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81.
Asymmetric Darzens reaction catalyzed by chiral selenides is described. A novel Lewis acid/Brønsted base catalyst formed by C2 symmetric chiral selenide-bearing isoborneol skeletons, which were readily prepared from (1S)-10-camphorsulfonic acid, and LiOH promoted the reaction of phenacyl bromide with aldehydes to afford the desired trans oxiranes with up to 62% ee. 相似文献
82.
In this paper, we theoretically and numerically investigate a new type of analytically solvable laser-driven systems inspired by electron-injection dynamics in dye-sensitized solar cells. The simple analytical expressions are found to be useful for understanding the difference between dye excitation and direct photo-injection occurring between dye molecule and semiconductor nanoparticles. More importantly, we propose a method for discriminating experimentally dye excitation and direct photo-injection using time-dependent fluorescence. We have found that dye excitation shows no significant quantum beat, whereas the direct photo-injection shows a significant quantum beat. 相似文献
83.
Shin-ichi Kato 《Journal of Functional Analysis》2010,258(5):1427-1451
A symmetric space analogue of Casselman's criterion for square integrability of representations of a p-adic group is established. It is described in terms of exponents of Jacquet modules along parabolic subgroups associated to the symmetric space. 相似文献
84.
85.
Hitoshi Osawa Toshiaki IwazumiHiroko Tokoro Shin-ichi OhkoshiKazuhito Hashimoto Hironobu ShojiEiju Hirai Tetsuya NakamuraSusumu Nanao Yasuhito Isozumi 《Solid State Communications》2003,125(5):237-241
The thermal phase transition of RbMnFe(CN)6 has been observed by Mn and Fe 3p-1s X-ray emission spectroscopy (XES) and 1s X-ray absorption spectroscopy (XAS). The thermal variations of the spin states and the valences of Mn and Fe were determined to be Mn2+(S=5/2)-NC-Fe3+(S=1/2) for the high-temperature (HT) phase and Mn3+(S=2)-NC-Fe2+(S=0) for the low-temperature (LT) phase. These transitions are thus caused by charge transfer between Mn and Fe. The temperature dependences of Mn and Fe 3p-1s XES and 1s XAS were observed as the composition of the spectra of the HT and LT phases. The ratios of the HT component in each spectrum show good agreement with the thermal transition curves observed with magnetic susceptibility measurements. 相似文献
86.
87.
H. Segawa S. Yamaguchi Y. Yamazaki T. Yano S. Shibata H. Misawa 《Applied Physics A: Materials Science & Processing》2006,83(3):447-451
Two-dimensional (2D) pillar arrays with submicrometer to micrometer repetitions have been fabricated from hybrid organic–inorganic
material by mask lithography or multi-beam interference lithography. The type of array structure depends on structural parameters
such as the pillar height, diameter and distance between neighboring pillars. Two kinds of periodic arrays, 2D arrays and
‘top-gathering’ arrays, can be obtained by controlling the structural parameters. In the top-gathering arrays, the pillars
are gathered at the top by means of self-organization, and ‘top-gathering’ units composed of four pillars can be formed.
PACS 68.35.Gy; 81.20.Fw; 82.50.-m 相似文献
88.
Associate Prof. Masanori Monde Mr. Shin-ichi Mihara Mr. Yoshiyuki Ono 《Heat and Mass Transfer》1988,22(1-2):91-95
An experimental study has been made of saturated boiling heat transfer for water and R113 in a narrow vertical rectangular channel (2 mm space, 20 mm wide, and 200 mm long) at atmospheric pressure, in which the vertical heated surface (10 mm long and 20 mm wide) is located on one side at a position of 150 mm from its entrance and bubbles are forcibly passed through it at a designated period from 0.33 to 1.0 sec. The experiment shows that the heat transfer coefficients are increased by the bubble passing through the heated surface for the value of thermal diffusivity,a, times period, T0, of the passing bubbles above about 6×10–9 m2 (a T
0>6×10–9 m2) while fora T
0< 6×10–9 m2, the heat transfer coefficients become independent of the period and the effectiveness of the enhancement of the heat transfer owing to the passing bubble disappears.
Nomenclature a thermal diffusivity of liquid - ¯h time-averaged heat transfer coefficient - q w heat flux at wall - T 0 period of passing bubble - T w(t) temperature of heated surface - T w amplitude of heated surface temperature Greek symbols thermal conductivity - thickness of liquid film 相似文献
Die obere Grenze der Verbesserung des Wärmeübergangs beim Sieden in einem vertikalen, rechteckigen Kanal infolge von aufsteigenden Blasen
Zusammenfassung Es wurden Experimente über den Wärmeübergang beim Sättigungssieden mit Wasser und R113 in einem engen, vertikalen, rechteckigen Kanal (2 mm Abstand, 20 mm Breite und 200 mm Länge) bei Umgebungsdruck durchgeführt, wobei die vertikale, beheizte Oberfläche (10 mm lang und 20 mm breit) auf der einen Seite in einem Abstand von 150 mm vom Eintritt angeordnet ist und die Blasen zwangsweise durch den Kanal sich mit einem Periodenabstand von 0,033 bis 1,0 s bewegen. Das Experiment zeigt, daß die Wärmeübergangskoeffizienten durch das Vorbeistreichen der Blasen an der beheizten Oberfläche verbessert werden, wenn das Produkt aus Temperaturleitfähigkeit,a, mal der Periode, T0, der vorbeistreichenden Blasen größer als 6×10–9 m2 liegt, während unterhalb dieses Wertes der Wärmeübergangskoeffizient unabhängig von der Blasenperiode ist und die Effektivität der Wärmeübergangsverbesserung infolge der Blasenströmung verschwindet.
Nomenclature a thermal diffusivity of liquid - ¯h time-averaged heat transfer coefficient - q w heat flux at wall - T 0 period of passing bubble - T w(t) temperature of heated surface - T w amplitude of heated surface temperature Greek symbols thermal conductivity - thickness of liquid film 相似文献
89.
Prof. Dr. Yasutomo Segawa Takehisa Maekawa Prof. Dr. Kenichiro Itami 《Angewandte Chemie (International ed. in English)》2015,54(1):66-81
Activation of aromatic C? H bonds by a transition metal catalyst has received significant attention in the synthetic chemistry community. In recent years, rapid and site‐selective extension of π‐electron systems by C–H activation has emerged as an ideal methodology for preparing organic materials with extended π‐systems. This Review focuses on recently reported π‐extending C–H activation reactions directed toward new optoelectronic conjugated materials. 相似文献
90.
The main purpose of this paper is to generalize the celebrated L~2 extension theorem of Ohsawa and Takegoshi in several directions: The holomorphic sections to extend are taken in a possibly singular hermitian line bundle, the subvariety from which the extension is performed may be non reduced, the ambient manifold is K¨ahler and holomorphically convex, but not necessarily compact. 相似文献