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71.
FENG JingLan WANG GuoLiang SUN JianHui SUN ShengPeng &LIU XiangFu Henan Key Laboratory for Environmental Pollution Control College of Chemistry Environmental Sciences Henan Normal University Xinxiang China State Key Laboratory of Pollution Control Resources Reuse College of Environmental Science Engineering Tongji University Shanghai China 《中国科学:化学》2010,(5)
The concentrations of Cd,Cr,Cu,Ni,Pb and Zn were determined in the water and surface sediments from the Henan reaches of the Yellow River.Twenty-three sampling sites along the Yellow River and its tributaries were selected.Generally,metal concentrations were found to decrease in sequences of Zn>Cu>Pb>Cr>Ni>Cd in water and Zn>Cr>Pb>Ni>Cu>Cd in sediments.High levels of metal concentration were determined at a few stations of the river and its tributaries,such as Yiluo River,Si River and Qin River.The pollutio... 相似文献
72.
Colombini MP Carmignani A Modugno F Frezzato F Olchini A Brecoulaki H Vassilopoulou V Karkanas P 《Talanta》2004,63(4):839-848
The materials used in the decoration of three painted astragaloi (knucklebones) from the Koroneia cave (Greece) were investigated by means of sequential application of non-destructive and destructive techniques: optical microscopy, environmental scanning electron microscopy coupled with X-ray microanalysis (ESEM-EDX), Fourier transform infrared spectroscopy (FTIR) with micro-attenuated total reflection (μ-ATR) technique, high performance liquid chromatography (HPLC) coupled with UV-fluorescence and gas chromatography-mass spectrometry (GC-MS) were used.The main results highlighted that the three astragaloi were prepared with a ground of ochre or iron clay and painted with a proteinaceous matter such as binder egg tempera. Both FTIR and GC-MS agree in the detection of lipids that can be related to egg. Organic dyestuffs identified as madder lake and shellfish purple were used together with inorganic pigments. 相似文献
73.
A. Rodionov R. Kalendarev J. Eiduss Yu. Zhukovskii 《Journal of Molecular Structure》1996,380(3):257-266
DTA studies were performed to investigate the polymerization of molecular (yellow) arsenic (y-As), in the dark and also under illumination/irradiation. The semiempirical quantum chemical CNDO/BW method for calculating the dimerization reaction pathway of two As4 molecules was applied, and showed that the stability of y-As decreases, due to the formation of stable fragments of the polymeric phase (a-As). Using the principle of orbital symmetry conservation, it was shown that polymerization takes place most favourably from a staggered “face-to-face” configuration of As4 molecules. Dark polymerization proceeds under activation. For a result of the initial stage of polymerization, CNDO/BW simulation predicts the formation of an As8 dimer. The molecular cluster As8 of D2h symmetry forms a six-membered chairshaped ring which constitutes one of the dominating units in the polymeric phase (a-As). 相似文献
74.
The following complex oxynitride perovskites have been prepared: LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2, and BaSc0.05Ta0.95O2.1N0.9. Synchrotron X-ray powder diffraction analyses show that LaMg1/3Ta2/3O2N and LaMg1/2Ta1/2O5/2N1/2 are isostructural to the oxide La2Mg(Mg1/3Ta2/3)O6 (space group P21/n), whereas BaSc0.05Ta0.95O2.1N0.9 has a simple cubic symmetry similarly to BaTaO2N. The orderings of octahedral cations are markedly diminished in the above oxynitrides, as compared with the related oxides such as La2Mg(Mg1/3Ta2/3)O6 and Ba2ScTaO6. The optical band gaps are similar for the homologous compositions, LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2 and LaTaON2 (1.9 eV), and BaSc0.05Ta0.95O2.1N0.9 and BaTaO2N (1.8 eV), while the absorption edges become broader for the complex derivatives. As revealed from the impedance spectroscopic analysis, the oxynitrides have clearly different dielectric components from those of comparable oxides containing Ta5+. Impedance spectroscopy reveals interesting capacitor geometry in BaSc0.05Ta0.95O2.1N0.9 in which the semiconducting oxynitride grains are separated by insulating secondary phases. Most notably BaSc0.05Ta0.95O2.1N0.9 has a bulk component with a high relative permittivity (κ=7300) and the grain boundary component with an even higher κ. 相似文献
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77.
黄河小浪底坝区泥化夹层分布及其抗剪试验方法的分析 总被引:1,自引:0,他引:1
在大量地质勘探试验研究资料的基础上 ,分析研究了形成泥化夹层的母岩和地质构造力 ,泥化夹层的类型及其粒度成分以及泥化夹层的分布规律。还分析研究了不同试验方法对泥化夹层抗剪强度的影响 ,并着重分析研究了我院研制的控制膨胀饱和固结慢剪的试验成果。 相似文献
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79.
为了评估鲁西南沿黄县区(东明县、牡丹区、鄄城县、郓城县)玉米中铅、镉、砷、铬重金属的污染风险,采集该地区玉米果穗,利用电感耦合等离子体质谱(ICP-MS)仪测定其玉米籽粒中铅、镉、砷、铬的含量,并使用单因子污染指数法、内梅罗综合多因子指数法和目标危险系数法开展玉米籽粒重金属污染评价和健康风险评价。结果表明,鲁西南沿黄县区玉米籽粒中重金属铅、镉、砷、铬的含量均未超出GB 2762—2017中规定的限量,重金属含量以Cr最高;鲁西南沿黄县区P综和TTHQ均小于1,说明玉米籽粒中的重金属元素含量为清洁安全等级,食用该地区玉米对人体的健康风险较低。 相似文献
80.
大孔树脂吸附和分离密蒙花黄色素 总被引:19,自引:0,他引:19
本文研究了用大孔树脂吸附和分离密蒙花黄色素,比较了四种树脂对密蒙花黄色素的吸附。选用经x—5作吸附剂,洗脱剂用60%乙醇,产品质量较传统法好,提取率达8%,x-5树脂非常稳定,使用15次后其吸附率仅降低4.95%。 相似文献