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51.
H Fujita Y Sasaki H Kohno Y Ohkubo A Ambo K Suzuki M Hino 《Chemical & pharmaceutical bulletin》1990,38(8):2197-2200
Nine analogs based on a structure of Tyr-D-Arg-Phe-X (X = alkylamides or alkylhydrazide containing electron-withdrawing atoms or groups) were newly synthesized and their biological properties were examined by the opioid receptor binding properties of mu-, delta- and kappa-receptors, guinea-pig ileum (GPI) assay and analgesic activity in the tail pinch test after subcutaneous administration in mice. Analogs with X = NHCF2CF3, Sar-ol, or NH(CH2)2CN showed potent activities in the GPI and analgesic assays and high affinity for mu-receptor. An analog with X = taurinamide was found to possess 4-fold higher mu-receptor selectivity than that of [D-Ala2, MePhe4, Gly-ol5]enkephalin (DAGO). The receptor binding properties of previously reported analogs [Chem. Pharm. Bull., 33, 1528 (1985); ibid., 33, 4865 (1985); ibid., 36, 4834 (1988)] were also examined for overall discussion of the structure-activity relationships of this series of tripeptide amides. 相似文献
52.
[reaction: see text] Inclusion ability of thiacalix[4]arenetetrasulfonate (TCAS) toward water-miscible organic molecules such as alcohols, ketones, cyclic ethers, and so on was studied by salting-out of the inclusion complex. NMR spectra of the recovered precipitates showed size selectivity to include the guest molecules. X-ray crystallographic analyses of TCAS salts including acetone and 1,4-dioxane suggested that guests are retained with the aid of cation coordination and H-bonding. 相似文献
53.
Lipophilic acyclic dibenzopolyether diamides, 12 kinds, have been designed to prepare solvent polymeric membrane ion-selective electrodes (ISEs) for Pb(2+). The ionophores include 1,5-bis[2-(N,N-dialkylcarbamoylmethoxy)phenoxy]-3-oxapentanes1-4, 1,5-bis[2-(N,N-dialkylcarbamoylpentadecyloxy)phenoxy]-3-oxapentanes 5-8, and 1,2-bis[2-(2'-N,N-dialkylcarbamoylpentadecyloxy)phenoxy]ethanes 9-12. Linear response concentration range of the ISE based on 9 is 3 x 10(-2) - 1 x 10(-6) M of Pb(2+) (average slope = 28.5 mV decade(-1)). Potentiometric selectivities of the ISEs based on 1-12 for Pb(2+) over other heavy metal cations, alkali metal cations, and alkaline earth metal cations have been assessed. These ISEs exhibit remarkably high selectivities for Pb(2+) relative to heavy metal cations, such as Cu(2+), Fe(2+), and Ni(2+), the selectivity coefficients (K(Pot)(Pb,Cu)) being 5 x 10(-5) - 6 x 10(-5) for 1-4 and ca. 6 x 10(-4) for 9. For the Pb(2+) selectivities over alkali metal cations, such as Na(+) and K(+), 9 which has an ethylene glycol spacer and a N,N-diethyl group is superior to other dibenzopolyether diamide ionophores 1-8 and 10-12. 相似文献
54.
Tomonari Wakabayashi Daisuke Kasuya Haruo Shiromaru Shinzo Suzuki Koichi Kikuchi Yohji Achiba 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,40(1):414-417
Systematic fractional change in the yield of various isomers of fullerenes was revealed to strongly depend on temperature of a buffer gas. A new kinetic consideration is proposed for understanding the observed temperature- and pressure-dependence of yield of fullerenes. The model consists of three competitive reactions in consideration of plausible behaviors of a precursor, (1) decomposition into smaller fragments, (2) isomerization leading to formation of a stable fullerene cage, and (3) growth into a larger carbon cluster. Arrhenius activation energy of formation of stable fullerenes was determined to be 0.8 eV for both C60 and C70, while a higher energy of 2.0?3.3 eV for seven different isomers of higher fullerenes ranging from C76 to C84. Correlation in the activation energy is noted for a series of higher fullerenes with different sizes, suggesting the existence of a specific precursor in their formation processes. 相似文献
55.
T Suzuki E Sato Y Matsuda H Tada K Unno T Kato 《Chemical & pharmaceutical bulletin》1989,37(4):1051-1054
Zein microspheres conjugated with antitumor drugs (mitomycinc (MMC), daunomycin hydrochloride (DM), peplomycin sulfate (PEP] were prepared by using a dimethyl sulfoxide (DMSO)-H2O system. MMC with low solubility in H2O was easily entrapped by the standard procedure, whereas some modifications were required for moderately and highly soluble drugs such as DM and PEP. Colorimetric determination of the drugs in microspheres was easily achieved by use of the phenol-sulfuric acid method for drugs with sugar moieties in their molecules, such as DM and PEP, while a simple treatment of the microspheres with concentrated sulfuric acid was applied in the case of drugs having a chromophore in their molecules, such as DM and MMC. 相似文献
56.
Yoshiyuki Goh Takao Iijima Masao Tomoi 《Journal of polymer science. Part A, Polymer chemistry》2002,40(15):2702-2716
Novel quaternary ammonium bis(2‐oxybenzoyloxy)borate salts ( 1a – 1c ) or quaternary ammonium bis(1,2‐benzenedioxy)borate salts ( 2a and 2b ) with tetra‐n‐butylammonium (TBA+), tetra‐n‐octylammonium (TOA+), or bis(triphenylphosphoranylidene)ammonium (PNP+) cations were synthesized as latent catalysts of epoxy/phenol–novolac resins by the complexation between boric acid and salicylic acid or catechol, followed by neutralization with quaternary ammonium hydroxide. Polyaddition reactions of diglycidyl ether of bisphenol A (DGEBA) and 4,4′‐bisphenol F (44BPF) or bisphenol F (BPF‐D) with the ammonium borates were investigated as model reactions of epoxy/phenol–novolac resin systems with respect to the thermal latency and storage stability of the catalyst. The polyaddition of DGEBA/44BPF with 1a – 1c in diglyme at 150 °C for 6 h proceeded up to 85–96% conversions and gave polymers with number‐average molecular weights of 4180–10,500, whereas the polyaddition at 80 °C for 6 h gave less than 8% conversions. However, the polyaddition with 2a containing TBA+ cation proceeded to only a 32% conversion at 150 °C for 6 h in diglyme and to a 64% conversion even at 180 °C for 6 h in triglyme and only gave low molecular weight oligomers, and no reaction proceeded in the polyaddition at 80 °C. However, polyaddition with 2b containing PNP+ cation proceeded up to a 96% conversion at 150 °C for 6 h in diglyme and gave a higher molecular weight polymer with a number‐average molecular weight of 8050, whereas the polyaddition at 80 °C for 6 h gave only a 5% conversion. The catalytic activity of ammonium borates 1a – 1c and 2a and 2b depended on the borate anion structure: 1a and 1c with bis(2‐oxybenzoyloxy)borate anion revealed higher activity than 2a and 2b with bis(1,2‐benzenedioxy)borate anion, respectively. In comparison with tetra‐n‐butylammonium bromide (TBAB) as a conventional ammonium salt or tetra‐n‐butylammonium tetrakis(benzoyloxy)borate (TBA‐TBB), 1a – 1c and 2b revealed better thermal latency. The catalytic activity of ammonium borates also depended on the bulkiness of the ammonium cation, and the order of activity was 1c (PNP+) > 1b (TOA+) ≧ 1a (TBA+) and 2b (PNP+) > 2a (TBA+). The storage stability of DGEBA/BPF‐D with the ammonium borate catalysts 1a – 1c and 2a and 2b in bulk at 40 °C was much better than that with TBAB and TBA‐TBB. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2702–2716, 2002 相似文献
57.
Electrothermal atomization of arsenic with a metal micro-tube atomizer has been studied. Thiourea and thionalide were found to give effective atomization of arsenic. A method involving extraction of the thionalide complex for determining traces of arsenic in water and soil is described. 相似文献
58.
Concanavalin A (Con A) or wheat germ agglutinin (WGA) was immobilized on a silica-based support, and the chromatographic behaviours of a series of dansylated ovalbumin-derived glycopeptides on small columns of the resultant gels were compared. These columns had high contents of lectins, and allowed differentiation of these glycopeptides. This method was rapid and reproducible, and enabled sensitive detection of these fluorescent glycopeptides. The structural requirement of these glycopeptides to manifest affinity to the immobilized lectins is also discussed, based on binding constants obtained from their retention times. 相似文献
59.
Takaaki Horaguchi Hiroaki Yagoh Kiyoshi Tanemura Tsuneo Suzuki 《Journal of heterocyclic chemistry》1986,23(3):657-663
4,5-Dihydro-3H-naphtho[1,8-bc]furans 4 and 6 which have various substituents (R1 and R2) have been synthesized from 8-oxo-5,6,7,8-tetrahydro-1-naphthyloxyacetic acids 1 and 3 or their ethyl esters 2 . The reaction of acids 1 and 3 with sodium acetate in acetic anhydride gave a mixture of furans 4 and 6 and lactones 5 and 7 . The ratios of the products were varied according to the types of substituents (R1 and R2) in acids 1 and 3 . As the substituent R1 (R2 = hydrogen) in acids 1 was changed from hydrogen to a methyl, ethyl or isopropyl group, production of furans 4 became more difficult. However, when a phenyl group was used as the substituent, furan 4 was obtained in good yield. Similarly, as the substituent R2 (R1 = hydrogen) in acids 1 was changed from hydrogen to a methyl, ethyl or isopropyl group, furan formation was more difficult. In contrast, acids 3 which had electron-withdrawing substituents such as chlorine, bromine or a nitro group at the 4-position afforded furans 6 in good yield. 4,5-Dihydro-3H-naphtho[1,8-bc]furans 4 and 4,5-dihydro-3H-naphtho[1,8-bc]furan-2-carbocylic acids 8 were synthesized from the reaction of esters 2 and potassium hydroxide in dioxane. When the substituents R1 or R2 in esters 2 were varied from hydrogen to a methyl, ethyl or isopropyl group the total yields of furans 4 and furancarboxylic acids 8 were reduced. 相似文献
60.
Reaction of a preformed lithium enolate and trimethyl orthoformate with added boron trifluoride leads to the corresponding α-dimethoxymethyl ketone. 相似文献