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91.
Kanyiva KS Kashihara N Nakao Y Hiyama T Ohashi M Ogoshi S 《Dalton transactions (Cambridge, England : 2003)》2010,39(43):10483-10494
A combination of Ni(cod)(2) and PCyp(3) is found to be an effective catalyst for chemoselective activation of the C-H bond of fluoroarenes over C-F bonds followed by insertion of alkynes to allow direct alkenylation of the electron-deficient arenes. The characteristics of the reactions are: a C-H bond ortho to a fluorine substituent is selectively activated; the reactivity of fluorobenzenes is roughly proportional to the number of fluorine atoms. The reaction conditions tolerate a broad range of both alkynes and fluoroarenes containing both electron-withdrawing and -donating groups, thus allowing efficient synthesis of a variety of substituted ethenes containing a fluoroaryl motif in high regio- and stereoselective manners. Mechanistic studies including both labeling experiments and stoichiometric reactions reveal that oxidative addition of C-H bonds in fluoroarenes to nickel(0) is kinetically highly facile whereas that of C-F bonds is thermodynamically favoured. 相似文献
92.
Masato Saitoh 《Journal of sound and vibration》2011,330(9):2062-2072
In this study, a lumped parameter model that properly simulates the impedance characteristics at the extremity of a uniform, isotropic, homogeneous rod on a viscoelastic medium is proposed. The lumped parameter model consists of springs, dashpots, and so-called “gyro-mass elements”. The gyro-mass elements generate a reaction force proportional to the relative acceleration of the nodes between which they are placed. This model consists of units arranged in series, each unit consisting of a spring, a damper, and a gyro-mass element arranged in parallel. A formula is proposed for determining the properties of the elements in the units calculated from a closed-form solution based on a modal expansion. The impedance function simulated by the proposed model shows good agreement with the rigorous impedance function derived from the differential equation of motion of the rod. The results obtained by employing this model in some example applications show that the accuracy of the model is appreciably high when compared with conventional finite element models. A great advantage of this model is that a significant reduction of the number of degrees of freedom can be achieved for solving recent vibration problems with high-frequency excitations, such as ultrasonic vibrations. 相似文献
93.
We propose and demonstrate a scheme for boosting the efficiency of entanglement distribution based on a decoherence-free subspace over lossy quantum channels. By using backward propagation of a coherent light, our scheme achieves an entanglement-sharing rate that is proportional to the transmittance T of the quantum channel in spite of encoding qubits in multipartite systems for the decoherence-free subspace. We experimentally show that highly entangled states, which can violate the Clauser-Horne-Shimony-Holt inequality, are distributed at a rate proportional to T. 相似文献
94.
For an affine algebra of nonexceptional type in the large rank we show the fermionic formula depends only on the attachment of the node 0 of the Dynkin diagram to the rest, and the fermionic formula of not type A can be expressed as a sum of that of type A with Littlewood–Richardson coefficients. Combining this result with Kirillov et al. (2002) [13] and Lecouvey et al. (2011) [18] we settle the X=M conjecture under the large rank hypothesis. 相似文献
95.
96.
We shall give a necessary and sufficient condition for uniformly integrable martingales to converge in the norm topology in a Banach function space. This yields a new characterization of the probabilisticA p -condition introduced by Izumisawa and Kazamaki [4]. 相似文献
97.
Atsushi Sudo Masato Sato Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2001,39(21):3789-3796
A polymer with a 2‐azetidinone moiety in its main chain was efficiently synthesized by [2 + 2] cycloaddition of bisimine with bisketene. The bisketene was easily prepared by dehydrochlorination of the corresponding dicarboxylic acid chloride and was used without purification. The treatment of the obtained polymer with lithium aluminum hydride resulted in a reductive ring‐opening reaction of the 2‐azetidinone moiety in the main chain that gave the corresponding linear polyamine with hydroxymethyl side chains. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3789–3796, 2001 相似文献
98.
Microwave-assisted synthesis method enabled the preparation of the (tris-acetylacetonate)(2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolinate) terbium(III) (Tb(acac)3(dmdpphen)) complex with outstanding high green luminescence. This method is appropriate for green chemistry and energy-saving processes. The Tb(acac)3(dmdpphen) complex has good thermal stability. Emission peaks are assigned to the f-f transitions of the Tb3+. The Tb(acac)3(dmdpphen) complex is expected to be used in functional materials of electronic products. 相似文献
99.
Tetsushi Kijima Masakazu Nishida Haruhiko Fukaya Masato Yoshida Hideo Sawada 《Journal of polymer science. Part A, Polymer chemistry》2013,51(12):2555-2564
A reddish‐brown fluoroalkyl end‐capped 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) oligomer/acetone composite was prepared by heating the white oligomer powder with acetone at 80 °C for 3 h. The color was not observed in the corresponding non‐fluorinated AMPS oligomer/acetone composite, which was prepared under similar conditions. The coloring was probably caused by the formation of acetone polyaldol condensation products in the fluorinated oligomeric gel network cores. The colored RF‐(AMPS)n‐RF/acetone composite powders were stable and did not exhibit any color change after 2 years in natural light at room temperature. The colored composite powders dissolved in methanol to give a reddish‐brown solution at room temperature. However, the retro‐polyaldol condensation decolored the solution after 1 day at room temperature. This is the first example of the retro‐aldol polycondensation of acetone under mild conditions. The decoloration increased by between 38‐ and 70‐fold under UV irradiation, compared with that in dark conditions. The coloring–decoloring behavior was consistent and repeatable; therefore our fluorinated oligomer/acetone composites are promising candidates for new fluorinated coloring materials. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2555–2564 相似文献
100.
Yusuke Iwasaki Masato Goto Keisuke Mochizuki Emi Terayama Rie Ito Koichi Saito Norihiro Sugino Tsunehisa Makino Hiroyuki Nakazawa 《Biomedical chromatography : BMC》2011,25(4):503-510
A selective and sensitive HILIC‐MS/MS method for the simultaneous quantification of nicotine and its metabolites in human maternal and cord sera was developed and validated. After solid‐phase extraction, LC separation was achieved on a hydrophilic interaction chromatography. The validated method is capable of selective identification as well as accurate and sensitive quantification. Analyte recovery ranged from 86.2 to 107.7% and intra‐ and inter‐day assay precision were less than 15% relative standard deviation. This sensitive HILIC‐MS/MS method can be used to determine nicotine and its metabolic profile in smokers. This validated method is useful for the determination of nicotine and its metabolites in human serum in future studies of the effects of nicotine exposure on neonatal outcome. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献