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排序方式: 共有72条查询结果,搜索用时 15 毫秒
41.
Yutaka Watanabe Chikara Nakamoto Shoichiro Ozaki Michikatsu Sato Kyoko Koizumi 《Journal of carbohydrate chemistry》2013,32(6):685-692
Abstract The absolute configuration of 4-α-D-glucopyranosyl-myo-inositol, one of the enzymatic transglycosylation products from cyclodextrin to myo-inositol, was confirmed by chemical synthesis. The glycosylation was shown to proceed in a highly diastereoselective manner by HPLC analysis of the chemically synthesized racemic glycoside. 相似文献
42.
An efficient and generally applicable method for stepwise α-alkylatton of esters, nitriles, and ketones via the α-tert-butylthio derivatives is described. The method involves reductive-protonation and reductive-alkylation of α-alkylthio α,α-bis-alkylated carbonyl compounds which are prepared by stepwise alkylation of the corresponding simple α-alkylthio carbonyl precursors. The reduction is conveniently performed by use of stoichiometric amounts of a dissolving metal, particularly lithium, affording correspondingly the α-mono-and the α,α-bis-alkylated carbonyl compounds in good yields. 相似文献
43.
The chemical structure of methylated poly(1‐vinylimidazole) (PVIm‐Me) has been tuned for gene carrier properties, which are cell viability, the stability of its DNA polyion complexes, and gene expression. The resulting PVIm‐Me with lower methylation degree (6 and 20 mol%) exhibited no significant cytotoxicity, as compared with 40 mol% PVIm‐Me, in spite of the same concentration and chemical structure of positive charges. The DNA complex with 20 mol% PVIm‐Me stably retained the DNA, as compared with 6 or 40 mol% PVIm‐Me, which was examined by competitive exchange with dextran sulfate. As a result, the DNA complex with 20 mol% PVIm‐Me mediated most efficient gene delivery, where the resulting transfection activity was higher than that mediated by a positive control, poly(ethylenimine). These results suggest that the optimization of the balance of the methylimidazolium and the imidazole groups of PVIm‐Me is essential for gene carrier design. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
44.
Fang Cao Ryuji Hata Pengxiang Zhu Shoichiro Takeda Tadashi Yoshida Nobuhiro Hakuba Masahiro Sakanaka Kiyofumi Gyo 《BMC neuroscience》2010,11(1):115
Background
Because of the lack of reproducible brainstem ischemia models in rodents, the temporal profile of ischemic lesions in the brainstem after transient brainstem ischemia has not been evaluated intensively. Previously, we produced a reproducible brainstem ischemia model of Mongolian gerbils. Here, we showed the temporal profile of ischemic lesions after transient brainstem ischemia. 相似文献45.
Yagai S Iwashima T Kishikawa K Nakahara S Karatsu T Kitamura A 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(15):3984-3994
Self-assembling building blocks that are readily functionalizable and capable of achieving programmed hierarchical organization have enabled us to create various functional nanomaterials. We have previously demonstrated that N,N'-disubstituted 4,6-diaminopyrimidin-2(1 H)-one (DAP), a guanine-cytosine hybridized molecule, is a versatile building block for the creation of tapelike supramolecular polymer species in solution. In the current study, DAP was functionalized with azobenzene side chains. 1H NMR, UV/Vis, and dynamic light scattering studies confirmed the presence of nanometer-scale tapelike supramolecular polymers in alkane solvents at micromolar regimes. At higher concentrations (millimolar regimes), the supramolecular polymers hierarchically organized into lamellar superstructures to form organogels, as shown by X-ray diffraction and polarized optical microscopy. Remarkably, the azobenzene side chains are photoisomerizable even in the supramolecular polymers, owing to their loosely packed state supported by the rigid hydrogen-bonded scaffold, enabling us to establish photocontrollable supramolecular polymerization and higher order organization of the tapelike supramolecular polymers into lamellar superstructures. 相似文献
46.
Taoka T Iwasaki S Okamoto S Sakamoto M Nakagawa H Otake S Fujioka M Hirohashi S Kichikawa K 《Magnetic resonance imaging》2006,24(5):651-656
PURPOSE: The purpose of this study was to evaluate the relationship between pituitary stalk compression by the dorsum sellae and clinical or laboratory findings in short stature children. MATERIALS AND METHODS: We retrospectively reviewed magnetic resonance images of the pituitary gland and pituitary stalk for 34 short stature children with growth hormone (GH) deficiency and 24 age-matched control cases. We evaluated the degree of pituitary stalk compression caused by the dorsum sellae. Body height, GH level, pituitary height and onset age of the short stature were statistically compared between cases of pituitary stalk compression with associated stalk deformity and cases without compression. RESULTS: Compression of the pituitary stalk with associated stalk deformity was seen in nine cases within the short stature group. There were no cases observed in the control group. There were no significant differences found for body height, GH level and pituitary height between the cases of pituitary stalk compression with associated stalk deformity and cases without compression. However, a significant difference was seen in the onset age between cases with and without stalk compression. CONCLUSION: Pituitary stalk compression with stalk deformity caused by the dorsum sellae was significantly correlated with late childhood onset of short stature. 相似文献
47.
Shoichiro Ozaki Yutaka Watanabe Tomonori Hoshiko Hiroshi Fujisawa Atsuhiko Uemura Kazuhiko Ohrai 《Tetrahedron letters》1984,25(44):5061-5062
Acylglycosyl halides react smoothly with N1 - and N3-(octylthio)-carbonylpyrimidines in the presence of tert-amine to give the corresponding nucleosides in good yields. 相似文献
48.
Phosphatidylinositol polyphosphate (PIPx) are related with tyrosine kinase activation and cell proliferation and carcinogenesis. PIPx is an important target compound for synthetic organic chemist. PIPx having saturated fatty acid components have been reported. Recently we have succeeded in the synthesis of phosphatydylinositol-3,4,5-trisphosphate with unsaturated fatty acid component by the reaction of diethyl chlorophosphite with l,2-di-O-cyclohexylidene-3,4-O-(tetraisopropyldisiloxane 1,3-diyl)-6-O-(4-oxopentanoyl)-myo-inositol. 相似文献
49.
Shoichiro Asayama Takashi Sekine Ai Hamaya Hiroyoshi Kawakami Shoji Nagaoka 《先进技术聚合物》2005,16(7):567-570
In this study, poly(L ‐histidine) with several aminoethyl groups, i.e. aminated poly(L ‐histidine), is reported to be able to make complexes with DNA and to transfect cells in vitro in the presence of serum. The present study was performed to determine whether the pH of the medium had an influence on the complex formation with DNA, on the cell membrane fusion activity and on the transfection efficiency. Agarose gel retardation assays proved that the polyion complex formation of the aminated poly(L ‐histidine) with DNA was affected by pH of the medium, owing to the basicity (protonation–deprotonation) of the imidazole groups with a pKa value around 6.0. Hemolysis assay showed that the resulting DNA complex enhanced membrane disruptive ability at endosomal pH. The aminated poly(L ‐histidine) gene carrier demonstrated significant transfection efficacy which was decreased by the inclusion of chloroquine as an endosomolytic agent. These results suggest that the aminated poly(L ‐histidine) promises to be a new pH‐sensitive DNA carrier for endosomal escape. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
50.
Hirakawa S Kawamata J Suzuki Y Tani S Murafuji T Kasatani K Antonov L Kamada K Ohta K 《The journal of physical chemistry. A》2008,112(23):5198-5207
Two-photon absorption (TPA) properties of newly synthesized conjugated ketone derivatives that include nonalternant azulenyl moieties in the pi-conjugation system, alpha,alpha'-bis(1-azulenylidene)cyclopentanone (1Az), alpha,alpha'-bis(2-azulenylidene)cyclopentanone (2Az), and alpha,alpha'-bis(6-azulenylidene)cyclopentanone (6Az) are reported. TPA spectra of these azulenyl compounds were measured using the open-aperture Z-scan method with a femtosecond laser. The TPA cross section at the peak position (sigma(2)peak) of 1Az was found to be the largest among the three azulenyl compounds, which is almost 7 times larger than that of the alpha,alpha'-bis(1-naphthylidene)cyclopentanone (1Nph), an alternant isomer of 1Az with the same number of pi-electrons. The small detuning energies of the azulenyl compounds compared to those of 1Nph were responsible for the large TPA cross sections. We report that a compound having an azulenyl moiety can be a promising TPA material. 相似文献