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81.
Jun-Ichi Anzai Yoko Sakata Yasuhiro Suzuki Akihiko Ueno Tetsuo Osa 《Journal of polymer science. Part A, Polymer chemistry》1983,21(3):855-864
Crown ether-modified polyethylenimines (PEI-CR) were prepared to elucidate their cation binding efficiency and selectivity by liquid-liquid and solid-liquid extraction methods. With alkali metal cations it was found that polyethylenimines containing benzo-15-crown-5 moieties (Ia and Ib) extracted all cations examined more efficiently than their monomeric analogs, especially in the cases of K+ and Rb+ cations. The solid-liquid extraction revealed clearly that the polymers complexed with K+ and Rb+ cations according to a 1:2 cation-to-crown stoichiometry. The high selectivities of the polymers for K+ and Rb+ were interpreted in terms of the favourable conformation of the polymer chain for the formation of intramolecular 1:2 complexes. On the contrary, these polymers bound alkali earth cations less effectively with low selectivities. 相似文献
82.
[reaction: see text]. Phenylalanine-derived B-aryl-N-tosyloxazaborolidinones selectively activate one of two enantiotopic oxygen atoms in prochiral anti dioxane acetals derived from meso-1,3-diols, leading to enantioselective formation of ring-cleavage products. The reaction is utilized as a key step in asymmetric desymmetrization of meso-1,3-diols. 相似文献
83.
Mariko Kusabe Hiromitsu Kozuka Satoru Abe Hiroshi Suzuki 《Journal of Sol-Gel Science and Technology》2007,44(2):111-118
Hydroxypropylcellulose (HPC)–titania hybrid thin films were prepared by sol–gel method where titanium tetraisopropoxide Ti(OC3H7
i
)4 was hydrolyzed under acidic conditions in the presence of HPC, followed by dip-coating and drying at 120 °C for 24 h. The
viscosity average molecular weight of HPC was 55,000–70,000 or 110,000–150,000, and the TiO2/(HPC + TiO2) mass ratio ranged from 0 to 1, which was calculated on the assumption that all Ti(OC3H7
i
)4 is converted into TiO2. The films were 0.35–1.0 μm thick, transparent in visible region and opaque in ultraviolet (UV) region, where the optical
absorption coefficient in UV region increased with increasing titania content. The refractive index increased with increasing
titania content, ranging from 1.6 to 1.8 for the hybrid thin films. The pencil hardness increased from 6B to 5H, the durability
in hot water significantly increased and the contact angle of water on films increased from 35° to 89° with increasing titania
content. Crack-free films could be deposited on organic polymer substrates irrespective of titania or HPC contents, where
cracking did not occur at higher HPC contents even when the substrate was bent. 相似文献
84.
H Kimata K Nakajima H Suzuki T Koide S Yamamoto T Narita 《Chemical & pharmaceutical bulletin》1991,39(12):3327-3330
To study the thrombolytic effect of tissue plasminogen activator (t-PA) on cerebral emboli, we characterized cerebral embolization in stroke-prone spontaneously hypertensive rats (SHRSPs) and Wistar Kyoto rats (WKYs). [125I]Fibrin clot particles (20-100 microns diameter) were injected twice at an interval of 90 min into the left internal carotid artery of WKYs and SHRSPs. After each injection, spontaneous embolus dissolution was monitored with a gamma-ray detector placed on the head of the embolic rats. Embolus dissolution was spontaneously generated in 15 min after the injection of fibrin clots. In WKYs, 21% and 42% of the clots were dissolved 30 and 90 min after the second embolization, respectively. On the other hand, the spontaneous embolus dissolution in SHRSPs was significantly lower than that of WKYs, indicating that the endogenous fibrinolytic ability of SHRSPs is less potent than that of normotensive rats. The intravenous administration of t-PA at doses of 75, 250 and 750 micrograms/kg caused a dose-dependent embolus dissolution in SHRSPs. Furthermore, systematically applied t-PA produced embolus dissolution without causing systemic plasminogen activation, fibrinogen breakdown or bleeding. In conclusion, the intravenous administration of t-PA produces selective embolus dissolution without systemic fibrino(geno)lysis in a cerebral embolic SHRSP. 相似文献
85.
The relative gamma-ray intensities in the energy region between 122 and 411 keV in the decay of152Eu were measured by using a Ge(Li) detector. Its efficiency calibration was carried out with the radioactive sources of241Am,57Co,203Hg,137Cs,133Ba,75Se,169Yb and192Ir. 相似文献
86.
Two novel quassinoids, javanicolides A and B, and one novel quassinoid glucoside, javanicoside A were isolated from the seeds of Brucea javanica Merr. (Simaroubaceae), along with four known quassinoids, yadanziolides A and D, and bruceins D and E, and two known quassinoid glucosides, yadanziosides D and L. Their structures were elucidated by the analysis of spectral data and chemical evidence. 相似文献
87.
Summary A porous polymer resin loaded with hydrous zirconium oxide (Zr-gel) was evaluated as a stationary phase for the liquid chromatographic separation of disubstituted aromatic compounds. The prepared Zr-gel was used to separate disubstituted phenols andortho-substituted benzoic acid derivatives in reversed-phase mode. The retention time of catechol was greater than those of other disubstituted phenols; this implies that the Zr-gel has specificity for the phenolic hydroxyl group. The retention behavior ofortho-substituted benzoic acid derivatives on the Zr-gel was also evaluated in reversedphase mode using buffer. Phthalic acid was specifically retained in the vicinity of pH 6.0, which has been regarded as the equal adsorbic point. Similar behavior was also observed for salicylic acid, although the retention time of salicylic acid was less than that of phthalic acid. It seems that the specific retention behavior of hydrous zirconium oxide is a result of complexation with ligands such as hydroxyl and carboxyl groups. The results of this study have revealed that the retention mechanism of hydrous zirconium oxide is a combination of ion exchange and interaction based on complexation with ligands. 相似文献
88.
Toshinobu Suzuki Yasushi Nagae Keiryo Mitsuhashi 《Journal of heterocyclic chemistry》1986,23(5):1419-1421
Novel synthesis of the title compounds by the facile cyclization between 2,3-dichloro-5,6-dicyanopyrazine and various 2-aminopyridines under relatively mild conditions is described. The reactivity depended on the basicity of 2-aminopyridines. 相似文献
89.
Yoshikatsu Ito Meng Ji-Ben Shin Suzuki Yoshitaka Kusunaga Teruo Matsuura Keiichi Fukuyama 《Tetrahedron letters》1985,26(17):2093-2096
In contrast to simple imidazoles, 1-methy1–2,4,5-triphenylimidazole () produced stable oxetane photoadducts - with good efficiency upon irradiation in the presence of benzophenone derivatives - in acetonitrile solution. Irradiation in the solid-phase was also studied. The oxetanes - readily underwent cycloreversion by acid catalysis or by heating. 相似文献
90.
Naganawa H Suzuki H Noro J Kimura T 《Chemical communications (Cambridge, England)》2005,(23):2963-2965
The weakly coordinating hydrophobic anion TFPB-, whose surface is covered with a hydrophobic field, gives rise to a selective separation of Am(III) from lanthanides(III) in their solvent extraction even with a hard-donor extractant that shows no selectivity for Am(III) in traditional solvent extraction. 相似文献