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排序方式: 共有93条查询结果,搜索用时 31 毫秒
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Luis C. Mendes Andrea D. Tedesco Mauro S. Miranda Marcia R. Benzi Beatriz S. Chagas 《Polymer Testing》2005,24(8):963-968
In this third work, we evaluated the degree of conversion (DC) versus depth of dental filling composite named Prodigy Condensable™ using infrared spectroscopy. Confirming previous results, there was a gradual reduction of DC with increasing depth but the composite exhibited extreme values of DC, an upper value (45.9%) on the surface and a lower one (6.1%) at a depth of 5 mm. The composite presented the worst performance among materials studied. The composite formulation was 80% of inorganic fillers and BisfenolA/dimethacrylate (BisGMA) (18%)/triethyleneglycoldimethacrylate (TEGDMA) (2.0%) as monomers. As stated before, type/ratio/viscosity of monomers and type, amount, size and size distribution of fillers all together had an important role in the cure reaction contributing to the final performance of the composite. 相似文献
3.
Alves GA Amato S Anjos JC Appel JA Astorga J Bracker SB Cremaldi LM Darling CL Dixon RL Errede D Fenker HC Gay C Green DR Halling AM Jedicke R Karchin PE Kwan S Leuking LH Mantsch PM de Mello Neto JR Metheny J Milburn RH de Miranda JM da Motta Filho H Napier A Passmore D Rafatian A dos Reis AC Ross WR Santoro AF Sheaff M Souza MH Spalding WJ Stoughton C Streetman ME Summers DJ Takach SF Wallace A Wu Z 《Physical review D: Particles and fields》1994,49(9):R4317-R4320
4.
Alves GA Amato S Anjos JC Appel JA Astorga J Bracker SB Cremaldi LM Dagenhart WD Darling CL Dixon RL Errede D Fenker HC Gay C Green DR Jedicke R Karchin PE Kennedy C Kwan S Lueking LH de Mello Neto JR Metheny J Milburn RH de Miranda JM da Motta Filho H Napier A Passmore D Rafatian A dos Reis AC Ross WR Santoro AF Sheaff M Souza MH Spalding WJ Stoughton C Streetman ME Summers DJ Takach SF Wallace A Wu Z 《Physical review letters》1996,77(12):2388-2391
5.
Alves GA Amato S Anjos JC Appel JA Bracker SB Cremaldi LM Darling CL Dixon RL Errede D Fenker HC Gay C Green DR Jedicke R Kaplan D Karchin PE Kwan S Leedom I Lueking LH Luste GJ Mantsch PM de Mello Neto JR Metheny J Milburn RH de Miranda JM da Motta Filho H Napier A Rafatian A dos Reis AC Reucroft S Ross WR Santoro AF Sheaff M Souza MH Spalding WJ Stoughton C Streetman ME Summers DJ Takach SF Wu Z 《Physical review letters》1993,70(6):722-725
6.
Tedesco E Della F Favaretto L Barbarella G Albesa-Jové D Pisignano D Gigli G Cingolani R Harris KD 《Journal of the American Chemical Society》2003,125(40):12277-12283
The "rigid-core" material 3,5-dimethyl-2,3'-bis(3-methylthiophene)-dithieno[3,2-b:',3'-d]thiophene-4,4-dioxide (DTTOMe4) has the highest photoluminescence ever reported for thiophene-based molecules in the solid state. We report the structure of this material, determined directly from powder X-ray diffraction data using the Genetic Algorithm method for structure solution, followed by Rietveld refinement, and the structural properties are discussed in relation to the structures of the corresponding subsystems DTTO and DTTOMe. While the crystal structures of the latter compounds contain cofacial dimers, the crystal structure of DTTOMe4 comprises layers of molecules aligned in an antiparallel fashion. Intermediate neglect of differential overlap with single configuration interaction (INDO/SCI) calculations on the intermolecular interactions in the three crystal structures show that the different solid-state photoluminescence efficiencies of DTTOMe4, DTTOMe, and DTTO cannot be correlated with the different types of dipole-dipole alignment in the solid state. Instead, photoluminescence efficiencies correlate well with the rate of formation of nonradiatively decaying charge-transfer pairs upon photoexcitation. Because of larger intermolecular distances in DTTOMe4, the photoluminescence is less effectively quenched by charge-transfer processes than in DTTOMe and DTTO. 相似文献
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8.
Gonçalves SA De Pauli SH Tedesco AC Quina FH Okano LT Bonilha JB 《Journal of colloid and interface science》2003,267(2):494-499
The counterion binding at a water/Aerosol-OT (AOT)/heptane microemulsion interface was treated in the context of the pseudo-phase ion exchange formalism. Two approaches were used to determine the selectivity coefficient for copper/sodium counterion binding at the AOT microemulsion interface: measurements of the Cu(II) concentration taken up by the reverse micelle in a Winsor II microemulsion system and steady-state emission quenching measurements of an anionic water-solubilized probe, the tris-(4,4'-dicarboxy-2,2'-bipyridine) ruthenium (II) ion. In addition, the selectivity coefficient for methyl viologen/sodium at the microemulsion surface was determined by the same photophysical technique. The value for copper (II)/sodium exchange (K(Cu/Na)) is 1.1+/-0.3 and that for methyl viologen/sodium (K(MV/Na)) is 0.9+/-0.3. The results show that the pseudo-phase ion exchange model can be used to obtain the selectivity coefficient in a microemulsion system. 相似文献
9.
Indoor radon concentrations have been measured with the α track etch integrated method in public buildings in the town of Pietramelara, north-western Campania, Southern Italy. In particular, our measurements were part of an environmental monitoring program originally aimed at assessing the range of seasonal fluctuations in indoor radon concentrations, at various floors of the studied buildings. However, subsequent analysis of the data and its comparison with the meteorological data recorded in the same period has shown an unexpected pattern at the different floors. In this report we present data suggesting that, besides the well-known medium and longterm periodicity, there could also be a differentiation in major meteorological controlling factors at the different floors of the buildings, a fact that does not appear to have been reported previously. While the lower floors proved to be markedly affected by rainfall, for the upper floors, instead, a different behaviour has been detected, which could possibly be related to global solar radiation. 相似文献
10.
Ocular toxoplasmosis signs in mice embryo 总被引:1,自引:1,他引:0
Ocular toxoplasmosis is present in 20% of infected immunocompetent individuals. Toxoplasmosis is the most common cause of posterior uveitis in immunocompetent subjects and congenital toxoplasmosis transmission was the first parasite to be linked to human lesions in the eye. An experimental model for congenital ocular toxoplasmosis was developed in C57BL/6 mice with the purpose to evaluate Toxoplasma induced ocular pathology during fetal life. Toxoplasma gondii, ME-49 strain, was used to infect pregnant females. Histological analysis of pre-natal fetal eyes from infected female mice, did not show parasite infestation, however, alterations were observed in the outer nuclear layer (ONL) and in the inner nuclear layers (INL) of the retina. Edema was also observed, characterized by the increase of interstitial spaces forming lacunae between the ONL and INL cells and a net of vessels associated with an intense inflammatory infiltrate. These histological observations suggest that ocular lesions are not delayed manifestations of toxoplasmosis. The eye was affected in the initial phase of disease, and these alterations were of similar nature as those observed in mice at later stages of infection. 相似文献