呈现上升趋势。由此可见，水位变化对植物群落结构和物种多样性产生很大影响，在低海拔区段，消落带物种组成简单化，耐水淹和繁衍能力强的植物成为优势物种；随着海拔上升，水淹胁迫减弱，出现更多适应水位变化的植物种类，使植物群落沿海拔变化形成不同的分布特征。这些研究结果对三峡库区消落带生态修复植物的筛选，以及物种多样性的提高具有参考价值。     

Prenatal diagnosis of partial monosomy 18p(18p11.2→pter) and trisomy 21q(21q22.3→qter) with alobar holoprosencephaly and premaxillary agenesis

A prenatal diagnosis of partial monosomy 18p(18p11.2→pter) and trisomy 21q(21q22.3→qter) in a fetus with alobar holoprosencephaly (HPE) and premaxillary agenesis (PMA) but without the classical Down syndrome phenotype is reported. A 27-year-old primigravida woman was referred for genetic counselling at 21 weeks' gestation due to sonographic findings of craniofacial abnormalities. Level II ultrasonograms manifested alobar HPE and median orofacial cleft. Cytogenetic analysis and fluorescence in situ hybridization (FISH) on cells obtained from amniocentesis revealed partial monosomy 18p and a cryptic duplication of 21q,46,XY,der(18)t(18;21)(p11.2;q22.3), resulting from a maternal t(18;21) reciprocal translocation. The breakpoints were ascertained by molecular genetic analysis. The pregnancy was terminated. Autopsy showed alobar HPE with PMA, pituitary dysplasia, clinodactyly and classical 18p deletion phenotype but without the presence of major typical phenotypic features of Down syndrome. The phenotype of this antenatally diagnosed case is compared with those observed in six previously reported cases with monosomy 18p due to 18;21 translocation. The present study is the first report of concomitant deletion of HPE critical region of chromosome 18p11.3 and cryptic duplication of a small segment of distal chromosome 21q22.3 outside Down syndrome critical region. The present study shows that cytogenetic analyses are important in detecting chromosomal aberrations in pregnancies with prenatally detected craniofacial abnormalities, and adjunctive molecular investigations are useful in elucidating the genetic pathogenesis of dysmorphism. Copyright © 2001 John Wiley & Sons, Ltd.