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991.
992.
We study various variations on selective separability in non-regular topological spaces. We use the notions of θ-closure and θ-density to define selective versions of θ-separability. These properties are also related to topological games. 相似文献
993.
994.
995.
Shipeng Wu Yinghao Wang Prof. Qiue Cao Prof. Qihua Zhao Dr. Wenhao Fang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(9):3019-3028
High-surface-area mesoporous CeO2 (hsmCeO2) was prepared by a facile organic-template-induced homogeneous precipitation process and showed excellent catalytic activity in imine synthesis in the absence of base from primary alcohols and amines in air atmosphere at low temperature. For comparison, ordinary CeO2 and hsmCeO2 after different thermal treatments were also investigated. XRD, N2 physisorption, UV-Raman, H2 temperature-programmed reduction, O2 temperature-programmed desorption, EPR spectroscopy, and X-ray photoelectron spectroscopy were used to unravel the structural and redox properties. The hsmCeO2 calcined at 400 °C shows the highest specific surface area (158 m2 g−1), the highest fraction of surface coordinatively unsaturated Ce3+ ions (18.2 %), and the highest concentration of reactive oxygen vacancies (2.4×1015 spins g−1). In the model reaction of oxidative coupling of benzyl alcohol and aniline, such an exceptional redox property of the hsmCeO2 catalyst can boost benzylideneaniline formation (2.75 and 5.55 mmol h−1 based on >99 % yield at 60 and 80 °C, respectively) in air with no base additives. It can also work effectively at a temperature of 30 °C and in gram-scale synthesis. These are among the best results for all benchmark ceria catalysts in the literature. Moreover, the hsmCeO2 catalyst shows a wide scope towards primary alcohols and amines with good to excellent yield of imines. The influence of reaction parameters, the reusability of the catalyst, and the reaction mechanism were investigated. 相似文献
996.
Dr. Manuel Vázquez Sulleiro Ramiro Quirós-Ovies Mariano Vera-Hidalgo Dr. I. Jénnifer Gómez Dr. Víctor Sebastián Prof. Jesús Santamaría Prof. Emilio M. Pérez 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(9):2993-2996
The combination of 2D materials opens a wide range of possibilities to create new-generation structures with multiple applications. Covalently cross-linked approaches are a ground-breaking strategy for the formation of homo or heterostructures made by design. However, the covalent assembly of transition metal dichalcogenides flakes is relatively underexplored. Here, a simple covalent cross-linking method to build 2H-MoS2–MoS2 homostructures is described, using commercially available bismaleimides. These assemblies are mainly connected vertically, basal plane to basal plane, creating specific molecular sized spaces between MoS2 sheets. Therefore, this straightforward approach gives access to the controlled connection of sulfide-based 2D materials. 相似文献
997.
It is shown that the probability law of a diffusion process conditioned on weakly corrupted observations is asymptotically Gaussian when properly scaled. The method of proof involves Fisher information matrices and a Cramér-Rao inequality. 相似文献
998.
《Stochastics An International Journal of Probability and Stochastic Processes》2013,85(3-4):207-226
In the present paper, a framework for parametric estimation in nonlinear time series is developed. Strong consistency and asymptotic normality of minimum Hellinger distance estimates for a determined class of nonlinear models are investigated. The main Interest for these estimates is motivated by their robustness under perturbations as it has been emphazized in Beran [2]. The first part of the paper is devoted to the study of some probabilistic properties which ensure the existence and the optimal properties of the estimates 相似文献
999.
Kenji TAKAHASHI 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2013,89(6):201-225
A group of enzymes, mostly hydrolases or certain transferases, utilize one or a few side-chain carboxyl groups of Asp and/or Glu as part of the catalytic machinery at their active sites. This review follows mainly the trail of studies performed by the author and his colleagues on the structure and function of such enzymes, starting from ribonuclease T1, then extending to three major types of carboxyl peptidases including aspartic peptidases, glutamic peptidases and serine-carboxyl peptidases. 相似文献
1000.
The geometrical anisotropy in the shape of swallow-tailed ST liquid crystalline molecules results in an extremely strong tendency of an antiparallel order in the short range. Dielectric measurements on a binary system of a ST and a double ST compound show that even at a mole fraction of 0.5 this effect can be observed. The strong deviations from the statistical distribution of the directions of the molecular long axis is caused by the asymmetric repulsive forces and the dipole-dipole interaction. 相似文献