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971.
Two coordination polymers, namely {[Co(L)(H2O)]·H2O}n(1) and [Mn(L)(phen)]n(2, H2L = 5-(pyridin-4-yl)isophthalic acid, phen = 1,10-phenanthroline), have been hydrothermally synthesized and characterized by elemental analysis, IR, TG, magnetic properties, and single-crystal X-ray diffraction. 1 belongs to the triclinic system, space group P1 with a = 7.2188(7), b = 10.0835(8), c = 10.2069(7) ?, α = 113.713(7), β = 99.490(7), γ = 104.516(8)o, V = 628.24(9) ?3, C13H11NCoO6, Mr = 336.16, Z = 2, Dc = 1.777 Mg/m3, μ(MoKα) = 1.395 mm–1, F(000) = 342, S = 1.041, the final R = 0.0381 and wR = 0.0819 for 3744 observed reflections(I 2σ(I)) and R = 0.0448 and wR = 0.0874 for all data. 2 belongs to the monoclinic system, space group P2/c with a = 12.9185(3), b = 10.4343(2), c = 31.7650(6)?, β = 101.282(2)o, V = 4199.08(13)?3, C50H30N6Mn2O8, Mr = 952.68, Z = 4, Dc = 1.507 Mg/m3, μ(MoKα) = 5.447 mm–1, F(000) = 1944, S = 1.128, the final R = 0.1003 and wR = 0.1052 for 8247 observed reflections(I 2σ(I)) and R = 0.2595 and wR = 0.2625 for all data. Single-crystal X-ray diffraction studies show that compound 1 features a 2D sheet structure based on a dicobalt(II) subunit, which is further extended into a 3D metal-organic supramolecular framework by O–H···O hydrogen bond. Compound 2 also possesses a 2D sheet, which is held together into a 3D supramolecular architecture via C–H···O hydrogen bond and π-π stacking interactions. Magnetic studies for compound 2 show antiferromagnetic coupling between the adjacent metal centers, with J = –11.8 cm–1 and g = 2.12 for 2. 相似文献
972.
973.
974.
975.
明胶空心胶囊样品经硝酸微波消解,采用石墨炉原子吸收光谱法测定其中铬的残留量。采用灰化温度为900℃,原子化温度为2 500℃。铬的质量浓度在2~30μg·L-1范围内与其吸光度呈线性关系,检出限(3s/k)为0.103mg·kg-1。应用此方法分析了明胶空心胶囊样品。用标准加入法进行回收试验,所得回收率在95.9%~102%之间,测定值的相对标准偏差(n=9)均小于2.0%。 相似文献
976.
Size controlled synthesis of ornithine‐based polypeptides by ring‐opening polymerization of α‐(amino acid)‐N‐carboxyanhydrides 下载免费PDF全文
977.
The COSY-TOF Collaboration F. Hauenstein E. Borodina H. Clement E. Doroshkevich R. Dzhygadlo K. Ehrhardt W. Eyrich W. Gast A. Gillitzer D. Grzonka S. Jowzaee P. Klaja L. Kober K. Kilian M. Krapp M. Mertens P. Moskal J. Ritman E. Roderburg M. Röder W. Schroeder T. Sefzick J. Smyrski P. Wintz P. Wüstner 《The European Physical Journal A - Hadrons and Nuclei》2016,52(11):337
978.
We explore two- and three-state Markov models driven out of thermal equilibrium by non-potential forces, to demonstrate basic properties of the steady heat capacity based on the concept of quasistatic excess heat. It is shown that large enough driving forces can make the steady heat capacity negative. For both the low- and high-temperature regimes we propose an approximative thermodynamic scheme in terms of “dynamically renormalized” effective energy levels. 相似文献
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980.
Ondřej Zvěřina Pavel Coufalík Josef Komárek Petr Gadas Jiřina Sysalová 《Chemical Papers》2014,68(2):197-202
An analysis of suspended particulate matter, with an emphasis on the Hg chemical forms, is presented. Dust samples originating from an area highly affected by traffic pollution in the city of Prague (Czech Republic) were sampled over a period of three years from air-conditioner filters and fractioned by size. The samples were morphologically characterised by scanning electron microscopy. The main method used for the analysis of constituent mercury compounds was sequential extraction by leaching solutions in combination with thermal desorption. The total mercury content ranged from 0.37 mg kg?1 to 0.82 mg kg?1. It emerged that the mercury was distributed in a wide spectrum of forms, and various trends in the distribution of these forms among the different size classes were observed. The fraction leached by nitric acid (consisting of elemental and complex-bound mercury) was the main constituent of total mercury. The highest content of this fraction was observed in the finest particle size class. The heterogeneity of morphology of the material increased with the size fraction. 相似文献