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21.
22.
Xu J Hasegawa M Harada K Kobayashi H Nagai H Namikoshi M 《Chemical & pharmaceutical bulletin》2006,54(6):852-854
Four new tetramic acid derivatives, named melophlins P, Q, R, and S (1-4), were isolated from two marine sponges of the genus Melophlus collected at Palau, together with seven known melophlins A, D, E, G, H, I, and O. The structures of the new compounds were elucidated on the basis of their spectral data. The absolute stereochemistries at the tetramic acid moieties of the new compounds were determined as 1 : 1 mixtures (racemic) by ESI-LC/MS analysis of derivatives obtained by oxidation and hydrolysis of the respective parent compounds. Melophlins P-S (1-4) showed cytotoxicity against the murine leukemia cell line L1210 with IC(50) values of 20.0, 10.5, 0.85, and 5.13 muM, respectively. 相似文献
23.
Density functional theory (DFT) calculations were employed to investigate the electronic properties of an H-atom terminated graphene patch (hydrographene) smaller than a rhombic C96H26 structure with zigzag edges. Depending on shapes and sizes of hydrographenes, some hydrographenes have the triplet ground state where unpaired electrons are localized on their zigzag edges. The stability of the triplet spin state is diminished, decreasing the hydrographene sizes. The existence of the localized spin densities allows triplet dioxgen to bind into a hydrographene. According to the DFT calculations, the energetics of the dioxygen bindings is negatively influenced by downsizing hydrographenes, as well as depends on their shapes. The size-and shape-dependences of the dioxygen bindings reflect from the stability of the triplet state of a hydrographene, because its localized unpaired electrons can be utilized to be attached to an unpaired electron of triplet dioxygen. 相似文献
24.
Oda A Torigoe H Itadani A Ohkubo T Yumura T Kobayashi H Kuroda Y 《Angewandte Chemie (International ed. in English)》2012,51(31):7719-7723
In its element: Zn(2+) at the M7 site of MFI-type zeolites activates H(2), via ZnH and OH species, and leads to Zn(0) species. The Zn(0) species returns to its original state, a Zn(2+) ion, upon evacuation of the zeolite at 873?K (see picture). The formation of the Zn(0) species is supported by DFT calculations. 相似文献
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26.
Design and Synthesis of 6 α-Corticosteroid Haptens and Their Bovine Serum Albumin(BSA) Conjugates 总被引:1,自引:0,他引:1
The site of attachment of protein carrier to corticosteroids has great influence on the specificity of produced antibody.In order to obtain highly specific and accurate antibodies for bioimmunoassay determination of cortisol,different tether lengths of 60633-corticosteroid haptens and their BSA conjugates were designed and synthesized. 相似文献
27.
In this paper, twelve linear primitive reference patterns are proposed for synthesizing a matched spatial filter, known as a shape invariant filter, which can recognize all patterns with various shapes. Furthermore, reprocessed data, given by correlation between the input object of the system and the reference patterns “correlation diagrams” are introduced for processing peak signals in a digital system. By correlating the diagram from the input object with the standard diagrams, the 26 of the alphabet letters were recognized in the experiment. Moreover, feasibility of the rotational invariance of the filter was suggested by the computer simulation. 相似文献
28.
Hisayoshi Kobayashi Masaru Yamaguchi Satohiro Yoshida 《Theoretical chemistry accounts》1982,60(5):391-398
A new method is presented to analyze the various interactions in reaction systems. The method is especially suited for large and strongly interacting systems where other analyzing methods are not practical. The method could isolate the particular interaction from the whole interaction by a procedure termed the partial diagonalization of the bond order matrix. The usefulness of the method is exemplified by the adsorption of CO on Pt and W surfaces. The interactions on the W surface are much stronger than those on the Pt surface, which is consistent with the experimental data. The role of individual interactions for the weakening of the C-O bond and the formation of the Pt-C and W-C bonds is discussed separately. 相似文献
29.
Hisayoshi Kobayashi Satohiro Yoshida Kenichi Fukui Kimio Tarama Hiroshi Kato 《Chemical physics letters》1978,53(3):457-461
The periodic model of finite surfaces has been employed to investigate the localizability of the chemisorption interaction and to examine the validity of the cluster model. The adsorbate—surface interaction is estimated by the usual perturbation method. The model is applied to chemisorption of hydrogen molecule on a Ni(100) surface. As for the present calculations, the period model is shown to be advantageous over the cluster model in representing both the adsorbate-free surface state and the adsorbate—surface interaction. 相似文献
30.
Hiroaki Tada Tetsuji Ishida Ayako Takao Seishiro Ito Sudip Mukhopadhyay Tomoki Akita Koji Tanaka Hisayoshi Kobayashi 《Chemphyschem》2005,6(8):1537-1543
TiO2 particles loaded with silver nanoparticles with a mean diameter of 1.5 nm exhibit a high photocatalytic activity (84 % conversion after 1 h irradiation) for the reduction of nitrobenzene to aniline with 100 % selectivity in the presence of CH3OH (concentration=100 mM). High-resolution transmission electron microscopic studies of Pt-photodeposited Ag/TiO2 demonstrate that the Ag nanoparticles act as reduction sites in the photocatalytic reaction. Both spectroscopic measurements and density functional theory (DFT) calculations reveal that nitrobenzene is selectively adsorbed onto the Ag surfaces of Ag/TiO2 via partial electron transfer from Ag to nitrobenzene, whereas the interaction between aniline and Ag/TiO2 is weak. The kinetic analysis indicates that the recombination between the electrons flowing into the Ag nanoparticle and the holes left in the TiO2 valence band is significantly suppressed, particularly in the presence of CH3OH. The high activity and selectivity in the present Ag/TiO2-photocatalyzed reduction are rationalized in terms of the charge separation efficiency, the selective adsorption of the reactants on the catalyst surfaces, and the restriction of the product readsorption. 相似文献