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241.
242.
Ono S Yoshida T Maeda K Kosaka K Inoue Y Imada T Fukaya C Nakamura N 《Chemical & pharmaceutical bulletin》1999,47(12):1694-1712
A novel series of platelet receptor glycoprotein (Gp) IIb/IIIa antagonists with condensed heterocycles as their basic core was synthesized. In an in vitro assay, trans-4-(5-amidinobenzofuran-2-carboxamido)cyclohexyloxyacetic+ ++ acid 17e and trans-3-[4-(5-amidinobenzofuran-2- carboxamido)cyclohexyl]propionic acid 17f produced marked inhibitions with IC50 values of 0.018 and 0.006 microM, respectively in a human platelet adenosin-5'-diphospate (ADP)-induced aggregation assay; they also exhibited a wide spectrum of inhibition toward major aggregation agonists (ADP, collagen, thrombin, PMA (tumor promoter) and arachidonic acid). These compounds were > 2-3 orders of magnitude more effective in inhibiting platelet aggregation than human umbilical vein endothelial cell (HUVEC) binding. The oral administration of 10 mg/kg of either 17e and 17f to guinea pig, resulted in a 60% inhibition of ex vivo platelet aggregation after 5 h. Oral administration of ethyl trans-4-(5-amidinoben-zofuran-2- carboxamido)cyclohexyloxyacetate 18e (10 mg/kg) resulted in 80% inhibition of platelet aggregation in dogs for 6 h after oral administration with a return to baseline by 24 h. Ethyl trans-3-[4-(5-amidinobenzofuran-2-carboxamido)cyclohexyl]propionat e 18f (AR0598) produced 80% inhibition for 5 h after oral administration. Prodrug 18e showed a good profile in dogs with a long duration of action. 18e (AR0510) was selected as suitable clinical candidate for development as an orally active antithrombotic agent. 相似文献
243.
Numazawa M Komatsu S Tominaga T Yamashita K 《Chemical & pharmaceutical bulletin》2008,56(9):1304-1309
Aromatase, which is responsible for the conversion of androgens to estrogens, is a potential therapeutic target for the selective lowering estrogen level in patients with estrogen-dependent breast cancer. We prepared and tested series of the pyridine- and other heterocyclic ring-containing derivatives of 2- and 4-aminoestrones, estrone, and estradiol, compounds 5, 10, 12 and 15. The isonicotinyl derivatives of 2- and 4-aminoestrone, compounds 5c and 10c, were fairly potent competitive inhibitors of aromatase (K(i), 2.1+/-0.14 and 1.53+/-0.08 microM for 5c and 10c, respectively) and other compounds did not show, to a significant extent, the aromatase inhibitory activity. This result suggests that the isonicotinyl-substituted derivatives 5c and 10c would be accessible to the active site of aromatase. 相似文献
244.
For the purpose of designing new functional silsesquioxanes (POSS), the structure and stability of the analogous compounds of the heavier group 14 and 4 elements such as germanium (Ge-POSS), tin (Sn-POSS) and zirconium (Zr-POSS) analogues of POSS were investigated and compared with those of the parent POSS and the titanium analogue (Ti-POSS) with electronic structure theory calculations, including electron correlation effects. In order to obtain information about the metalloxane (-X-O-X-) linkage, the structures and properties of the building blocks of metallasilsesquioxanes, such as dimetalloxanes, H(OH)2XOX(OH)2H, X = Ge, Sn and Zr, and cyclometalloxanes, [H(OH)XO]n , n = 3-6, X = Ge, Sn and Zr, were examined. The stability of the Si/Ge-mixed POSS were also studied in comparison with POSS and the completely germanium-substituted POSS. 相似文献
245.
Gérald Faussurier Christophe Blancard Takako Kato Richard M. More 《High Energy Density Physics》2009,5(4):283-293
Thermodynamics of irreversible processes is applied to study the interaction of matter and a radiation field in non-local thermodynamic equilibrium within the framework of the average-atom model. The rate of entropy production of matter and the radiation field, in contact with a free electron reservoir in local thermodynamic equilibrium, is obtained using conjugates of the state variables. The average-atom one-electron populations are determined by minimizing the rate of entropy production at fixed electronic density, electronic temperature, and radiation field. Numerical results and comparisons with experiment for a photoionized iron plasma are presented and discussed. Our approach, which is based on first principles, can be used in a large variety of non-local thermodynamic equilibrium situations. 相似文献
246.
247.
Takako Kudo Fujiko Hashimoto Mark S. Gordon 《Journal of computational chemistry》1996,17(9):1163-1170
The geometry optimizations for several conformations of tri-, tetra-, and pentacyclosiloxane (H2SiO)n (n = 3, 4, and 5) were carried out, and the relative stabilities were compared at the Hartree-Fock (HF) and second order perturbation theory (MP2) levels of theory using the 6–31G* and 6–311G(d, p) basis sets. At the highest levels of theory, the only minimum for n = 4 (D4) occurs at the highly symmetric D4h structure. In contrast, several, nearly isoenergetic, minima are found on the D5 surface. These have C1, C2, Cs, and D5h symmetries. While the C1 structure has the lowest MP2/6–311G(d, p) energy, this species is predicted to be highly fluxional, and the distribution of isomers is dependent on temperature. © 1996 by John Wiley & Sons, Inc. 相似文献
248.
Dr. Katsuhiko Takeuchi Ming-Yu Chen Dr. Hao-Yu Yuan Dr. Hiroki Koizumi Dr. Kazuhiro Matsumoto Dr. Norihisa Fukaya Dr. Yoong-Kee Choe Shinji Shigeyasu Seiji Matsumoto Dr. Satoshi Hamura Prof. Dr. Jun-Chul Choi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(72):18066-18073
We have successfully isolated and characterized the zinc carbamate complex (phen)Zn(OAc)(OC(=O)NHPh) ( 1 ; phen=1,10-phenanthroline), formed as an intermediate during the Zn(OAc)2/phen-catalyzed synthesis of organic carbamates from CO2, amines, and the reusable reactant Si(OMe)4. Density functional theory calculations revealed that the direct reaction of 1 with Si(OMe)4 proceeds via a five-coordinate silicon intermediate, forming organic carbamates. Based on these results, the catalytic system was improved by using Si(OMe)4 as the reaction solvent and additives like KOMe and KF, which promote the formation of the five-coordinated silicon species. This sustainable and effective method can be used to synthesize various N-aryl and N-alkyl carbamates, including industrially important polyurethane raw materials, starting from CO2 under atmospheric pressure. 相似文献
249.
Morioka T Shibata O Kawaguchi M 《Langmuir : the ACS journal of surfaces and colloids》2010,26(23):18189-18193
The morphologies of Langmuir-Blodgett (LB) films of two fractionated poly(n-hexyl isocyanate) (PHIC) and those of their binary mixtures were observed by AFM, together with those of an unfractionated PHIC. The low molecular weight PHIC formed random packing of bundles consisting of rigid rods, while the high molecular weight PHIC formed random packing of bundles consisting of hairy rods. Bundle interpenetration was observed only for the latter in the semidilute regime. In the bilayer region, the area occupied by the PHIC bundles in the upper layer was obviously smaller for the high molecular weight PHIC than for the low molecular weight PHIC, suggesting that the bundles of high molecular weight PHIC more easily interpenetrate than those of low molecular weight PHIC. For the blended films composed of both low and high molecular weight PHICs, the characteristic morphologies of the respective PHIC samples were no longer present. Moreover, the morphologies of the blended films appeared to resemble each other at any molar fraction owing to the ideal miscibility of the low molecular weight and high molecular weight PHICs. The morphologies of the blended films were also similar to that of the unfractionated PHIC film in the dilute regime. In the semidilute regime, the blended films became rounded owing to an increase in bundles interpenetration between PHICs as compared to that in the dilute regime, whereas the morphology of unfractionated PHIC films remained unchanged as compared to that in the dilute regime. 相似文献
250.
Kitahara K Yoshihama I Hanada T Kokuba H Arai S 《Journal of chromatography. A》2010,1217(46):7249-7254
Monodispersed molecularly imprinted polymer particles selective for cholesterol were prepared by the copolymerization of styrene and divinylbenzene in the presence of template silica gel particles (particle size: 5 μm; pore size: 10 nm) functionalized with cholesterol on the surface, followed by dissolution of the cholesterol-bonded silica gel with a NaOH aqueous solution. Transmission and scanning electron micrographs of the molecularly imprinted polymer (MIP) particles revealed good monodispersity and porous structure. The MIP particles were packed into a high performance liquid chromatographic column, and its recognition ability of cholesterol was evaluated using cholesterol, cholesterol esters and fatty acid methyl esters by comparison with the non-imprinted polymer (NIP) particles prepared from styrene and divinylbenzene without cholesterol. The MIP particles showed a high affinity for cholesterol and cholesterol esters (K(MIP)'/K(NIP)' > 5.7). 相似文献