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191.
Jian Yan Xiang‐Ming Zhang Zhong‐Rong Li Lin Zhou Jian‐Chao Chen Li‐Rong Sun Ming‐Hua Qiu 《Helvetica chimica acta》2005,88(2):240-244
Three new triterpenoids, (3β,8β,14α,21α)‐26,27‐dinoronocerane‐3,8,14,21‐tetrol ( 1 ), (3β,8β,14α,21β)‐26,27‐dinoronocerane‐3,8,14,21‐tetrol ( 2 ), and lycopodiin A ( 3 ), together with four known compounds, lycoclavanol ( 4 ), lycoclaninol ( 5 ), α‐onocerin ( 6 ), and 3‐epilycoclavanol ( 7 ), were isolated from Lycopodium japonicum Thunb (Lycopodiaceae). Their structures were established by means of spectroscopic analyses. Compounds 3 and 7 showed moderate antitumor activity. Compounds 4 and 6 exhibited acetylcholinesterase inhibition activity. 相似文献
192.
"Living"/controlled radical polymerization of styrene was carried out with diethyl 2,3-dicyano-2,3-diphenylsuccinate (DCDPS)/CuCl2/bipyridine (bipy) initiation system at 120℃. The molecular weights of resultant PSt increased with the monomer conversion and the polydispersities were in the range of 1.37 ~ 1.52. A linear ln([M]o/[M])versus time plot was also obtained indicating the constant concentration of growing radicals during the polymerization with this initiation system. End group analysis by 1H-NMR spectroscopic studies showed that the end groups of the polymer obtained is cω-functionalized by a chlorine group from the catalyst and a-functionalized by a (carbethoxy-cyano-phenyl)methyl group from the fragments of the initiator. Having C1 atom at the chain end, the PSt obtained can be used as a macroinitiator to promote a chain-extension reaction with fresh St and block copolymerization reaction with a second monomer, such as methyl methacrylate, in the presence of CuC1/bipy catalyst via a conventional ATRP process. 相似文献
193.
Wang C Zhu G Li J Cai X Wei Y Zhang D Qiu S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(17):4975-4982
We demonstrate a novel strategy for the preparation of mesoporous silica-supported, highly dispersed, stable metal and bimetal nanoparticles with both size and site control. The supporting mesoporous silica, functionalized by polyaminoamine (PAMAM) dendrimers, is prepared by repeated Michael addition with methyl acrylates (MA) and amidation reaction with ethylenediamine (EDA), by using aminopropyl-functionalized mesoporous silica as the starting material. The encapsulation of metal nanoparticles within the dendrimer-propagated mesoporous silica is achieved by the chemical reduction of metal-salt-impregnated dendrimer-mesoporous silica by using aqueous hydrazine. The site control of the metal or bimetal nanoparticles is accomplished by the localization of inter- or intradendrimeric nanoparticles within the mesoporous silica tunnels. The size of the encapsulated nanoparticles is controlled by their confinement to the nanocavity of the dendrimer and the mesopore. For Cu and Pd, particles locate at the lining of mesoporous tunnels, and have diameters of less than 2.0 nm. For Pd/Pt, particles locate at the middle of mesoporous tunnels and have diameters in the range of 2.0-4.2 nm. The Pd and Pd/Pt nanoparticles are very stable in air, whereas the Cu nanoparticles are stable only in an inert atmosphere. 相似文献
194.
Magnetic diphase nanostructures of ZnFe2O4/γ-Fe2O3 were synthesized by a solvothermal method. The formation reactions were optimized by tuning the initial molar ratios of Fe/Zn. All samples were characterized by X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, and Raman spectra. It is found that when the initial molar ratio of Fe/Zn is larger than 2, a diphase magnetic nanostructure of ZnFe2O4/γ-Fe2O3 was formed, in which the presence of ZnFe2O4 enhanced the thermal stability of γ-Fe2O3. Further increasing the initial molar ratio of Fe/Zn larger than 6 destabilized the diphase nanostructure and yielded traces of secondary phase α-Fe2O3. The grain surfaces of diphase nanostructure exhibited a spin-glass-like structure. At room temperature, all diphase nanostructures are superparamagnetic with saturation magnetization being increased with γ-Fe2O3 content. 相似文献
195.
Zhao L Zhu G Zhang D Di Y Chen Y Terasaki O Qiu S 《The journal of physical chemistry. B》2005,109(2):764-768
Using 1,2-bis(trimethoxysilyl)ethane as organosiloxane precursor and a triblock copolymer surfactant, Pluronic F127, as template, a highly ordered mesoporous organosilica with large cagelike pores has been successfully synthesized. Its structure was resolved to be 3-D cubic Fmm by high-resolution transmission electron microscopy. The intergrowth of hexagonal close-packed and cubic close-packed phases was observed in this material. The effect of different siliceous precursors on the mesostructure was also investigated. 相似文献
196.
HO. radical is an aggressive reagent to abstract hydrogen from diverse substitutes and lead them to degradation, however, in
reaction of active oxygen species with lignins, complex phenolic polymers, in dispersed lignocellulose such as pulp for environment-benign
delignification, HO. radicals should be eliminated as more as possible to prevent cellulose from unfavorably concomitant degradation. A reaction
system of O3 is constructed under UV laser flash irradiation, and HO. radicals are controlled efficiently by it. A new mechanism is proposed, for the first time, that O. radicals generated from reaction of O3 with UV laser flash irradiation might be the contributor to scavenge HO. radicals. 相似文献
197.
198.
199.
Three new compounds, a one-dimensional (1D) zinc phosphite, (C4H8N2H4)[Zn(HPO3)2] (I), two three-dimensional (3D) metal phosphites (C4H8N2H4)[Zn3(HPO3)4] (II) and (C4H8N2H4)[Zn(3−x)Cox(HPO3)4(H2O)2] (x≈0.83) (III) have been synthesized under hydrothermal conditions templated by piperazine and characterized by single-crystal X-ray diffraction, XRD, IR, UV-vis spectra and SQUID magnetometer. Compound I displays 1D chain-like structure, containing corner-shared (cs) four-membered rings. Interestingly, the structures of II and III show 1D chains similar to those observed in I. It is noteworthy that III represents the first cobalt-substituted zinc-phosphite. Crystal data: I, monoclinic, C2/c, a=17.748(2) Å, b=7.428(9) Å, c=8.8071(11) Å, β=105.345(3)°, V=1091.9 Å3, Z=4. II, Monoclinic P21/c, a=9.9435(4) Å, b=10.1438(3) Å, c=17.8164(5) Å, β=95.665(2)°, V=1788.27 Å3, Z=4, and III, Monoclinic P21/c, a=7.2338(2) Å, b=15.0238(5) Å, c=9.2153(3) Å, β=107.741(2)°, V=953.88(5) Å3, Z=2. 相似文献
200.
Three new eremophilane‐type sesquiterpenes, (6β,8α)‐6‐(acetyloxy)‐8‐hydroxyeremophil‐7(11)‐en‐12,8‐olide ( 1 ), (6α,8α)‐6‐hydroxyeremophil‐7(11)‐en‐12,8‐olide ( 2 ), and (6α,8α)‐6‐(acetyloxy)eremophil‐7(11)‐en‐12,8‐olide ( 3 ) ((8α)‐eremophil‐7(11)‐en‐12,8‐olide = (4aR,5S,8aR,9aS)‐4a,5,6,7,8,8a,9,9a‐octahydro‐3,4a,5‐trimethylnaphtho[2,3‐b]furan‐2(4H)‐one), besides the recently elucidated eremoligularin ( 4 ) and bieremoligularolide ( 5 ), as well as a new highly oxygenated monoterpene, rel‐(1R,2R,3R,4S,5S)‐p‐menthane‐1,2,3,5‐tetrol ( 12 ), together with six known constituents, i.e., the sesquiterpenes 6 and 7 , the norsesquiterpenes 8 – 10 , and the monoterpene 13 , were isolated from the roots of Ligularia muliensis. In addition, an attempt to dimerize 1 to a bieremophilenolide (Scheme) resulted in the generation of the new derivative (6β,8β)‐6‐(acetyloxy)‐8‐chloroeremophil‐7(11)‐en‐12,8‐olide ( 11 ). The new structures were established by means of detailed spectroscopic analysis (IR, FAB‐, EI‐, or HR‐ESI‐MS as well as 1D‐ and 2D‐NMR experiments). Compounds 4 and 5 were evaluated for their antitumor effects in vitro (Table 3). 相似文献