1,721,042 research outputs found
The immunosuppressant FK506 inhibits the damage to mouse pancreatic islets induced by low dose streptozocin
No full textDiabetes mellitus was induced in 40 male C57BL6 mice by injection of a low dose of streptozocin (45 mg/kg body weight) on 5 consecutive days. Twenty four of the mice were immunosuppressed by administration of 1.5 mg FK506/kg body weight daily for 10, 15, 18 and 24 days. Administration of FK506 almost completely inhibited the streptozocin-induced islet damage, and consequently glycaemia remained normal. In FK506-treated animals any inflammatory infiltrate was very sparse and was limited to the vascular pole of the islets. Immunocytochemical results demonstrated that infiltrating cells were Ia-immunoreactive, but were not activated. Ultrastructural observations confirmed the absence of B cell necrosis and degranulation in FK506-treated mice; the few infiltrating elements encountered did not contain phagocytic vesicles or show other signs of activation. © 1994 Springer-Verlag
Morphology and molecular biology: can the latter ignore the former? An imaginary dialogue
No full text
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
Uncovering Intramolecular π-Type Hydrogen Bonds in Solution by NMR Spectroscopy and DFT Calculations
No full textReaction between the phosphinito bridged diplatinum species [(PHCy2)Pt(μ-PCy2){κ2P,O-μ-P(O)Cy2}Pt(PHCy2)](Pt-Pt) (1), and (trimethylsilyl)acetylene at 273 K affords the σ-acetylide complex [(PHCy2)(η1-Me3SiC≡C)Pt(μ-PCy2)Pt(PHCy2){κP-P(OH)Cy2}](Pt-Pt) (2) featuring an intramolecular π-type hydrogen bond. Scalar and dipolar couplings involving the POH proton were detected by 2D NMR experiments. Relativistic DFT calculations of the geometry, relative energy, and NMR properties of model systems of 2 confirmed the structural assignment and allowed the energy of the π-type hydrogen bond to be estimated (ca. 22 kJ mol-1). Hydrogen bonds in solution: The existence of a π-type hydrogen bond between the PO-H and the C≡C triple bond in the σ-acetylide complex [(PHCy2)(η1-Me3SiC≡C)Pt(μ-PCy2)Pt(PHCy2){κP-P(OH)Cy2}](Pt-Pt) (2) in solution was proven by multinuclear NMR spectroscopy and confirmed by relativistic DFT calculations on model systems of 2. The estimated hydrogen-bonding energy and the calculated coupling values and chemical shift indicate a remarkably strong π-type interaction (see scheme)
meso-Octaethylporphyrinogen displaying site selectivity in the stepwise synthesis of polymetallic aggregates with interesting redox properties: the π-binding ability of metalla-porphyrinigens
No full textThe present report deals with the synthetic approach to homo- and heteronuclear polymetallic aggregates using the Ni-II-meso-octaethylporphyrinogen complex [{eta(3)-(Et8N4Ni)}{Li(thf)(2)}(2)] (1) as a pi ligand in the reaction with metal halides. The metallation reaction occurs via the probable intermediate of an isomeric form of 1, namely 2, which should be considered an organolithium derivative. Among the polymetallic aggregates, complexes [{eta(5)-(Et8N4Ni)}(2)Co]. 2[Li(thf)(4)] (6) and [{eta(2)-eta(4)-(Et8N4Ni)}(2)Ni-2(mu-Cl)][Li(thf)] (8) display a thermal and photochemical lability. Electron transfer reactions can be photochemically or thermally induced resulting in the formation of metal(0) and oxidized forms of the meso-ctaethylporphyrinogen skeleton
Dynamic stereochemistry of bis-β-diketonato-1,5-cyclooctadiene ruthenium(II) complexes
No full textTris(chelate)2(diene)ruthenium(II) complexes have been synthesized. All three possible diastereoisomers of Ru(bzac)2(cod) (where cod=1,5-cyclooctadiene and bzac=benzoylacetonato) have been isolated and diastereoisomerization processes were observed at elevated temperature. The energy barriers were found to be in the range of 35-36 kcal/mol. The DNMR behaviour of Ru(S2CNMe2)2(cod) and Ru(S2PMe2)2(L) complexes is also discussed. We synthesized a new Ru(N-isopropylsalicylaldiminato)2(cod) tris-chelate which was found to clathrate some solvents. © 1991
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