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排序方式: 共有551条查询结果,搜索用时 46 毫秒
111.
Oseki Y Fujitsuka M Cho DW Sugimoto A Tojo S Majima T 《The journal of physical chemistry. B》2005,109(41):19257-19262
Photoinduced intramolecular charge separation (CS) and recombination (CR) processes of the tetrathiophene-substituted benzene dyads with an amide spacer (4T-PhR, R = 4-H (1), 4-CN (2), 3,4-(CN)2 (3), 4-NO2 (4), 3,5-(NO2)2 (5)) in solvents of different polarities were investigated using various fast spectroscopies. It was revealed that the CS rates depend on the ability of the acceptor and solvent polarity. Ultrafast CS with the rate of 5 x 10(12) s(-1) was revealed for 5 in PhCN and MeCN. The ultrafast CS can be attributed to the large electronic coupling matrix element between the donor and the acceptor despite the relative long donor-acceptor distance. The existence of the state with large electron density on the spacer between 14T*-PhR and LUMO should facilitate the CS process in the present dyad system. It was also revealed that the CR rates in these dyads were rather fast because of the enhanced superexchange interaction through the amide spacer. 相似文献
112.
Kikuchi Y Yamada H Kunimori H Tsukada T Hozawa M Yokoyama C Kubo M 《Langmuir : the ACS journal of surfaces and colloids》2005,21(8):3273-3278
In this study, the aggregation and breakup behaviors of latex particles in shear flow confined between two parallel plates were investigated using an in situ observation apparatus with a laser scanning confocal microscope. To investigate the effects of shear rate and the gap width between two parallel plates on the size and structure of the aggregates in the steady state, the distributions of the projected cross-sectional area and perimeter-based fractal dimension of the aggregates were measured. As a result, the average size of the aggregates decreases as shear rate increases and the gap width decreases due to the hydrodynamic effect acting on the aggregates. The size distributions of the aggregates become narrow as the gap width decreases. In addition, the fractal dimension, that is, the structure of the aggregates, was almost independent of shear rate and the gap width and approximately 1.2, which suggests that the aggregates are relatively compact. 相似文献
113.
S. Hisamatsu T. Katsumata Y. Takizawa 《Journal of Radioanalytical and Nuclear Chemistry》1992,161(2):455-463
Tritium (3H) concentrations in diet samples from Akita City, northern Japan, and in human tissue samples from the general population of Akita Prefecture were analyzed to study fallout3H transfer.3H concentrations in human soft-tissue samples have been previously found to be similar to those in diet samples. In this study, higher organically-bound3H (OBT) concentrations were found in human costal cartilage and sternum samples than in the soft-tissues. Mean residence times of OBT in the cartilage and sternum were estimated to be 57 years and <6 years, respectively, with a single compartment model which took into account compartment growth. 相似文献
114.
Nguyen Chung Thanh Takanori Kajioka Yasunori Taga Satoshi Ogawa Yosuke Miyahara Mitsunori Oda 《Tetrahedron》2006,62(48):11227-11239
After a preliminary search of the reaction conditions for the Suzuki-Miyaura cross-coupling of haloazulenes with arylboronic acids, the title compounds were synthesized either by the direct coupling reaction between 1,3-dihaloazulene and the corresponding N,N-disubstituted 4-aminophenylboronic acids or by a two-step sequence involving the cross-coupling with 4-bromophenylboronic acid and subsequent Pd-catalyzed amination. Application of the title diamines to a hole-injecting material in organic electroluminescent devices was carried out to provide their prominent characteristics as a novel durable, non-cyanine and non-polyamine substance without color fade. The diamine derivatives, extended by an ethynyl unit between the azulenyl core and the 4-aminophenyl moiety, were also synthesized and found, unfortunately, unsuitable for vacuum deposition in preparing a multilayer composite. 相似文献
115.
Y. Ohtsuka M. Yamamoto Y. Takaku S. Hisamatsu J. Inaba 《Journal of Radioanalytical and Nuclear Chemistry》2006,268(2):397-403
Summary A
rapid method was developed using ultrafilters with a tangential flow filtering
system for molecular size separation of naturally occurring 210Pb
and 210Po in a freshwater sample. Generally, ultrafiltering of a
large volume water sample for measuring the nuclides was too time consuming and
not practical. The tangential flow filtering system made the filtering time
short enough to adapt for in-situ ultrafiltering the large volume sample. In this
method, a 20 liter water sample was at first passed through the 0.45mm pore size
membrane filter immediately after sample collection to obtain suspended
particle matter [>0.45mm particulate fraction (PRT)]. Two ultrafilters (Millipore
Pellicon 2ò)
were used sequentially. The nuclides in the filtrate were separated into three
fractions: high molecular mass (100 kDa-0.45mm; HMM), low molecular mass (10 k-100 kDa;
LMM) and ionic (<10 kDa; INC) fractions. It took 80 minutes to process the
sample after collection. The cut-off molecular size of each ultrafilter was
confirmed by size exclusion chromatographs (SEC) of the LMN and the HMM
fractions. Adsorption of the nuclides and organic compounds in the sample onto
the ultrafilters was negligibly small. Good reproducibility of the nuclide
concentrations in each fraction was confirmed by repeated experiments. The
method was successfully applied to obtaine the molecular size distributions of 210Pb
and 210Po in an oligotrophic lake, Lake Towada located in the northern
area of Japan.</p>
</p> 相似文献
116.
117.
Minoru Yamaji Hideki Okamoto Kenta Goto Shin-ichiro Kato Fumito Tani Yosuke Nakamura 《Tetrahedron letters》2018,59(13):1216-1219
We prepared isomeric compounds 2a and 2b having fused skeletons of coumarin and fluorene by photochemical cyclization of olefin 1. They were successfully separated by chromatography, and characterized by NMR spectroscopic and X-ray crystallographic analyses. The molecular structure of 2a was nonplanar due to the repulsion between the carbonyl group of the coumarin moiety and the methylene group at 9-position on the fluorene skeleton whilst that of 2b was planar. They showed different absorption and fluorescence features in solution whereas their spectral profiles of triplet–triplet absorption and phosphorescence were similar to each other. 相似文献
118.
Yosuke Uchinashi Katsunori Tanaka Yoshiyuki Manabe Yukari Fujimoto 《Journal of carbohydrate chemistry》2013,32(2):55-67
Efficient α-sialylation with a C5 azide sialyl donor was investigated under microfluidic conditions using a microreactor composed of a Comet X-01 micromixer and a tube reactor. Precise temperature control realized excellent α-selectivity, and Siaα(2,6)Gal, Siaα(2,3)Gal, and Siaα(2,9)Sia disaccharides were obtained in moderate to good yields. 相似文献
119.
120.
Yosuke Ishii 《Journal of Physics and Chemistry of Solids》2010,71(4):511-576
We have investigated the Li-ion battery anode properties of several kinds of mesoporous composites of carbon and titanium dioxides (titania, TiO2) prepared by tri-constituent co-assembly method. The maximum reversible capacity (197 mAh/g) at current density of 50 mA/g was obtained for the composite of TiO2:carbon=7:3 calcined at 600 °C. It was also found that the composite maintained the high reversible capacity as large as 109 mAh/g even at the high current density of 1000 mA/g. 相似文献