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N-亚硝基化合物与癌 总被引:2,自引:0,他引:2
人类癌症约有60~90%是受环境影响而产生,其中90%又与化学物质有关,因此化学致癌物是环境中主要致癌因子。N-亚硝基化合物是化学致癌物中比较普通和重要的一种,它经前体物硝酸盐、亚硝酸盐和胺,并通过食物和水在体内合成。常食新鲜蔬菜和水果,少食腌熏食品和含有硝酸盐和亚硝酸盐的肉制品,限制硝酸盐和亚硝盐的摄入量,对预防肿瘤的发生极为重要。 相似文献
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测定N—亚硝基化合物的分光光度法 总被引:2,自引:0,他引:2
利用N-亚硝基化合物的化学去亚硝基反应,建立了一种间接测定N-亚硝基化合物的分光光度法。实验结果表明,N-二苯基亚硝胺在0.2 ̄9.0mg/L浓度内呈线性关系。该法应用于香烟烟丝及侧流烟雾萃取液的分析,4次测定RSD及回收率分别为1.86% ̄6.32%,86.2% ̄96.6%;3.01% ̄5.03%,101.1% ̄109.1%。 相似文献
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质子交换膜燃料电池(PEMFC)因能量转化率高、 污染小、 工作温度低、 启动速度快而被广泛应用. Nafion系列膜成本高、 结构特性模糊, 阻碍了质子传导性能的进一步提高和对传导机理的精确理解. 因此开发具有结构明确、 传导路径清晰的高质子传导率的晶态材料对于燃料电池领域具有重要意义. 本文利用有机配体5-羟基间苯二甲酸作为模板诱导[Mo2S2O2]2+阳离子, 自组装成一种多核多氧硫钼酸盐簇[N(CH3)4]2H2· [(Mo2S2O2)8(OH)16(C8O5H4)2]·22H2O(Mo16). 该化合物清晰明确的结构和结构中存在的密集氢键网络可用于进行质子传导性能的研究. 交流阻抗测试结果表明, Mo16在宽温度范围内具有较高的质子传导性能. 在97%湿度(RH), 85 ℃条件下其质子传导率可达1.9×10-2 S/cm, 表明该化合物具有作为高效质子导体的良好前景. 相似文献
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本文在测定了五个新颖双核钼(Ⅴ)簇合物的晶体结构(QH)_4[Mo_2O_4(NCS)_6](1),H(PyH)_3·[Mo_2O_4(C_2O_4)_2(H_2O)_2]_2·2H_2O(2),(QH)_3[Mo_2O_4(C_4H_3OCOO)(NCS)_4](3),(QH)_3[Mo_2O_4·(CH_3OH)(NCS)_5](4)和(PyH)_4[Mo_2O_3(SO_4)(NCS)_6](5)以及文献报道该类型化合物结构数据的基础上,综述了含氧桥双核钼(Ⅴ)簇合物的结构特征,并应用SCC-EHMO方法探讨了该类型化合物的电子结构和成簇机理,最后用简正坐标分析法,研究了含氧桥双核钼(Ⅴ)化合物簇胳单元[Mo_2O_4]~(2 )和[Mo_2O_3SO_4]~(2 )的振动结构及其红外谱带归属。 相似文献
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本文在测定了五个新颖双核钼(V)簇合物的晶体结构(QH)4[Mo2O4(NCS)6](1),H(PyH)3.[Mo2O4(C2O4)2(H2O)2]2.2H2O(2), (QH)3[Mo2O4(C4H3OCOO)(NCS)4](3),(QH)3[Mo2O4.(CH2OH)(NCS)5](4)和(PyH)4[Mo2O3(SO4)(NCS)6](5)以及文献报道该类型化合物结构数据的基础上, 综述了含氧桥双核钼(V)簇合物的结构特征, 并应用SCC-EHMO方法探讨了该类型化合物的电子结构和成簇机理, 最后用简征坐标分析法, 研究了含氧桥双核钼(V)化合物簇胳单元[Mo2O4]^2^+和[Mo2O3SO4]^2^+的振动结构及其红外谱带归属。 相似文献
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StructuralFeaturesandInterrelationofTwoNewTrinuclearMo-SClusterCompoundsLuShao-Fang;WuQiang-Jin;ChenHong-Bing;YuRong-Min;Huan... 相似文献
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本文用含硅氢键化合物与含双键的氟化合物的加成反应,制备了一系列未见报导的含氟有机硅化合物。在用氯丙烯与2,2,3,3-四氟丙醇制2,2,3,3-四氟丙基烯丙醚时,对方法进行了改进,提高了产率。本文还报道了含氟有机硅聚合物方面的工作。 相似文献
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A new molecular structural characterization(MSC)method called molecular vertexes correlative index(MVCI)was constructed in this paper.The index was used to describe the structures of 45 compounds and a quantitative structure-activity relationship(QSAR)model of toxicity(–lgEC50)was obtained through multiple linear regression(MLR)and stepwise multiple regression(SMR).The correlation coefficient(R)of the model was 0.912,and the standard deviation(SD)of the model was 0.525.The estimation stability and prediction ability of the model were strictly analyzed by both internal and external validations.The Leave-One-Out(LOO)Cross-Validation(CV)correlation coefficient(RCV)was 0.816 and the standard deviation(SDCV)was 0.739,respectively.For the external validation,the correlation coefficient(Rtest)was 0.905 and the standard deviation(SDtest)was 0.520,respectively.The results showed that the index was superior in molecular structural representation.The stability and predictability of the model were good. 相似文献
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A series of fused and spiro pyrazolones, isoxazolines, pyrimidines, β‐lactams, and thiazolidinones incorporating 4‐amino‐2‐methyl‐5,10‐dioxo‐1,5,10,11‐tetrahydrobenz[g]quinoline 3‐carbonitrile 1 and 4‐amino‐2‐methyl‐5,6,11‐trioxo‐1,4,4a,5,6,11,12,12a‐octahydro‐1,12‐diazanaphthacene 3‐carbonitrile 2. 7,8a‐c, 15,16a‐c, 19,20a‐d, 21,22a‐d , have been synthesised by cyclocondensation addition reaction and cycloaddition reaction of hydrazines, hydroxylamine, urea, thiourea, monochloroacetyl chloride and mercaptoacetic acid with the synthesised 15,16a‐c and 17,18a‐c . 相似文献
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Matthias Glätzle Dr. Almut Pitscheider Prof. Dr. Oliver Oeckler Prof. Dr. Klaus Wurst Prof. Dr. Hubert Huppertz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(7):1767-1772
Pr5(BO4)3−x(BO3)x(F,OH)2.67O0.28 (x≈1.6), a boron-containing fluoride-oxoapatite-like compound, was obtained by the application of high-pressure/high-temperature synthesis. It exhibits a superstructure of the apatite type with a tripled c lattice parameter (space group P63/m) and shows complex anion disorder along the 63 screw axis and occupation of distorted octahedra, as well as almost trigonal planar sites, by oxygen and fluorine atoms. Furthermore, a distinct BO4/(BO3+F) group disorder is found; 46 % of the sites being occupied by BO4 groups and 54 % by BO3 groups, with a fluoride ion located near the missing oxygen atom. The rare earth cations in the 4f sites exhibit a specific distorted tricapped trigonal prismatic coordination with a mean metaprism twist angle of 21.3°. The crystal structure of Pr5(BO4)3−x(BO3)x(F,OH)2.67O0.28 (x≈1.6) shows much “flexibility” resulting in split and off-site positions of all other rare earth cations. The title compound therefore combines many structural features of apatite-like compounds, for example biologically highly-important carbonated apatites, shedding more light onto the complex structural chemistry of apatites. 相似文献
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A pure sample of nitrosyl chloride has been prepared either by reaction of phosphorus trichloride with concentrated nitric acid or by reaction of phosphorus trichloride with sodium nitrate in presence of water. The nitrosyl chloride gas has been characterized by i.r. spectral data and elemental analysis. 相似文献
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A. Aliev D. Endara M. Huve M. Colmont P. Roussel L. Delevoye T. T. Tran P. S. Halasyamani O. Mentre 《ChemInform》2014,45(13):no-no
Single crystals of [Bi2(Bi1.56K0.44)O3] K0.88(PO4)2 (I), [Bi10 (Bi0.5Cd0.5)8O16] (Bi0.6Cd0.8)2(PO4)8 (II), and [Bi18Zn10O21] Zn5(PO4)14 (III) are prepared by melting K2CO3 (or CdO or ZnO), Bi2O3, and (NH4)2HPO4 in a 1:1:2 molar ratio (open Au tube, 900—950 °C, 10 h). 相似文献
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El-Hag F. A. A. Abdel-Hafez N. A. Abbas E. M. H. El-Manawaty M. A. El-Rashedy A. A. 《Russian Journal of General Chemistry》2019,89(1):128-137
Russian Journal of General Chemistry - Reaction of thiopyrimidine derivative 3 with hydrozonoyl chlorides 4a–4e gives new fused heterocyclic compounds 7a–7e containing triazole ring.... 相似文献
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Masaaki Yoshifuji Shigeru Sasaki Daisuke Shiomi Takashi Niitsu Naoki Inamoto 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):325-328
Abstract Sterically stabilized diphosphenes and 1,3-diphosphaallenes by 2, 4 - tri- t - butylphenyl or 2,4,6-tri-t- pentylphenyl groups were prepared. 相似文献