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41.
A general expression of the perfect matching number for thel x m x n cubic lattice was conjectured and examined for infinitely large systems. The asymptotic value of the square of the perfect matching number was calculated by numerical integration. The present treatment will give a key to obtain the true analytic solution of the perfect matching numbers for the 3-dimensional lattices. 相似文献
42.
Kaizaki Sumio Kita Przemyslaw Wiśniewska Joanna Sakagami Narumi 《Transition Metal Chemistry》1998,23(4):511-515
Three new complex ions, [Cr(NCS)(R-pdtrp)]-, [Cr(R-pdtrp)(NCSHg)]+ and [Cr(edtrp)(NCSHg)]+, that are derivatives of the trans-equatorial isomers of [Cr(R-pdtrp)(H2O)]0 and [Cr(edtrp)(H2O)]0 (edtrp= ethylenediamine-N,N,N-tripropionate, R-pdtrp= R-propane-1,2-diamine-N,N,N-tripropionate) have been obtained and characterized in solution. Rate constants and activation parameters, including, in two cases, volumes of activation, have been determined. Rate retardation for NCS- ligand release has been observed with increasing acidity within the pH 0–2 range. The mechanism of the reactions has been discussed. 相似文献
43.
Grubišic Sonja Gruden-Pavlović Maja Niketić Svetozar R. Sakagami-Yoshida Narumi Kaizaki Sumio 《Transition Metal Chemistry》2003,28(1):37-42
The structure of trans-equatorial [Cr(edtrp)(H2O)] · 3H2O (edtrp3– is the anion of ethylenediamine-N,N,N-tripropionic acid) was determined by single crystal X-ray diffraction. The chromium(III) ion is surrounded octahedrally by the two nitrogen and three oxygen atoms of the quinquedentate edtrp3–, forming a five-membered diamine ring and the three six-membered -propionato chelate rings. The remaining coordination position is occupied by the H2O ligand. The crystal structure conformation is compared to the result of recent molecular mechanics analysis. The ring strain of R and G chelate rings was found to be in agreement with the previously proposed mechanisms for the C—N bond cleavage and recombination. 相似文献
44.
Takuji Ishikawa Tesuhiro Kodani Tsukasa Moriya Minoru Toriumi Hirokazu Aoyama Takamitsu Furukawa Kiyoshi Fujii 《Journal of fluorine chemistry》2004,125(11):1791-1799
We have synthesized various main-chain fluorinated polymers and studied base-resin properties, such as transparency at 157 nm, solubility in a standard alkaline developer, and lithographic performance. Main-chain-fluorinated polymers were synthesized by copolymerization of tetrafluoroethylene (TFE) with cyclic monomers, especially newly synthesized norbornene derivatives. We studied the correlation between pKa(OH) and the solubility of the copolymers of TFE and functional (fluoroalkyl alcohol group) norbornenes. Their solubility depends on the pKa value of the fluoroalkyl alcohol groups.We studied the impact of the polymerization initiators on base-resin properties. High transparency was obtained by using the fluorocarbon initiator. It was also confirmed that the monocyclic component improves dry-etch resistance and that fluorination at the terminal groups improves alkaline solubility.In addition, we found that the development characteristics of TFE/norbornene copolymers were significantly improved by the stereoselective (endo versus exo) partial protection of the hydroxyl groups in the fluoroalkyl alcohol moiety attached to norbornene unit. The polymer protected only in the exo position of the norbornene unit in the copolymer had a higher Rmax and a higher contrast. Positive-working resists based on these fluoropolymers were developed and 55 nm dense lines could be delineated by exposure at 157 nm wavelength with an alternating phase shift mask on a 0.9 NA 157 nm exposure tool. 相似文献
45.
A gold electrode modified with copper complexes containing a tridentate aromatic amine compound (bis(6-methyl-2-pyridylmethyl)amine ethyl sulfide, which is a model for the nitrite reduction centre of copper-containing nitrite reductase, catalyzed electrochemically the reduction of nitrite to nitrogen monoxide under acidic conditions. 相似文献
46.
Nobuyasu Itoh Takamitsu Otake Yoshie Aoyagi Mayumi Matsuo Takashi Yarita 《Chromatographia》2009,70(7-8):1073-1078
We applied liquid chromatography-dopant-assisted atmospheric pressure photoionization-mass spectrometry to quantify four distinct pesticides (isoprothiolane, fenitrothion, fthalide, and ethophenprox) in unpolished rice flour. Although the effect of acetone as a dopant on enhancement of ionization differed among the pesticides, the analytical results by LC-DA-APPI-MS with a dopant flow rate of 50 μL min?1 were not only repeatable (relative SD < 9%, n = 3) but also comparable to those by gas chromatography–mass spectrometry. 相似文献
47.
48.
C. Akira Horiuchi Yoshikazu Saitoh Takamitsu Utsukihara Shigeo Takahashi Masatoshi Matsushita Liangyou He T. Tomoyoshi Takahashi Chikao Hashimoto Takashi Sugiyama Sukekatsu Nozaki 《应用有机金属化学》2006,20(10):663-668
Reaction of α,β‐unsaturated ketones with cerium(IV) salts or lanthanide triflates in alcohols gave good yields of the corresponding β‐alkoxy compounds. In the case of 2‐cyclopentenone and 2‐cyclohexenone, the 1,1,3‐trialkoxy acetal derivatives were obtained preferentially accompanied by β‐alkoxyketone, except 2‐cycloheptenone. However, in the reaction of 2‐cycloheptenone with alcohol using cerium(IV) sulfate (CS)‐molecular sieve, 1,1,3‐trialkoxy derivatives were obtained. Also, in the cases of 1‐penten‐3‐one, 4‐hexen‐3‐one and 3‐hepten‐2‐one, 1,1,3‐trialkoxy derivatives were obtained preferentially. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
49.
Youngchan Kim Dr. Kazuya Kanemoto Ken Shimomori Prof. Dr. Takamitsu Hosoya Prof. Dr. Suguru Yoshida 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(28):6136-6140
Catalytic thiolation and azidation of a single C−F bond of trifluoromethylarenes were achieved assisted by an ortho-silyl group with all-in-one reagents to generate a trityl cation and nucleophiles. The reactions catalyzed by ytterbium triflate efficiently afforded a wide variety of difluoromethylenes avoiding the further C−F bond cleavage, by virtue of the mild conditions without the generation of a Brønsted acid. 相似文献
50.
In fluorinated alcohols, the cationic Rh(I) species, which is derived from [Rh(COD)Cl]2 and AgSbF6, efficiently catalyzed intramolecular [4+2] cycloaddition reactions of ester-tethered 1,3-diene-8-yne derivatives. The catalytic system was also effective in intramolecular [5+2] cycloaddition reactions of ester-tethered omega-alkynyl vinylcyclopropane compounds. 相似文献