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61.
S. M. Fields R. C. Kong J. C. Fieldsted M. L. Lee P. A. Peaden 《Journal of separation science》1984,7(6):312-318
Fused silica capillary columns with internal diameters from 100 to 25 μm were coated with SE-54 and evaluated under supercritical fluid chromatographic conditions using carbon dioxide as mobile phase. Experimental results compared well with theoretical predictions. At ten times the optimum mobile phase velocity and for a capacity factor, k of 3, efficiencies of 2300 to 5600 plates m?1 were obtained for column diameters of 100 to 25 μm, respectively. 相似文献
62.
Campos LM Dang H Ng D Yang Z Martinez HL Garcia-Garibay MA 《The Journal of organic chemistry》2002,67(11):3749-3754
A detailed thermochemical analysis of the alpha-cleavage and decarbonylation reactions of acetone and several ketodiesters was carried out with the B3LYP/6-31G* density functional method. The heats of formation of several ground-state ketones and radicals were calculated at 298 K to determine bond dissociation energies (BDE) and radical stabilization energies (RSE) as a function of substituents. Results show that the radical-stabilizing abilities of the ketone substituents play a very important role on the thermodynamics of the alpha-cleavage and decarbonylation steps. An excellent correlation between calculated values and previous experimental observations suggests that photochemical alpha-cleavage and decarbonylation in crystals should be predictable from knowledge of excitation energies and the RSE of the substituent. 相似文献
63.
Biofingerprinting chromatogram analysis, which is defined as the comparison of fingerprinting chromatograms of the extract of traditional Chinese medicines (TCMs) before and after the interaction with biological systems (DNA, protein, cell, etc.), was proposed for screening and analysis of the multiple bioactive compounds in TCMs. A method of microdialysis sampling combined with high performance liquid chromatography (HPLC) was applied to the study of DNA-binding property for the extracts of TCMs. Seven compounds were found to bind to calf thymus DNA (ct-DNA) from the TCMs of Coptis chinensis Franch (Coptis), but only three ones from Phellodendron amurense Rupr. (Phellodendron) and none from Sophoraflavescens Ait. (Sophora) to bind to ct-DNA, respectively. Three of them were identified as berberine, palmatine and jatrorrhizine and their association constants (K) to ct-DNA were determined by microdialysis/HPLC. Competitive binding behaviors of them to ct-DNA were also investigated. 相似文献
64.
65.
Modeling of a counterflow plasma reactor 总被引:2,自引:0,他引:2
Modeling of a counterflow plasma reactor is presented, using liquid injection for the synthesis of fine particles. An experimental reactor has been developed in this laboratory, and feasibility has been demonstrated for synthesizing advanced ceramic powders. The flow field calculations show two major recirculating regions which are of importance for increasing the particles' residence time inside of the reactor. In addition, the temperature within these recirculation zones remains relatively uniform. For simulation, water droplet trajectories have been calculated for droplets produced by an injection probe. It is shown that the droplets in a size range below 50 m in diameter will follow the streamlines and evaporate completely within a short traveling distance. This finding suggests that this reactor configuration provides a favorable environment for the synthesis of fine particles using liquid precursors. 相似文献
66.
67.
Conclusions The simple synthesis of optically active R,Z-14-methyl-8-hexadecenal (cis-trogodermal), the principal components of the aggregation pheromone ofTrogoderma granarium, was accomplished. The synthesis was based on the use of R-1-bromo-4-methylhexane and Z-4-chloro-2-buten-1-ol as the sources of the chiral and olefin fragments.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 906–910, April, 1987. 相似文献
68.
Xingang Kong Jiarui Zhang Jianfeng Huang Jiayin Li Yi Qin Ting Zhao Qi Feng 《中国化学快报》2019,30(3):771-774
SnNb2O6 and Sn2Nb2O7 nanosheets were synthetized via microwave assisted hydrothermal method, and innovatively employed as anode materials for lithium-ion battery. Compared with Sn2Nb2O7 and the previously reported pure Sn-based anode materials, the SnNb2O6 electrode exhibited outstanding cycling performance. 相似文献
69.
N-杂环卡宾(NHC)配体的优异催化性能引起了人们的广泛关注,已成功应用于多种烯烃聚合反应。本文主要介绍NHC及其在开环易位聚合、烯烃配位聚合和原子转移自由基聚合等反应中的应用。在此基础上,指出了今后NHC配体在聚合反应研究的发展方向。 相似文献
70.
Xiaolei Du Lili Xu Zhe Zhang Yang Wang Huifen Li Weiliang Cui Huibin Lin 《Molecules (Basel, Switzerland)》2022,27(19)
Steaming is a characteristic pharmaceutical skill in Traditional Chinese Medicine (TCM). Polygonum multiflorum radix (PM) and its steamed products have been used in Asia for centuries. Raw Polygonum multiflorum radix (RPM) is commonly used to promote defecation but can exert toxicity, especially in liver injury. However, RPM can be made converted into Polygoni multiflori radix praeparata (PMP) by steaming; this is considered a good method to reduce defecation and liver injury caused by PM in Asia. The chemical constituents of TCM are the key to its action. We systematically analyzed the effect of steaming on PM constituents, defecation, and liver injury. We identified 13 main constituents from PM and PMP; the results showed that after being steamed, two constituents (TSG, catechin) had decreased, six constituents (such as procyanidin B1 or B2) had disappeared, four constituents (such as emodin, physcion) had increased, emodin-8-O-β-D-glucoside remained unchanged in PMP. Pharmacological experiments showed that PM could promote defecation; however, there were no obvious effects in response to PMP. Only a high dose of PM for 14 days caused some degree of liver injury, although this injury disappeared after 14 days of drug withdrawal. Network pharmacology and molecular docking studies showed that TSG, emodin and physcion were the most effective in promoting defecation and causing liver injury. Collectively, our findings show that steaming can reduce the effect of PM on promoting defecation and reducing liver injury. TSG may be one of the important constituents in PM that can promote defecation and cause liver injury. 相似文献