排序方式: 共有19条查询结果,搜索用时 218 毫秒
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高碘甲状腺病:一个不容忽视的公共卫生问题 总被引:1,自引:0,他引:1
我国基本实现消除碘缺乏病阶段目标后,全民食盐加碘带来的负面影响已成为目前不容忽视的公共卫生问题。从临床病理资料统计、流行病学调查和全国监测数据分析3个方面论述了全民食盐加碘后出现高碘甲状腺病的证据及严重性。 相似文献
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烃基锡的膦(磷)酸衍生物具有较强的杀虫、杀菌及除草等生物活性,受到人们的极大关注[1,2],尤其是三烃基锡(IV)二硫代磷酸酯的合成及应用研究已有较多报道[3,4],但三烃基锡(IV)膦酸衍生物的合成研究很少[5],而三烃基锡(IV)不饱和烃基膦酸衍生物R3SnOP(O)(OH)R’(R’为炔基或烯基)的研究尚未见文献报道。我们以三苄基氯化锡和炔基(烯基)膦酸单钠为原料,合成了6种三苄基锡(IV)炔基(烯基)膦酸类化合物。并用元素分析、红外光谱、核磁共振、氢谱和锡谱、质谱及热重分析等手段表征了这些化合… 相似文献
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合成了四(邻氟苄基)锡(1)和一维链状三苄基锡二茂铁甲酸酯(2),经X射线衍射方法测定了化合物的晶体结构。化合物1属四方晶系,空间群I41/a,晶体学参数a=1.96794(16)nm,b=1.96794(16)nm,c=0.59316(5)nm,V=2.2972(3)nm3,Z=4,Dc=1.605g·cm-3,μ(MoKα)=11.58cm-1,F(000)=1112,R1=0.0208,wR2=0.0576。化合物2属单斜晶系,空间群为P21/n,晶体学参数:a=1.59354(12)nm,b=1.00723(8)nm,c=1.70026(13)nm,β=91.001(10)°,V=2.7286(4)nm3,Z=4,Dc=1.521g·cm-3,μ(MoKα)=14.74cm-1,F(000)=1256,R1=0.0384,wR2=0.0952。晶体的中心锡原子分别呈四配位畸变四面体构型和五配位畸变三角双锥构型。对其结构进行量子化学从头计算,探讨了配合物的稳定性、分子轨道能量以及部分前沿分子轨道的组成特征。测定了配合物的热稳定性和体外抗癌活性。 相似文献
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三苄基氯化锡与碘乙酸在苯溶剂中反应,合成了三苄基碘化锡。经X射线衍射方法测定了化合物的晶体结构。该晶体属三方晶系,空间群R3,晶体学参数a=1.6891(2)nm,b=1.6891(2)nm,c=0.60371(12)nm,γ=120°,Z=3,V=1.4917(4)nm3,Dc=1.733g.cm-3,μ(Mo Kα)=2.835 mm-1,F(000)=750,R1=0.072 2,wR2=0.171 2。中心锡与亚甲基碳和碘原子构成畸型四面体。对其结构进行量子化学从头计算,探讨了化合物的稳定性、分子轨道能量以及一些前沿分子轨道的组成特征。 相似文献
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Abstract Iodization of consumed salts is mandatory in many countries fighting against to iodine deficiency. In salts iodine stability is affected by storage conditions. In this study, stabilization of iodine in salt has been determined by using Isotope Dilution Analysis. Heating, heating with oxidizing agent, incubation by time were the parameters which have been determined. Iodine loss was 41.16% by heating at 200°C up to 24 hours. When the iodized salt heated with oxidized agent iodine loss rose up to 58.46% in 24 hours. Iodine loss mechanism seems similar in both cases. However iodine loss is greater in the presence of H2O2. After the salt was stored at room temperature with a relative humidity of 30%–45% and in sealed paper bags for three years, 58.5% of iodine content lost in approximately 3.5 years. 相似文献
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