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101.
102.
New, bent-core, polycatenar pyridine mesogens are described. Binding to silver(I) leads to complexes properly described as discotic. 相似文献
103.
Recent high-resolution FTIR studies of thioketene-H2,-HD, and -D2 have improved the precision with which a number of fundamental vibrations are determined and enabled accurate sets of rotation and distortion constants to be determined. These have been used, in conjunction with recent results for ketene, to determine the harmonic potential function for thioketene and the zero-point average molecular structure. A marked change in the methylene group geometry between thioketene and ketene is observed, such that a considerable increase in the CH bond length and concomitant decrease in the HCH angle occurs on sulfur substitution. 相似文献
104.
Duncan K. H. Fong 《The Journal of the Operational Research Society》1992,43(1):63-69
In the stochastic lead time inventory model with two suppliers and different normal lead times, the mean and variance of the lead-time demand distribution are traditionally computed using numerical integration. Tables are made available to help practitioners determine the minimum size of replenishments when orders to the suppliers are placed at the same time. This paper presents closed-form solutions to evaluate the required quantities of interest and tries to correct some mistakes in the existing tables. The expressions given here may also provide insight into the choice of sole versus dual suppliers. 相似文献
105.
Marcela Cecilia González-Araya Luís Alberto Duncan Rangel Marcos Pereira Estellita Lins Luiz Flávio Autran Monteiro Gomes 《Annals of Operations Research》2002,116(1-4):271-288
This paper presents an application of the UTA method for building utility functions for the evaluation criteria defined by the Staff Evaluation Commission (CAD) of the Rio de Janeiro Federal University (UFRJ). Every year, the CAD-UFRJ gives the staff evaluation results for each Postgraduate Engineering Programme. However, the method used to generate the staff evaluation is assumed unknown. Trying to find the CAD-UFRJ preference structure, the evaluation results supplied by CAD-UFRJ are used to apply the UTA method. Some additional information obtained from the CAD-UFRJ data is incorporated in the optimal solutions analysis. 相似文献
106.
Stephen P. Watson Richard D. Wilson Duncan B. Judd Stephen A. Richards 《Tetrahedron letters》1997,38(52):179-9068
The development of a novel solid phase synthesis of some 5-aminopyrazoles and derivatives is described. Reaction of hydrazines with solid supported β-keto-nitrile (1) affords 5-aminopyrazoles (2) the amino group of which is readily acylated or sulphonylated. Generation of the solid supported β-keto-nitrile (1) is non trivial and represents a key step in the overall synthesis. 相似文献
107.
We report here, a method of accelerating the rate of aminolysis of PFP sulfonates to yield sulfonamides using tetrabutylammonium salts. We have previously explored the utility of employing PFP sulfonates in the formation of sulfonamides; however we demonstrate here the advantages of combining the existing methodology with a revised protocol which allows the diversity within both the sulfonate ester and the amine to be extended. 相似文献
108.
Cooperative Lewis Pairs Based on Late Transition Metals: Activation of Small Molecules by Platinum(0) and B(C6F5)3
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Sebastian J. K. Forrest Jamie Clifton Dr. Natalie Fey Prof. Paul G. Pringle Dr. Hazel A. Sparkes Prof. Duncan F. Wass 《Angewandte Chemie (International ed. in English)》2015,54(7):2223-2227
A Lewis basic platinum(0)–CO complex supported by a diphosphine ligand and B(C6F5)3 act cooperatively, in a manner reminiscent of a frustrated Lewis pair, to activate small molecules such as hydrogen, CO2, and ethene. This cooperative Lewis pair facilitates the coupling of CO and ethene in a new way. 相似文献
109.
Matthew A. Bedics Hayleigh Kearns Jordan M. Cox Sam Mabbott Fatima Ali Neil C. Shand Karen Faulds Jason B. Benedict Duncan Graham Michael R. Detty 《Chemical science》2015,6(4):2302-2306
Surfaced enhanced Raman scattering (SERS) nanotags operating with 1280 nm excitation were constructed from reporter molecules selected from a library of 14 chalcogenopyrylium dyes containing phenyl, 2-thienyl, and 2-selenophenyl substituents and a surface of hollow gold nanoshells (HGNs). These 1280 SERS nanotags are unique as they have multiple chalcogen atoms available which allow them to adsorb strongly onto the gold surface of the HGN thus producing exceptional SERS signals at this long excitation wavelength. Picomolar limits of detection (LOD) were observed and individual reporters of the library were identified by principal component analysis and classified according to their unique structure and SERS spectra. 相似文献
110.
Robert Szczęsny Tadeusz M. Muzioł Duncan H. Gregory Edward Szłyk 《Chemical Papers》2015,69(4):569-579
Four copper(II) oxime complexes, [Cu(HPPK)(PPK)X] (HPPK = phenyl-2-pyridylketoxime and X = CI? (I), CF3COO? (II), C3F7COO? (III), and [Cu(PPK)2]2 (IV)), were synthesized and characterized by elemental analysis, infrared spectroscopy (IR), and single-crystal X-ray diffraction (XRD). XRD analysis revealed that I–III contain copper(II) coordinated by four nitrogen atoms from two oxime molecules in the basal plane and one monodentate anion X in the apical position of a distorted square pyramid. Complex IV is dimeric and it is formed by two Cu(PPK)2 units. Bridges between these units are formed by the two oxygen atoms of the deprotonated oxime groups. Thermal stability of I–IV was investigated by thermogravimetric analysis (TGA) in air and in nitrogen atmosphere, respectively. Evolved gaseous decomposition products were characterized by IR. I–IV decompose via multistep processes. Fluorocarbons and CO2 were observed to be the most abundant gaseous species evolved. Preliminary ammonolysis experiments were performed to examine the possibility of using II and IV as precursors for the synthesis of copper nitride. Moreover, solutions of IV were spin-coated onto silicon substrates. Surface structure and morphology of the resulting films were studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM) and layers with island-like distribution of material were observed. 相似文献