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排序方式: 共有866条查询结果,搜索用时 109 毫秒
861.
862.
Esther Amevor Simona Bronco Giambattista Consiglio Silvia Di Benedetto 《Macromolecular Symposia》1995,89(1):443-454
Strictly alternating copolymers between olefins and carbon monoxide are synthesized using cationic palladium catalysts modified by phosphorus or nitrogen ligands. Basic chelate diphosphines as the ligand allow the regioregular copolymerization of aliphatic olefins thus affording, e.g. in the case of propene, poly(1-oxo-2-methyltrimethylene). Steric control of the copolymerization process towards the production of overwhelmingly isotactic copolymers is possible particularly when using atropisomeric ligands. In the case of styrene as the substrate and for all ligands employed the copolymerization process is regioregular. Prevailing syndiotactic structure is obtained with 1,10-phenanthroline or 2,2′-bipyridine as the ligand. Chelate thioether ligands allow the preparation of a completely atactic material. For 4-tert-butylstyrene an isotactic structure became accessible by using chiral bisoxazolidines. The prevailing structure of the copolymers of cyclopentene corresponds to a 1,3-enchainment of the olefin units most probably associated with a prevailing diisotactic structure 相似文献
863.
Emilay B. T. Diogo Dr. Fábio G. Delolo Gabriela A. P. Graça Esther R. S. Paz Ícaro A. O. Bozzi Prof. Dr. Renata Diniz Juliano P. Passos Prof. Dr. Tulio Matencio Dr. Liane K. Soares Prof. Dr. Diego Alves Pedro M. S. Costa Prof. Dr. Claudia Pessoa Prof. Dr. Cynthia L. M. Pereira Prof. Dr. Lutz Ackermann Prof. Dr. Eufrânio N. da Silva Júnior 《European journal of organic chemistry》2023,26(38):e202300506
Undivided electrochemical cells enable economical preparation of sulphur-containing naphthoquinones through electrochemical sulphenylation of quinoidal compounds. The environmentally friendly and efficient protocol eliminates the use of chemical oxidants and facilitates the synthesis of the desired molecules. This approach offers an efficient and versatile method to synthesize quinones that exhibit cytotoxicity against cancer cell lines. 相似文献
864.
Charlotte M. Wentz Kätchen K. Lachmayr Dr. Esther H. R. Tsai Prof. Dr. Lawrence R. Sita 《Angewandte Chemie (International ed. in English)》2023,62(23):e202302739
Experimental results are presented that serve to lower the barrier for developing the science and technology of non-classical thermotropic glycolipid mesophases, which now include dodecagonal quasicrystal (DDQC) and Frank–Kasper (FK) A15 and σ mesophases that can be produced under mild conditions from a versatile class of sugar-polyolefin conjugates. By employing “alloys” comprised of mono- and disaccharide-polyolefin conjugates, and optionally with vitamin E as a small molecule phase modulator, we report the spontaneous formation of stable A15 mesophases at ambient temperature. We further document a rich thermotropic phase map that includes DDQC, A15, and σ mesophases of tunable periodicity that are connected through rapid thermotropic phase transitions as a function of increasing temperature in the order: liquid-like packing (LLP)→DDQC → A15→σ→ disorder. This first direct observation of a rapid thermotropic A15→σ phase transition provides support for a diffusionless martensitic process proceeding through strain-induced introduction of planar defects into the A15 lattice. 相似文献
865.
866.
Esther Oger Nathan R. M. Crawford Rebecca Kelting Patrick Weis Manfred M. Kappes Reinhart Ahlrichs 《ChemInform》2008,39(7):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option. 相似文献