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141.
Ivan Tafteberg Jakobsen 《Discrete Mathematics》1974,9(3):265-276
It is shown that the number of vertices of valency 2 in a critical graph with chromatic index 4 is at most 1/3 of the total number of vertices, and that there exist critical graphs with just one vertex of valency 2, but none with exactly two vertices of valency 2. From this bounds for the number of edges are deduced. The paper ends with a presentation of a catalogue of all critical graphs with chromatic index 4 and at most 8 vertices, and all simple critical graphs with chromatic index 4 and at most 10 vertices. 相似文献
142.
Catalytic Asymmetric [4+2]‐Cycloadditions Using Tropolones: Developments,Scope, Transformations,and Bioactivity 下载免费PDF全文
Niels Hammer Dr. Jeremy D. Erickson Dr. Vibeke H. Lauridsen Joakim B. Jakobsen Bente K. Hansen Kristian M. Jacobsen Prof. Dr. Thomas B. Poulsen Prof. Dr. Karl Anker Jørgensen 《Angewandte Chemie (International ed. in English)》2018,57(40):13216-13220
An organocatalyzed asymmetric [4+2]‐cycloaddition between tropolones and electron‐deficient dienophiles is presented. Complex and biologically interesting dihydrohomobarrelenone scaffolds are formed through a Diels–Alder reaction utilizing bifunctional Brønsted‐base catalysis, affording the corresponding bridged bicyclic cycloadducts in up to quantitative yields with good enantio‐ (up to 92 % ee) and diastereoselectivity (up to >20:1 d.r.). The synthetic value of the obtained products is explored by downstream transformations, including photoisomerizations, and their biological relevancy by in vivo testing in MCF‐7 cancer cells. 相似文献
143.
In Situ Total X‐Ray Scattering Study of WO3 Nanoparticle Formation under Hydrothermal Conditions 下载免费PDF全文
Dr. Dipankar Saha Dr. Kirsten M. Ø. Jensen Dr. Christoffer Tyrsted Espen D. Bøjesen Dr. Aref Hasen Mamakhel Dr. Ann‐Christin Dippel Dr. Mogens Christensen Prof. Dr. Bo B. Iversen 《Angewandte Chemie (International ed. in English)》2014,53(14):3667-3670
Pair distribution function analysis of in situ total scattering data recorded during formation of WO3 nanocrystals under hydrothermal conditions reveal that a complex precursor structure exists in solution. The WO6 polyhedra of the precursor cluster undergo reorientation before forming the nanocrystal. This reorientation is the critical element in the formation of different hexagonal polymporphs of WO3. 相似文献
144.
145.
In this paper we discuss the problem of prior for the maximum entropy principle. We show that stochastic relations can be
used to constrain priors and in some case uniquely determine them. The principle of maximum entropy turns stochastic relations
into (over)determined systems of partial difference equations for the partition function. All statistical consequences of
the stochastic relations are determined by the space of solutions of the system. 相似文献
146.
147.
Folkenberg JR Mortensen NA Hansen KP Hansen TP Simonsen HR Jakobsen C 《Optics letters》2003,28(20):1882-1884
Modal cutoff is investigated experimentally in a series of high-quality nonlinear photonic crystal fibers. We demonstrate a suitable measurement technique with which to determine the cutoff wavelength and verify the technique by inspecting the near field of the modes that may be excited below and above the cutoff. We observe a double-peak structure in the cutoff spectra, which is attributed to splitting of the higher-order modes. The cutoff is measured for seven different fiber geometries with different pitches and relative hole sizes, and very good agreement with recent theoretical work is found. 相似文献
148.
Dr. Antony J. Williams Taye B. Demissie Dr. Espen Hansen Dr. Jeanette H. Andersen Dr. Johan Svenson Kirill Blinov Dr. Michal Repisky Dr. Fabian Mohn Dr. Gerhard Meyer Prof. Dr. John‐Sigurd Svendsen Prof. Dr. Kenneth Ruud Prof. Dr. Mikhail Elyashberg Dr. Leo Gross Prof. Dr. Marcel Jaspars Dr. Johan Isaksson 《Angewandte Chemie (International ed. in English)》2012,51(49):12238-12241
149.
150.
We discuss the connection between Gaussian and Poisson noise Wick-type stochastic partial differential equations. 相似文献