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131.
Sesquiterpene Lactone Glycosides from Carpesium macrocephalum 总被引:1,自引:0,他引:1
Two new sesquiterpene lactone glycosides were isolated from the seeds of Carpesium meacrocephalum. Their structures were elucidated as 2α-O-β-D-glucopyranosy-5α,11αH-eudesma-4(15)-en-12,8β-olide and 2α-O-β-D-glucopyranosy-5αH-eudesma-4(15),11(13)-dien-12,8β-olide by spectral methods (HRMS,1D and 2D NMR). 相似文献
132.
Heat transfer from a plasma flow to a metallic or nonmetallic spherical particle is studied in this paper for the extreme case of free-molecule flow regime. Analytical expressions are derived for the heat flux due to, respectively, atoms, ions, and electrons and for the floating potential on the sphere exposed to a two-temperature plasma flow. It has been shown that the local or average heat flux density over the whole sphere is independent of the sphere radius and approximately in direct proportion to the gas pressure. The presence of a macroscopic relative velocity between the plasma and the sphere causes substantially nonuniform distributions of the local heat flux and enhances the total heat flux to the sphere. The heat flux is also enhanced by the gas ionization. Appreciable difference between metallic and nonmetallic spheres is found in the distributions along the oncoming flow direction of the floating potential and of the local heat flux densities due to ions and electrons. The total heat flux to the whole sphere is, however, almost the same for these different spheres. For a fixed value of the electron temperature, the heat flux decreases with increasing temperature ratio Te/Th. 相似文献
133.
Sorption behavior of 2,4-dichlorophenol on marine sediment 总被引:1,自引:0,他引:1
The sorption behavior of 2,4-dichlorophenol on marine sediments treated by different methods was investigated systematically. The sorption of 2,4-dichlorophenol on marine sediments was completed mainly via ion exchange and surface polar sorption. Both the Freundlich and Langmuir isotherms were fit for describing its sorption behavior. The sorption behavior of 2,4-dichlorophenol was affected by various factors including aqueous salinity and temperature. The sorption amount of 2,4-dichlorophenol on marine sediments increased with increasing ion strength, but decreased with increasing temperature. 相似文献
134.
Two new alkaloids, i.e., (2,3‐dihydro‐1‐oxo‐1H‐pyrrolo[1,2‐a]pyrrol‐7‐yl)methyl (2S*,3S*)‐3‐[(β‐D ‐glucopyranosyl)oxy]‐2‐hydroxy‐2‐(1‐methylethyl)butanoate ( 1 ) and 1,2‐dihydro‐8‐methoxy‐2‐oxoquinoline‐4‐carboxylic acid ( 2 ), were isolated from the alcoholic extract of the whole plant of Cynoglossum gansuense, together with twelve known compounds Their structures were characterized by means of spectroscopic methods, especially by 1H‐, 13C‐, and 2D‐NMR, as well as by HR‐MS experiments and comparison with literature data. 相似文献
135.
Ping He 《Journal of fluorine chemistry》2005,126(1):113-120
The reactions of fluoroalkanesulfonyl azides RfSO2N31 with N-alkylindoles 2 have been studied in detail. It was found that both solvent and the amount of the azides seriously affected the product distribution. 1 reacted with equimolar of 2 in ether or 1,4-dioxane affording 2-(N-substituted-indolinylidene)fluoroalkane sulfonylimines 3 as major product; While, treatment of 2 with 2 equiv. of 1 in ethanol, an unexpected product N-substituted-2-fluoroalkanesulfonimino-3-diazo-indolines 4 were obtained in good yield. The reaction mechanism was discussed. 相似文献
136.
We optimized the hot water extraction of polysaccharides from the root of Henry wood betony (RHWPs) using a uniform test and explored their anti-tumor activities in vitro and in vivo. The optimal extraction conditions were as follows: 40 min extraction time, liquid/solid ratio 30 mL/g, 100 min soaking time, two extraction cycles, 100% ethanol concentration, and extraction temperature of 80 °C. The molecular weight distribution of RHWPs with MWs was 228,600 g/mol and 5001 g/mol. The IR spectrum further indicated that RHWPs are acidic polysaccharides containing pyranose and furan rings. The main monosaccharides found in RHWPs were mannose, ribose, l-rhamnose monohydrate, glucuronic acid, galacturonic acid, glucose, galactose, xylose, arabinose, and fucose. RHWPs inhibited the proliferation of S180 tumor cells and induced apoptosis in vitro. Oral administration of RHWPs to tumor-bearing mice significantly inhibited the growth of the S180 xenografts, accelerated apoptosis in tumor cells, and expanded the necrotic regions. Furthermore, RHWPs also markedly increased the levels of TNF-α, IFN-γ, and IL-2 in the sera of tumor-bearing mice, and activated immune cells such as lymphocytes, NK cells, and macrophages, thereby inducing tumor cell apoptosis. Taken together, RHWPs are a promising anti-tumor agent that ought to be explored further. 相似文献
137.
本文介绍水杨配合与4-氨基-3,5-二乙基-1,2,4-三唑缩合而成对称三唑Schif碱(SAETZ)与氯化铜(CuCl2)形成一种新的配合物Cu(SAETZ)2(SAETZ=4-(邻羟苯基亚甲基)-亚胺-3,5-二乙基-1,2,4-三唑)。配合物的晶体结构表明,分子中两个偶氮甲碱的N原子及两个酚氧原子与中心Cu原子形成规则的平面配位结构。晶体属单斜晶系,空间群P21/n,a=8.688(2),b=9.314(1),c=16.515(4),β=94.34(2)。,V=1332.5(7)3,Z=2。 相似文献
138.
139.
[reaction: see text] A molecular shuttle containing an alpha-CD macrocycle, an azobenzene unit, and two different fluorescent naphthalimide units was synthesized. The cis-trans photoisomerization of the azobenzene unit resulted in the motion of the CD macrocycle on the track. Because of the easy regulation and full reversibility of the fluorescence change of the two stopper units, the molecular shuttle could be used as a molecular storage medium or switch with all-optical inputs and outputs. 相似文献
140.