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151.
Some recent treatment of inflation in anisotropic universes is reviewed and we introduce results related toSO(3) Higgs fields and their influence on the violation of local isotropy.Presented at the International Conference Selected Topics in Quantum Field Theory and Mathematical Physics, Bechyn, Czechoslovakia, June 23–27, 1986.On leave of absence fromU.F.R.J., Inst. de Física, 21940, Rio de Janeiro, Brazil.Working for a Ph. D. degree. 相似文献
152.
153.
Valentina Nascimento Melo de Oliveira Franciane Gonçalves dos Santos Vanessa Pinheiro Gonçalves Ferreira Héverton Mendes Araújo Cláudia do Ó Pessoa Roberto Nicolete 《合成通讯》2013,43(19):2522-2532
A facile synthesis of 3,5-disubstituted 1,2,4-oxadiazole derivatives under focused microwave irradiation (FMWI) is reported. Arylamidoximes 1a–i and dicyclohexylcarbodiimide (DCC) were carried out in DMF under FMWI to obtain 1,2,4-oxadiazoles 2a–i in 61–81% yields. All compounds exhibited antiproliferative activities in vitro against three human cancer cell lines HCT-116, PC-3, and SNB-19. 相似文献
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155.
Paulo C. Nascimento Luciana Didonet Del-Fabro Cristiane Luisa Jost Denise Bohrer Leandro Machado de Carvalho Marcelo Barcellos Rosa 《Journal of Analytical Chemistry》2009,64(7):677-682
A spectrophotometric method for simultaneous determination of Al(III) and Fe(III) using the chelator Desferal® (desferrioxamine B) was developed. Partial least squares (PLS) regression was performed to resolve the overlapped signals obtained from Al(III) and Fe(III) complexes. The parameters controlling behavior of the system were investigated and optimum conditions were selected. PLS was the choice for the analysis of binary mixtures of Fe(III) and Al(III) over the range of 0.1 to 0.8 mg L?1 by using the data of first derivative spectra. Absorbance data were taken between 200 and 600 nm. The calculated sensitivity values for the multivariate method were 4.88 and 5.64 for Al(III) and Fe(III), respectively. Multivariate detection limits were 0.075 and 0.064 mg L?1 for Al(III) and Fe(III), respectively. The method was applied to real post-hemodialysis samples, and sample digestion by UV irradiation was discussed. 相似文献
156.
I. L. Caldas R. L. Viana Z. O. Guimarães-Filho A. M. Batista S. R. Lopes F. A. Marcus M. Roberto K. C. Rosalem J. D. Szezech Jr. D. Toufen K. W. Gentle I. C. Nascimento Y. K. Kuznetsov 《Brazilian Journal of Physics》2014,44(6):903-913
Plasma turbulence at the edge of tokamaks is an issue of major importance in the study of the anomalous transport of particles and energy. Although the behavior of a turbulent plasma seems intractable, it turns out that many of its aspects can be described by low-dimensional non-integrable dynamical models. In this paper, we consider a number of dynamical effects occurring in tokamak plasma edge—in particular the role of internal transport barriers. Furthermore, we present experimental results on turbulent-driven transport for two machines—the Brazilian TCABR tokamak and University of Texas’ Helimak—that can be explained by those theoretical models. 相似文献
157.
Daiane Dias Paulo C. do Nascimento Cristiane L. Jost Denise Bohrer Leandro M. de Carvalho Andrea Koschinsky 《Electroanalysis》2010,22(10):1066-1071
Determination of sulfide compounds in hydrothermal vent fluid samples was performed by DPCSV. The methodology was applied to speciate sulfides via primitive and first‐derivative curve interpretation. Hydrogen sulfide, methanethiol, and propanethiol were simultaneously assayed in samples containing no ethanethiol. In the presence of ethanethiol, the organic sulfides were determined without speciation. Sulfides were determined in an acidic electrolyte, and detection limits ranging from 0.1 to 1.1 μmol L?1 were calculated. The method was tested in real hydrothermal vent fluid samples, with recoveries ranging from 86.9% (R–SH) to 115.3% (H2S). Interference of the metallic species present in seawater was investigated. 相似文献
158.
Tiago A. Fernandes Adelino M. Galvão Ana M. Botelho do Rego M. Fernanda N. N. Carvalho 《Journal of polymer science. Part A, Polymer chemistry》2014,52(23):3316-3323
The number of CuCl units per camphor ligand in [{CuCl}2L]n was extended to three or four in [{CuCl}3L]n ( 2 ) or [{CuCl}4L]n ( 1 ). The Hartree‐Fock ab initio calculations support the polymeric structure of 1 and 2 that catalyze the cyclization of 4‐pentyn‐1‐oic acid ( A ) forming 5‐methylenedihydrofuran‐2(3H)‐one ( B ) and/or 2‐methyl‐5‐oxotetrahydrofuran‐2‐ylpent‐4‐ynoate ( C ). The catalytic activity of 1 , 2 and other polynuclear Cu(I) complexes ( 3–5 ) was evaluated under solvent free conditions and/or solution. In the absence of solvent, catalyst 2 displays the highest activity and selectivity (75.8/23.1, C to B ratio, at 5.4% loading) while 4 reaches the highest level of A → B conversion (97.5 %) in solution. Selected reactions were followed by NMR and the kinetic constants calculated. A mechanism is proposed based on the equations used for the calculations. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3316–3323 相似文献
159.
Rosilene S. Nascimento Nilton O.C. e Silva Denise B.C. Mendes José Bento B. Silva 《Talanta》2010,80(3):1102-1109
In this study we compared the use of ordinary least squares and weighted least squares in the calibration of the method for analyzing essential and toxic metals present in human milk by ICP-OES, in order to avoid systematic errors in the measurements used. Human milk samples were provided by maternity clinic Odete Valadares and digested by means of a high-performance microwave (MW) oven. Evaluation of plasma short and long-term stability was made using a solution of digested milk (1:50) with 2.0 mg L−1 Mg in HNO3 2% (v/v). The detection power resulted to be at or below the μg L−1 level, whilst the precision expressed as relative standard deviation R.S.D. was almost always equal to or better than 3.3%. Certified reference material Infant Formula (NIST SRM 1846) was used to assess the accuracy of the proposed method, which proved to be accurate and precise. Recovery rates were in the range of 83-117%. Aqueous calibration was carried out for each element under study. 相似文献