1,721,121 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Organometallic polymer from N,N-diethylpropargylamine containing Ni coordination centers
No full textSynthesis of conjugated polymeric nanobeads for photonic bandgap materials
No full textPolyphenylacetylene (PPA) and poly[phenylacetylene-(co-2-hydroxyethyl methacrylate)] (P(PA/HEMA)) nanobeads with controlled dimension and low size dispersion were synthesized by a modified emulsion polymerization. A systematic study of the influence of reaction conditions on the chemical and physical characteristics of the nanobeads and on their ability to form ordered arrays was performed. In particular the following parameters were investigated: (i) the role of the co-solvent and initiator on the shape, size and dispersion of the nanobeads, (ii) the effect of the reaction time on the particles size, (iii) the effect of the PA/HEMA ratio on the surface-charge density of the co-polymer nanobeads. © 2006 Elsevier B.V. All rights reserved
Use of the Extended One Pot (EOP) Procedure for the Preparation of Ethynylated Thiophene Derivatives and Related Palladium-Ethynylthiophene Organometallic Oligomers
No full textGrowth control and long-range self-assembly of poly(methyl methacrylate) nanospheres
No full textA systematic investigation of the reaction time and role of a cosolvent (toluene) in inducing several beneficial effects on nanobead properties was performed to achieve the synthesis of poly(methyl methacrylate) nanospheres. In particular, good dimensional control in the range of 100-400 nm, very low polydispersity, and a spherical shape were consistently obtained. Different parameters affecting the self-assembly mechanism leading to the deposition of hard-sphere photonic crystals were studied, and the features underlying their role were examined. Photonic crystals were produced by the evaporation of nanosphere suspensions at different temperatures, relative humidities, and suspension ionic strengths and with different substrate materials. The proper conditions for obtaining large crystal domains were determined. © 2006 Wiley Periodicals, Inc
NEXAFS study of a Pt-containing rod-like organometallic polymer (Pt-DEBP). Molecular orientation onto HOPG, Au/Si(111), Cr/Si(111) and Si(111) surfaces
No full textInteraction of H2O, O2 and CO2 with the surface of polyphenylacetylene films investigated by XPS
No full textH2O surface interaction of oxygen-free polyphenylacetylene films investigated by XPS
No full textThe interaction of water with the surface of polyphenylacetylene (PPA) films is dependent on the preparation ana casting procedures. Films with an oxygen-free surface were obtained. Molecular adsorption of H2O is indicated to be the major phenomenon by XPS. On annealing up to almost-equal-to 250-degrees-C partial loss of adsorbed water occurs. The thickness of the reacted surface layer is estimated to be almost-equal-to 6.0 angstrom when the PPA film is exposed to water vapour at pressure p almost-equal-to 760 Torr
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