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81.
82.
The effect of the calcium-binding protein regucalcin on the Ca2+ transport system in the liver microsomes from fed rats was investigated. Ca2+ transport was assayed by the method of Millipore filtration to estimate microsomal 45Ca2+ accumulation following addition of 10 mM adenosine triphosphate (ATP). 45Ca2+ uptake was retarded by the presence of regucalcin (1.0-4.0 microM). This retardation was remarkable at 1 min after regucalcin addition, while appreciable retardation was no longer seen at 5 min. Regucalcin (2.0 microM)-induced retardation of 45Ca2+ uptake was prevented by the presence of calmodulin (5 micrograms/ml). Calmodulin alone (1 and 5 micrograms/ml) caused a significant increase in 45Ca2+ uptake at 3 min after the start of incubation. Also, regucalcin (2.0 microM)-induced retardation of 45Ca2+ uptake was completely blocked by the presence of a Ca2(+)-trapping agent, oxalate (3 mM). On the other hand, 45Ca2+, which accumulated in microsomes during 5 min after ATP addition, was markedly released by the addition of regucalcin. This release was dose-dependent (0.5-4.0 microM). Guanosine triphosphate (GTP; 10-100 microM) caused a significant release of 45Ca2+ from the microsomes. The presence of regucalcin (2.0 microM) further enhanced the GTP effect. Regucalcin (2.0 microM)-induced release of 45Ca2+ was not blocked by the presence of the protein thiol-protecting agent dithiothreitol (0.1 mM). The presence of oxalate (3 mM) completely blocked the effect of regucalcin on 45Ca2+ release from the microsomes. These results indicate that regucalcin stimulates Ca2+ release from liver microsomes, and that the protein retards the microsomal Ca2+ uptake. The present study suggests that regucalcin can regulate the Ca2+ transport system in rat liver microsomes. 相似文献
83.
We report in this study the presence of Janus particles, which are candidates for use with electronic color papers. We used negatively charged polystyrene particles (370 nm) as the core particles, and gold was then sputtered onto their packed monolayer under several conditions. The sputtered particles were next redispersed into the aqueous medium by gentle sonication. Gold nanoparticles localized on one side of the cores could also serve as seeds for subsequent shell growth by electroless gold plating. Through these treatments, a series of well-dispersed Janus particles were obtained with gold nanostructures of different size and shape only on one side. Their dispersions showed different colors originating from the surface plasmon resonance absorption of gold nanoparticles localized on the hemisphere. The particles obtained by this approach have potential applications such as in sensors and electronic color paper. 相似文献
84.
Solid-supported α,α′-dioxothiones are easily obtained starting from β-ketoester modified Wang and hydroxymethylated polystyrene resins. The hetero Diels-Alder reactions (HDAR) of these species, used either as electron-poor dienes or dienophiles, followed by a simple cleavage of the products from the resin by trans-esterification with sodium methoxide, allowed the isolation of the desired cycloadducts in overall yields up to 90%. 相似文献
85.
Mori Toshiyuki Drennan John Wang Yarong Li Ji-Guang Ikegami Takayasu 《Journal of Thermal Analysis and Calorimetry》2002,70(2):309-319
Doped ceria (CeO2) compounds are fluorite type oxides that show oxygen ionic conductivity higher than yttria stabilized zirconia, in oxidizing
atmosphere. In order to improve the conductivity, the effective index was suggested to maximize the oxygen ionic conductivity
in doped CeO2 based oxides. In addition, the true microstructure of doped CeO2 was observed at atomic scale for conclusion of conduction mechanism. Doped CeO2 had small domains (10-50 nm) with ordered structure in a grain. It is found that the electrolytic properties strongly depended
on the nano-structural feature at atomic scale in doped CeO2 electrolyte.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
86.
(2R,5S)-2-Methyl-5-hexanolide and its antipode were synthesized in highly optically pure state (?98–99% e.e.) starting from ethyl (S)-lactate and the enantiomers of methyl β-hydroxyisobutyrate. The specific rotations of our samples were [α]D±91.0-93.5° (CHCl3), while the reported values of the samples prepared by resolution or asymmetric synthesis were ±64.5–65.6°. 相似文献
87.
The α-haloester having an internal double bond was allowed to react with a catalytic amount of Pd(PPh3)4 to afford a cyclized product in a fairly good yield and the same product was obtained by treatment with Pd(OAc)2 to ketene silyl acetal. 相似文献
88.
Kazuo Iguchi Soichiro Kaneta Kenichiro Mori Yasuji Yamada Atsushi Honda Yo Mori 《Tetrahedron letters》1985,26(47):5787-5790
New halogenated marine prostanoids, chlorovulone I, II and III were isolated from the stolonifer Quoy and Gaimard. The structure elucidation and the antitumor activity of chlorovulones were described. 相似文献
89.
Both the enantiomers of 2,3-dihydro-2-isopropyl-2,5-dimethylfuran were synthesized employing the Sharpless asymmetric epoxidation reaction. The (R)-(—)-enantiomer of this cyclic enol ether was also synthesized starting from (R)-(—)-linalool. 相似文献
90.
The reaction of cycloalkanones with silicon tetraisothiocyanate in the presence of (Me3SiO)2SO2?nBu3SnF or Zn(NCS)2 provides 1-cycloalkenyl isothiocyanates in good yields under mild conditions. 相似文献