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1.
2.
D. L. Allara C. W. White R. L. Meek T. H. Briggs 《Journal of polymer science. Part A, Polymer chemistry》1976,14(1):93-104
Two surface analysis techniques (Rutherford backscattering and surface composition by analysis of neutral and ion impact radiation) have been applied to the study of interfacial copper transport in the oxidation of polyethylene films over copper surfaces. Analysis of films oxidized several thousand hours at 40, 57, and 87°C shows maximum concentrations of copper species in the polymer matrix of ~0.1M extending to depths of several thousand angstroms. These results, together with previous infrared spectroscopic studies, allow some significant conclusions and hypotheses to be drawn as regards the roles of heterogeneous and homogeneous catalytic processes which occur in the thermal-oxidative degradation of polyethylene–copper systems. 相似文献
3.
The concept of decisional power introduced by Hoede and Bakker is investigated. The one‐dictator system is proven to give the minimum value for the index of democracy. Next to results on power in structures with representation there is a discussion of the effect of vote binding. 相似文献
4.
Justin S. Marcum Tiffany R. Taylor Prof. Simon J. Meek 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(33):14174-14179
A catalytic method for the site-selective and enantioselective synthesis of functionalized arenes by the intermolecular hydroarylation of terminal and internal 1,3-dienes with aryl pinacolato boronates is reported. The reactions are promoted by 5.0 mol % of a readily available monodentate phosphoramidite-Ni complex in ethanol, affording a variety of enantioenriched products in up to 96 % yield and 99:1 er. Mechanistic studies indicate that Ni–allyl formation is irreversible and related to the nature of the arylboronate. 相似文献
5.
Joseph M. Zanghi Simon J. Meek 《Angewandte Chemie (International ed. in English)》2020,59(22):8451-8455
A catalytic diastereo‐ and enantioselective method for the preparation of complex tertiary homoallylic alcohols containing a vicinal quaternary carbon stereogenic center and a versatile alkenylboronic ester is disclosed. Transformations are promoted by 5 mol % of a readily available copper catalyst bearing a bulky monodentate phosphoramidite ligand, which is essential for attaining both high dr and er. Reactions proceed with a wide variety of ketones and allylic 1,1‐diboronate reagents, which enables the efficient preparation of diverse array of molecular scaffolds. 相似文献
6.
Platinum(II) dimethyl complexes of the three triphosphines PhP(CH2CH2CH2PPh2)2, PhP(CH2CH2PPh2)2, and PhP(CH2CH2PMe2)2 have been shown by 31P NMR to undergo exchange of the terminal phosphino groups. An exchange route involving a five-coordinate platinum(II) complex is proposed. 相似文献
7.
[reaction: see text] Cyclopropanation of allylic tertiary amines using the Simmons-Smith reagent has been achieved by employing chelating groups in close proximity to the amine. The chelating groups promote cyclopropanation at the expense of N-ylide formation. Using pseudoephedrine as the chelating group, high diastereoselectivity is observed. 相似文献
8.
Gareth AD Hardy Nesrina Imami Mark R Nelson Ann K Sullivan Ron Moss Marlén MI Aasa-Chapman Brian Gazzard Frances M Gotch 《Journal of immune based therapies and vaccines》2007,5(1):6-12
Background
Fully functional HIV-1-specific CD8 and CD4 effector T-cell responses are vital to the containment of viral activity and disease progression. These responses are lacking in HIV-1-infected patients with progressive disease. We attempted to augment fully functional HIV-1-specific CD8 and CD4 effector T-cell responses in patients with advanced chronic HIV-1 infection. 相似文献9.
10.
A note on finding clothoids 总被引:2,自引:0,他引:2
The clothoid is a spiral that is used as transition curve in highway and railway route design. Although its defining formulas are transcendental functions, recent work has shown that it can be used fairly easily on small computers. A single nonlinear equation must be solved in each of four common arrangements of the clothoid. The purpose of this work is to give starting intervals for which Newton's root finding method applied to those equations is guaranteed to converge. 相似文献