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81.
Synthesis and structure of 4-phenoxy-H[1λ4,2,4,6]thiatriazino[4,3a]benzimidazole-2-oxide 5, 3-amino-4H[1λ4,2,4,6]thiatriazino[2,3-a]benzimidazole-1-oxide 6 and 3-amino-5-dimethylamino-2-tosyl-1λ4, 2,4,6-thiatriazine-1-oxide 7, obtained by hydrolysis of the corresponding arenesulfonyl imino compounds are discussed. The molecular and crystal structure of N-benzoyl-? tosyl-guanidine is presented. 相似文献
82.
The refractive index of SiO2-P2O5 glass prepared by a modified chemical vapor deposition method is measured using an interference microscope. It is found that the refractive index in bulk form increases linearly at 9.5×10-4 (mol.%)-1 as the P2O5 concentration increases. It is also found that quenching at extremely high speed reduces the refractive index over 2 mol.% P2O5. The wavelength dispersion of the refractive index dn/dλ is constant up to 5 mol.% P2O5 producing a refractive index difference of 5×10-3 compared with fused silica. Consequently, this glass materials is thought to be suitable for wide band-width optical fiber applications. 相似文献
83.
84.
Kukovecz A Hodos M Horváth E Radnóczi G Kónya Z Kiricsi I 《The journal of physical chemistry. B》2005,109(38):17781-17783
We discuss the formation mechanism of titania nanotubes synthesized by the hydrothermal method. On the basis of a comprehensive analysis of TEM, HRTEM, FT-Raman, and N(2) adsorption data, we point out some major shortcomings of the currently accepted trititanate sheet rollup mechanism. We suggest that a novel formation mechanism, oriented nanotube crystal growth from nanoloop seeds, can explain the experimental findings better than the ones proposed so far. 相似文献
85.
Budai M Reynaud-Angelin A Szabó Z Tóth S Rontó G Sage E Gróf P 《Journal of photochemistry and photobiology. B, Biology》2004,77(1-3):27-38
The ultraviolet A (UVA) radiation component of sunlight (320-400 nm) has been shown to be a source of oxidative stress to cells via generation of reactive oxygen species. We report here some consequences of the UVA irradiation on cell membranes detected by electron paramagnetic resonance (EPR) spectroscopy. Paramagnetic nitroxide derivatives of stearic acid bearing the monitoring group at different depths in the hydrocarbon chain were incorporated into human fibroblasts membranes to analyze two main characteristics: kinetics of the nitroxide reduction and membrane fluidity. These two characteristics were compared for control and UVA-irradiated (0-250 kJ/m(2)) cells. The term relative redox capacity (RRC) was introduced to characterize and to compare free radical reduction measured by EPR with some well-known viability/clonogenicity tests. Our results showed that UVA-irradiation produces a more rigid membrane structure, especially at higher doses. Furthermore, we found that trends agree in survival measured by neutral red (NR), trypan blue (TB), and clonogenic efficiency compared with RRC values measured by EPR for low and medium exposure doses. Above 100 kJ/m(2), differences between these tests were observed. Antioxidant effect was modeled by alpha-tocopherol-acetate treatment of the cells before UVA irradiation. While NR, TB and clonogenicity tests showed protection at the highest UVA doses (>100 kJ/m(2)), results obtained with EPR measurements, both membrane fluidity and kinetics, or using MTT test did not exhibit this protective effect. 相似文献
86.
Gyürky Gy. Fülöp Zs. Somorjai E. Kiss G. Rolfs C. 《The European Physical Journal A - Hadrons and Nuclei》2004,20(2):355-358
The absolute strengths of the
keV resonance in the
reaction and of the
keV resonance in the
reaction have been measured to
meV and
meV, respectively, in good agreement with previous values. These resonances can be used to measure the absolute acceptance of the recoil separator ERNA to a precision of about 10%.Received: 12 December 2003, Revised: 10 February 2004, Published online: 3 August 2004PACS:
24.30.-v Resonance reactions - 25.40.Lw Radiative capture - 26.20. + f Hydrostatic stellar nucleosynthesis 相似文献
87.
A shear cell was constructed in two variants for simultaneous small-angle X-ray scattering and freeze fracture. Using this cell, the changes in the layer structure and the domain formation of the Synperonic A7-water system were investigated under shear. The reconstructions of both the layer and domain structures were not observed in the steady state after 1 h (following a 2 h long shear period). Destruction of the lamellar arrangement and formation of aggregates occurred during the stress. It was concluded that the tixotropic behavior originates rather from the change of the domain structure with a typical size range of microm than from the changes of the inner structure of domains with lamellar arrangement. 相似文献
88.
Tibor Novák Péter Bakó György Keglevich András Dobó Károly Vékey László Tóke 《Journal of inclusion phenomena and macrocyclic chemistry》2001,40(3):207-212
Five chiral -D-glucose-based monoaza-15-crown-5 ethers with phosphinoxidoalkyl side chains of one to five carbon atoms (5a–e)have been synthesised. The cation binding ability of the new lariat ethers was evaluated bythe picrate extraction method. The substituents at the nitrogen atom were not a major influenceon the cation extraction ability of the azacrown ether; the compounds showed, however, a significant asymmetric induction as phase transfer catalysts in the Michael addition of2-nitropropane to chalcone (95% ee). 相似文献
89.
Development of chemically modified glass surfaces for nucleic acid,protein and small molecule microarrays 总被引:1,自引:0,他引:1
Microarrays have become a widely used tool to investigate the living cell at different levels. DNA microarrays enable the expression analysis of thousand of genes simultaneously, while protein arrays investigate the properties and interactions of proteins with other proteins and with non-proteinaceous molecules. One crucial step in producing such microarrays is the permanent immobilization of samples on a solid surface. Our goal was to develop diverse linker systems capable of anchoring different biological samples, especially DNA and drug-like small molecules. We developed 6 different chemical surfaces having a 3-D-like linker system for biomolecule immobilization, and compared them to previously described immobilization strategies. The attachment chemistry utilizes the amino reactive properties of acrylic and epoxy functions. The capacity of the support was increased by creating a branching structure holding the reactive functions. The method of anchoring was investigated through a model reaction. From HPLC and mass spectrometry measurements we concluded that the covalent binding of DNA occurs through nucleobases. The tested systems offer the capability to permanently immobilize several biomolecular species in an array format. 相似文献
90.
JPC – Journal of Planar Chromatography – Modern TLC - Fumonisins were produced by six strains of Fusarium moniliforme and Fusarium proliferatum on inoculated rice culture. For study of... 相似文献