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31.
[reaction: see text] A rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to fumaric and maleic compounds has been developed. While phosphorus-based chiral ligands fail to induce high stereoselectivity, chiral norbornadiene ligands have proved to be uniquely effective to achieve high enantioselectivity in these 1,4-addition reactions. 相似文献
32.
Mamoru Furuya Hiroshi Niitsuma 《Proceedings of the American Mathematical Society》2004,132(11):3189-3193
We introduce the concept of -adic -basis as an extension of the concept of -basis. Let be a regular local ring of prime characteristic and a ring such that . Then we prove that is a regular local ring if and only if there exists an -adic -basis of and is Noetherian.
33.
A volume change method for measuring crystal densities is described. It allows the densities of unstable hydrated crystals at room temperature to be determined, by measurements of volume changes during the solidification of aqueous solutions. NaCl x 2H2O, KCl, MgSO4 x 12H2O and K2HPO4 x 6H2O were measured by the method and their densities (SE) are 1.61+/-0.02, 1.99+/-0.05, 1.45+/-0.01 and 1.75+/-0.02 g ml(-1) respectively. Data of NaCl x 2H2O and KCl are in good agreement with the previously reported values. 相似文献
34.
Irie H Washizuka S Yoshino N Hashimoto K 《Chemical communications (Cambridge, England)》2003,(11):1298-1299
Nitrogen-substituted titanium dioxide thin films were found to undergo hydrophilic conversion under irradiation with visible light. The hydrophilicity was enhanced by increasing the degree of nitrogen substitution at oxygen sites. The water contact angle for the thin film with the greatest hydrophilicity, TiO1.9884N0.0116, changed from 20 degrees to 6 degrees following irradiation. 相似文献
35.
Hayashi T Ueyama K Tokunaga N Yoshida K 《Journal of the American Chemical Society》2003,125(38):11508-11509
As a new type of chiral ligand, a C2-symmetric norbornadiene derivative (1R,4R)-2,5-dibenzylbicyclo[2.2.1]hepta-2,5-diene (1) was prepared and used for the rhodium-catalyzed asymmetric addition of organoboron and -tin reagents to alpha,beta-unsaturated ketones, which gave high yields of the 1,4-addition products with up to 99% enantioselectivity. 相似文献
36.
N. Hori A. Furuya M. Tsuruta F. Misaizu K. Ohno 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):41-44
Photoinduced dissociation in the ultraviolet region has been investigated for Ag nF n-1
+ cluster ions. Photodissociation spectrum of
Ag2F+
in the energy of 3.8–5.6 eV exhibits several sharp bands corresponding to the transition to electronically excited states.
In this dissociation, only the Ag2
+ ion was observed as a fragment ion. Theoretical calculation indicates that the parent Ag2F+ ion has a linear Ag-F-Ag equilibrium geometries in the ground and excited states. Since conformational changes by excitation
of bending vibration are necessary for the fragmentation of an F atom, this indicates that production of Ag2
+ from Ag2F+ is a result of internal conversion and following conformational changes. 相似文献
37.
38.
Experiments have been conducted to investigate an effect of inlet restriction on the thermal-hydraulic stability. A Test
facility used in this study was designed and constructed to have non-dimensional values that are nearly equal to those of
natural circulation BWR. Experimental results showed that driving force of the natural circulation at the stability boundary
was described as a function of heat flux and inlet subcooling independent of inlet restriction. In order to extend experimental
database regarding thermal-hydraulic stability to different inlet restriction, numerical analysis was carried out based on
the homogeneous flow model. Stability maps in reference to the core inlet subcooling and heat flux were presented for various
inlet restrictions using the above-mentioned function. Instability region during the inlet subcooling shifted to the higher
inlet subcooling with increasing inlet restriction and became larger with increasing heat flux.
Received on 17 January 2000 相似文献
39.
Minghui Song Kazutaka Mitsuishi Kazuo Furuya 《Physica E: Low-dimensional Systems and Nanostructures》2005,29(3-4):575
Nanometer-sized W-dendrites are fabricated on Al2O3 substrates with an electron-beam-induced deposition process. Dependence of growth of nanodendrite on surface topography is investigated with transmission electron microscopy. It is confirmed that the nanodendrite grows on convex surfaces but not around a hole on a substrate. These are attributed to different distribution of charges on surfaces with different topographies during electron beam irradiation when charges are produced on the surface due to emission of second electrons. The charges accumulate on convex surface and do not distribute around a hole. Therefore, the nanodendrite grows on the former and not on the latter. 相似文献
40.
Yoshihiro Takebayashi Hiroyuki Hotta Atsushi Shono Katsuto Otake Kiwamu Sue Satoshi Yoda Takeshi Furuya 《Journal of solution chemistry》2009,38(5):545-555
Acid-base equilibria between 2,5-dichlorophenol (DCP) and various bases (LiOH, NaOH, and KOH) were studied in ambient to supercritical
methanol, by measuring the absorption spectrum of DCP at alkali metal hydroxide molalities ranging up to 10 mmol⋅kg−1, at temperatures up to 250 °C and a pressure of 25.0 MPa. The spectrum was deconvoluted into contributions for the acidic
(HA) and basic (A−) forms of DCP, taking into account a blue shift of the phenolate (A−) spectrum due to the effect of ion pairing with an alkali metal cation. Degrees of dissociation of DCP determined from the
spectra suggested that the dissociation constant of DCP has a maximum around 150 °C, whereas that of KOH decreases with temperature.
The phenolate-alkali metal ion pairing was examined from the peak shift of the phenolate spectrum in the presence of Li+, Na+, and K+. A smaller cation radius and higher temperature (thus a lower dielectric constant for methanol) give rise to stronger electrostatic
interaction in the ion pair. The basicities of the alkali metal hydroxides in supercritical methanol were compared using DCP
as an indicator, and were shown to follow the order LiOH < NaOH ≤ KOH. This order is the same as that for the catalytic effect
of alkali metal hydroxides on the methylation of phenol in supercritical methanol (Takebayashi et al.: Ind. Eng. Chem. Res.
47:704–709, 2008).
Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users. 相似文献