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21.
An antiviral nucleoside or virazole was synthesized efficiently and regioselectively starting with benzyl cyanoformate. 相似文献
22.
T Tatee K Narita S Kurashige S Ito H Miyazaki H Yamanaka M Mizugaki T Sakamoto H Fukuda 《Chemical & pharmaceutical bulletin》1986,34(4):1643-1655
23.
The adsorbability of pertechnetate ion (TcO
4
–
) reached 96% for an active carbon at the 0.1 g/50 ml concentration level, increasing with diminution of acid and its salt concentrations, and depending on the type of anions present. With constant anion concentration, TcO
4
–
adsorbability rose with decreasing pH in the acidic region, followed in the region around neutrality by a plateau, and in the basic region by an appreciable decline of TcO
4
–
adsorbability. In the acidic region, part of once-adsorbed TcO
4
–
appeared to be displaced by other anions. Reversibility was noted between the adsorption and desorption of TcO
4
–
. 相似文献
24.
Separation of salidroside from Rhodiola crenulata by high-speed counter-current chromatography 总被引:3,自引:0,他引:3
High-speed counter-current chromatography (HSCCC) was used to purify salidroside from an extract of Rhodiola crenulata with two steps using a two-phase solvent system composed of ethyl acetate-n-butanol-water (1:4:5, v/v) in the first run and chloroform-methanol-isopropanol-water (5:6:1:4) in the second run. The method yielded 21.9 mg of salidroside from 1.216 g of the crude sample at 98% purity determined by HPLC analyses. Identification was performed by 1H NMR, 13C NMR, and MS. 相似文献
25.
To sophisticate the nuclear fuel recycling processes, the transfer percentages for Pd, Mo, Te, and Sb should be determined. Each element solution containing NaNO3 or HNO3 was fed consistently into the thin film evaporator regulated in vac and at 50 °C. The analyte percentages in the inside of the lid, in the condenser, and in the distillate were 10-1%/m2, 10-3%/m2, and 10-3% (DF = 105), respectively. The Mo percentage in the condenser was lower by a factor of 10 than those of other elements investigated. The NO3
- percentages were nearly constant despite increasing HNO3 concentrations, however, the ratios decreased with increasing NaNO3 concentrations. 相似文献
26.
M Sugiyama T Sakamoto K Tabata K Endo K Ito M Kobayashi H Fukumi 《Chemical & pharmaceutical bulletin》1989,37(8):2122-2131
Thiazolo[3,2-a]thieno[3,2-d]-, [3,4-d]- and [2,3-d]pyrimidin-5-one derivatives (6, 11 and 16), and polymethylene condensed thieno[3,2-d]-, [3,4-d]- and [2,3-d]pyrimidin-5-one derivatives (19-21), in which the oxygen atom of the oxazolidine moiety in 3 was replaced by a sulfur atom or methylene groups, were synthesized and evaluated for gastric antisecretory activity in pylorus-ligated rats. The structure-activity relationships of these compounds are discussed. 相似文献
27.
Y Nishioka S Kyotani M Okamura M Miyazaki Y Sakamoto M Morita K Okazaki S Ohnishi Y Yamamoto K Ito 《Chemical & pharmaceutical bulletin》1992,40(1):267-268
Hepatic artery of dogs was embolized with cisplatin (CDDP) albumin microspheres containing chitin and chitosan to investigate the in vivo CDDP release kinetics from CDDP albumin microspheres, the CDDP cumulative characteristics in the liver, and the influence of microsphere administration on hepatic tissue. Results showed that changes in blood CDDP content were dependent on CDDP albumin microsphere type and that release kinetics were better sustained when chitin was added to the microspheres or when the microspheres were treated with chitosan. In particular, the administration of CDDP in the chitin-containing CDDP chitosan albumin microspheres showed a blood CDDP content of approximately 0.26 micrograms Pt/ml 14 d after administration. The administration of chitin-containing or chitosan treated CDDP microspheres showed a CDDP content in the hepatic tissue of 0.14 to 0.23 micrograms Pt/g 28 d after administration. They also showed better control of CDDP release than those without chitin or chitosan treatment. No CDDP influence on hepatic tissue was observed. We conclude that, even in vivo, chitin and chitosan are effective embolic materials. 相似文献
28.
Transition probabilities were evaluated for the X(1)A(1)-A(1)B(1) and A(1)B(1)-B(1)A(1) systems of SiH(2) and SiD(2) to analyze the X-->A-->B photoexcitation. The Franck-Condon factors (FCFs) and Einstein's B coefficients were computed by quantum vibrational calculations using the three-dimensional potential energy surfaces (PESs) of the SiH(2)(X(1)A(1),A(1)B(1),B(1)A(1)) electronic states and the electronic transition moments for the X-A, X-B, and A-B system. The global PESs were determined by the multireference configuration interaction calculations with the Davidson correction and the interpolant moving least-squares method combined with the Shepard interpolation. The obtained FCFs for the X-A and A-B systems exhibit that the bending mode is strongly enhanced in the excitation since the equilibrium bond angle greatly varies with the three states; the barrier to linearity is evaluated to be 21,900 cm(-1) for the X state, 6400 cm(-1) for the A state, and 230-240 cm(-1) for the B state. The theoretical lifetimes for the pure bending levels of the A and B states were calculated from the fluorescence decay rates for the A-X, B-A, and B-X emissions. 相似文献
29.
Synthesis and photochemical properties of photoactivated antitumor prodrugs releasing 5-fluorouracil
A new family of antitumor prodrugs (1-3) of 5-fluorouracil (5-FU) possessing photolabile 2-nitrobenzyl chromophores have been designed and synthesized to investigate the efficiency and mechanism of photoactivated 5-FU release upon UV-irradiation at lambda(ex)= 365 nm. The photoactivated prodrug 3 derived from conjugation of 2 with a tumor-homing cyclic peptide Cys-Asn-Gly-Arg-Cys (CNGRC) was so designed as to manifest a tumor-targeting function. 相似文献
30.
Takeo Ito Hideki Shirakawa Sakuji Ikeda 《Journal of polymer science. Part A, Polymer chemistry》1974,12(1):11-20
A direct method of simultaneously polymerizing and forming acetylene monomer to produce uniformly thin films of polyacetylene was investigated in terms of catalyst system, catalyst concentration, and polymerization temperature. The best catalyst was a Ti(OC4H9)4–Al(C2H5)3 system (Al/Ti = 3–4) and the critical concentration was 3 mmole/l. of Ti(OC4H9)4. Below the critical concentration, only a solid or a powder was obtained. The configuration of the polymers obtained depends strongly upon the polymerization temperature. Thus an all-cis polymer was obtained at temperatures lower than ?78°C, whereas an all-trans polymer resulted at temperatures higher than 150°C. Observations either in an electron microscope by direct transmission or in a scanning electron microscope showed that the film is composed of an accumulation of fibrils about 200–300 Å in width and of indefinite length. 相似文献