1,720,962 research outputs found
Synthesis of variously 1,8-naphthyridine derivatives and evaluation of their antimicobacterial activity
No full textA series of 1,8-naphthyridine derivatives variously substituted in the 2, 3, 4 and 7 positions were synthesized for in vitro evaluation of antimycobacterial activity in accordance with an international program with the tuberculosis antimicrobial acquisition and coordinating facility (TAACF). Several compounds 4, 8, 12, 14, 19, 29 and 30, when tested at a concentration of 6.25 μg/ml against Mycobacterium tuberculosis H37Rv, showed an interesting activity with % inhibition in the range 38-96%. The most effective substituent in position 2, 4 or 7 of the 1,8-naphthyridine nucleus seem to be the piperidinyl group
Synthesis and antiplatelet activity of some 2,7-di(N-cycloamino)-3-phenyl-1,8-naphthyridine derivatives
No full textSeveral 2,7-di(N-cycloamino)-3-phenyl-1,8-naphthyridine derivatives were synthesized and tested for their ability to inhibit human platelet aggregation in vitro induced by arachidonic acid, collagen and ADP. Only five compounds showed any appreciable activity, and the results of all the active derivatives were similar to those of papaverine in the test with arachidonic acid and collagen. Moreover, the most active compounds were investigated in the test with ADP and again showed a significant activity. The tested compounds that possessed the best activity were also shown to increase the c-AMP level significantly without involving the adenylyl cyclase system. (C) 2001 Elsevier Science S.A. All rights reserved
Synthesis and evaluation of antihypertensive activity of 1,8-naphthyridine derivatives. Part X
No full textA series of 4-(N-methylencycloalkylamino)-1,8-naphthyridine derivatives variously substituted in positions 2 and 7 were synthesized and pharmacologically investigated for possible antihypertensive activity. These compounds were tested to determine a possible vasodilator mechanism of action. Compounds 22, 23, 27-29, 47 and 48 showed satisfactory levels of potency (pIC(50) > 5), which in one case (compound 23) reached a really interesting value (pIC(50) 6.92). Furthermore, for some selected compounds (19, 22, 23, 26, 28, 29, 47), the vasorelaxing activity was also evaluated in the presence of the guanylate cyclase blocker ODQ or of the adenylate cyclase blocker SQ 22536, and some of these can be considered as possible guanylate-cyclase inhibitors. Finally, compounds 19, 22 and 23 were also tested in the presence of the ATP-sensitive potassium channel blocker glybenclamide and seem to possess activating properties on these potassium channels. (C) 2001 Editions scientifiques et medicales Elsevier SAS
Synthesis and antiplatelet activity of some 3-phenyl-1,8-naphthyridine derivatives
No full textA series of 2-cycloalkylamino-3-phenyl-1,8-naphthyridine derivatives, variously substituted in the 6- and 7-positions were synthesized and tested for their ability to inhibit human platelet aggregation in vitro induced by arachidonate, collagen and ADP. Compounds 5a,b, 7a,b, 8a and 10c,d showed a remarkable activity similar to that of indomethacin in the test with arachidonate and collagen. In the test with ADP only compound 8a showed a significant activity. The presence of a morpholinyl or piperidinyl group in position 2 and of a chloro or methoxy group in position 7 of the 1,8-naphthyridine nucleus seem to favour a higher activity. However on the basis of the pharmacological results, no structure-activity relationship can be deduced. Compounds 5b and 7b, which possess the best activity in the arachidonate test, were also shown to increase the c-AMP level significantly, without involving the adenylyl cyclase system
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
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