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排序方式: 共有343条查询结果,搜索用时 15 毫秒
61.
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Ercules E.S. Teotonio Hermi F. Brito Hans Viertler Wagner M. Faustino Oscar L. Malta Gilberto F. de S Maria Cludia F.C. Felinto Regina H.A. Santos Marco Cremona 《Polyhedron》2006,25(18):3488-3494
Europium complexes presenting general formulas [Eu(ACIND)3(H2O)2] and [Eu(ACIND)3(TPPO)2] have been synthesized and characterized. In these formulas ACIND is stands for the ligands 2-acetyl-1,3-indandionate (AIND), 2-isovaleryl-1,3-indandionate (ISOVIND) or 2-benzyl-1,3-indandionate (BIND). The [Eu(ISOVIND)3(H2O)(EtOH)] complex was also prepared and its structure determined by single crystal X-ray analysis, showing that this complex crystallize in a monoclinic space group P21/n with the water molecules bridging through the hydrogen bond. The Eu(III) ion is eight-coordinate in a bicapped trigonal prismatic geometry defined by the oxygen donor atoms with a site of symmetry close to C2ν. Isovaleryl groups in the ISOVIND molecules in the structure are disordered over two positions of the europium complex. Carbon atoms in ethanol molecule are disordered by the thermal vibration. Photoluminescence properties of these complexes in solid state were investigated both experimentally and theoretically, suggesting an efficient ligand-to-metal intramolecular energy transfer process. 相似文献
63.
Ivn Brito Aldo Mundaca Alejandro Crdenas Matías Lpez‐Rodríguez 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(10):o606-o608
In the title disulfide, C12H8N6O2S2, all bond lengths and angles are within normal ranges, and the molecules are linked into centrosymmetric R22(20) dimers by simple C—H...N interactions. Weak intermolecular C—H...π(arene) and π–π interactions, involving the benzene CH groups and the benzene rings, and the pyridine rings, respectively, further stabilize and reinforce the crystal structure. 相似文献
64.
J. -C. Diels J. J. Fontaine J. C. McMichael C. Y. Wang A. Andreoni R. Cubeddu S. Cova A. Longoni W. Knox G. Mourou T. M. Nordlund C. H. Brito Cruz F. De Martini P. Mataloni E. Palange J. M. Catherall P. M. Radmore G. H. C. New A. Müller F. P. Schäler Zs. Bor B. Rácz D. Relser A. Laubereau B. Pouligny J. R. Lalanne B. Couilaud A. Ducasse C. Vaucamps D. Schubert J. Schwarz H. Wabnitz B. Wilhelmi 《Applied physics. B, Lasers and optics》1982,28(2-3):172-179
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66.
The relativistic theory of elasticity is reviewed within the spherically symmetric context with a view towards the modeling
of star interiors possessing elastic properties such as the ones expected in neutron stars. Emphasis is placed on generality
in the main sections of the paper, and the results are then applied to specific examples. Along the way, a few general results
for spacetimes admitting isometries are reviewed, and their consequences are fully exploited in the case of spherical symmetry
relating them next to the the case in which the material content of the spacetime is some elastic material. Specific examples
are provided satisfying the dominant energy condition and admitting a constitutive equation, including a static two-layer
star ‘toy model’ consisting of an elastic core surrounded by a perfect fluid corresponding to the interior Schwarzschild solution
matched to the vacuum Schwarzschild solution. This paper extends and generalizes the pioneering work by Magli and Kijowski
(Gen Relat Gravit 24:139, 1992), Magli (Gen Relat Gravit 25:1277, 1993; 25:441, 1993), and complements, in a sense, that by
Karlovini and Samuelsson in their interesting series of papers (Karlovini and Samuelsson in Class Quantum Grav 20:363, 2003;
21:1559, 21:4531, 2004). 相似文献
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68.
Rodrigo Brito Santos Railmara Pereira da Silva Felipe Akihiro Melo Otsuka Danielle de Jesus Trindade Aline Costa Santos Humberto Reis Matos 《Biomedical chromatography : BMC》2019,33(4)
Hexokinases play a critical role in the cellular uptake and utilization of glucose. As such, they are of fundamental importance to all cells. By catalyzing glucose to produce glucose‐6‐phosphate, hexokinases control the first irreversible step of glucose metabolism and initiate all major pathways of glucose consumption. Our objective was to develop and validate highly sensitive and selective high‐performance liquid chromatography with photodiode array detector (HPLC‐PDA) assays allowing the determination of adenosine diphosphate, which was used for the determination of hexokinase activity. Samples were analyzed by HPLC‐PDA using a C18 analytical column (250 × 4.6 mm) for chromatographic separation. Optimal detection was achieved based on isocratic elution with a mobile phase consisting of a mixture of sodium phosphate monobasic buffer and methanol. This method met all of the requirements of specificity, sensitivity, linearity, precision, accuracy and stability generally accepted in bioanalytical chemistry and was successfully applied to a study of hexokinase activity in an alloxan‐induced diabetic rat model. Determination of hexokinase activity will permit characterization of cellular metabolic state in many diseases, such as cancer and diabetes. 相似文献
69.
Francisco Gabriel Santos Silva Raildo Alves Fiuza Junior Jefferson Santos da Silva Carlos Magno S. R. de Brito Heloysa Martins Carvalho Andrade Jardel Pereira Gonçalves 《Journal of Thermal Analysis and Calorimetry》2014,116(1):287-293
The pozzolanic properties of the equilibrium catalyst (Ecat), an abundant waste from fluid catalytic cracking units of oil refineries, have been studied in cementitious matrices. The consumption of calcium hydroxide is usually taken as a means to assess the pozzolanicity of a material, ignoring the formation of C–S–H and other hydrates, the main product of the pozzolanic reaction. The use of thermal analysis methods allows the identification and quantification of the products of the hydration reaction, based on the loss of chemically combined water of phases present in a cementitious matrix. In the present study, TG/DTG techniques were used to quantify the amount of C–S–H + ettringite, C–A–S–H + C–A–H, and calcium hydroxide in cement–Ecat pastes, containing 0–40 % Ecat, aged for 1–28 days. The influence of the content of these phases on the mechanical properties of the resulting samples was also investigated by axial compression. The results further confirmed the pozzolanic activity of Ecat, so that the production of C–S–H and C–A–S–H increased with the aging time, but in a smaller amount than in the reference paste. The compressive strength test showed that the pastes containing 10 % Ecat, aged for 14 and 28 days, presented improved properties as compared to the corresponding references. 相似文献
70.