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排序方式: 共有204条查询结果,搜索用时 31 毫秒
91.
92.
Eiji Ihara Toshimitsu Hiraren Tomomichi Itoh Kenzo Inoue 《Journal of polymer science. Part A, Polymer chemistry》2008,46(5):1638-1648
Palladium‐mediated polymerization of cyclic diazoketones was investigated. Although cyclic diazoketones 1a,b derived from cyclohexanone and 1‐tetralone did not homopolymerize, they can be used as a comonomer for copolymerization with polymerizable acyclic diazoketones. On the other hand, an α,β‐unsaturated cyclic diazoketone 2a prepared from 2‐cyclohexen‐1‐one polymerized to give a polymer poly 2a ′ with Mn = 1400 in a 23.8% yield. Addition of some nucleophiles to C?C bond in poly 2a ′ was carried out. Copolymerization of 2a and its dimethyl‐substituted analogues 2b,c with acyclic diazoketones was also investigated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1638–1648, 2008 相似文献
93.
Atsushi Asai Yoshiaki Mishina Toshimitsu Ogura Masaaki Omiya 《Journal of sound and vibration》2004,277(3):539-545
The Japanese Environmental Agency (now the Ministry of the Environment) updated the environmental quality standards for noise in April 1999. The new standards replaced the median value of percentile level L50 for noise evaluation with the equivalent sound pressure level LAeq. The standards renewed the classification of areas and time sections. The most significant change was the introduction of category of artery-road-adjacent area.This report sets the range of the artery-road-adjacent area to 20 m or less from the applicable road to compare the new standards with the old, based on data collected in Nagoya City. The achieved rates for the new standards seem to be on the whole the same as those for the old standards. However, a detailed analysis reveals some differences, such as higher achieved rates in the artery-road-adjacent areas and lower achieved rates in the general areas for the new standards than for the old. 相似文献
94.
Takaoki Ishii Ryo Watanabe Toshimitsu Moriya Prof. Dr. Hirohisa Ohmiya Prof. Dr. Seiji Mori Prof. Dr. Masaya Sawamura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(40):13547-13553
Catalyst–substrate hydrogen bonds in artificial catalysts usually occur in aprotic solvents, but not in protic solvents, in contrast to enzymatic catalysis. We report a case in which ligand–substrate hydrogen‐bonding interactions cooperate with a transition‐metal center in alcoholic solvents for enantioselective catalysis. Copper(I) complexes with prolinol‐based hydroxy amino phosphane chiral ligands catalytically promoted the direct alkynylation of aldehydes with terminal alkynes in alcoholic solvents to afford nonracemic secondary propargylic alcohols with high enantioselectivities. Quantum‐mechanical calculations of enantiodiscriminating transition states show the occurrence of a nonclassical sp3‐C? H???O hydrogen bond as a secondary interaction between the ligand and substrate, which results in highly directional catalyst–substrate two‐point hydrogen bonding. 相似文献
95.
Toshimitsu Suzuki Shun-Ichi Izuka Shigeki Kondo Yoshinobu Takegami 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(3):633-642
The polymerization and catalytic behavior of a Ziegler type catalyst supported on poly(ethylene-co-vinyl alcohol) (EVA) were investigated. The rate of ethylene polymerization by a catalyst prepared from titanium tetrachloride supported on EVA (vinyl alcohol 18 mole %) and triethylaluminum (AlEt3) is much higher than that of an n-butoxytitanium trichloride (BTT)-AlEt3 catalyst. The polymer-supported catalyst has prolonged high activity during polymerization compared with the BTT-AlEt3 catalyst. The stabilization of the catalyst seems to depend on its slower reduction by alkylaluminum compounds, due to steric hindrance by bulky polymer ligands. Polypropylene prepared by the polymer supported Ziegler catalyst is essentially atactic, and it differs little from that prepared with a BTT-AlEt3 catalyst. Vinyl chloride was also polymerized by this catalyst. The catalytic activity was, however, very small. 相似文献
96.
97.
Tomoyuki Sugimoto Toshimitsu Hamasaki 《Annals of the Institute of Statistical Mathematics》2006,58(4):647-674
We consider a semiparametric cure model combining the Cox model with the logistic model. There are the two distinct methods
for estimating the nonparametric baseline hazard function of the model; one is based on a pseudo partial likelihood and the
other is to use an EM algorithm. In this paper, we discuss the consistency and the asymptotic normality of the estimators
from the two methods. Then, we show that the estimator from the pseudo partial likelihood can be characterized by the (forward)
Volterra integral equation, and the estimator from the EM algorithm by the Fredholm integral equation. These characterizations
reveal differences in the properties between the estimators from the two methods. In addition, a simulation study is performed
to numerically confirm the results in several finite samples. 相似文献
98.
T. Okane T. Kashiwakura S. Suzuki S. Sato T. Kinoshita A. Kakizaki T. Ishii 《Zeitschrift für Physik B Condensed Matter》1993,91(4):437-443
We have studied the valence band photoemission spectra of Ni(100) and Ni(110) single crystals near the excitation threshold for 3p core electrons. The resonant behavior of the 6 eV satellite does not depend on both the surface orientation and the polarization of the electric vector of an incident light for excitation. These results indicate that the 6 eV satellite should be under little influence of spatial symmetry of the valence band. In the angle-resolved photoemission spectra of Ni(100), we have observed another broad feature near the 6 eV satellite. It shows the large energy dispersion and is interpreted as due to the interband transition. In Ni(110), we have observed the weak valence band satellites at binding energies of about 9.3 eV and 13.4 eV. They do not show well-defined resonance around the 3p threshold. 相似文献
99.
Hybrids of Copolymers of Fluorene and C60‐Carrying‐Carbazole with Semiconducting Single‐Walled Carbon Nanotubes
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Fumiyuki Toshimitsu Hiroaki Ozawa Prof. Naotoshi Nakashima 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(8):3359-3366
Three different copolymers of C60‐carrying‐carbazole and fluorene units with different copolymer composition ratios were designed and synthesized. On the basis of photoluminescence, atomic force microscopy, and Vis‐NIR and Raman spectroscopic analysis, we found that these copolymers solubilize only semiconducting single‐walled carbon nanotubes (sem‐SWNTs) to form copolymer/sem‐SWNT hybrids, in which energy transfer from the copolymer/C60 moieties to the SWNTs was revealed. By comparing two possible hybrid structures with molecular‐mechanics simulations, the greatest stabilization was found when the C60 moieties lay on the sem‐SWNT surfaces. 相似文献
100.
Ohta A Danev R Nagayama K Mita T Asakawa T Miyagishi S 《Langmuir : the ACS journal of surfaces and colloids》2006,22(20):8472-8477
An aggregation behavior of potassium N-acyl phenylalaninate in dilute aqueous solution was investigated. It was found that this surfactant formed large aggregates at lower concentrations, which were then transformed to micelles at higher concentrations. Fluorescence intensity measurements using a probe were used to examine the effects of alkali concentration, acyl chain length, and solvent isotope on the aggregation behavior. The influence of the alkali concentration suggested that formation of an acid-soap dimer brought about the construction of the large particles at very dilute concentrations. Increases in both the acyl chain length and replacement of H(2)O with D(2)O resulted in stronger hydrophobic interactions; consequently, the large aggregate formation was enhanced. This aggregation behavior has not been observed when racemic modification of N-acyl phenylalaninate has taken place. By using cryo-transmission electron microscopy (TEM) with a Zernike differential contrast phase plate, it was found that the large aggregates were tubes with bilayer structures, which were then transformed into spherical micelles via threadlike micelles with increasing concentration due to a drastic increase in the concentration of ionic species in the aggregate. 相似文献