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51.
Using elastic recoil detection analysis and low energy electron diffraction we have investigated the adsorption process of hydrogen on the
surface. We find that (1) room temperature adsorption of atomic hydrogen induces a structure transformation from the
to Si(111)-1 × 1-Ag(H) structures, (2) a saturation coverage of hydrogen is 1.5 monolayer, which almost coincides with the one on a clean 7 × 7 surface, and (3) thermal desorption of hydrogen from the ordered 1 × 1-Ag(H) surface results in the recovery of the original
surface. 相似文献
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53.
Effect of Acid Treatment of Montmorillonite on “Support‐Activator” Performance to Support Metallocene for Propylene Polymerization Catalyst 下载免费PDF全文
Takao Tayano Hideshi Uchino Takehiro Sagae Katsuyuki Yokomizo Koji Nakayama Shigeki Ohta Hiroshi Nakano Masahide Murata 《大分子反应工程》2017,11(2)
This work is focused on montmorillonite (MMT)‐based “support‐activators” (S‐As) for the metallocene‐catalyzed propylene polymerization. This catalyst was previously industrialized; however, for further technological advances, the activation mechanism is investigated. The chemical and morphological requirements of the S‐A are surveyed using both commercially available raw clay minerals (non‐acid‐treated) and acid‐treated clay minerals. The S‐A possessing strong‐acid sites (pK a < ?8.2) gives a highly active catalyst. Acid treatment of MMT induces morphological changes as well as the formation of strong acid sites. Based on pore size distribution analysis and atomic force microscopy observations, it is concluded that the strong acid sites are located in the small pores around the edge of the clay mineral (not in the interlayer), where the structure is disordered by the acid treatment.
54.
Chuan ZhuMotoki Yamane 《Tetrahedron》2011,67(26):4933-4938
A simple and efficient synthesis of cinnolines was achieved by a palladium-catalyzed annulation methodology. 3,4-Disubstituted cinnolines are prepared via palladium-catalyzed annulation of 2-iodophenyltriazenes with an internal alkyne in moderate to good yields. Several internal alkynes are applicable to this reaction and it is compatible with a number of functional groups. 相似文献
55.
In this study, we show that earnings forecasting creates an index-tracking portfolio that dominates the historical model trade-off curve. We find that using Toyo Keizai earnings forecasts improves geometric means by over 300 basis points compared to the historical model. Weighted latent root regression is used in this study to create portfolios that have outperformed the Japanese market in backtest and in real-time performance. 相似文献
56.
When two waves are coupled in Bi12SiO20 crystals, the polarization states of the signal wave are affected by the self-diffraction. We have theoretically studied the influence of the self-diffraction on the polarization of the signal wave. The change of polarization states are strongly affected by the self-diffraction effect when the external field is applied. We present a new method that converts the change of polarization into an intensity signal. 相似文献
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Hideshi Nakamura Yasushi Ohizumi Junichi Kobayashi Yoshimasa Hirata 《Tetrahedron letters》1984,25(23):2475-2478
A new bromine-containing alkaloid, keramadine, has been isolated from the Okinawan sea sponge Agelas sp. as a novel antagonist of serotonergic receptors and its structure has been elucidated by n.m.r. spectrometry. 相似文献
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