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排序方式: 共有2104条查询结果,搜索用时 24 毫秒
911.
Moon Hwan Cho Sang Hyeok Yu Marty D. Utterback Ronnie D. Price Richard A. Bartsch 《Journal of inclusion phenomena and macrocyclic chemistry》1994,20(2):131-142
Five new lipophilic dicarboxylic acids with systematic structural variation in the bridge which joins the two lipophilic carboxylic acid units have been synthesized. Potentiometric equilibrium measurements of hydrogen ion concentrations have been employed to determine the protonation constants for these lipophilic di-ionizable acyclic ligands in 90% methanol-10% water (v/v) at 25.0 °C and an ionic strength of 0.10 M and the stability constants for their complexes with Mg2+, Ca2+, and Sr2+. Although all five ligands exhibit the highest stability constants for Ca2+, the magnitude of the differences between the stability constants for complexation of Ca2+ versus Mg2+ or Sr2+ is found to vary widely depending upon the identity of the bridging unit which joins the two carboxylic acid end groups. 相似文献
912.
Moon H Kim SW Lee J Rhee SK Choi ES Kang HA Kim IH Hong SI 《Applied biochemistry and biotechnology》2003,111(2):65-80
As a novel feeding strategy for optimizing human epidermal growth factor (hEGF) production with a recombinant Hansenula polymorpha DL-1 using the methanol oxidase (MOX) promoter in H. polymorpha DL-1, independent exponential feeding of two substrates was used. A simple kinetic model considering the cell growth on two substrates was established and used to calculate the respective feeding rates of glycerol and methanol. In the fedbatch culture with methanol-only feeding, the optimal set point of specific growth rate on methanol was found to be 0.10 h-1. When the fed-batch cultures were conducted by the independent feeding of glycerol and methanol, the actual specific growth rate on glycerol and methanol was slightly lower than the set point of specific growth rate. By the uncoupled feeding of glycerol and methanol the volumetric productivity of hEGF increased from 6.4 to 8.0 mg/(L.h), compared with methanol-only feeding. 相似文献
913.
Fluorescence quenching of poly(phenylene ethynylene) (PPE) particles by a Cy-5 labeled oligonucleotide is 2 orders of magnitude more sensitive than direct excitation of the Cy-5 fluorophore. 相似文献
914.
Yang Kyoo Han Moon Young Jin Sam Kwon Choi 《Journal of polymer science. Part A, Polymer chemistry》1983,21(1):73-81
Polymerization of acrylonitrile initiated by a potassium superoxide (KO2)-nitrobenzene system was carried out in anhydrous dimethylsulfoxide (DMSO) at 25°C. The initial rate of polymerization was rapid and a high-molecular-weight polymer was obtained. The molecular weight was proportional to monomer concentration and inversely to concentration of initiator within 5 min. The overall activation energy was estimated as ?2.6kcal/mol deg in the temperature range of 20–50°C. In addition to nitrobenzene anion radical, other anion radicals generated by one-electron transfer from KO2 to charge transfer agents such as m-dinitrobenzene benzoquinone, benzophenone, and naphthalene were effective in the polymerization of acrylonitrile. It is proposed that polymerization proceeds via an anionic mechanism that involves one-electron transfer from anion radicals to monomer. 相似文献
915.
Connected open structures from close-packed colloidal crystals by hyperthermal neutral beam etching 总被引:1,自引:0,他引:1
Cho YS Yi GR Moon JH Kim DC Lee BJ Yang SM 《Langmuir : the ACS journal of surfaces and colloids》2005,21(23):10770-10775
We report the fabrication of connected open structures from close-packed colloidal crystals by hyperthermal neutral beam etching. Colloidal crystal films of polystyrene microspheres were prepared by a vertical deposition method. Exposure of the colloidal crystal films to hyperthermal neutral beam made isolated microspheres in the face-centered cubic lattice, each of which was connected with its twelve nearest neighbors through very thin cylinders. Due to the charge neutrality of impinging gas molecules of the hyperthermal neutral beam, the spherical shape of polymer microspheres was almost maintained during the etching process. The Bragg reflection peaks were modulated by the etched volume of colloidal crystals. Finally, the inverse structures of such open structures were replicated by a simple room-temperature chemical vapor deposition and subsequently burning out polymer template spheres. 相似文献
916.
Moon G. Kim Larry W. Amos Edwin E. Barnes 《Journal of polymer science. Part A, Polymer chemistry》1993,31(7):1871-1877
Various molecular weight fractions and oligomers isolated from a novolac type resorcinol–formaldehyde (RF) wood adhesive resin were studied by 13C-NMR, gel permeation chromatography (GPC), and intrinsic viscosity measurements. The 13C-NMR results indicate that methylene groups occur mostly between C4–C′4 and C2–C′4 carbons and in minor amounts between C2–C′2 carbons of resorcinol rings. By suppressing the nuclear Overhauser effect (nOe) and using a long delay time for 13C-NMR measurements, reasonable methylene/aromatic carbon ratios were obtained from the aromatic C1 carbon patterns that have resulted from different numbers of methylene groups bonded on the aromatic ring. This analysis results indicate that the RF resin has an appreciable amount of branch structures and compare favorably with the gel permeation chromatography and intrinsic viscosity measurement results. © 1993 John Wiley & Sons, Inc. 相似文献
917.
Bong‐Hwan Han Moon‐Gun Choi 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):1001-1003
The structure of tetrakis(3,4‐ethylenedioxy‐2‐thienyl)silane carbon tetrachloride solvate, Si(C6H5O2S)4·CCl4, has been determined in the noncentrosymmetric space group I. The Si and C atoms of the CCl4 are located on the fourfold inversion axes. The Si atom has a tetrahedral geometry. The thiophene ring in the 3,4‐ethylenedioxythiophene group is nearly planar to within 0.005 Å, and the ethylenedioxy moiety is in a half‐chair conformation. 相似文献
918.
Sang Heup Moon 《Catalysis Surveys from Asia》2003,7(1):11-20
Acidic components when added to Mo-based catalysts enhance the activity of the catalysts for the hydrodesulfurization (HDS) of methyl-substituted dibenzothiophenes (DBTs), the major refractory compounds included in gas oil. However, the enhancing effect of the acidic species is frequently retarded by impurities present in the gas oil, particularly by basic nitrogen compounds. Accordingly, evaluations of the performance of such acid-modified catalysts in HDS should take into account the combined effects of acidic and basic components. The performance is strongly dependent on the types of DBT compounds, acidic and basic species involved in the reaction, and promoters of the Mo-based catalysts. 相似文献
919.
920.
Moon HS Jacobson EM Khersonsky SM Luzung MR Walsh DP Xiong W Lee JW Parikh PB Lam JC Kang TW Rosania GR Schier AF Chang YT 《Journal of the American Chemical Society》2002,124(39):11608-11609
The first orthogonal combinatorial synthesis of a high-purity triazine library was demonstrated. Novel triazine-based microtubule inhibitors were discovered by an efficient zebrafish embryo screening and in vitro microtubule polymerization assay. 相似文献