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31.
JEROME E. DOBSON 《Geographical review》1998,88(1):3-28
ABSTRACT. Iodine is essential for modern humans and may have been essential for Neandertals as well. Today about 30 percent of the world's population is at risk of iodine deficiency disorders (idd ), 750 million people suffer from goiter, 43 million have idd -related brain damage and mental retardation, and 5.7 million are afflicted by cretinism, the most severe form of idd . Distinctive Neandertal skeletal traits are identical to those of modern humans who suffer from cretinism. Cro-Magnon Venus figurines also exhibit distinctive traits associated with cretinism among modern humans. This new evidence, coupled with recent mitochondrial dna findings, suggests that a single genetic alteration, which improved the ability of the thyroid gland to extract and utilize iodine, may account for differences between Neandertals and modern humans. Late Pleistocene human evolution, consequently, may be explained by several alternative interpretations involving iodine pathology and/or biological adaptation. Speciation may have resulted from the geographical isolation of inland populations. 相似文献
32.
泡沫塑料吸附磺——四氯化碳萃取光度法间接测定矿石中的金 总被引:2,自引:0,他引:2
本文利用泡沫塑料吸附富集金,灰化塑料后,采用I2-CCl4萃取光度法测定矿石中的金,取得了较为满意的结果。 相似文献
33.
利用HNO3-KClO3饱和液溶解矿样后,加NH4Cl蒸干破坏氮的氧化物,用六偏磷酸钠作掩蔽剂,采用I2-CCl4萃取光度法测定矿石中的铜,取得了较为满意的结果。 相似文献
34.
Hongxia Yang Wei Liu Bing Li Huijuan Zhang Xiaoduan Liu Dengyun Chen 《Geostandards and Geoanalytical Research》2007,31(4):345-351
Methods based on high performance liquid chromatography coupled with inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) for iodine speciation analysis are described. Experiments were performed relating to iodine species, preservative medium and time. The concentration and pH of the buffer are also discussed in relation to separation efficiency. The developed methods allowed the fast and sensitive determination of iodine species with detection limits of 0.025 μg l−1 (as 1) for both iodide and iodate with < 5% relative standard deviation (RSD) for 50 nmol l−1 . Attempts were made to quantify total organo-iodine by size-exclusion chromatography (SEC). By way of example, a number of groundwater samples were analysed by these methods, revealing that iodide is the main iodine species in the sampled waters, but that high concentrations of organo-iodine compounds were observed in some samples as well. In summary, the total concentration and the dominant species of iodine in aquatic freshwater environments is easily and accurately measured using this new method. 相似文献
35.
电感耦合等离子体质谱法同时测定地质样品中锗碘 总被引:2,自引:8,他引:2
样品用NaOH全熔,热水提取,分取部分溶液通过强酸性阳离子交换树脂,分离溶液中大量的钠离子后,采用电感耦合等离子体质谱法同时测定锗和碘。方法的检出限Ge、I分别为0.043μg/g和0.22μg/g,经土壤国家一级标准物质分析验证,结果与标准值相符,12次测定的RSD均小于10%。 相似文献
36.
目的:探讨肘部固定夹板应用于CT增强患者中的临床实际价值。对象与方法:将预做CT增强检查的120例患者,随机分为对照组(60例)和观察组(60例)。对照组所有患者在进行CT增强检查前肘关节部位不使用肘部固定夹板;观察组所有患者在进行CT增强检查前肘关节部位使用肘部固定夹板,比较两组患者碘对比剂渗漏的发生率及护理服务满意度。结果:对照组60例患者中发生渗漏10例,发生率为16.7%,护理服务满意度80%。观察组60例患者中发生渗漏2例,发生率3.3%,护理服务满意度95%。观察组碘对比剂渗漏的发生率明显低于对照组,而护理服务满意度优于对照组,两组比较差异具有统计学意义(P0.05)。结论:肘部固定夹板应用于CT增强患者时,明显降低了碘对比剂渗漏发生率,并提升了护理服务满意度。患者很容易接受,值得临床推广应用。 相似文献
37.
The F,Cl, Br and I Contents of Reference Glasses BHVO‐2G,BIR‐1G,BCR‐2G,GSD‐1G,GSE‐1G,NIST SRM 610 and NIST SRM 612 下载免费PDF全文
Michael A. W. Marks Mark A. Kendrick G. Nelson Eby Thomas Zack Thomas Wenzel 《Geostandards and Geoanalytical Research》2017,41(1):107-122
Halogen contents for the widely distributed reference glasses BHVO‐2G, BIR‐1G, BCR‐2G, GSD‐1G, GSE‐1G, NIST SRM 610 and NIST SRM 612 were investigated by pyrohydrolysis combined with ion chromatography, total reflection X‐ray fluorescence analysis, instrumental neutron activation analysis, the noble gas method, electron probe microanalysis and laser ablation‐inductively coupled plasma‐mass spectrometry. Glasses BHVO‐2G, GSD‐1G and GSE‐1G have halogen contents that can be reproduced at the 15% level by all bulk techniques and cover a significant range in halogen mass fractions for F (~ 20–300 μg g?1), Cl (~ 70–1220 μg g?1) and Br (~ 0.2–285 μg g?1) and I (~ 9–3560 ng g?1). The BIR‐1G glass has low F (< 15 μg g?1), Cl (~ 20 μg g?1), Br (15 ng g?1) and I (3 ng g?1). The halogen contents for the silica‐rich NIST SRM 610 and 612 glasses were poorly reproduced by the different techniques. The relatively high Cl, Br and I abundances in glasses GSD‐1G and GSE‐1G mean that these glasses are well suited for calibrating spatially resolved micro‐analytical studies on silicate glasses, melt and fluid inclusions. Combined EPMA and laser ablation‐inductively coupled plasma‐mass spectrometry data for glass GSE‐1G demonstrate homogeneity at the 10% level for Cl and Br. 相似文献
38.
近40年土壤碘的油气勘查表明,土壤碘是战术性油气勘查的一个辅助指标,但是土壤碘的战略性油气勘查意义却未见报道。应用松辽盆地中部8.15万km2的多目标地球化学勘查数据,在研究土壤碘的近地表影响因素的基础上,试验了表层土壤碘(1个点/4 km2)和深层土壤碘(1个点/16 km2)的地球化学异常对油气的指示意义,首次发现了与油气有关的土壤碘的巨环状地球化学异常。研究表明,土壤碘的地球化学异常主要与大中型油气田和富生油凹陷相联系,1个点/16 km2的土壤采样密度可以较好地进行战略性油气勘查。松嫩平原土壤碘的影响因素主要有地貌景观、土壤类型、土壤pH值、人为耕作和河流等因素。 相似文献
39.
我国是世界上已知面积最大的水源性高碘国家,碘的长期过量摄入对居民健康产生极大威胁。在不同的环境水文地质条件下,高碘地下水成因模式可概括为:埋藏-溶解型、压密-释放型和蒸发-浓缩型。基于对高碘地下水成因机理的认识,我们利用大数据模型预测了全国高碘地下水赋存情况,发现其高风险区(p>0.5)约占国土面积的19.8%,且涵盖了全部已知的高碘地下水分布区。开展地下水系统中有机碘形态定量表征、碘的水文地球化学行为微观机理识别和迁移活化过程定量模拟研究,将深化对高碘地下水成因与分布规律的认识,为供水水质安全和预防水源性高碘甲肿提供重要的科学依据。 相似文献
40.