Seven new sesquiterpene lactone glycosides (1-7) were isolated from the H2O-soluble fraction from the MeOH extract of the roots of Ferula varia. Their structures were elucidated by extensive spectroscopic analyses. The absolute configurations of compounds 1 and 2 were determined by modified Mosher's method. 相似文献
Feeding studies of six 13C-labeled sterols, including clerosterol, to hairy roots of Ajugareptans var. atropurpurea have established that clerosterol is a precursor of three phytoecdysteroids, cyasterone, isocyasterone and 29-norcyasterone. 相似文献
A cationic fluorescent nanogel thermometer based on thermo‐responsive N‐isopropylacrylamide and environment‐sensitive benzothiadiazole was developed with a new azo compound bearing imidazolium rings as the first cationic radical initiator. This cationic fluorescent nanogel thermometer showed an excellent ability to enter live mammalian cells in a short incubation period (10 min), a high sensitivity to temperature variations in live cells (temperature resolution of 0.02–0.84 °C in the range 20–40 °C), and remarkable non‐cytotoxicity, which permitted ordinary cell proliferation and even differentiation of primary cultured cells. 相似文献
Let be a bounded domain in , , and let . We consider positive functions on such that for all bounded harmonic functions on . We determine Lipschitz domains having such with .
Di(2-pyridyl)ketone dimethylplatinum(ii), (dpk)PtII(CH3)2, reacts with CD3OD at 25 °C to undergo complete deuteration of Pt–CH3 fragments in ∼5 h without loss of methane to form (dpk)PtII(CD3)2 in virtually quantitative yield. The deuteration can be reversed by dissolution in CH3OH or CD3OH. Kinetic analysis and isotope effects, together with support from density functional theory calculations indicate a metal–ligand cooperative mechanism wherein DPK enables Pt–CH3 deuteration by allowing non-rate-limiting protonation of PtII by CD3OD. In contrast, other model di(2-pyridyl) ligands enable rate-limiting protonation of PtII, resulting in non-rate-limiting C–H(D) reductive coupling. Owing to its electron-poor nature, following complete deuteration, DPK can be dissociated from the PtII-centre, furnishing [(CD3)2PtII(μ-SMe2)]2 as the perdeutero analogue of [(CH3)2PtII(μ-SMe2)]2, a commonly used PtII-precursor.Di(2-pyridyl)ketone dimethylplatinum(ii), (dpk)PtII(CH3)2, reacts with CD3OD at 25 °C to undergo complete deuteration of Pt–CH3 fragments in ∼5 h without loss of methane to form (dpk)PtII(CD3)2 in virtually quantitative yield.相似文献
Vinyl ethers containing tricarbonyl(14-η4-1,3-pentadiene)-ruthenium(0) and -iron(0) species were prepared utilizing selective dienylation with penta-dienylpotassium and were polymerized with cationic initiators to give high molecular weight polymers. The diene-metal moieties were converted into tricarbonyl(13-η3-allyl)metal species by protonation with dry HCl. Tricarbonyl(3-allyl-14-η4-1,3-pentadiene)iron(0) also undergoes cationic polymerization but the presence of its isomer, tricarbonyl(3-propenyl-14-η4-1,3-pentadiene)iron(0) inhibits the polymerization. 相似文献
An elimination method is presented for laser isotope separation. It consists of flow cycles of feed molecules, in which an isotope component of non-interest, instead of the one of interest, is photolyzed to be eliminated, and the residue is recycled for photlysis. An isotope can be enriched as much as desired even if the isotope selectivity in the photolysis is low. The separation of 13C is demonstrated by employing multiphoton dissociation using a TEA CO2 laser. 相似文献
Diethylzinc was allowed to react with γ-alumina in n-heptane at 50°C, and the copolymerization of propylene oxide and carbon dioxide was investigated in some detail at 30–90°C by using the reaction product as a catalyst. From an analysis of the catalyst it was found that diethylzinc reacted with the surface hydroxyl groups of γ-alumina mainly to give the following A-type species by evolving ethane: The catalyst showed considerably high activity for the copolymerization. The polymer obtained was a white solid with a high molecular weight soluble in benzene, acetone, dioxane, and methylene chloride and insoluble in diethyl ether and water. It was confirmed as an alternate copolymer of propylene oxide and carbon dioxide. The copolymerization was also conducted with a reaction mixture of the catalyst and catechol in which the molar ratio of catechol to the A-type species was varied. The copolymerization activity decreased linearly with an increase in the molar ratio and disappeared completely at the molar ratio of unity. On the basis of these results it has been concluded that the A-type is the true active species for the copolymerization. 相似文献