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41.
42.
Nuclear relaxation times T1 and T1p and T2 of two Tl isotopes, 203Tl and 205Tl, in solid TINO2 were measured betwe en 120 and 430 K. The shorter component of the highly non-exponential T1 decay shows two minima above and below room temperature, which were assigned to Tl+ ionic diffusion to NO-2 reorientation. 相似文献
43.
The phosphorylation of disaccharides by inorganic cyclo-triphosphate (P(3m)) with a six-membered ring was examined in aqueous solution. In the phosphorylation of cellobiose, lactose, and alpha,alpha-trehalose with P(3m), beta-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl 1-triphosphate, beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranosyl 1-triphosphate, and 3-O-triphospho-alpha-D-glucopyranosyl-(1-->1)-alpha-D-glucopyranoside were synthesized with maximum yields of 28%, 35%, and 20%, respectively. In the reactions of maltose and sucrose with P(3m), two phosphorylated products were obtained in yields of 42% and 58%, respectively. The main phosphorylated products were assigned to alpha-D-glucopyranosyl-(1-->4)-beta-D-glucopyranosyl 1-triphosphate and beta-D-fructofuranosyl-(2-->1)-2-O-triphospho-alpha-D-glucopyranoside by heteronuclear multiple bond correlation (HMBC) NMR. The phosphorylation mechanism of disaccharides with P(3m) is discussed. 相似文献
44.
An iridoid glucoside dimer and a non-glycosidic iridoid from the leaves of Lasianthus wallichii 总被引:1,自引:0,他引:1
Takeda Y Shimidzu H Mizuno K Inouchi S Masuda T Hirata E Shinzato T Aramoto M Otsuka H 《Chemical & pharmaceutical bulletin》2002,50(10):1395-1397
A new iridoid glucoside dimer (1) and a non-glycosidic iridoid (2) was isolated together with the known compounds, asperuloside (3), paederoside (4), daphylloside (5), citroside A (6) and benzyl 6-O-alpha-L-rhamnopyranosyl-beta-D-glucopyranoside (7), from the leaves of Lasianthus wallichii. The structures of the new compounds were elucidated by spectroscopic and chemical evidence. 相似文献
45.
Analysis of herbicides in water using temperature-responsive chromatography and an aqueous mobile phase 总被引:1,自引:0,他引:1
Ayano E Okada Y Sakamoto C Kanazawa H Okano T Ando M Nishimura T 《Journal of chromatography. A》2005,1069(2):281-285
A simple and rapid method has been developed for herbicides in water using temperature-responsive liquid chromatography (LC) and a column packed with poly(N-isopropylacrylamide) (PNIPAAm), a polymer anchored on the stationary-phase surface of modified silica. PNIPAAm reversibly changes its hydrophilic/hydrophobic properties in water in response to temperature. The method was used to determine five sulfonylurea and three urea herbicides. Separation was achieved with a 10 mM ammonium acetate (pH 3.0) isocratic aqueous mobile phase, and by changing the column temperature. The analytes were extracted from water by off-line solid-phase extraction (SPE) with an N-vinyl-pyrrolidone polymer cartridge. The average recoveries of the eight herbicides from spiked pure water, tap water and river water were 70-130% with relative standard deviations (RSDs) of <10%. The limits of quantitation (LOQ) of the eight herbicides were between 1 and 4 microg l(-1). 相似文献
46.
The network of hydrogenated silicon nitride (a-SiNx:H) films deposited by plasma-enhanced chemical vapor deposition is compacted when the film is irradiated by high-energy photons in the range from vacuum-ultraviolet to soft X-rays (hν>100 eV). In situ monitoring by spectroscopic ellipsometry of the change in the film’s optical response discriminated between the photon-stimulated structural change and the solely temperature-dependent change of the dielectric constant. To elucidate the compositional difference before and after irradiation, the dielectric function of a-SiNx:H was modelled by a mixture of its component dielectric functions, i.e., of Si3N4, crystalline Si, and voids, under the Bruggeman effective medium approximation. Irradiation decreased the nominal volumes of void and c-Si components from their initial values by 44% and 49%, respectively. The resulting total 9.8% reduction in thickness can be explained by the compaction model. The photolytic origin of the reaction was demonstrated by the quick commencement and termination of the changes in optical evolution in response to the supply and cessation of irradiation, as well as by the insensitivity of the change in the refractive index to the temperature of irradiation. The microscopic process which is primarily responsible for the rearrangement of the network is cross-linking between the H-terminated –SiHx and –NHy species followed by the release of H2. In contrast to this, the creation of dangling bonds is a minor process. 相似文献
47.
NBS was found to be an efficient catalyst for condensations of indoles with aldehydes or ketones in the absence of solvent. 相似文献
48.
49.
Kikuchi T Akazawa H Tabata K Manosroi A Manosroi J Suzuki T Akihisa T 《Chemical & pharmaceutical bulletin》2011,59(3):378-381
Eleven triterpene acids, 1-11, isolated from the leaves of Eriobotrya japonica, were evaluated for inhibition of DNA topoisomerase (Topo) I and cytotoxicity against human leukemia (HL60) and melanoma cell lines (CRL1579). Among the compounds tested, four compounds, δ-oleanolic acid (4), ursolic acid (5), 3-O-(E)-p-coumaroyl tormentic acid (8), and betulinic acid (10), exhibited potent Topo I inhibitory activity (IC(50) 20.3-36.5 μM) and cytotoxicity against HL60 (EC(50) 5.0-8.1 μM). Upon assessing the apoptosis-inducing activity in HL60 cells, compound 8 exhibited induction of apoptosis detected by the observation of DNA fragmentation and membrane phospholipid exposure in flow cytometry. Western blot analysis showed that compound 8 markedly reduced the levels of procaspases-3 and 9, while being increased the levels of cleaved caspases-3 and 9. On the other hand, compound 8 exerted almost no influence on the expression of caspase-8. In addition, compound 8 increased significantly Bax/Bcl-2 ratio and activated caspase-2. These results suggested that compound 8 induced apoptotic cell death in HL60 via mainly mitochondrial pathway by, at least in part, Topo I inhibition. Therefore, compound 8 may be promising lead compound for developing an effective drug for treatment of leukemia. 相似文献
50.
Hideko Maeda Yu Ogawa Hirokazu Nakayama 《Journal of inclusion phenomena and macrocyclic chemistry》2014,78(1-4):217-224
The solubility of melatonin (MT) was improved with the addition of modified cyclodextrins (CDs). The solubilities of MT in the presence of β-cyclodextrin (β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), mono-6-O-maltosyl-β-cyclodextrin (mono-G2-β-CD), methyl-β-cyclodextrin (Me-β-CD), and sulfobutylether-β-cyclodextrin (SBE-β-CD) were higher than that of MT itself. In particular, the solubility of MT in the presence of SBE-β-CD was 11 times higher than that of MT itself. The stability constant (K) obtained based on the fluorescence intensity was 490 L/mol for the MT/SBE-β-CD inclusion complex. The structure of the MT/SBE-β-CD complex in aqueous solution was examined by 1H–1H rotating frame nuclear overhauser effect spectroscopy NMR. A 5-methoxy moiety of MT was included from the secondary hydroxyl face of SBE-β-CD. The MT/SBE-β-CD inclusion complex was prepared by the freeze-drying method. The results of X-ray diffraction and differential scanning calorimetry confirmed the formation of the complex in solid. 相似文献