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排序方式: 共有880条查询结果,搜索用时 15 毫秒
71.
The Sonogashira-Hagihara polymerization of 3′,5′-diiodo-N-α-tert-butoxycarbonyl-l-tyrosine methyl ester (1) and 3′,5′-diiodo-N-α-tert-butoxycarbonyl-O-methyl-l-tyrosine methyl ester (2) with para-diethynylbenzene (3) was carried out to obtain optically active poly(m-phenyleneethynylene-p-phenyleneethynylene)s [poly(1) and poly(2)] with Mn’s ranging from 9900 to 15,000 in 80-87% yields. Poly(1) exhibited intense CD signals in DMSO and THF, but did not in CH2Cl2, indicating that it took a predominantly one-handed helical conformation in the former two solvents. On the other hand, there was no evidence for poly(2) to take a helical structure in these solvents. Poly(1) turned the CD sign at 390 nm from plus to minus in DMSO/H2O = 9/1 (v/v) by the addition of NaOH. Alkaline hydrolysis of ester moieties of poly(1) and poly(2) gave the corresponding polymers having carboxy groups [poly(1a) and poly(2a)]. Poly(1a) and poly(2a) increased the CD intensity by the addition of NaOH. 相似文献
72.
73.
Morita M Tanji Y Mizoguchi K Soejima A Orito Y Unno H 《Journal of Bioscience and Bioengineering》2001,91(5):469-473
To characterize the enzymatic activity and antibacterial activity of endolysin encoded by a Bacillus amyloliquefaciens phage, the open reading frame encoding endolysin was amplified by PCR and cloned into the expression plasmid pET21d(+). The resultant plasmid was used to transform Escherichia coli JM109(DE3). Production of endolysin in the cytosol facilitated cell lysis without coproduction of holin, which is considered to degrade or alter the cytoplasmic membrane. The phage endolysin was overexpressed and purified. Although the specific activity of the purified phage endolysin towards lyophilized Micrococcus luteus cells was 1/11 of the activity of chicken egg white lysozymes, the endolysin showed stronger antibacterial activity towards E. coli W3110, E. coli JM109(DE3) and Pseudomonas aeruginosa PAO1 than chicken egg white lysozymes. The antibacterial activity of the endolysin towards these three bacterial strains was marked when EDTA was added to the endolysin solution. 相似文献
74.
75.
Effect of cellular inositol content on ethanol tolerance of Saccharomyces cerevisiae in sake brewing
The effect of cellular inositol content on the ethanol tolerance of sake yeast was investigated. In a static culture of strain K901 in a synthetic medium, when cells were grown in the presence of inositol in limited amount (L-cells), the inositol content of cells decreased by one-third that of cells grown in the presence of inositol in sufficient amount (H-cells). L-cells exhibited a higher death rate constant than H-cells in the presence of 12-20% ethanol, while no difference in specific ethanol production rate in the presence of 0-18% ethanol between the two cell types was observed. L-cells leaked more intracellular components, such as nucleotides, phosphate and potassium, in the presence of ethanol than H-cells. L-cells exhibited a lower intracellular pH value than H-cells, which represented the lowering of cell vitality by the decrease in H(+) extrusion activity. Furthermore, the plasma membrane H(+)-ATPase activity of L-cells was approximately one-half of that of H-cells. Therefore, it was considered that the decrease in viability in the presence of ethanol due to inositol limitation results from the lowering of H(+)-ATPase activity, which maintains the permeability barrier of the yeast membrane, ensuring the homeostasis of ions in the cytoplasm of yeast cells. It is assumed that the lowering of H(+)-ATPase activity due to inositol limitation is caused by the change in lipid environment of the enzyme, which is affected by inositol-containing glycerophospholipids such as phosphatidylinositol (PI), because in the PI-saturated mixed micellar assay system, the difference in H(+)-ATPase activity between L- and H-cells disappeared. In the early stage of sake mash, inositol limitation lowers the ethanol tolerance due to the decrease in H(+)-ATPase activity as in static culture. In the final stage of sake mash, the disruption of the ino1 gene responsible for inositol synthesis, resulted in a decrease in cell density. Furthermore, the ino1 disruptant, which was not capable of increasing the cellular inositol level in the final stage, exhibited a significantly higher methylene blue-staining ratio than the parental strain. It was suggested that the yeast cellular inositol level is one of the important factors which contribute to the high ethanol tolerance implied by the increased cell viability in the presence of ethanol. 相似文献
76.
Takuya Kitabatake Tetsuo Uchikoshi Fumio Munakata Yoshio Sakka Naoto Hirosaki 《Journal of the European Ceramic Society》2012,32(7):1365-1369
The compaction of a Eu-doped Ca-α-SiAlON phosphor powder was performed by electrophoretic deposition (EPD). The effect on the adhesion and optical properties of the silica precursor as both a binder of the powder and a filler of the air voids were evaluated. The adhesion of the silica impregnated composite film to the silica glass substrate was characterized by the tape test. The improvement of the external quantum efficiency was confirmed from the PL spectra measurement after the silica impregnation. The temperature dependence of the external quantum efficiency was also investigated in order to discuss the advantage of using the silica precursor as a binder for high-brightness LED applications. 相似文献
77.
Ronaldo Fumio Hashimoto Junior Barrera 《Journal of Mathematical Imaging and Vision》2001,15(3):197-216
W-operators are discrete set operators that are both translation invariant and locally defined within a finite window W. A particularly interesting property of W-operators is that they have a sup-decomposition in terms of a family sup-generating operators, that are parameterized by the operator basis. The sup-decomposition has a parallel structure that usually is not efficient for computation in conventional sequential machines. In this paper, we formalize the problem of transforming sup-decompositions into purely sequential decompositions (when they exist). The techniques were developed for general W-operators, specialized for increasing W-operators and applied on operators built by compositions of dilations and erosions. 相似文献
78.
79.
Elevated plasma bile acids in hypergalactosaemic neonates: a diagnostic clue to portosystemic shunts
N Sakura N Mizoguchi T Eguchi H Ono H Mawatari K Naitou K Ito 《Canadian Metallurgical Quarterly》1997,156(9):716-718
To determine whether plasma levels of total bile acids may provide a useful index for hypergalactosaemia due to porto-systemic shunts, these levels were determined in hypergalactosaemic neonates. Increased levels were found in all cases with portohepatic venous or portocaval shunts. The levels of both total bile acids and galactose were normalized when the shunts disappeared on the echograms. Both bile acids and galactose are almost completely absorbed by the liver via the first portal blood passage. Portosystemic shunts contribute to elevated levels of bile acids and galactose. CONCLUSION: Increased plasma levels of total bile acids serve as a diagnostic clue to the presence of portosystemic shunts in neonates with hypergalactosaemia. 相似文献
80.
Improvement of poly(vinyl alcohol)/poly(vinylpyrrolidone) blended hydrogel by radiation crosslinking
1IntroductionHydrogelisapolymericmaterial(syntheticornaturaJ)whichswellswhenplacedincontactwithwaterbutisnotsolubleandhastheabililtytoretainwaterwithinitsstructare.InIecentyears,muchattentionhasbeenfocusedontheresearchanddevelopmentofthepolymerhydIogelsforbiomaterials,suchascontactlenses,wounddressing,enzymeimmunoassay,cathetersanddIugdeliverysystems[1~3].Adressingisoftencoveredonthewotmdtoaccelerateitshealing.TheIearetwokindsofdiessings:drytypeandwettype.Ithasbeenreportedthatheallngwithawe… 相似文献