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951.
E. A. Oliveira M. P. C. Silva Z. M. B. Flgueiredo L. B. Carvalho 《Applied biochemistry and biotechnology》1989,22(1):109-114
Dacron (polyethylenetherephthalate) in the form of plates if proposed as a maxtrix to immobilized proteins. A three-step procedure is used to activate this support and to fix the protein on it. Amyloglucosidase was used as a model to test this method, and it showed advantages compared to the powder form of Dacron. 相似文献
952.
J. J. C. Teixeira-Dias R. Fausto L. A. E. Batista de Carvalho 《Journal of computational chemistry》1991,12(9):1047-1057
The Cα? C internal rotation in 2-methylpropionic, 2-methylthiopropionic (thiol and thion forms) and 2-methyldithiopropionic acids was studied by the ab initio SCF-MO method using 3-21G and 3-21G + d(0.65S) basis sets. Energies and structures of several conformations of these molecules, determined by gradient geometry refinement, are reported and used to assess the effects of oxygen-by-sulphur substitution on molecular properties. The nature and relative importance of intramolecular interactions involving both the α-methyl substituents and the C(?X)Y (X, Y? O or S) fragment are also discussed. 相似文献
953.
do Nascimento PC Bohrer D Rohlfes AL de Carvalho LM Ramirez A 《Fresenius' Journal of Analytical Chemistry》2001,370(1):92-96
A method has been developed for the chromatographic determination of methanethiol (MT) and ethanethiol (ET) as contaminants in amino acid parenteral nutrition (PN) solutions. The clean-up of the samples before chromatographic analysis was investigated by solid-phase extraction (SPE) on pre-columns filled with polyethylene powder (PE), aluminium oxide (AlOx), silica (SiOx), or polyurethane foam (PUF) as adsorbents. The thiols were more efficiently separated from the matrices by SPE on PUF pre-columns. Simultaneous derivatization and elution with DTNB (5,5'-dithiobis(2-nitrobenzoic acid)) enabled further discrimination between MT and ET by reversed-phase HPLC with spectrophotometric detection. The retention times for the derivatized MT and ET species were 12.5 and 23.0 min, respectively. Recoveries from spiked PN samples were calculated to be approximately 90%, and the MT and ET content of commercial PN solutions was determined using the methodology described. Detection limits of 15 and 10 microg L(-1) were calculated for MT and ET, respectively. 相似文献
954.
Ruben Dario Sinisterra Renata Vicentini Mielli Carlos Alberto Alves de Carvalho Wendel Gomes da Silva Antonio Salvio Mangrich Ana Maria da Costa Ferreira 《Journal of inclusion phenomena and macrocyclic chemistry》1999,33(2):203-216
The compound formed by the copper-Schiff base complex salicylideneserinatecopper(II), [Cu(sal-ser)(H2O)], interacting with -cyclodextrin was prepared, and characterized in the solid state by infrared, UV-visible and EPR spectroscopies, X- ray diffraction, and thermoanalytical techniques. The catalytic activity of this compound, [Cu(sal-ser)CD], in the decomposition of hydrogen peroxide, and in the dismutation of superoxide radicals was also verified, in comparison with the reactivity of the free complex, in aqueous solution. In both cases, a decreasing in the reaction rate was observed for the CD-containing compound. The results of structural characterization, in addition to the substantial differences observed in the catalytic activities of the compounds, are indicative of partial insertion of the copper complex in the cavity of the oligosaccharide. 相似文献
955.
A. O. Porto W. F. Magalhães C. F. Carvalho J. C. Machado 《Journal of Radioanalytical and Nuclear Chemistry》1995,198(1):151-159
Positron Lifetime Spectroscopy (LS) measurements were performed in a series of binary molecular solid solutions of the general formula M1–x
G
x
L3, where L(ligand)=acetylacetone, dipivaloylmethane, or N-benzoyl-N-phenylhydroxylamine, M=Al(III), Ga(III) or In(III), as matrix, and G=Cr(III), Mn(III), Fe(III), Co(III), Ru(III), Rh(III) and Ir(III), as guest molecules, and the corresponding mechanical mixtures. For the solid solutions, the o-Ps yield values (I
3) decrease very rapidly with the increase of the guest mole fraction, showing a high efficient Ps inhibition process, while for the corresponding mechanical mixtures, these values decrease linearly with the increase of the guest molecule concentration, indicating the presence of two distinct phases. These results confirm our previous proposal that the LS technique is able to characterize solid solutions formed by one matrix, in whichI
3 values are high, and one guest, in which theI
3 values are very low. 相似文献
956.
Karl E. Bessler Elisabeth B. Dourado Myller de S. Carvalho Sebastio S. Lemos Javier Ellena 《无机化学与普通化学杂志》2005,631(10):1935-1940
A convenient method for the preparation of diphenylboron chelates from ammonium tetraphenylborate is described. A variety of five‐ or six‐membered O,O‐, N,O‐ and N,N‐chelates were obtained in yields from 60 to 90 %. The isolated compounds were characterized by elemental analysis, IR spectroscopy and multinuclear magnetic resonance spectroscopy (1H, 13C, and 11B). The crystal and molecular structures of (pyridine‐2‐acetyloximato)diphenylboron and (1‐phenylazo‐2‐naphtholato)diphenylboron were determined by X‐ray diffraction on single crystals. 相似文献
957.
Aitala EM Amato S Anjos JC Appel JA Ashery D Banerjee S Bediaga I Blaylock G Bracker SB Burchat PR Burnstein RA Carter T Carvalho HS Costa I Cremaldi LM Darling C Denisenko K Fernandez A Gagnon P Gerzon S Gobel C Gounder K Granite D Halling AM Herrera G Hurvits G James C Kasper PA Kondakis N Kwan S Langs DC Leslie J Lichtenstadt J Lundberg B Manacero A MayTal-Beck S Meadows B de Mello Neto JR Milburn RH de Miranda JM Napier A Nguyen A d'Oliveira AB O'Shaughnessy K Peng KC Perera LP Purohit MV 《Physical review letters》1996,76(3):364-367
958.
Abachi S Abbott B Abolins M Acharya BS Adam I Adams DL Adams M Ahn S Aihara H Alitti J Álvarez G Alves GA Amidi E Amos N Anderson EW Aronson SH Astur R Avery RE Baden A Balamurali V Balderston J Baldin B Bantly J Bartlett JF Bazizi K Bendich J Beri SB Bertram I Bezzubov VA Bhat PC Bhatnagar V Bhattacharjee M Bischoff A Biswas N Blazey G Blessing S Bloom P Boehnlein A Bojko NI Borcherding F Borders J Boswell C Brandt A Brock R Bross A Buchholz D Burtovoi VS Butler JM Carvalho W Casey D 《Physical review D: Particles and fields》1996,53(11):6000-6016
959.
Roberto Markarian Sylvie Oliffson Kamphorst Sônia Pinto de Carvalho 《Communications in Mathematical Physics》1996,174(3):661-679
The elliptical stadium is a curve constructed by joining two half-ellipses, with half axesa>1 andb=1, by two straight segments of equal length 2h.Donnay [6] has shown that if 1 <a <
and ifh is big enough, then the corresponding billiard map has a positive Lyapunov exponent almost everywhere; moreover,h asa
In this work we prove that if
, then
assures the positiveness of a Lyapunov exponent. And we conclude that, for these values ofa andh, the elliptical stadium billiard mapping is ergodic and has theK-property.During this work, partially supported by Fac. de Ciencias, UruguayPartially supported by CNPq, Brasil 相似文献
960.
Abachi S Abbott B Abolins M Acharya BS Adam I Adams DL Adams M Ahn S Aihara H Alitti J Álvarez G Alves GA Amidi E Amos N Anderson EW Aronson SH Astur R Avery RE Baden A Balamurali V Balderston J Baldin B Bantly J Bartlett JF Bazizi K Bendich J Beri SB Bertram I Bezzubov VA Bhat PC Bhatnagar V Bhattacharjee M Bischoff A Biswas N Blazey G Blessing S Bloom P Boehnlein A Bojko NI Borcherding F Borders J Boswell C Brandt A Brock R Bross A Buchholz D Burtovoi VS Butler JM Carvalho W Casey D 《Physical review letters》1996,76(5):734-739