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451.
The gas-phase thermal rearrangement of exo-7-methylbicyclo[3.2.0]hept-2-ene yields almost exclusively 5-methylnorbornene products. Inversion (i) of configuration dominates this [1,3] sigmatropic shift although some retention (r) is also observed. Because the [1,3] migration can only occur suprafacially (s) in this geometrically constrained system, the si/sr ratio of 7 observed for the migration of C7 in exo-7-methylbicyclo[3.2.0]hept-2-ene indicates that the orbital symmetry rules are somewhat permissive for the [1,3] sigmatropic migration of carbon. 相似文献
452.
Iring Bender Dieter Gromes Heinz J. Rothe 《Zeitschrift fur Physik C Particles and Fields》1980,5(2):151-154
We study the nonlinear equations for matrix elements of the gluon fields between heavy quark-antiquark states in an SU(2) Yang-Mills theory, obtained by saturating the operator products with \(q\bar q\) -intermediate states only. Equations of this kind have been proposed by Giles and McLerran and Adler before. We present exact solutions to these equations consistent with the charge algebra. These solutions lead to total screening, i.e. the color charge of the gluons exactly cancels that of the quarks. We also calculate the energy of the system and find that the result is in agreement with the screening effect. 相似文献
453.
João Paulo Bender Marcio Antônio Mazutti Débora de Oliveira Marco Di Luccio Helen Treichel 《Applied biochemistry and biotechnology》2006,132(1-3):951-958
Inulinase is an enzyme relevant to fructose production by enzymatic hydrolysis of inulin. This enzyme is also applied in the
production of fructo-oligosaccharides that may be used as a new food functional ingredient. Commercial inulinase is currently
obtained using inulin as substrate, which is a relatively expensive raw material. In Brazil, the production of this enzyme
using residues of sugarcane and corn industry (sugarcane bagasse, molasses, and corn steep liquor) is economically attractive,
owing to the high amount and low cost of such residues. In this context, the aim of this work was the assessment of inulinase
production by solid state fermentation using by Kluyveromyces marxianus NRRL Y-7571. The solid medium consisted of sugar cane bagasse supplemented with molasses and corn steep liquor. The production
of inulinase was carried out using experimental design technique. The effect of temperature, moisture, and supplements content
were investigated. The enzymatic activity reached a maximum of 445 units of inulinase per gram of dry substrate. 相似文献
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Lu Y Roe JA Bender CJ Peisach J Banci L Bertini I Gralla EB Valentine JS 《Inorganic chemistry》1996,35(6):1692-1700
Preparation and characterization of two new site-directed mutant copper-zinc superoxide dismutase proteins from Saccharomyces cerevisiae, i.e., His46Cys (H46C) and His120Cys (H120C), in which individual histidyl ligands in the copper-binding site were replaced by cysteine, are reported here. These two mutant CuZnSOD proteins may be described as type 2 (or normal) rather than type 1 (or blue) copper-cysteinate proteins and are characterized by their yellow rather than blue color, resulting from intense copper-to-sulfur charge transfer bands around 400 nm, their type 2 EPR spectra, with large rather than small nuclear hyperfine interactions, and their characteristic type 2 d-d electronic absorption spectra. An interesting difference between these two copper site His-to-Cys mutations is that the imidazolate bridge between the two metal sites that is characteristic of the wild-type protein remains intact in the case of the H46C mutant but is not present in the case of the H120C mutant. 相似文献
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