1,720,987 research outputs found
Pyrrolocoumarin derivatives as potential photoreagents toward DNA.
No full textA number of new methyl derivatives of linear and angular pyrrolocoumarins were synthesized by direct Fischer’s indole synthesis. In the same way some linear and angular pyranocarbazolones. The synthesis were performed starting from the appropriate methyl-7-aminocoumarins and methyl groups were introduced into positions which look most promising for the photoreactivity toward DNA
Synthesis of some methylfurochromones as potential photochemotherapeutic agents.
No full textA number of new methylfurochromones with a linear psoralen-loke structure or an angular angelicin-like one were synthesized. The synthesis were performed starting from the appropriate 7-hydroxychromones on which the fura ring was built. Methyl groups were introduced into positions which look most promising for enhancement of the photoreactivity of the compound toward DNA
Methylfuroquinolinones: new furocoumarin isosters as potential photoreagents toward DNA.
No full textA number of methyl furoquinolinones, methylpsoralen isosters, were synthesized. The synthesis was performed starting from the appropriate methyl quinolin-2-ones on which the methylfuran ring was condensed. The compounds showed high molar absorbitivity at long wavelength with an improvement of photobinding to the biological targets
Synthesis of azapsoralen derivatives.
No full textA number of new isosters of psoralen, in wich the benzene ring of psoralen is substituted with a pyridine one were synthesized. The synthesis were performed starting from the appropriate hydroxypyranopyridinone on which the furan ring was built. Several derivatives in which an additional cyclohexene or benzene ring is condensed to the furan ring moiety have also been prepared
13C-NMR Spectra and carbon-proton coupling constants of various annulated furocoumarins
No full textThe 13C NMR spectra of variously annulated methylfurocoumarins are reported. The assignments of chemical shifts for all the C resonances have been achieved by using carbon-proton coupling costants, relaxation efficiency considerations and shift effects caused by the introduction of methyl groups at various position of the furocoumarin nucleus. Substituent effects on chemical shifts and C-H coupling constants are discussed
New synthesis of pyrrolo[3,2,1-ij]quinolin-4-one derivatives.
No full textA new convenient synthesis of pyrrolo[3,2,1-ij]quinolin-4-one derivatives is described. In this method, methyl-7-hydroxquinoline-2-ones are the starting materials onto which the third pyrrolo ring is condensed directly, yielding dehydrogenated methyl-9-hydroxypyrrolo[3,2,1-ij]quinolin-4-ones
Sintesi di nuovi inibitori delle topoisomerasi.
No full textLe topoisomerasi sono enzimi nucleari essenziali per varie funzioni vitali del ciclo cellulare. Per questo motivo esse costituiscono un bersaglio per la terapia antitumorale; attualmente esistono numerosi inibitori delle topoisomerasi clinicamente importanti, come camptotecina e derivati, amsacrina, etoposide e mitoxantrone. Allo scopo di preparare nuove molecole con attività inibitoria della topoisomerasi II è stata progettata la sintesi di ibridi molecolari funzionalizzando dei nuclei policiclici planari, in grado di intercalarsi nel DNA, con elementi strutturali rappresentati dalle catene di farmaci noti, come ad esempio l’amsacrina. Analizzando i requisiti sterici ed elettronici necessari per una corretta intercalazione, è stato scelto come sistema triciclico quello del piranochinolinone, che presenta analogie strutturali con l’amsacrina, in quanto differisce da essa per la sostituzione di uno dei due anelli aromatici con quello dell’alfa-pirone. Sono stati inoltre introdotti nell’anello non eterociclico sostituenti metossilici, in grado di stabilizzare il complesso di intercalazione
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
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