نتایج جستجو برای: clean ring
تعداد نتایج: 155265 فیلتر نتایج به سال:
Cobalt-porphyrin-catalysed intramolecular ring-closing C-H bond amination enables direct synthesis of various N-heterocycles from aliphatic azides. Pyrrolidines, oxazolidines, imidazolidines, isoindolines and tetrahydroisoquinoline can be obtained in good to excellent yields in a single reaction step with an air- and moisture-stable catalyst. Kinetic studies of the reaction in combination with ...
We investigate the persistent currents and magnetization of a mesoscopic system consisting of two clean metallic rings sharing a single contact point in a magnetic field. Many novel features with respect to the single-ring geometry are underlined, including the explicit dependence of wavefunctions on the Aharonov-Bohm fluxes, the complex pattern of twofold and threefold degeneracies, the key rô...
Our conclusion that a Juniperus virginiana stand in the central Appalachian Mountains is recovering from decades of acid deposition was based on tree ring carbon isotope ratios (δC) that show: (i) close correspondence between the timing of changes in direction of δC with declines in SO2 emissions occurring after the Clean Air Act; (ii) close similarities between patterns of δC after 1980 and du...
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