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991.
Rhodiola, in which there are abundant pharmacologically active ingredients, is one of the functional adaptogenic agent that aid specific bodily functions to adapt to the changes and stress of life in addition to being tonic. In an attempt to qualitatively and quantitatively determine the pharmacologically active ingredients in Rhodiola, a new method based on capillary electrophoresis with electrochemical detection (CE-ED) has been developed. The effects of working electrode potential, pH and concentration of running buffer, separation voltage, applied potential and injection time on CE-ED were investigated. Under the optimum conditions, the analytes could be well separated within 24 min at the separation voltage of 18 kV in a 80 mmol L(-1) borax running buffer (pH 9.0). Good linear relationship was established between peak current and concentration of analytes over two orders of magnitude with detection limits (S/N=3) ranged from 3.16 x 10(-7) to 1.11 x 10(-7)g mL(-1) for all target ingredients. This proposed method has been successfully applied for the analysis of real samples, with satisfactory results. 相似文献
992.
Jie Lian Qingpu Wang Aijian Wei Yurong Wang Ruifeng Zhang Xingkui Cheng 《Optics & Laser Technology》2005,37(5):622-419
Cerium-doped Sr0.60Ba0.40Nb2O6 (SBN:60) crystals were obtained by Czochralski method. Optical transmission spectra were measured and the absorption coefficients were calculated in the visible range. The results showed that Ce-doped crystals were transparent for wavelengths more than and the fundamental absorption edge shifted towards the longer wavelength direction with increasing Ce concentrations. In addition, the birefringence of crystals were investigated based on the theory of interference between extraordinarily and ordinarily polarized light, and the birefringence values were determined in the long wavelength region. As a result, the birefringence becomes larger by doping of SBN crystals with cerium. 相似文献
993.
Shuyong Zhang Mingying Qi Aixin Song Ying Li Lin Niu Shiling Yuan Jingcheng Hao 《大学化学》1986,36(1):2008024-0
First-class course construction is the foundation of first-class undergraduate education construction. Based on the understanding of the "Two properties and one degree" standard of first-class course, key characteristics of the first-class course construction are summarized as accurate positioning, clear teaching goals, good construction foundation, advanced pedagogy, first-class construction, remarkable effectiveness and preferential demonstration. Taking the construction of first-class physical chemistry course in Shandong University as an example, the course orientation, the determination of teaching objectives and the design and implementation of the teaching are introduced. The practice and experience of the course construction are demonstrated in five aspects as first-class foundation, first-class teachers, first-class resources, first-class pedagogical ideas and first-class achievements. It can be used as the reference for the future construction of first-class courses in other universities. 相似文献
994.
Xin Liu Jifa Zhang Kai Guo Airong Jia Miansong Zhang Yaping Shi 《Natural product research》2018,32(2):167-174
Phytochemical investigation of the 1-butanol soluble fraction of 60% ethanol extract of the seeds of Celosia cristata L. led to the identification of three new oleanane-type triterpenoid saponins. Using 1D and 2D NMR experiment methods, ESI-MS analysis and acid hydrolysis, their structures were identified as 3-O-[β-D-xylopyranosyl-(1 → 3)-β-D-glucuronopyranosyl]-2β-hydroxy-oleanolic acid-28-O-β-D-glucopyranoside (1), 3-O-[β-D-xylopyranosyl-(1 → 3)-β-D-glucuronopyranosyl]-2β, 23-dihydroxy-oleanolic acid-28-O-β-D-glucopyranoside (2) and 3-O-[β-D-glucopyranosyl-(1 → 4)-β-D-glucopyranosyl]-2-hydroxyl-medicagenic acid-28-O-β-D-glucopyranosyide (3), respectively. 相似文献
995.
A novel method: ionic liquid-based ultrasound-assisted extraction of polyphenols from Chinese purple yam 总被引:1,自引:0,他引:1
Junhong Zhang Aizhen Zong Tongcheng Xu Ping Zhan Lina Liu Bin Qiu 《Natural product research》2018,32(7):863-866
Chinese purple yam is famous for therapeutic and nutritional values in lowering blood glucose, blood pressure and even preventing and treating cardiovascular diseases. However, traditional extraction techniques for the functional polyphenolic compounds mostly utilise unfriendly organic solvent and easily cause degradation of polyphenols. In this study, a novel ionic liquid-based ultrasound-assisted extraction (IL-UAE) technique was utilised to obtain polyphenols. The optimal extraction condition included: solid–liquid ratio (0.05 g/mL), ionic liquid concentration (1.05 M), extraction temperature (67°C) and ultrasonic time (37 min). The maximum free radical scavenging activity (86.21%) and total antioxidant activity (2.21 mM) were achieved and matched well with the predicted values, superior to that of the extract from regular ethanol-based UAE. IL-UAE could be a rapid and green technique for efficient extraction of polyphenols from purple yam with low solvent consumption and few structural deterioration, exhibiting application potential in food and pharmaceutical industries. 相似文献
996.
Jiao Li Zichao Li Xihui Zhao Yujia Deng Yun Xue Qun Li 《Journal of Thermal Analysis and Calorimetry》2018,131(3):2167-2177
The calcium alginate/CaCO3 composites were prepared via in situ method, and their flame retardancy and thermal degradation mechanism were investigated. The composites as-prepared were analyzed by the scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, thermogravimetric analysis (TG), vertical burning (UL-94), cone calorimeter (CONE) and X-ray diffraction (XRD). The SEM demonstrated that the inorganic calcium salt in the composites had great influence on the morphology of materials. The TG results indicated the thermal stability of the composites was remarkably improved by 70 °C, compared with that of the calcium alginate. The combustion behaviors of the materials were assessed by CONE. In comparison with those of the calcium alginate, the peak heat release rate and total heat release of the composites decreased by 40.42 and 62.59%, respectively. The different degradation mechanisms of the calcium alginate and the composites were first proposed in detail based on the TG, XRD and SEM results. The composites exhibited excellent thermal stability and flame retardancy, which is promising to be developed for the application as flame-retardant materials in the future. 相似文献
997.
Coacervate behavior of polyelectrolyte complexes has been studied by many papers. Few studies have focused on the coacervate behavior of amphoteric polymer. In this study, amphoteric copolymer of diallyldimethylammonium chloride (DM) and sodium styrenesulfonate (SS) (the copolymer was noted as DMS) was synthesized with the mole content of SS to DM ranged from 0 to 10%. Firstly, DMS was characterized by static light scattering, FTIR, 1H-NMR, TGA and DSC. Then, its phase and coacervate behaviors were studied. Turbidity was utilized as an indicator for the coacervate formation. It was found that when the SS content was more than 4 mol%, DMS coacervate would be formed in deionized water at a certain concentration. Temperature and pH have no effect on the formation of DMS coacervate. Meanwhile, salts has a great influence on the DMS coacervation. Unlike the results of the other polyelectrolyte complexes, Na2SO4, Na2HPO4, NaCOOCH3, sodium citrate and NaI cannot prevent the DMS coacervate formation. However, the addition of NaCl, NaNO3, NaBr and NaSCN can prevent the coacervate formation. The influence cannot be described by Hofmeister-like behavior. Results of surface tension and fluorescence spectrum presented that the driving forces to formation of DMS coacervate are the electrostatic interaction and the intermolecular hydrophobic interaction. 相似文献
998.
999.
1000.
Benita Barton Pieter L. Pohl Eric C. Hosten 《Journal of inclusion phenomena and macrocyclic chemistry》2018,90(3-4):357-363
Interaction between cucurbit[6]uril (Q[6]) and the guest 1-hexyl-4-(4-pyridyl)pyridinium bromide (HV+) has been investigated by 1H NMR spectroscopy, mass spectrometry, isothermal titration calorimetry, and single-crystal X-ray diffraction analysis. Experimental results have shown that the host Q[6]) preferentially encapsulates the hexyl moiety of the 1-hexyl-4-(4-pyridyl)pyridinium bromide guest in its hydrophobic cavity to form a 1:1 inclusion complex, both in aqueous solution and in the solid state. This inclusion complex is stabilized through an interplay of hydrogen-bonding and ion–dipole interactions. 相似文献