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991.
992.
A water-soluble nanometer-scale metallocapped polyrotaxane has been prepared by the inclusion complexation of azo-calixarenes with metallo-bridged bis(beta-CD)s, displaying highly selective binding for Ca(2+). 相似文献
993.
994.
Gengliang Yang Zhiwei Li Dexian Wang Zhefeng Zhang Erdong Liu Yi Chen 《Chromatographia》2002,56(7-8):515-518
Summary A high-performance liquid chromatographic method was developed for the chiral separation of a new anti-diabetic agent, N-(trans-4-isopropylcyclohexylcarbonyl)-D-phenylalanine,
and its L-enantiomer. The separation was performed on a Sumichiral OA-3300 column. Optimized mobile phase was 0.025 mol.L−1 ammonium acetate in methanol solution. UV detection was at 210 nm. Baseline chiral separation was obtained within 12 minutes.
The detection limits are 80 pg for the D-enantiomer and 120 pg for the L-enantiomer. RSD of the method was below 1% (n=5). 相似文献
995.
996.
Summary Artificial Sim/Sb1 superlattices (m=15, 30, 60) were grown by molecular beam epitaxy at very low temperatures (200°C). Rutherford backscattering spectroscopy revealed the superlattices to be single crystalline with min values of less than 0.04. X-ray diffraction clearly showed the superlattice structure. However, residual surface segregation still activated at the low temperatures employed leads to a spread out of Sb atoms into the subsequently grown Si interspacing layers to an extent of about 2 nm. 相似文献
997.
A facile process to prepare uniform dumbbell-shaped ZnO crystallites was presented. The evidence in this Article discovered a unique morphological effect on the UV-blocking property. The as-prepared ZnO crystallites were characterized by XRD, HRTEM, FESEM, UV-blocking, and Raman scattering spectra. Our tentative investigation created a breakthrough to both the ultrahigh "Ultraviolet protection factor" (UPF) and the overall-range of complete UV-radiation blocking. Therefore, the as-prepared structural material demonstrated a significant advance in protective functional treatment and provided a potential commercialization. 相似文献
998.
M. Kh. Dzhukharova B. Tashkhodzhaev Z. Saatov N. D. Abdullaev 《Chemistry of Natural Compounds》1994,29(4):484-489
A new ecdysteroid with the composition C27H44O6 which has been called brahuisterone has been isolated from the epigeal part of the plantSilene brahuica Boiss. Its chemical and complete spatial structures have been established by spectral studies and the x-ray structural method (diffractometer, Cu-K radiations, 996 reflections, direct method, R=0.119).Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbekistan Republic, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 553–558, July–August, 1993. 相似文献
999.
The effects of molybdenum concentration, countercation (Co, Ni) and heat treatment on the state of heteropoly anion (HPA) in the oxide form of titania-supported 12-molybdophosphoric acid and its Co(Ni) salts have been studied using IR and DRS. 相似文献
1000.
A new chromogenic reagent tribromocarboxyarsenazo has been synthesized and the chromogenic reaction of this reagent with zirconium studied. In the medium of 0.5 mol/1 HCl, a blue complex is formed by the reaction of zirconium with tribromocarboxyarsenazo. The maximum absorption of the complex is at 633 nm, and the apparent molar absorptivity is 4.8 x 10(4) 1/mol/cm. Beer's law is obeyed over the zirconium concentration range 0-18, mug/25 ml. The method has been applied to the determination of zirconium in aluminum, copper and magnesium alloys with satisfactory results. 相似文献