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151.
152.
First-principles study of structural stability and elastic property of pre-perovskite PbTiO3 下载免费PDF全文
The structural stability and the elastic properties of a novel structure of lead titanate,which is named preperovskite PbTiO3 (PP-PTO) and is constructed with TiO6 octahedral columns arranged in a one-dimensional manner,are investigated by using first-principles calculations.PP-PTO is energetically unstable compared with conventional perovskite phases,however it is mechanically stable.The equilibrium transition pressures for changing from preperovskite to cubic and tetragonal phases are 0.5 GPa and 1.4 GPa,respectively,with first-order characteristics.Further,the differences in elastic properties between pre-perovskite and conventional perovskite phases are discussed for the covalent bonding network,which shows a highly anisotropic character in PP-PTO.This study provides a crucial insight into the structural stabilities of PP-PTO and conventional perovskite. 相似文献
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154.
Kuo Hsiung Lee 《中国化学快报》2012,23(5):583-586
Two novel styryllactones,goniodilactone(1) and gonioheptenolactone(2),were isolated from the leaves of Goniothalamus cheliensis Hu.Their structures were determined on the basis of spectroscopic data as well as X-ray crystallography analysis. Compounds 1 and 2 exhibited significant cytotoxicities in a panel of human cancer cells,including DU-145,PC-3,MCF-7,A-549, KB and KBvin,with GI50S in the range of 1.29-4.56μg/mL. 相似文献
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A comparative study has been carried out between experimentally and naturally weathered pyrites. Both were found to share similar species of weathering products and a similar weathering mechanism. The weathering products could be divided into sulphur-bearing or iron-bearing groups. The sulphur-bearing group was comprised of sulphate, sulphite, thiosulphate, elemental sulphur, polysulphide, and mono-sulphide. The iron-bearing group was comprised of goethite, hematite or magnetite, and iron sulphate. The weathering structural profile was also similar for both types of weathering, being composed of a surficial layer and a transitional layer. The surficial layer was made up of both the sulphur-bearing and the iron-bearing products, while the transitional layer was comprised of goethite, and hematite or magnetite. The inward migration of the weathering interface was stimulated by the diffusion of oxygen and moisture. The oxygen was considered to preferably squeeze the iron to form goethite, and the ferric ions of goethite to have acted as a bridge for electron transfer between the oxygen and bulk S22− and Fe2+ of pyrite. 相似文献
157.
Ying Chen Ping Xiang Gang Li Hui-Lan Chen Kandasamy Chinnakali Hoong-Kun Fun 《Supramolecular chemistry》2013,25(4):339-346
The crystal and molecular structures of alkylcobaloxime/ g -cyclodextrin ( g -CD) inclusion complexes: butyl(aqua)cobaloxime/ g -CD ( 1 ). hexyl(aqua)cobaloxime/ g -CD ( 2 ) and cyclohexyl(aqua)cobaloxime/ g -CD ( 3 ) were determined by X-ray diffraction analyses. Crystal data for 1 14H 2 O: P 2 1 2 1 2 1 , a =15.1335(3), b =18.9630(2), c =28.1545(5) Å, Z =4; 2 12H 2 O: P 2 1 2 1 2 1 , a =15.1135(4), b =19.1477(5), c =28.2715(7) Å, Z =4; 3 10H 2 O: P 2 1 2 1 2 1 , a =15.6898(2), b =16.9094(2), c =28.9762(2) Å, Z =4. The structural and conformational comparisons for the three g -CD inclusion complexes with their guest molecules as well as other CD inclusion analogs are discussed. 相似文献
158.
Li-Na Xiang Li-Juan Chen Lin Tan Chong Zhang Fu-Hu Cao Song-Tao Liu Yan-Mei Wang 《中国化学快报》2013,24(7):597-600
A novel polydopamine-graft-poly(2-methyl-2-oxazoline)(PDA-g-PMOXA) coating was prepared by immobilizing poly(2-methyl-2-oxazoline)(PMOXA) onto material surfaces through polydopamine (PDA) anchored coating for the first time.And then,the chemical composition,hydrophilicity,and protein-resistant properties of the PDA-g-PMOXA coating were studied using X-ray photoelectron spectroscopy(XPS),contact angel(CA) test,surface plasmon resonance(SPR),and quartz crystal microbalance with dissipation(QCM-D) measurement.Finally,the coating was applied to the capillary inner surface for protein separation by capillary electrophoresis(CE). 相似文献
159.
以乙二醇、乙醇为溶剂通过溶剂热法制备出立方状ITO纳米粉体,研究了反应时间、NaOH浓度对ITO纳米粉体形貌的影响,并讨论了溶剂体积比、NaOH浓度对ITO粉体导电性的影响及机理。结果表明:采用乙二醇与乙醇做溶剂,VEG:VEtOH=4:1时,制备出分散性良好的立方状ITO纳米粉体,平均粒径为10.7 nm,且其XRD衍射峰强度比I400/I222最高为0.380;乙二醇与乙醇做溶剂,VEG:VEtOH=4:1,且NaOH浓度为0.275 mol·L-1时,粉体电导率最高为46.75 mS·cm-1。 相似文献
160.
Kundawlet Alimaje Xiang Wang Zhe-Yu Zhang Jun Peng Zhen-Yu Shi Xia Yu Zi-Xing Ren 《Journal of Cluster Science》2013,24(4):1021-1030
Two bisupporting Keggin-type polyoxoanion-based hybrids decorated by [Zn(phen)2]2+ complexes, [Zn(phen)2]2(PW 11 VI WVO40) (1) and K[Zn(phen)2(H2O)]2(OH) (SiW12O40)·H2O (2) (phen = 1,10′-phenanthroline), have been hydrothermally synthesized, and characterized by elemental analysis, IR spectra, UV–Vis spectrum, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis, and single-crystal X-ray diffraction. The structural analyses reveal that compound 1 consists of a 0D bisupporting Keggin-type heteropoly blue cluster obtained by using reductant glucose, which is grafted by two [Zn(phen)2]2+ fragments; compound 2 presents a 1D infinite chain, which is constructed from bisupporting [SiW12O40]4? polyoxoanions decorated by [Zn(phen)2(H2O)]2+ fragments and K+ ions. Additionally, the electrochemical behaviors of two compounds were studied. 相似文献