1,720,974 research outputs found
Organische Chemie 2004
No full textBruckner R, Wurthner F, Tschierske C, et al. Organische Chemie 2004. Nachrichten aus der Chemie. 2005;53(3):251-272
Wavelength-Dependent Electron and Energy Transfer Pathways in a Side-to-Face Ruthenium Porphyrin / Perylene Bisimide Assembly
No full textA new side-to-face supramolecular array of chromophores, where a pyridyl-substituted perylene bisimide dye axially binds to two ruthenium porphyrin fragments, has been prepared by self-assembly. The array is formulated as DPyPBI[Ru(TPP)(CO)] 2 , where DPyPBI )N ,N ′-di(4-pyridyl)-1,6,7,12-tetra(4- tert -butylphenoxy)perylene-3,4:9,10-tetracarboxylic acid bisimide and TPP ) 5,10,15,20-tetraphenylpor- phyrin. The photophysical behavior of DPyPBI[Ru(TPP)(CO)] 2 has been studied by fast (nanoseconds) and ultrafast (femtoseconds) time-resolved techniques. The observed behavior sharply changes with excitation wavelength, depending on whether the DPyPBI or Ru(TPP)(CO) units are excited. After DPyPBI excitation, the strong fluorescence typical of this unit is completely quenched, and time-resolved spectroscopy reveals the occurrence of photoinduced electron transfer from the ruthenium porphyrin to the perylene bisimide dye (ô ) 5.6 ps) followed by charge recombination (ô ) 270 ps)
Organische Chemie 2002
No full textWurthner F, Herges R, Brase S, et al. Organische Chemie 2002. Nachrichten aus der Chemie. 2003;51(3):286-315
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Understanding the structural and charge transport property relationships for a variety of merocyanine single-crystals: A bottom up computational investigation
No full textMerocyanines consist of electronic donor (D) and acceptor (A) subunits connected via a methine bridge. They are highly polar organic π-conjugated molecules investigated for their self-assembly and optoelectronic properties. The accurate description of their structure-property relationships remains challenging. We report a comprehensive analysis modelling intra- and inter-molecular charge transport parameters for a library of merocyanines featuring different D/A combinations and lateral substituents. We found that constrained DFT correctly assesses the molecular and electronic structure in single crystals. The most effective charge transport pathways were identified and charge carrier mobilities were computed. We analyzed a large variety of single crystals highlighting the impact of alkyl substituents and casting conditions, drawing clear structure vs. charge transport relationships. Our modelling suggests that hole transport is maximized when dipolar molecules are packed in slipped not centrosymmetric pairs, arranged in 2D interconnected architectures. Computed and experimental charge mobilities for single crystals are in good agreement
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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