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排序方式: 共有626条查询结果,搜索用时 15 毫秒
171.
Ana Luiza Ribeiro de Souza Tatiana Andreani Fernando M. Nunes Douglas Lopes Cassimiro Adélia Emília de Almeida Clóvis Augusto Ribeiro Victor Hugo Vitorino Sarmento Maria Palmira Daflon Gremião Amélia M. Silva Eliana B. Souto 《Journal of Thermal Analysis and Calorimetry》2012,108(1):353-360
Praziquantel (PZQ) is the drug of choice for oral treatment of schistosomiasis and other fluke infections that affect humans.
Its low oral bioavailability demands the development of innovative strategies to overcome the first pass metabolism. In this
article, solid lipid nanoparticles loaded with PZQ (PZQ-SLN) were prepared by a modified oil-in-water microemulsion method
selecting stearic acid as lipid phase after solubility screening studies. The mean particle size (Z-Ave) and zeta potential
(ZP) were 500 nm and −34.0 mV, respectively. Morphology and shape of PZQ-SLN were analysed by scanning electron microscopy
revealing the presence of spherical particles with smooth surface. Differential scanning calorimetry suggested that SLN comprised
a less ordered arrangement of crystals and the drug was molecularly dispersed in the lipid matrix. No supercooled melts were
detected. The entrapment efficiency (EE) and loading capacity of PZQ, determined by high performance liquid chromatography,
were 99.06 ± 0.3 and 17.48 ± 0.05, respectively. Effective incorporation of PZQ into the particles was confirmed by small
angle X-ray scattering revealing the presence of a lipid lamellar structure. Stability parameters of PZQ-SLN stored at room
temperature (25 °C) and at 4 °C were checked by analysing Z-Ave, ZP and the EE for a period of 60 days. Results showed a relatively
long-term physical stability after storage at 4 °C, without drug expulsion. 相似文献
172.
173.
In this work, we study the transmission characteristics of a two-channels coupler model system using the Boundary Wall Method (BWM) to determine the solution of the corresponding scattering problem of an incident plane wave. We show that the BWM provides detailed information regarding the transmission resonances. In particular, we focus on the case of single channel input aiming to explore the energy switching performance of the coupler. We show that the coupler geometry can be tailored to allow for the first transmission resonances to be predominantly transmitted on specific output channels, an important characteristic for the realization of logical operations. 相似文献
174.
Michael R. Nunes Yoshitaka Gushikem Richard Landers Jairton Dupont Tania M. H. Costa Edilson V. Benvenutti 《Journal of Sol-Gel Science and Technology》2012,63(2):258-265
The water soluble charged silsesquioxane that contains the bridged 1,4-diazoniabicyclo[2.2.2]octane chloride group, was used as stabilizing agent and size controller in the synthesis of gold nanoparticles smaller than 15?nm in aqueous medium. The gold nanoparticle dispersion was converted in solid powder form by evaporation. This powder presented organized structure imposed by the presence of charged organic group, similar to organized structure already observed for pure silsesquioxane. The gold nanoparticles in solid powder form presented high storage stability for several months, at ambient conditions, and can be completely redispersed in water again. After redispersion, the optical properties of gold nanoparticles, observed by ultra-violet and visible spectroscopy, and their morphological characteristics, investigated by transmission electron microscopy, are preserved. The gold nanoparticle aqueous dispersion was used as a vehicle of nanoparticles in the synthesis of sol?Cgel silica based hybrid material. This xerogel was characterized by N2 adsorption?Cdesorption isotherms, showing 260?m2g?1, and it was applied in a satisfactory way as catalyst for p-nitrophenol reduction to p-aminephenol. 相似文献
175.
176.
Synthesis,characterization and assessment of the cytotoxic activity of Cu(II), Fe(III) and Mn(III) complexes of camphoric acid‐derived salen ligands
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Dina Murtinho Zênis N. da Rocha Ana Salomé Pires Roberto P. Jiménez Ana Margarida Abrantes Mafalda Laranjo Ana Catarina Mamede João Eduardo Casalta‐Lopes Maria Filomena Botelho Alberto A. C. C. Pais Sandra C. C. Nunes Hugh D. Burrows Telma Costa M. Elisa Silva Serra 《应用有机金属化学》2015,29(7):425-432
Novel Cu(II), Fe(III) and Mn(III) salen‐type metal complexes from (1R,3S)‐N,N′‐bis[salicylidene]‐1,3‐diamino‐1,2,2‐trimethylcyclopentane were synthesized and screened for their in vitro cytotoxic activity against three human cancer cell lines: melanoma, colorectal and breast. In vitro experiments carried out with the three metal complexes show that the copper complex exhibits the highest cytotoxic activity towards all cell lines studied, presenting IC50 values of 3.32–6.71 μM. A significant improvement in the anti‐proliferative effect, by 20‐fold, is observed with this complex when compared with conventional chemotherapy. The relationship between structure, redox characteristics and biological activity in human cancer cell lines was evaluated for the most efficient Cu(II) complex and associated with theoretical calculations. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
177.
178.
The objective of this paper is to improve the predictivity of squeal simulations by introducing uncertainty and robustness concepts during simulations. Complex eigenvalue analysis is a traditional way to detect numerically the unstable modes that can be associated with extensive vibration and noise pollution. This simulation, for which associated computational times are compatible with the design phase, is known to be insufficiently predictive. We first propose a complete strategy that relies on the integration of random fields into the contact interface, complex eigenvalue calculations, probabilistic analysis and a robustness criterion. Next, this strategy is applied to study the instabilities of a complete industrial brake system. Experimental comparisons highlight the efficiency of the improved squeal detection methodology. 相似文献
179.
Terezinha Nunes Peter Bryant Deborah Evans Laura Gottardis Maria-Emmanouela Terlektsi 《ZDM》2014,46(3):437-448
According to our analysis of cognitive demands, the concepts of classification, logical multiplication and ratio provide a basis for understanding sample space. These basic concepts develop during the elementary school years, which suggest that it is possible to teach elementary school children effectively about sample space. This hypothesis was tested in an intervention study, in which Grade 6 children (aged 10–11 years) were randomly assigned to one of three groups: a sample space group (SSG), a problem-solving group, and an unseen comparison group. The SSG showed significantly more progress than both comparison groups in three post-tests, including one given 2 months after the teaching had ended. We conclude that our analysis of the cognitive demands of sample space was supported and discuss the implications for mathematics education. 相似文献
180.
C. C. Silveira C. S. Botega C. R. B. Rhoden M. R. S. Nunes A. L. Braga E. J. Lenardão 《合成通讯》2013,43(18):3371-3380
Ethyl α-bromo-α-phenylseleno acetate 1 and ethyl α-bromo-α-phenylthio acetate 2 react with aldehydes in the presence of dibutyltelluride to give α-phenylchalcogeno-α,β-unsaturated esters, with Z preferential stereochemistry. 相似文献