1,721,933 research outputs found
Temporal variations in the size and composition of Formosan leaf-nosed bat (Hipposideros terasensis) colonies in central Taiwan.
No full textElectron transfer and binding affinities in an electrochemically controlled ligand transfer system containing zinc porphyrin and a meso-phenylenediamine substituent
No full text[[abstract]]Investigations on the transfer of the ligand, imidazole (HIm), between two covalently linked redox centres - zinc porphyrin and phenylenediamine (PD) - and the influence of the length of the linker are reported. Since the binding affinity of the ligand with zinc porphyrin is different from that of the ligand with the phenylenediamine moiety, the transfer of the ligand could be electrochemically controlled by adjusting the oxidation potentials. Changes in cyclic voltammograms and absorption spectra of the complexes revealed the site of ligand binding in the various oxidation states of the modified zinc porphyrins. Binding constants of the modified zinc porphyrins in various oxidation states were also determined by photometric titration with the ligand and digital simulations. Evidence for the delocalization of the electron from the zinc porphyrin to the phenylenediamine moiety and the influence of the delocalization on them were obtained from EPR studies.[[note]]SC
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
Variations on the Author
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
Excited State Luminescence of Multi-(5-phenyl-1,3,4-oxadiazo-2-yl)benzenes in an Electron-Donating Matrix: Exciplex or Electroplex?
No full text[[abstract]]Multi-(5-phenyl-1,3,4-oxadiazo-2-yl)benzenes show emission in organic solvents from ultraviolet to blue (339-447 nm). The reduction potentials E(1/2)(red) cover a large range of -2.11 V for 2,5-diphenyl-1,3,4-oxadiazole to -0.76 V for l,2,3,4,5,6-hexa(5-phenyl-1,3,4-oxadiazo-2-yl)benzene. An unexpectedly wide spectral range of the oxadiazole (OXD) exciplex emissions in PVK is observed, ranging from 406 to 603 nm. The OXDs also exhibit similar electroluminescence (EL) when blended into polyvinylcarbazole (PVK). A linear correlation between the lambda(max) of the electroluminescence and photoluminescence is observed, implying that the emission mechanisms in both processes are similar. In addition, the linear correlation between the E(1/2)(red) versus of lambda(max) of EL (eV) reflected that the term of the charge-transfer configuration of the contact electron-hole pair plays a major role in the exciplex emission. The exciplex EL of 1,2,5-tri(5-phenyl- 1,3,4-oxadiazo-2-yl)benzene (5) could be as high as 1.0 cd/A. Since the exciplex emission usually has a large Stokes shift, this provides a window for us to generate duo emissions for near white light EL with high efficiency. Among the devices we tried, the device of PVK/2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole/5/2,5,8,11-tetra-tert-butylperylene (100: 40:40:4) gave EL with good current efficiency of 1.63 cd/A.[[note]]SC
Electrochemically Controlled Multiple Hydrogen Bonding between Triarylamines and Imidazoles
No full text[[abstract]]By increasing the number of amino substituents on triarylamine, the extent of hydrogen bonding between the oxidized form of triarylamine and imidazole could be electrochemically controlled. Three behaviors, depending on the interaction between oxidized amine and imidazole, were obtained in CV patterns. DFT calculation was used to confirm that the electron density of protons of the amino group decreased as the amino moiety increased.[[note]]SC
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