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91.
A two-channel separable potential model is given such that the T-matrix is given in the form of a N/D matrix. This model is used to examine the relationships between the three different definitions for a resonance in the two-channel problem, particularly for a 3S1 Λp resonance. In order to obtain a phenomenological hyperon-nucleon (YN) scattering T-matrix in the present model, a least-squares fit is performed to the existing available data for the scattering cross sections and angular distributions at low energies using the s- and p-wave N/D solutions which carry sixteen independent parameters. Several solution sets of potential parameters are found, for which we can obtain good fits to the Λp → Λp, Σ?p → Λn and ΣN → ΣN data, particularly to the cross-section data for these processes. The p-wave contributions are estimated, and particularly the possibility of p-wave YN resonances is pointed out for the solutions for which we do not assume a 31 Λp resonance. 相似文献
92.
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94.
Efficient methods for stereoselective synthesis of various (E)-, (Z)-, and disubstituted 3-alkylideneoxindoles were investigated using tandem In-mediated carbometalation and ligandless Pd-catalyzed coupling reaction. 相似文献
95.
Iwamura H Wells DH Mathew SP Klussmann M Armstrong A Blackmond DG 《Journal of the American Chemical Society》2004,126(50):16312-16313
A new catalytic cycle involving only soluble proline complexes or adducts is proposed for the reactions in eq 1 based on kinetic observations and molecular modeling studies. This reaction pathway circumventing free proline and incorporating hydrogen-bonded reaction product helps to rationalize the observations of accelerating reaction rate in both the alpha-aminooxylation and alpha-amination reactions. 相似文献
96.
[see structure]. Synthesis and photochemistry of a new photochemically removable protecting group for alcohols is described. Four carbonates of galactose derivatives (1-4) were synthesized from the corresponding arylmethanols via 4-nitrophenyl carbonate intermediates. Among them, photolysis of anthraquinon-2-ylmethoxycarbonyl (Aqmoc) galactose (1) proceeded with overall photolysis efficiency of 150 (quantum yield 0.10, and molar absorptivity 1500 M(-1) x cm(-1)) and rate constant of approximately 10(6) s(-1). To demonstrate its application to a biologically related molecule, 5'-Aqmoc-adenosine (5) was synthesized and photolyzed to yield adenosine in 91% yield. 相似文献
97.
Adsorption of phenol from an aqueous solution in batch and continuous flow systems using carbon gels with a microhoneycomb structure (carbon gel microhoneycombs, CMHs) was studied. The obtained monolithic CMHs had fairly straight channels, 25–45 μm in diameter, and the thickness of the walls which form the channels was around 5 μm. The CMHs showed 370 times lower hydraulic resistance when compared with a column packed with particles having the same diffusion path length as it. The obtained CMHs have a hierarchical micro-meso porous structure giving BET surface area in the range of 513–1070 m2·g?1.When used for phenol adsorption from an aqueous solution, the CMHs quickly adsorbed phenol at first, and then, the uptake gradually increased, which indicates that the adsorption mechanism is based on not only simple physisorption. The phenol adsorption capacity increased with the increase in carbonization temperature of the CMH and the decrease in its hydrophilicity. CMHs carbonized at temperatures higher than 1073 K showed the highest phenol adsorption capacity which was around 160 mg·g?1. The CMHs could continuously adsorb phenol from aqueous solutions, and their length of unused bed (LUB) values depended on operation conditions but were in the range of 0.3–0.7 cm. The experimental results indicated that carbon cryogels with a microhoneycomb structure have a high potential to be used for effective separation of phenol. 相似文献
98.
Norifumi Kishi Dr. Zhiou Li Dr. Yoshihisa Sei Prof. Dr. Munetaka Akita Dr. Kenji Yoza Prof. Dr. Jay S. Siegel Dr. Michito Yoshizawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(20):6313-6320
This article reports that an M2L4 molecular capsule is capable of encapsulating various neutral molecules in quantitative yields. The capsule was obtained as a single product by mixing a small number of components; two PdII ions and four bent bispyridine ligands containing two anthracene panels. Detailed studies of the host capability of the PdII‐linked capsule revealed that spherical (e.g., paracyclophane, adamantanes, and fullerene C60), planar (e.g., pyrenes and triphenylene), and bowl‐shaped molecules (e.g., corannulene) were encapsulated in the large spherical cavity, giving rise to 1:1 and 1:2 host–guest complexes, respectively. The volume of the encapsulated guest molecules ranged from 190 to 490 Å3. Within the capsule, the planar guests adopt a stacked‐dimer structure and the bowl‐shaped guests formed an unprecedented concave‐to‐concave capsular structure, which are fully shielded by the anthracene shell. Competitive binding experiments of the capsule with a set of the planar guests established a preferential binding series for pyrenes≈phenanthrene>triphenylene. Furthermore, the capsule showed the selective formation of an unusual ternary complex in the case of triphenylene and corannulene. 相似文献
99.
Kishi N Li Z Yoza K Akita M Yoshizawa M 《Journal of the American Chemical Society》2011,133(30):11438-11441
A new M(2)L(4) molecular capsule with an aromatic shell was prepared using two Pd(II) ions and four bisanthracene ligands. The self-assembled capsule possesses a cavity with a diameter of ~1 nm that can encapsulate medium-sized spherical and planar molecules as well as a very large molecule (C(60)) in quantitative yields. The encapsulated guests are fully segregated and shielded from the external environment by the large anthracene panels. 相似文献
100.
Shigeru Murata Tadashi Sugawara Nobuaki Nakashima Keitaro Yoshihara Hiizu Iwamura 《Tetrahedron letters》1984,25(18):1933-1936
Laser-flash photolysis studies have been carried out on a solution of ap- and sp-9-(2-azido-4,6-dimethylphenyl)fluorenes (3) in methanol-ether at 25°C. The rates of formation of azanorcaradiene (5) from ap-nitrene (4) ap, and of 9-methoxyfluorene (7) from o-quinoid intermediate (6) were determined. The deuterium isotope effect on the migration of the hydrogen is discussed. 相似文献