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81.
Annalisa Bertoli Lidia Fanfoni Fulvia Felluga Giuliana Pitacco Ennio Valentin 《Tetrahedron: Asymmetry》2009,20(19):2305-2310
Three α-methylene-γ-carbomethoxy-γ-butyrolactams (methyl α-methylene-pyroglutamates) 11, 12 and 13, differing in the substitution at the heterocyclic nitrogen, as well as the structurally related γ-lactones 14 and 15 were synthesised and resolved enzymatically by hydrolysis of their ester function, mediated by commercially available hydrolytic enzymes. In particular, the α-chymotrypsin proved to be active to all the substrates examined, displaying a different degree of activity and enantioselectivity, this latter increasing significantly towards the substrate with an aromatic substituent at the nitrogen. 相似文献
82.
C. Saragovi F. Labenski de Kanter L. Kleiman R. Valentin C. Puglisi 《Hyperfine Interactions》1990,57(1-4):2285-2290
Several natural biotite samples were studied by M.E., electron microprobe and XRD. The M.E. parameters allow to group them
as oxybiotites, normal biotites, chloritized biotites and muscovitized biotites. Mechanisms of oxybiotite formation and processes
undergone by the rocks are discussed. 相似文献
83.
Dumitru Oancea Valentin Munteanu Domnina Razus 《Journal of Thermal Analysis and Calorimetry》2010,102(3):993-1000
The transient response of the input power necessary to maintain isothermal conditions after a step temperature perturbation
applied to a platinum wire immersed in a gaseous fuel/air mixture allows for the measurement of the reaction heat flow rate,
directly related to the rate of the catalytic combustion. The S-shaped variation of this rate in time is employed to evaluate
the induction period of the catalytic ignition. The effect of mixture composition, total pressure, and catalyst temperature
on the induction period for the catalytic ignition of lean to stoichiometric n-pentane/air mixtures on isothermally heated platinum wire is reported and discussed. The mixture composition was varied between
1.40 and 2.56% n-pentane in air, the total pressure between 20 and 101 kPa, and the wire temperature between 470 and 600 K. The reaction rates,
turnover frequencies, overall and partial reaction orders, and activation energies were determined from the analysis of the
obtained results and compared to other reported data. 相似文献
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Reyes Malavé Osuna Rocio Ponce Ortiz Mari Carmen Ruiz Delgado Valentin G Nenajdenko Viktor V Sumerin Elizabeth S Balenkova Víctor Hernández Juan Teodomiro López Navarrete 《Chemphyschem》2007,8(5):745-750
Herein, we study the conjugation properties of three different thienoacenes, each of which has three or four fused thiophene rings, by means of Fourier transform Raman spectroscopy. The B3LYP/6-31G** vibrational analysis of all of the collected spectroscopic data evidences that the selective enhancement of a limited number of Raman scatterings is related to the occurrence in the three thienoacenes of a vibronic coupling between the lowest unoccupied frontier molecular orbital (LUMO) and some Raman-active skeletal nu(C==C) stretching modes of 1600-1300 cm(-1). 相似文献
88.
Yury Rodimkov Evgeny Efimenko Valentin Volokitin Elena Panova Alexey Polovinkin Iosif Meyerov Arkady Gonoskov 《Entropy (Basel, Switzerland)》2021,23(1)
When entering the phase of big data processing and statistical inferences in experimental physics, the efficient use of machine learning methods may require optimal data preprocessing methods and, in particular, optimal balance between details and noise. In experimental studies of strong-field quantum electrodynamics with intense lasers, this balance concerns data binning for the observed distributions of particles and photons. Here we analyze the aspect of binning with respect to different machine learning methods (Support Vector Machine (SVM), Gradient Boosting Trees (GBT), Fully-Connected Neural Network (FCNN), Convolutional Neural Network (CNN)) using numerical simulations that mimic expected properties of upcoming experiments. We see that binning can crucially affect the performance of SVM and GBT, and, to a less extent, FCNN and CNN. This can be interpreted as the latter methods being able to effectively learn the optimal binning, discarding unnecessary information. Nevertheless, given limited training sets, the results indicate that the efficiency can be increased by optimizing the binning scale along with other hyperparameters. We present specific measurements of accuracy that can be useful for planning of experiments in the specified research area. 相似文献
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