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排序方式: 共有183条查询结果,搜索用时 171 毫秒
1.
CeOs4Sb12晶体中由于导电电子与Ce3+ 4f1电子之间存在c-f杂化作用导致费米面附近存在能量间隙.这种c-f近藤相互作用和能量间隙是理解CeOs4Sb12物理性质,如近藤绝缘体行为、Ce3+磁矩在低温下猝灭以及重费米性等电、磁性质的关键.当用LAM-D中子谱仪对粉末CeOs4Sb12进行测量时,可以得到不同温度下CeOs4Sb12的非弹性中子散射谱.结果表明CeOs4Sb12中存在近藤相互作用,其作用强度为3.1 meV,证实了CeOs4Sb12为近藤绝缘体.中子测量得出CeOs4Sb12德拜温度为317 K. 相似文献
2.
CeOs4Sb12晶体中由于导电电子与Ce3+ 4f1电子之间存在c-f杂化作用导致费米面附近存在能量间隙.这种c-f近藤相互作用和能量间隙是理解CeOs4Sb12物理性质,如近藤绝缘体行为、Ce3+磁矩在低温下猝灭以及重费米性等电、磁性质的关键.当用LAM-D中子谱仪对粉末CeOs4Sb12进行测量时,可以得到不同温度下CeOs4Sb12的非弹性中子散射谱.结果表明CeOs4Sb12中存在近藤相互作用,其作用强度为3.1 meV,证实了CeOs4Sb12为近藤绝缘体.中子测量得出CeOs4Sb12德拜温度为317 K.
关键词:
非弹性中子散射
填充式方钴矿
近藤绝缘体 相似文献
3.
M Ogawa H Matsuda H Eto T Asaoka T Kuraishi A Iwasa T Nakashima K Yamaguchi 《Chemical & pharmaceutical bulletin》1991,39(9):2301-2307
A series of vinylimidazoles containing a hetero atom such as sulfur or oxygen at a beta-position of the vinyl group was prepared and the antifungal activities were tested. It was found that sulfur-substituted derivatives such as (E)-1-[2-(methylthio)-1-[2-(pentyloxy)phenyl]ethenyl]-1H-imidazole (5a-5) and (E)-1-[1-[2-(hexyloxy)phenyl]-2-(methylthio)ethenyl]-1H-imidazole (5a-6) showed excellent antifungal activities against dermatophytes and yeast cells. The stereochemistry of the hydrochloride salt of 5a-5 was determined by X-ray crystallography. The structure-activity relationships were discussed. 相似文献
4.
Mikio Ohno Keiichi Ohno Junkichi Sohma 《Journal of polymer science. Part A, Polymer chemistry》1987,25(5):1273-1284
Plasma-polymerized methyl methacrylate (PPMMA) film was produced by a radio-frequency glow discharge of methyl methacrylate (MMA) gas with argon. PPMMA deposited under a plasma of mild energy was separated into a soluble fraction (sol-PPMMA) and an insoluble matrix (insol-PPMMA), which is highly crosslinked, by solvent-extraction and filtration. The chemical structure of the sol-PPMMA was determined by pyrolysis/gas chromatography, IR spectroscopy, 1H-NMR, 13C-NMR, and elemental analysis techniques. On the other hand, the structure of the insol-PPMMA was examined with IR spectroscopy, 13C-NMR with CP/MAS method, and elemental analysis. The crosslinking mechanism in the plasma polymerization of MMA is discussed on the basis of product analyses of the sol-PPMMA and the insol-PPMMA. 相似文献
5.
The mechanism of uv (λ > 325 nm) photodegradation of polypropylene (PP) containing N,N,N′,N′-tetramethyl-p-phenylenediamine (T4MPD) has been investigated by means of ESR spectroscopy. The observed spectra after uv irradiation of both isotactic-PP (IPP) and stereoblock-PP (SPP) samples in vacuum at 77 K consisted principally of a broad singlet which was assigned to a T4MPD cation radical (T4MPD+·). On the other hand, the spectrum observed after irradiation of an atactic polypropylene (APP) sample at 77 K in vacuum was resolved into several components which decayed almost up to ca. 263 K to give rise to the broad singlet of T4MPD+·. One component was a sharp quartet which was assigned to a methyl radical, ·CH3·. The other component, a singlet, was attributed to a trapped electron, et?.By comparison of the ESR spectrum of deuterated T4MPD with that of the normal compound it was found that 60 ~ 70% of the methyl radicals arose from the added T4MPD due to β-scission, which also formed the N,N,N′-trimethyl-p-phenylenediamine radical, T3MPD·. The T3MPD· radical presumably captures an electron at lower temperatures to become a carbanion, T3MPD?, which releases the electron to reproduce the T3MPD· radical at elevated temperatures. This production of the radical T3MPD· due to the liberation of an electron provides an explanation for the observed increase in intensity of the decay curve in the temperature range from ? 168 K to 185 K. The remaining fraction, 30 ~ 40%, of the total methyl radicals was produced from the PP matrix by an energy transfer from the excited T4MPD1 to the PP matrix. The broad singlet which appeared in the temperature range near 195 K was attributed to an acyl radical ~CH2CH(CH3)CH2?O from the observed g-value. By photoillumination of this sample this broad singlet was converted reversibly into the quartet which was assigned to the radical ~CH2CH(CH2·)CH2CHO. 相似文献
6.
7.
Abstract— The photoreaction cycle of 13- cis -bacteriorhodopsin (13- cis -bR) was investigated by low temperature spectrophotometry using two different preparations; 13- cis -bR constituted from bacterioopsin and 13- cis -retinal, and dark-adapted bacteriorhodopsin (bRD ), which is an equi-molar mixture of 13- cis -bR and trans -bR.
By irradiation with 500 nm light at — 190°C, 13- cis -bR was converted to its batho-product, batho-13- cis -bR (batho-bR13 ), which is different from batho-product from trans -bR, batho-bRt . On warming batho-bR13 to -5°C in the dark, it completely changed to trans -bR. We estimated the composition of 13- cis -bR and trans -bR in the warmed sample spectrophotometrically and then the absorption spectrum of batho-bR13 was calculated. The absorption maximum lies at 608 nm, 1250 cm−1 longer than that of 13- cis -bR; the molar extinction coefficient (ε) is about 74000 M −1 cm−1 , larger than that of 13- cis -bR (52000 M −1 cm−1 ).
On the warming the sample containing batho-bR13 formed by irradiating 13- cis -bR or bRD at — 190°C, we could not detect other intermediates such as the lumi- or meta-intermediates seen in trans-bR system. 相似文献
By irradiation with 500 nm light at — 190°C, 13- cis -bR was converted to its batho-product, batho-13- cis -bR (batho-bR
On the warming the sample containing batho-bR
8.
Abdel-Moneim Abu-Elfotoh Kazuyuki TsuzukiTram Bao Nguyen Soda ChanthamathKazutaka Shibatomi Seiji Iwasa 《Tetrahedron》2013
Ruthenium(II)/dimethyl phenyloxazoline (Ru(II)/dm-Pheox) complex 2a and its macroporous-polymeric-catalyst 4 were found to be very rapid and efficient catalysts in the hydrogen peroxide oxidation of 1,2- and 1,4-dihydroxy arenes. Most of the quinone products were delivered in 99% yield. The polymeric-catalyst 4 could be reused at least five times. 相似文献
9.
10.
A high‐performance liquid chromatography assay with a triazole‐bonded column for evaluation of d‐amino acid oxidase activity 下载免费PDF全文
Megumi Iwasaki Yoshiyuki Kashiwaguma Chihiro Nagashima Mao Izumi Ayano Uekusa Sumiko Iwasa Mayu Onozato Hideaki Ichiba Takeshi Fukushima 《Biomedical chromatography : BMC》2016,30(3):384-389
Elution profiles of kynurenic acid (KYNA) and 7‐chlorokynurenic acid (Cl‐KYNA) were examined by high‐performance liquid chromatography (HPLC) using a triazole‐bonded stationary phase column (Cosmosil® HILIC) under isocratic elution of a mobile phase consisting of CH3CN–aqueous 10 mm ammonium formate between pH 3.0 and 6.0. The capacity factors of KYNA and Cl‐KYNA varied with both the CH3CN content and the pH of the mobile phase. The elution order of KYNA and Cl‐KYNA was reversed between the CH3CN‐ and H2O‐rich mobile phases, suggesting that hydrophilic interactions and anion‐exchange interactions caused retention of KYNA and Cl‐KYNA in the CH3CN‐ and H2O‐rich mobile phases, respectively. The present HPLC method using a triazole‐bonded column and fluorescence detection (excitation 250 nm, emission 398 nm) was applied to monitor in vitro production of KYNA from d ‐kynurenine (d ‐KYN) by d ‐amino acid oxidase (DAO) using Cl‐KYNA as an internal standard. A single KYNA peak was clearly observed after enzymatic reaction of d ‐KYN with DAO. Production of KYNA from d ‐KYN was suppressed by the addition of commercial DAO inhibitors. The present HPLC method can be used to evaluate DAO activity and DAO inhibitory effects in candidate drugs for the treatment of schizophrenia. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献