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22.
A convergent two-step process is described for the synthesis of ene-1,5-diols that provides for union of two carbonyl electrophiles via a formal pentenyl dianion equivalent. 相似文献
23.
Alec L. Matheson Michael I. Stessin 《Proceedings of the American Mathematical Society》2005,133(11):3361-3370
We prove that Cauchy transforms of characteristic functions of subsets of positive measure of the unit circle are equidistributed in the unit disk in the sense that the -closure of the polynomial algebra in these Cauchy transforms coincides with the -closure of the polynomial algebra in a canonical inner function. As a corollary to this result we find conditions describing when the polynomial algebra in two singular inner functions determined by point masses is dense in the Hardy spaces .
24.
The last few years have seen a significant increase in publicly available software specifically targeted to the analysis of
extreme values. This reflects the increase in the use of extreme value methodology by the general statistical community. The
software that is available for the analysis of extremes has evolved in essentially independent units, with most forming extensions
of larger software environments. An inevitable consequence is that these units are spread about the statistical landscape.
Scientists seeking to apply extreme value methods must spend considerable time and effort in determining whether the currently
available software can be usefully applied to a given problem. We attempt to simplify this process by reviewing the current
state, and suggest future approaches for software development. These suggestions aim to provide a basis for an initiative
leading to the successful creation and distribution of a flexible and extensible set of tools for extreme value practitioners
and researchers alike. In particular, we propose a collaborative framework for which cooperation between developers is of
fundamental importance.
AMS 2000 Subject Classification Primary—62P99 相似文献
25.
26.
The convergence of the full perturbation theory expansion for the Fermi contact term in the spin-spin coupling constant of hydrogen fluoride has been studied. By examining the contribution of higher virtual states as the basis set is expanded to 18 atomic orbitals, it is shown that at this level of approximation the expansion does not converge. The need to also establish convergence before accepting values calculated from configuration interaction wavefunctions is discussed.The Puerto Rico Nuclear Center is operated by the University of Puerto Rico for the United States Atomic Energy Commission under Contract No. AT(40-1)-1833. 相似文献
27.
搭建了一套研究金属和金属氧化物表面的超快激发态电子动力学和光化学动力学的飞秒双光子光电子能谱仪. 该装置将半球形电子能量分析仪和成像技术相结合,同时测量光电子的能量和角度分布.通过Mach-Zehnder干涉仪测量时间分辨的双光子光电子能谱获得超快激发电子态的动力学信息. 这一功能在Cu(111)上得到了证实. 另外还发展了一个通过实时测量双光子光电子能谱来研究表面光化学的方法,并成功应用到CH3CH2OH/TiO2(110)体系. 研究表明,只有将两种方法结合起来才能正确地研究光诱导的表面激发共振的动力学. 相似文献
28.
Palladium-catalyzed Negishi cross-coupling of 3-bromo-1-(tert-butyldimethylsilyl)-1,2-dihydro-1,2-azaborine while maintaining the B?H functionality has been demonstrated. 17 examples, including dialkylzinc, alkyl-, alkenyl-, aryl-, as well as nitrogen-, sulfur-, and oxygen-containing heteroaryl-zinc halide reagents have been coupled to generate new C(3) substituted 1,2-azaborines in moderate to excellent yields. 相似文献
29.
Nils Bartels Bastian C. Krüger Daniel J. Auerbach Alec M. Wodtke Tim Schfer 《Angewandte Chemie (International ed. in English)》2014,53(50):13690-13694
The loss or gain of vibrational energy in collisions of an NO molecule with the surface of a gold single crystal proceeds by electron transfer. With the advent of new optical pumping and orientation methods, we can now control all molecular degrees of freedom important to this electron‐transfer‐mediated process, providing the most detailed look yet into the inner workings of an electron‐transfer reaction and showing how to control its outcome. We find the probability of electron transfer increases with increasing translational and vibrational energy as well as with proper orientation of the reactant. However, as the vibrational energy increases, translational excitation becomes unimportant and proper orientation becomes less critical. One can understand the interplay of all three control parameters from simple model potentials. 相似文献
30.
Two reaction sequences commencing with different starting materials were successfully employed for the synthesis of frondosin A analogues, including (+/-)-frondosin A dimethyl ether. Construction of the bicyclo[5.4.0]undecane core in each case was achieved through an expedient microwave-assisted tandem 5-exo cyclization--Claisen rearrangement process. 相似文献