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Aline de Souza Ramos Joyce Benzaquem Ribeiro Leonardo Vazquez Selma Gomes Ferreira Leite Francisco Radler de Aquino Neto 《Tetrahedron letters》2009,50(52):7362-6129
The enantioselective reduction of ethyl benzoylacetate (EBA) into ethyl (S)-3-hydroxy-3-phenylpropanoate (S-HPPE) by nine yeast strains and three filamentous fungi strains is described. The conversion obtained was in the range 0-89% and the enantiomeric excess was 100% in many cases. Conversion levels were higher when the reduction was performed with microorganisms immobilized in calcium alginate and enantioselectivity remained excellent. Some reaction’s conditions of bioreduction by immobilized cells of Rhodotorula rubra were studied using a 25-2 fractional factorial design. 相似文献
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We review different studies of the Periodic Law and the set of chemical elements from a mathematical point of view. This discussion
covers the first attempts made in the 19th century up to the present day. Mathematics employed to study the periodic system
includes number theory, information theory, order theory, set theory and topology. Each theory used shows that it is possible
to provide the Periodic Law with a mathematical structure. We also show that it is possible to study the chemical elements
taking advantage of their phenomenological properties, and that it is not always necessary to reduce the concept of chemical
elements to the quantum atomic concept to be able to find interpretations for the Periodic Law. Finally, a connection is noted
between the lengths of the periods of the Periodic Law and the philosophical Pythagorean doctrine. 相似文献
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Salles Thiago Rocha Leonardo Gonçalves Marcos 《Advances in Data Analysis and Classification》2021,15(2):379-405
Advances in Data Analysis and Classification - Random forest (RF) classifiers do excel in a variety of automatic classification tasks, such as topic categorization and sentiment analysis. Despite... 相似文献
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Leonardo Bargigli 《Journal of statistical physics》2014,155(4):810-825
Economic networks share with other social networks the fundamental property of sparsity. It is well known that the maximum entropy techniques usually employed to estimate or simulate weighted networks produce unrealistic dense topologies. At the same time, strengths should not be neglected, since they are related to core economic variables like supply and demand. To overcome this limitation, the exponential Bosonic model has been previously extended in order to obtain ensembles where the average degree and strength sequences are simultaneously fixed (conditional geometric model). In this paper a new exponential model, which is the network equivalent of Boltzmann ideal systems, is introduced and then extended to the case of joint degree-strength constraints (conditional Poisson model). Finally, the fitness of these alternative models is tested against a number of networks. While the conditional geometric model generally provides a better goodness-of-fit in terms of log-likelihoods, the conditional Poisson model could nevertheless be preferred whenever it provides a higher similarity with original data. If we are interested instead only in topological properties, the simple Bernoulli model appears to be preferable to the correlated topologies of the two more complex models. 相似文献