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611.
Qing-Jun Lou 《复变函数与椭圆型方程》2019,64(4):586-605
In this paper, via variational methods, we consider the existence and concentration of positive solutions for a system of Schrödinger–Poisson equation involving concave–convex nonlinearities under some suitable assumptions of weight functions. 相似文献
612.
Two dendritic block copolymers with the same contents of PPO and PEO but different branches and blocks were synthesized by anion polymerization. Their aggregation behavior and aggregation morphology were investigated by steady-state fluorescence and transmission electron microscopy. For SD64 copolymer with PPO-PEO diblock branch, it can be proved that only intermolecular aggregates are formed, the aggregation number and aggregation diameter are increased with concentration. Whereas for SD343 dendritic copolymer with PPO-PEO-PPO triblock branch, hydrophobic PPO chains located on the edge of SD343 copolymers can associate within the same polymer chain and also between different polymer chains, so the aggregates were inclined to change from intramolecular micelles to intermolecular clusters with concentration increasing. 相似文献
613.
Synthesis of 1,2,3-triazole-based dendritic architectures bearing a chalcone unit at the surface group has been achieved through a click reaction by the convergent synthetic strategy, in which tri- and tetra-azide were used as core units. 相似文献
614.
Three kinds of amide dendritic gelators, G1-C12-G1, G2-C12-G2 and gelator-1, were synthesized, and their self-assemble behavior in methyl methacrylate (MMA) was firstly investigated. The structures of the amide dendritic gelators were confirmed by 1H-NMR and Mass spectra (MS). The gelation ability of the amide dendritic gelators was researched through tube inversion experiment, the results of which showed that different structures led to quite different gelation ability, including gel-sol temperature and critical concentration to form a stable gel. SEM experiments showed that three kinds of gelator formed different gel morphologies in MMA, all of which were nanoscale gel. All the three amide dendritic gelators could not only form stable gel network at certain temperature with different concentrations in MMA, but also in each case, an optically transparent gel was formed, which indicated dendrimers in the MMA had a good compatibility. 相似文献
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617.
抑制二次电子倍增效应是提高空间大功率微波器件和粒子加速器等设备性能的重要课题,而使用表面处理降低材料的二次电子发射系数是抑制二次电子倍增的有效手段.为优化寻找抑制效果最好的表面形貌,本文采用蒙特卡罗方法模拟了各种微米量级不同表面形貌的二次电子发射特性,研究占空比、深宽比、结构形状及排列方式等的影响.模拟结果表明,正方形、圆形、三角形凸起和凹陷结构的二次电子发射系数随占空比和深宽比的增大而减小,但存在饱和值;凸起结构的排列方式对二次电子发射系数的影响不大,但是凸起结构形状却对二次电子发射系数的影响较大,其中三角形的抑制效果最佳.对凹陷结构而言,不同形状的抑制效果差别不大;同时,占空比和深宽比相同时,凸起结构较凹陷结构抑制效果更佳.究其原因,核心在于垂直侧壁的“遮挡效应”,凹陷结构遮挡效应的大小与“陷阱”垂直高度有关,而凸起结构遮挡效应的大小和凸起部分的斜方向投影大小有关. 相似文献
618.
The precise control of the two faces, concave/convex faces, is an attractive challenge to realizing novel dynamic molecular systems. Herein, we report the synthesis, X-ray crystal structure, and bowl-to-bowl inversion behavior of a platinum complex with azabuckybowl as a monodentate ligand. X-ray crystallography revealed that the azabuckybowl is orthogonally coordinated to the plane containing the Pt center and other ligands. One and two-dimensional NMR studies have also confirmed that this complex was observed as mixtures of two isomers, although the isomeric ratio was highly biased. Theoretical calculations indicate that the difference in thermodynamic stability of these isomers is due to the direction of the concave/convex face of an azabuckybowl ligand. 相似文献
619.
Growth rates of boric acid crystals have been measured both in pure aqueous solution and under the influence of electrical field as a function of supersaturation and electrical field intensity in a laboratory scale fluidized bed crystallizer at the temperature of 30°C. The effect of electrical field was estimated from the growth rate data to evaluate the relative magnitude of two resistances, diffusion and integration. In absence of electrical field, the obtained results indicate that the controlling mechanism is mainly integration. However, in presence of electrical field, growth rate of boric acid were controlled by diffusion and reaction steps. In the absence of electrical field, boric acid crystals grow dendritically at any level of supersaturation from pure boric acid solution. In case of electrical field, the dendritic structure was depressed. 相似文献