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排序方式: 共有158条查询结果,搜索用时 49 毫秒
31.
Mariano Asteasuain Matheus Soares Marcelo K. Lenzi Michael Cunningham Claudia Sarmoria José Carlos Pinto Adriana Brandolin 《大分子反应工程》2007,1(6):622-634
This is the first of a series of works aiming at developing a tool for designing “living” free radical polymerization processes in tubular reactors, in order to achieve tailor‐made MWDs. A mathematical model of the nitroxide‐mediated controlled free radical polymerization is built and implemented to predict the complete MWD. It is shown that this objective may be achieved accurately and efficiently by means of the probability generating function (pgf) transformation. Comparison with experimental data is good. The potential of the resulting model for optimization activities involving the complete MWD is also shown.
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C. Albano N. Camacho M. Hernández A. Matheus A. Gutiérrez 《Macromolecular Symposia》2009,286(1):195-202
Lightweight aggregate is an important material in reducing the unit weight of concrete and it is essential in the construction of high-rise buildings; besides, the use of recycled PET bottles as lightweight aggregate in concrete is an effective contribution for environmental preservation. So, the objective of the present work is to study the flexural strength of PET-concrete and PET thermal degradation in the concrete, when the blends with 10 and 20 vol% of PET are exposed to different temperatures (200, 400, 600 °C). The flexural strength of PET-concrete exposed to a heat source is strongly dependent on the temperature, the water/cement ratio, as well as on the content and particle size of PET. Furthermore, the activation energy for PET degradation is affected by temperature, location of PET particles on the slabs and the water/cement ratio. A higher content of water gives rise to hydrolytic degradation on PET and a higher vapor pressure that increases the formation of cracks on the concrete. The values of activation energy are higher on the center of the slabs than on the surface, due to the poor heat conduction of concrete. 相似文献
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Wu T Nauwelaerts K Van Aerschot A Froeyen M Lescrinier E Herdewijn P 《The Journal of organic chemistry》2006,71(15):5423-5431
A method has been developed for the synthesis of bisheaded nucleosides with thymine and adenine base moieties. We have demonstrated that, when incorporated in oligonucleotides, extrahelical A-T base interactions are possible when the bisheaded nucleosides are positioned in opposite strands of the duplex and are separated from each other by one regular base pair. 相似文献
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Yunierkis Pérez-Castillo Maykel Cruz-Monteagudo Cosmin Lazar Jonatan Taminau Mathy Froeyen Miguel Ángel Cabrera-Pérez Ann Nowé 《Molecular diversity》2014,18(3):637-654
Antibiotic resistance has increased over the past two decades. New approaches for the discovery of novel antibacterials are required and innovative strategies will be necessary to identify novel and effective candidates. Related to this problem, the exploration of bacterial targets that remain unexploited by the current antibiotics in clinical use is required. One of such targets is the \(\beta \) -ketoacyl-acyl carrier protein synthase III (FabH). Here, we report a ligand-based modeling methodology for the virtual-screening of large collections of chemical compounds in the search of potential FabH inhibitors. QSAR models are developed for a diverse dataset of 296 FabH inhibitors using an in-house modeling framework. All models showed high fitting, robustness, and generalization capabilities. We further investigated the performance of the developed models in a virtual screening scenario. To carry out this investigation, we implemented a desirability-based algorithm for decoys selection that was shown effective in the selection of high quality decoys sets. Once the QSAR models were validated in the context of a virtual screening experiment their limitations arise. For this reason, we explored the potential of ensemble modeling to overcome the limitations associated to the use of single classifiers. Through a detailed evaluation of the virtual screening performance of ensemble models it was evidenced, for the first time to our knowledge, the benefits of this approach in a virtual screening scenario. From all the obtained results, we could arrive to a significant main conclusion: at least for FabH inhibitors, virtual screening performance is not guaranteed by predictive QSAR models. 相似文献
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Guanaes Lais Danciguer Guimarães Matheus Murmel Ducatti Diogo R. B. Duarte Maria Eugênia R. Barreira Sandra M. W. Noseda Miguel D. Gonçalves Alan Guilherme 《Chemistry of Heterocyclic Compounds》2021,57(12):1195-1203
Chemistry of Heterocyclic Compounds - In the present work, we have synthesized new molecular hybrids consisting of porphyrin ring system connected at the meso positions with phenyl groups and/or,... 相似文献
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Francisco A. Martins Lucas A. Zeoly Rodrigo A. Cormanich Matheus P. Freitas 《Tetrahedron》2018,74(8):880-883
The preferred conformations of a small polyfunctional molecule containing fluorine, chlorine and hydroxyl groups, the 1-chloro-1,1-difluoro-2-pentanol (CDP), were completely elucidated using 1H, 13C and 19F NMR in three different solvents. While the Cl-C-C-O dihedral angle was asserted using coupling constant data for the diastereotopic fluorines, the Et-C-C-O torsional angle was analyzed by means of 1H NMR spectra with selective irradiation of the diastereotopic hydrogens and fluorines. In addition, unusual couplings of the hydroxyl hydrogen with a diastereotopic hydrogen and fluorines provided information on the O-H orientation. The behavior of 1JC,F when the solvents varied agrees with a weak F???HO intramolecular hydrogen bond. These findings were corroborated, and the governing interactions rationalized with the aid of high level CCSD(T) theoretical calculations. Noteworthy, hyperconjugation involving the electron-acceptor σ*C-Cl orbital drives the conformational equilibrium rather than the fluorine gauche effect. 相似文献
38.
Nicolás Andruskiewitsch João Matheus Jury Giraldi 《Linear and Multilinear Algebra》2018,66(5):961-991
We compute all Nichols algebras of rigid braided vector spaces of dimension 2 that admit a non-trivial quadratic relation. 相似文献
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