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排序方式: 共有167条查询结果,搜索用时 15 毫秒
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Krisztina Sebk‐Nagy Lszl Biczk Akimitsu Morimoto Tetsuya Shimada Haruo Inoue 《Photochemistry and photobiology》2004,80(1):119-126
Effects of solvent, pH and hydrogen bonding with N‐methylimidazole (MIm) on the photophysical properties of 1‐hydroxyfluorenone (1HOF) have been studied. Fluorescence lifetime, fluorescence quantum yield and triplet yield measurements demonstrated that intersystem crossing was the dominant process in apolar media and its rate constant significantly diminished with increasing solvent polarity. The acceleration of internal conversion in alcohols paralleled the strength of intermolecular hydrogen bonding. The faster energy dissipation from the singlet‐excited state in cyclohexane was attributed to intramolecular hydrogen bonding. The pKa of 1HOF decreased from 10.06 to 5.0 on light absorption, and H3O+ quenched the singletexcited molecules in a practically diffusion‐controlled reaction. On addition of MIm in toluene, dual fluorescence was observed, which was attributed to reversible formation of excited hydrogen‐bonded ion pair. Rate constants for the various deactivation pathways were derived from the combined analysis of the steady‐state and the time‐resolved fluorescence results. 相似文献
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Yoshitomo Kashiwagi Yumiko Takamori Kentaro Yoshida Tetsuya Ono 《Electroanalysis》2013,25(12):2575-2577
This paper describes the electrocatalytic oxidation of amines on TEMPO (2,2,6,6‐tetramethylpiperidine‐1‐oxyl)‐modified electrodes prepared by electrochemical copolymerization of TEMPO precursor containing pyrrole side chain and 2,2′‐bithiophene. The modified electrode exhibits electrocatalytic activity for the oxidation of primary and secondary amines. Cyclic voltammetric studies showed that the peak current of the cyclic voltammogram increased linearly with increasing concentration of amine in the sample solution. 相似文献
5.
Over the past two decades, the spatiotemporal analysis of fluorescently labeled single RNA species has provided a broad insight into the synthesis, localization, degradation, and transport of RNA. To elucidate the dynamic behavior of functional RNAs in living cells, researchers throughout the world have proposed numerous fluorometric strategies for intracellular RNA imaging. Because, like most other biological molecules, RNA is intrinsically nonfluorescent, the development of methods for the labeling of RNAs of interest with fluorescent molecules is essential. Several artificial tag sequences have been attached onto the 3′ end of target RNAs and used as scaffolds for interacting with their fluorescent counterparts. In this Personal Account, we focus on the methods that have been developed to show how RNAs expressed in cells can be labeled and visualized by fluorescent proteins, small molecules, or nucleic acids. Each of these methods is designed to increase the sensitivity and specificity for imaging or to decrease the background fluorescence. 相似文献
6.
Sera M Ichikawa H Yokoo T Akimitsu J Nishi M Kakurai K Kunii S 《Physical review letters》2001,86(8):1578-1581
The magnetic field induced antiferromagnetic moment M(AF) at low magnetic fields in the antiferroquadrupolar (AFQ) ordered phase of CeB6 was investigated by elastic neutron diffraction experiments for H parallel [110]. The peak intensity at the AF magnetic reciprocal point (1 / 2,1 / 2,1 / 2) corresponding to M(2)(AF) increases with decreasing temperature below the AFQ ordering temperature T(Q), and exhibits a broad maximum at T approximately 3 K and decreases with a further decrease of temperature. This unusual behavior of M(AF) at low fields is explained as a result of the competition between the AF-octupolar and AF-exchange interactions in the O(xy) type AFQ ordered state. 相似文献
7.
H. Takahashi N. Mri Y. Nagata S. Nakamura T. Uchida J. Akimitsu Y. Tokura 《Physica C: Superconductivity and its Applications》1993,210(3-4):485-488
The superconducting transition temperature (Tc) of Ba0.62K0.38Bio3 (Tc=30 K) has been measured under high pressure up to 8 GPa. It is observed that Tc increases initially with pressure, as reported by Uwe et al., Shirber et al. and Huang et al., but decreases above 4 GPa. The Hall coefficient of Ba0.62K0.38BiO3 has been measured up to 1.2 GPa. The absolute value of the Hall coefficient decreases with pressure by 10% GPa, the value of which is almost the same as that obtained in most CuO-based high-temperature superconductors. 相似文献
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S. Ohsugi S. Matsumoto Y. Kitaoka M. Matsuda M. Uehara T. Nagata J. Akimitsu 《Hyperfine Interactions》2004,159(1-4):9-14
Nuclear spin–lattice relaxation rate T
1
−1 has been measured for the ladder sites of two single crystals Sr14Cu24O41 (Sr14-A,B) by 63Cu NMR/NQR. The hole localization around 100 K appears as a peak in the T variation of T
1
−1(NQR). On the other hand, it is suppressed in the T
1
−1 (NMR) data under the magnetic field H ∼ 11 T, and a new peak appears around 20 K. T
1
−1(NMR) around the peak is more enlarged for Sr14-B than for Sr14-A. Hence, holes on the ladders of Sr14-B tend to be more localized.
This is considered to be an origin for the occurrence of the magnetic order in Sr14-B under H ∼ 11 T. 相似文献