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排序方式: 共有247条查询结果,搜索用时 15 毫秒
1.
The structure of senecicannabine(), a new mcrocyclic pyrrolizidine alkaloid isolated from , has been established by chemical study and X-ray analysis. 相似文献
2.
Summary
Vacuum Fusion Determination of Micro-quantities of Bulk Gases in Low Carbon Iron Without an Effect of Surface Gases
Micro-quantities of bulk and surface oxygen and hydrogen in low carbon iron was simultaneously determined by the surface-area-variation method using vacuum fusion analysis. Among the difference of three surface treatments, silicon carbide abrasive, electropolishing and hydrogen reduction methods, bulk oxygen and hydrogen were in agreement within their errors, however, surface oxygen and hydrogen were influenced from the surface treatments. Even in the case of electropolishing, which gave the smallest surface oxygen value, bulk oxygen less than 10g/g is needed to discriminate from the surface oxygen. Bulk hydrogen of 0.03g/g was determined without the effect of surface hydrogen in the hydrogen reduction treatment. 相似文献
3.
The state of an arsenic layer electrodeposited at various potentials on platinum electrodes has been examined electrochemically. The relation between the state and the electrocatalytic activity for hydrogen evolution has been investigated. The number of vacant sites have been found to increase with lowering of the deposition potential. The activity has been found to depend not on the amount of deposited arsenic but on the number of vacant sites. The difference in the effects of arsenic and of copper on hydrogen evolution is pointed out. This is attributed to the difference in the affinity of the ad-atoms for hydrogen. 相似文献
4.
K Takada M Oh-hashi Y Furuya H Yoshikawa S Muranishi 《Chemical & pharmaceutical bulletin》1989,37(2):471-474
Solid dispersions composed of three components, ciclosporin A (CiA), surfactant (HCO-60) and a pharmaceutical additive, were prepared. As an additive, cellulose acetate phthalate (CAP), methacrylic acid and methacrylic acid methylester copolymer (Eudragit L-100) and hydroxypropylmethylcellulose phthalate (HP-55), which are generally used as enteric coating materials, were employed. The dissolution behavior of CiA from these enteric solid-dispersion system was studied according to the paddle method of JP XI in comparison with that of Sandimmun, an olive oily CiA solution as a reference. Solid dispersion of CiA preparation did not dissolve in the 1st test fluid (pH 1.2) in 2 h. In the 2nd fluid (pH 6.8), about 80% of CiA was dissolved within 12 min, though the dissolution rate was dependent on both the quality and quantity of the additives. An in vivo systemic and lymphatic availability study was performed with rats whose carotid artery and thoracic lymph duct were cannulated. After intrastomach administration of each CiA preparation to rats at a dose of 7 mg/kg, blood and lymph samples were collected for 6 h. One of the HP-55 preparations gave the highest plasma CiA level, Cmax = 0.99 +/- 0.20 (S.E., n = 4) micrograms/ml, and also showed the highest lymphatic availability, the percentage of dose delivered to the lymphatics in 6 h was 1.98 +/- 0.10% and the maximum lymph CiA level was 76.8 +/- 12.86 micrograms/ml. Lymphatic availability of CiA from Sandimmun was 0.78 +/- 0.11% and the peak plasma CiA level was 0.46 +/- 0.10 microgram/ml.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
5.
Hydrogen evolution on a platinum electrode decays against Xpt with the deposition of Sn ad-atoms and Pb ad-atoms in the same way as it decays with that of Ge ad-atoms, in which all of these ad-atoms occupy two platinum sites. In general the decay depends on the number of sites occupied by an atom of the ad-atom species.The potential ranges for oxygen adsorption by Sn ad-atoms and Pb ad-atoms are 0.45 to 1.24 V and 0.48 to 0.77 V, respectively, but the oxygen adsorbed by the latter ad-atoms is very small in amount. 相似文献
6.
T Nakajima Y Takashima A Furuya Y Ozawa Y Kawashima 《Chemical & pharmaceutical bulletin》1990,38(6):1680-1683
Indomethacin (IM) sustained-release suppositories were prepared by the fusion method using sugar ester and polyethylene glycol 4000 (PEG). The suppositories were evaluated by in vitro release testing, X-ray analysis and in vivo absorption testing in rabbits. X-ray analysis showed that IM was amorphous in PEG-base suppositories. In a release test, slow-release was obtained when the sugar ester content of a suppository was 60%. The IM plasma level following the administration of the suppository was well sustained in the absorption test. The main slow-release mechanism is considered to be the release of IM from the matrix composed of sugar ester and PEG, which is represented by the Higuchi equation. A good correlation between the release test and the absorption test was obtained. It is considered that the amorphous state of IM in this type of sustained-release suppository would enhance the release and absorption of IM in the rectum of the rabbit, whose rectal fluid volume is small. 相似文献
7.
Masaki Takeguchi Kazutaka Mitsuishi Miyoko Tanaka Kazuo Furuya 《Microscopy and microanalysis》2004,10(1):134-138
About 1 monolayer of palladium was deposited onto a silicon (111) 7 x 7 surface at a temperature of about 550 K inside an ultrahigh vacuum transmission electron microscope, resulting in formation of Pd2Si nanoislands and a 1 x 1 surface layer. Pd clusters created from an excess of Pd atoms on the 1 x 1 surface layer were directly observed by in situ plan view high-resolution transmission electron microscopy. When an objective aperture was introduced so that electron diffractions less than 0.20 nm were filtered out, the lattice structure of the 1 x 1 surface with 0.33 nm spacing and the Pd clusters with a trimer shape were visualized. It was found that image contrast of the 1 x 1 lattice on the specific height terraces disappeared, and thereby an atomic structure of the Pd clusters was clearly observed. The appearance and disappearance of the 1 x 1 lattice was explained by the effect of the kinematical diffraction. It was identified that a Pd cluster was composed of three Pd atoms without a centered Si atom, which is consistent with the model proposed previously. The feature of the Pd clusters stuck at the surface step was also described. 相似文献
8.
Yasunori Inoue Hiro-o Hamaguchi Kotaro T. Yamamoto Mitsuo Tasumi Masaki Furuya 《Photochemistry and photobiology》1985,42(4):423-427
Abstract— Fluorescence spectra of native rye phytochrome were determined under different light conditions at liquid nitrogen temperature. Fluorescence spectrum of the red-light-absorbing form (Pr) had a major peak at about 685 nm (14 600 cm−1 ) and a broad sub-peak at about 515 nm (19 400 cm−1 ). The peak height at 685 nm was reduced by irradiation with monochromatic light of 640 nm, and a new peak became obvious at about 702 nm (14250 cm−1 ). This spectral change was almost completely reversed by subsequent irradiation with 700-nm light. Fluorescence spectrum of the photoequilibrium mixture of Pr and far-red-light absorbing form under continuous red light showed a sharp peak at about 685 nm having a peak height ca. 12% of Pr, and a broad sub-peak at about 508 nm (19 700 cm−1 ). Light of 730 nm did not reduce the peak height at about 685 nm but induced a new shoulder at about 699 nm (14300 cm−1 ). Monochromatic light of 640 and 700 nm given following the light of 730 nm could not reverse the spectral change at 699 nm induced by the irradiation with 730-nm light. Fluorescence spectrum of Pr in partially degraded phytochrome was similar to that in native phytochrome but the peak position in the red region was shifted by about 5 nm (100 cm−1 ) to the blue. 相似文献
9.
Summary HPLC determination of pheophytinatonicke(II) (Pheo-Ni) prepared by the replacement of magnesium(II) in chlorophyll with nicke(II)
is described. The good separation of PheoNi was obtained by using chemically bonded C18 as the stationary phase and acetone-methanol (50∶50, vol/vol) as the mobile phase. Conventional spectrophotometric method
was also used for the determination of PheoNi. For the synthetic samples prepared by mixing (pheophytinato a) nicke(II) [(Pheo-a)
Ni] and (pheophytinato b) nicke(II) [(Pheo-b) Ni], analytical values obtained by the spectrophotometric method were very high
compared to those obtained by HPLC. In the proposed HPLC method, (Pheo-a) Ni and (Pheo-b). Ni could be determined in the concentration
range of 0.028–30μg/ml and 0.038–30μg/ml with relative standard deviations (n=10) of 3.1% and 0.8%, respectively. 相似文献
10.
The number of iridium sites and that of rhodium sites occupied by a foreign atom was determined with the aid of the pulse technique. In the case of iridium the foreign atoms included are Cu, Ag, Cd, Hg, In, Tl, Pb, Se, Te, As and Bi. The approximate value is 1 for the first two, 2 for the next five and 2.5–2.7 for the others. In the case of rhodium substrate, the foreign atoms included are Cu, Ag, Cd, Hg, In, Tl, Ge, Pb, As, Sb, Se, Te, and Bi. The approximate value is 1 for the first two, 2 for the next six, 2.4–2.6 for the next four and 3.0 for the last one. Silver and copper ad-atoms are closely packed both on the iridium and rhodium surface, but the ad-atoms of the other elements are arranged on the surfaces leaving empty sites for geometrical reasons, even when the monolayer is apparently complete. 相似文献