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排序方式: 共有216条查询结果,搜索用时 15 毫秒
21.
Doris Chen Elizabeth V. Jones Corey W. Williams Tan-Khang N. Huynh Tristan C. McPhail Prof. Dr. Stefan France 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(52):e202201368
Herein, a SnCl4-catalyzed intramolecular, interrupted homo-Nazarov cascade biscyclization to access angular (hetero)aryl-fused polycycles is reported. Subsequent decarboxylation of the readily enolizable products afforded the angular products in up to 71 % yield over two steps, with the trans-diastereomers as the major products. The cyclopropyl homo-Nazarov cyclization precursors were formed using a scalable and modular synthetic route that, ultimately, offers access to 6,6,6-, 6,6,5-, 6,5,6-, 6,6,5,6-, and 6,6,6,5-fused angular polycyclic products. To showcase the rigor and utility of the method, an 8-step total synthesis of (±)-1-oxoferruginol, an antibacterial aromatic abietane diterpenoid, was disclosed. 相似文献
22.
The bulk resistivities of vanadium phosphate glasses in the compositional range from 65 to 85 mole % V2O5 were measured and fitted as a function of composition to the equation for conductivity as proposed by Mott and later modified by Sayer and Mansingh for n, the number of unoccupied mearest sites surrounding the final hopping site of the small polaron. The fit to the experimental data was found to be best if the number n is chosen to be proportional to the total number of V5+ sites in the glass. Also n is found to be non-integer and can be regarded as the effective number of unoccupied sites surrounding the final site in the sense of eqn (24) developed in this paper. Values for n ranged from 0.2 to 5 for different compositions of the glass. A model for the structure of vanadium phosphate glass is proposed to explain the data. 相似文献
23.
24.
J. Großfeld A. Simmer J. van Loon W. Springer S. Juschkewitsch V. Kubelka J. Wagner S. Zuravlev Thompsonwerke W. Normann H. P. Trevithik M. F. Lauro A. Bömer A. Gehrke G. de Belsunce J. I. Lurje F. Fritz Zitek R. Otto A. Halter J. M. Purdy W. G. France W. L. Evans H. P. Kaufmann und M. Keller 《Fresenius' Journal of Analytical Chemistry》1931,83(5-6):223-230
Ohne Zusammenfassung 相似文献
25.
Wagner J Andres H Rohrbach S Wagner D Oberer L France J 《The Journal of organic chemistry》2005,70(23):9588-9590
[Reaction: see text]. Sanglifehrin A is a novel complex natural product showing strong immunosuppressive activity and remarkably high affinity for cyclophilin A. To assess its pharmacokinetic properties in vivo, an efficient synthetic route was developed to introduce a tritium label in position C35 of sangliferin A via an oxidation/reduction strategy. The synthetic approach is particularly attractive, because the C35-oxo intermediate 7 is available in good yield on large scale and the reducing agent, lithium tri-sec-butylborotritide, is readily available. An attempt to apply a similar strategy to the alcohol in position C31 led primarily to C31-epi-hydroxy sanglifehrin A under a variety of conditions. 相似文献
26.
振动谱学研究中的光谱线型函数 总被引:2,自引:1,他引:2
本文讨论了在振动谱带计算拟合处理中的光谱线型函数问题,推导出适用于单道及多道拉曼光谱仪及色散型红外谱仪谱带线型公式。通过实验及拟合计算证实了它们的适用性并讨论了可能的误差源。理论计算和实验验证结果说明:在振动谱的谱带拟合计算中,应使用根据测谱条件计算求得的谱带线型函数,以保证拟合结果的可靠性。 相似文献
27.
J. Giovinazzo B. Blank C. Borcea M. Chartier S. Czajkowski G. de France R. Grzywacz Z. Janas M. Lewitowicz F. de Oliveira Santos M. Pfützner M.S. Pravikoff J.C. Thomas 《The European Physical Journal A - Hadrons and Nuclei》2001,10(1):73-84
Decay studies of very neutron-deficient nuclei ranging from 39Ti to 49Ni have been performed during a projectile fragmentation experiment at the GANIL/LISE3 separator. For all nuclei studied in
this work, 39, 40Ti, 42, 43Cr, 46Mn, 45, 46, 47Fe and 49Ni, half-lives and decay spectra have been measured. In a few cases, γ coincidence measurements helped to successfully identify
the initial and final states of transitions. In these cases, partial decay scheme are proposed. For the most exotic isotopes,
39Ti, 42Cr, 45Fe and 49Ni, which are candidates for two-proton radioactivity from the ground state, no clear evidence of this process is seen in
our spectra and we conclude rather on a delayed particle decay.
Received: 26 July 2000 / Accepted: 20 December 2000 相似文献
28.
Gregory G Wildgoose Shelley J Wilkins Gareth R Williams Robert R France David L Carnahan Li Jiang Timothy G J Jones Richard G Compton 《Chemphyschem》2005,6(2):352-362
We demonstrate that graphite powder and multiwalled carbon nanotubes (MWCNTs) can be derivatised by 4-nitrobenzylamine (4-NBA) simply by stirring the graphite powder or MWCNTs in a solution of acetonitrile containing 10 mM 4-NBA. We propose that 4-NBA partially intercalates at localised edge-plane or edge-plane-like defect sites and this hypothesis with a range of experimental data provided by electrochemistry in both aqueous and nonaqueous media, electron microscopy and X-ray powder diffraction. 相似文献
29.
Eliette Pinel Marie‐France Barthe Jrmie De Baerdemaeker Rgis Mercier Sylvie Neyertz N. Dominique Albrola Corine Bas 《Journal of Polymer Science.Polymer Physics》2003,41(23):2998-3010
The microstructures of a series of copolyimide films were characterized with different experimental methods such as density measurements, X‐ray diffraction, ultraviolet‐visible spectrophotometry, positron annihilation spectroscopy, and dynamic mechanical analysis. The experimental data were linked to the chemical structures of the polymers and especially the alicyclic and fluorinated monomers. Some analysis responses were directly dependent on the fluorine atoms and, therefore, did not provide clear information about the microstructures. The chain organization in the amorphous films appeared to be significantly dependent on the effect of the casting solvent. The influence of the alicyclic group content was quite significant for a nonsubstituted diamine but was strongly attenuated with a fluorinated diamine. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2998–3010, 2003 相似文献
30.