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11.
本文依据生态学理论对海岛土地及土地系统生态功能进行了重新的认识,并探讨了海岛土地系统生态设计的依据、原则和模式.设计中强调以土地系统生态保护性功能为主体,以海岛土地系统高层次调合发展作为海岛建设的最终目标.  相似文献   
12.
Routine sonography prior to genetic amniocentesis revealed the presence of a large complex mass with pulsating channels over the anterior fetal chest wall. This led to early termination of pregnancy in a fetus affected with the rare Klippel-Trenaunay-Weber Syndrome.  相似文献   
13.
基于2016—2019年全国城市环境空气质量国控监测点位自动监测数据,分析了汾渭平原城市空气质量状况。结果表明:2019年,汾渭平原优良天数比例为61.7%,略高于"2+26"城市,明显低于全国及其他区域,空气污染较重。2016—2019年,汾渭平原超标天数中PM2.5、PM10、O3作为首要污染物的占比较高,PM2.5、PM10仍是影响汾渭平原空气质量的最主要污染物,O3和NO2的影响逐年升高。汾渭平原PM2.5浓度呈夏季低、秋冬季高的特点,2019年与2016—2018年PM2.5均值比较,1、2、4月分别偏高7.5%、36.7%、6.8%,其他月份均偏低,表明1、2、4月空气质量总体恶化,其他月份有所改善。汾渭平原O3浓度呈夏季高、秋冬季低的特点,O3浓度总体呈升高趋势,年平均升高10.3 μg/m3,临汾市年平均升幅最显著(26.7 μg/m3),不同百分位O3浓度均呈升高趋势,且高百分位浓度升幅明显高于低百分位浓度,年平均升幅最高出现在第90百分位浓度。2016—2019年,O3单项污染物超标导致优良天数比例损失分别为5.4个百分点、13.0个百分点、11.1个百分点和14.4个百分点,总体呈上升趋势,表明O3超标对空气质量影响越来越显著。煤炭消耗量、生铁产量、粗钢产量的大幅升高对空气质量有一定影响,建议加大对相关企业污染物的排放量检查,确保超低排放或采取可行的清洁能源替代。温度与O3浓度呈正相关,2017—2019年,温度大于25 ℃的天数中94.2%出现在6—8月,O3-8h超标天数占全部超标天数的81.4%,因此应加强温度较高月份的O3管控。  相似文献   
14.
环境卫星CCD影像在太湖湖泛暗色水团监测中的应用   总被引:1,自引:0,他引:1  
太湖地区2009年5月11日、2010年8月21日、2011年7月28日和2011年9月24日的环境卫星CCD影像显示,在太湖西部沿岸带、竺山湖等水域存在湖泛暗色水团现象。由于环境CCD缺少辅助反演气溶胶信息的2.1um波段,试验了基于空气自动监测子站获得的与环境卫星CCD成像时间接近的地面能见度测量数据进行FLAASH大气校正的方法,反演结果总体上符合水体光谱特征。提取了湖泛水体、对照水体阳区在CCD各波段的光谱反射率数据统计特征。结果表明,和对照水体相比,湖泛水体在环境卫星CCD的可见光—近红外波段具有较低的反射率,与人眼观察湖泛水色暗黑的感官一致,另一方面,湖泛水域由于仍有一定的藻类存在,在环境卫星CCD近红外(波段4 )具有比可见光(波段3)略高的反射率,其规律与基于Landsat ETM的湖泛暗色水团遥感分析结果相一致。  相似文献   
15.
没食子酸—H_2O_2—甲醛—Co(Ⅱ)化学发光体系测定钴   总被引:1,自引:0,他引:1  
本文用没食子酸—H_2O_2—甲醛—CO(Ⅱ)化学发光体系建立了痕量钴的化学发光测定法.方法检出限达0.5ng/ml 钴,线性范围是1×10~(-9)—8×10~(-7)g/ml 钴,测定的相对标准偏差小于1.0%,考察了24种常见离子的干扰情况.方法已用于水样中痕量钴的测定.  相似文献   
16.
The heart is often perceived as a difficult organ to understand by ultrasound during fetal life. This is undoubtedly reflected in the low detection rate of cardiac abnormalities as compared to those of most other organ systems in the fetus. In this article we start by updating classical concepts of cardiac embryology, many of which were previously difficult to understand since they were overly simplistic or purely observational. We then lead on to the structure and growth of the fully formed fetal heart where we review the anatomy and ultrasound appearances in detail and provide comparisons with major abnormalities. We emphasise the fact that a solid understanding of cardiac anatomy can enable those involved in fetal medicine to make full use of the views of the heart that are obtained by ultrasound and which are often only transient. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   
17.
Hypospadias is one of the most prominent and characteristic midline defects in male infants with the Wolf-Hirschhorn (4p —) syndrome. In this report we present a case in which hypospadias was identified prenatally at 29 weeks' gestation in association with intrauterine growth retardation. Cytogenetic evaluation after birth confirmed a 46, XY, del(4)(p14) karyotype. The prenatal identification of hypospadias in fetuses with intrauterine growth retardation and normal amniotic fluid should suggest a diagnosis of Wolf-Hirschhorn syndrome.  相似文献   
18.
We report the results of carrier and prenatal diagnosis for hypoxanthine guanine phosphoribosyltransferase (HPRT) deficiency, Lesch—Nyhan syndrome, by carrier testing of 83 women and prenatal analysis of 26 pregnancies. Our diagnostic methodologies include mutation detection and linkage analysis for probands and their families and biochemical measurement of HPRT enzyme activity for at-risk pregnancies. Identification of the mutation in the index case of each family permits precise carrier diagnosis using polymerase chain reaction (PCR) amplification of HPRT gene sequences and automated DNA sequencing. We demonstrate 100 per cent sensitivity for the detection of mutations in the HPRT gene of affected males and highly efficient carrier testing of at-risk females. Two other molecular methods proven to have high utility include PCR-based dosage analysis and linkage analysis by PCR amplification of a short tandem repeat (STR) in intron 3 of the HPRT gene. As a result, 45 at-risk women, 56 per cent of those tested, were identified not to be carriers of their family's HPRT gene mutation. Seven of these women were the mothers of affected males and prenatal testing for future pregnancies was recommended because of the possibility of gonadal mosaicism. Thirty-eight of these women were more distant relatives of affected males, thereby eliminating the need for future prenatal procedures. These studies illustrate the utility and precision of molecular methodologies for carrier and prenatal diagnosis of Lesch—Nyhan syndrome. These studies also illustrate that molecular diagnostic studies of affected males and carrier testing prior to pregnancy can clarify genetic risk predictions and eliminate unnecessary prenatal procedures.  相似文献   
19.
The autopsy findings of a fetus with deletion of the long arm of chromosome 8 are described. Many of the features are similar to those of the tricho-rhino-phalangeal syndromes, types I and II, which are associated with deletions on chromosome 8q24. Other findings in this case, such as total absence of the corpus callosum and intestinal malrotation, have not been described in these syndromes. Genes involved in the development of the latter malformations may reside in adjacent regions on the long arm of chromosome 8. An elevated serum level of beta human chorionic gonadotropin (βhCG) was found during pregnancy. This aberration should be included with other chromosomal disorders which may be detected by this test.  相似文献   
20.
X-linked agammaglobulinaemia is an inherited recessive disease in which the primary defect lies in the failure of pre-B cells to develop into mature circulating B cells, due to a defective B-cell cytoplasmic tyrosine kinase (btk). For this study we introduced a new RFLP marker, SP282, which is tightly linked to the XLA locus. In conjunction with the marker DXS178, SP282 was used to identify a carrier female and predict her male offspring to be normal. Subsequently the fetus was shown to have a normal number of circulating B cells, and at 2·5 years of age, the non-affected phenotype of the child was confirmed.  相似文献   
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