1,720,995 research outputs found
Conformational Analysis Of Fluoroacetoxime And Of Its O-methyl Ether By 1h, 13c And 15n Nmr And Theoretical Calculations
No full textThe solvent dependence of the 1H, 13C and 15N NMR spectra of (E)-fluoroacetoxime [(E)-FAO] and of (E)-fluoroacetoxime 0-methyl ether [(E)-FAOME], was examined and the HF, CF and NF couplings are reported. Density functional theory (DFT) at the B3LYP/6-311++g(2df,2p) level with ZPE (zero point energy) correction was used to obtain the rotamer geometries. In both (E)-FAO and (E)-FAOME the DFT method gave two energy minima corresponding to the cis (F - C - C=N, 0°) and gauche (F - C - C=N, 124.1°) rotamers. In contrast, in (Z)-FAO the DFT method gave only one energy minimum corrsponding to the trans rotamer. The 4JHF and 1JCF couplings in (E)-FAO were analyzed by solvation theory assuming the cis and gauche forms to give Ecis - Egauche = 3.3 kcal mol-1 in the vapor phase, decreasing to 1.54 kcal mol-1 in CCl4 and - 1.19 kcal mol-1 in DMSO (1 kcal = 4.184kJ. In (E)-FAOME the observed couplings, when analysed similarly by solvation theory, gave Ecis - Egauche = 2.2 kcal mol-1 in the vapor phase, 0.91 kcal mol-1 in CCl4 and - 1.18 kcal mol-1 in DMSO. The 3JNF coupling was independent of the molecular conformation, as it did not change with the solvent polarity. Copyright © 2003 John Wiley & Sons, Ltd.1714248McCarty, C.G., (1970) The Chemistry of the Carbon-nitrogen Double Bond, , Patai S (ed). Wiley: Chichester, chap. 2Fry, A.J., Reed, R.G., (1977) The Chemistry of Double Bonded Functional Groups, Supplement A, , Patai S (ed.). Wiley: Chichester, chap. 11Goda, H., Sato, M., Ihara, H., Hirayama, C., (1992) Synthesis, p. 849(1972) CIBA Symposium, Carbon-fluorine Compounds, Chemistry, Biochemistry and Biological Activities, , Association of Scientific Publishers: AmsterdamTaylor, N.F., (1988) Fluorinated Carbohydrates, Chemical and Biochemical Aspects. ACS Symposium Series, 374. , American Chemical Society: Washington, DCO'Hagan, D., Rzepa, H.S., (1997) Chem. Commun., p. 645Saegebarth, E., Krishner, L.C., (1970) J. Chem. Phys., 52, p. 3555Durig, J.R., Hardin, J.A., Phan, H.V., Little, T.S., (1989) Spectrochim. Acta, Part A, 45, p. 1239Abraham, R.J., Jones, A.D., Warne, M.A., Rittner, R., Tormena, C.F., (1996) J. Chem. Soc., Perkin Trans. 2, p. 533Olivato, P.R., Ribeiro, D.S., Rittner, R., Hase, Y., Del Pra, D., Bombieri, G., (1995) Spectrochim. Acta, Part A, 51, p. 1479Dal Colle, M., Distefano, G., Modelli, A., Jones, D., Guerra, M., Olivato, P.R., Ribeiro, D.S., (1998) J. Phys. Chem. A, 102, p. 8037Ribeiro, D.S., Abraham, R.J., (2002) Magn. Reson. Chem., 40, p. 49Olivato, P.R., Ribeiro, D.S., Zukerman-Schpector, J., Bombieri, G., (2001) Acta Crystallogr., Sect. B, 57, p. 705Abraham, R.J., Fisher, J., Loftus, P., (1988) Introduction to NMR Spectroscopy, , Wiley: New YorkAbraham, R.J., Bretschneider, E., (1974) Internal Rotation in Molecules, , W. J. Orville-Thomas (ed.). Wiley: London, chap. 13Frisch, M.J., Trucks, C.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Zakrzewski, V.G., Pople, J.A., (1998) Gaussian 98, Revision A.7, , Gaussian: Pittsburgh, PAAbraham, R.J., Tormena, C.F., Rittner, R., (1999) J. Chem. Soc., Perkin Trans. 2, p. 1663Tormena, C.F., Rittner, R., Abraham, R.J., Basso, E.A., Pontes, R.M., (2000) J. Chem. Soc., Perkin Trans. 2, p. 2054Abraham, R.J., Tormena, C.F., Rittner, R., (2001) J. Chem. Soc., Perkin Trans. 2, p. 815Tormena, C.F., Rittner, R., Abraham, R.J., (2002) J. Phys. Org. Chem., 15, p. 211Tormena, C.F., Amadeu, N.S., Rittner, R., Abraham, R.J., (2002) J. Chem. Soc., Perkin Trans. 2, p. 773Abraham, R.J., (1999) Prog. Nucl. Magn. Reson. Spectrosc., 35, p. 85Abraham, R.J., Leonard, P., Smith, T.A.D., Thomas, W.A., (1996) Magn. Reson. Chem., 34, p. 71Hirota, E., (1970) J. Chem. Phys., 42, p. 2071Enevoldsen, T., Oddershede, J., Sauer, S.P.A., (1998) Theor. Chem. Acc., 100, p. 275Peralta, J.E., Barone, V., Contreras, R.H., (2001) J. Am. Chem. Soc., 123, p. 9162Peralta, J.E., Barone, V., Azua, M.C.R., Contreras, R.H., (2001) Mol. Phys., 99, p. 655Barone, V., Peralta, J.E., Contreras, R.H., (2001) J. Comput. Chem., 22, p. 1615Krivdin, L.B., Sauer, S.P.A., Peralta, J.E., Contreras, R.H., (2002) Magn. Reson. Chem., 40, p. 187Freitas, M.P., Rittner, R., Tormena, C.F., Abraham, R.J., (2001) J. Phys. Org. Chem., 14, p. 317Contreras, R.H., Peralta, J.E., (2000) Prog. Nucl. Magn. Reson. Spectrosc., 37, p. 321Braun, S., Kalinowski, H.O., Berger, S., (1996) 100 and More Basic NMR Experiments, , VCH: Weinhei
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
Theoretical And Experimental Investigation On The Rotational Isomerism In A-fluoroacetophenones
No full textThe geometries involved in the conformational equilibria of α-fluoroacetophenone, p-nitro-α-fluoroacetophe- none, and p-methoxy-α-fluoroacetophenone were investigated. Theoretical calculations showed that cis and gauche forms (F - C - C=0) are their most stable conformers and that in the vapor phase the gauche conformer is predominant. The three compounds were synthesized, and the conformational behavior in solution was estimated from infrared (IR) and nuclear magnetic resonance (NMR) spectra obtained in solvents of different polarity. Their IR spectra showed one carbonyl absorption for the cis and one for the gauche conformer, and that the cis conformer was preferred in the more polar solvents, 1JCF, 2JC(O)F, and 2JHF coupling constants were obtained from their NMR spectra, and they also showed a preference for the cis conformer when more polar solvents were used. The vapor phase calculations showed a conformational preference for the gauche form. However, when the solvent effects were included in the calculations, the results were in complete agreement with the experimental data (NMR and IR), the cis conformer being the most stable one. © 2009 American Chemical Society.1131229062913Moss, S.J., Murphy, C.D., Hamilton, J.T.G., McRoberts, W.C., O'Hagan, D., Schaffrath, C., Harper, D.B., (2000) Chem. Commun, p. 2281O'Hagan, D., Harper, D.B.J., (1999) Fluor. Chem, 100, p. 127Purser, S., Moore, P.R., Swallow, S., Gouverneur, V., (2008) Chem. Soc. Rev, 37, p. 320O'Hagan, D., (2008) Chem. Soc. Rev, 37, p. 308Phan, H.V., Durig, J.R., (1990) J. Mol. Struct. (THEOCHEM), 209, p. 333Pontes, R.M., Fiorin, B.C., Basso, E.A., (2004) Chem. Phys. Lett, 395, p. 205Abraham, R.J., Tormena, C.F., Rittner, R., (1999) J. Chem. Soc, Perkin Trans, 2, p. 1663Abraham, R.J., Jones, A.D., Warne, M.A., Rittner, R., Tormena, C.F., (1996) J. Chem. Soc, Perkin Trans. 2, p. 533Abraham, R.J., Tormena, C.F., Rittner, R., (2001) J. Chem. Soc, Perkin Trans. 2, p. 815van der Veken, B.J., Truyen, S., Herrebout, W.A., Watkins, G., (1993) J. Mol. Struct, 293, p. 55Tormena, C.F., Rittner, R., Abraham, R.J., Basso, E.A., Pontes, R.M., (2000) J. Chem. Soc, Perkin Trans, 2, p. 2054Tormena, C.F., Amadeu, N.S., Rittner, R., Abraham, R.J., (2002) J. Chem Soc, Perkin Trans. 2, p. 773Olivato, P.R., Guerrero, S., Hase, Y., Rittner, R., (1990) J. Chem. Soc, Perkin Trans. 2, p. 465Catalano, D., Celebre, G., Emsley, J.W., Longeri, M., Luca, G.D., Veracini, C.A., (1998) J. Chem. Soc, Perkin Trans. 2, p. 1823Rodriguez, A.M., Giannini, F.A., Baldoni, H.A., Santagata, L.N., Zamora, M.A., Zacchino, S., Sosa, C.P., Csizmadia, I.G., (1999) J. Mol. Struct, 463, p. 271Frisch, M.J., (2003) Gaussian 03, , Gaussian Inc, Pittsburgh, PAHehre, W.J., (2003) A Guide to Molecular Mechanics and Quantum Chemical Calculations, , Wavefunction Inc: Irvine, CAFliikiger, P., Liithi, H.P., Portmann, S., Weber, J., (2000) Molekel 4.3, , Swiss Center for Scientific Computing: Manno, Switzerland;Portmann, S., Liithi, H.P., (2000) CHIMIA, 54, p. 766Tomasi, J., Scrocco, E., Miertus, S., (1981) Chem. Phys, 55, p. 117Bridge, C.F., O'Hagan, D.J., (1997) Fluor. Chem, 82, p. 21Yoshinaga, F., Tormena, C.F., Freitas, M.P., Rittner, R., Abraham, R.J., (2002) J. Chem. Soc, Perkin Trans. 2, p. 1494Eliel, E.L., Wilen, S.H., Mander, L.N., (1994) Stereochemistry of Organic Compounds, , Wiley: New Yor
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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