322,846 research outputs found
Glycal-mediated Syntheses of Enantiomerically Pure 3-Azido-2,3-Dideoxy-Hexopyranosides and 3-Amino-2,3-Dideoxy-Hexopyranolactones.
No full textOxime-based methods for synthesis of stereodefined acyclic polyfunctionalized d-azidonitriles and 5-substituted isoxazoles from carbohydrate derivatives.
No full textA new, simple, and high-yielding synthesis of 2,9-Dihydro-1 H- pyrido[3,4- b ]indol-1-ones
No full textA new, simple, and high-yielding method was developed to prepare 2,9-dihydro-1H-pyrido[3,4-b]indol-1-ones by selective cyclization of the appropriate N-(2,2-dimethoxyethyl)-1H-indole-2-carboxamide in polyphosphoric acid at 110 °C for 30 minutes. The reaction yield was strongly dependent on the acid used. The method was less affected by the presence of electron-donating and -withdrawing substituents at 5-position of the indole nucleus. © Georg Thieme Verlag Stuttgart, New York
A Highly Efficient and Stereocontrolled Synthesis of 2-Deoxy-1,5-thioanhydro-L-hexitols from D-Glycals in a Tandem Nucleophilic Displacement Reaction
No full text2-Deoxy-1,5-thioanhydro-L-hexitols have been synthesized in a concise sequence that includes: i) ring opening of glycals with aqueous mercury(II) acetate/sodium borohydride; ii) mesylation of the free hydroxy groups of the multifunctionalized open intermediates; and iii) S-heterocyclization by treatment with sodium sulfide. The thiosugar derivatives are obtained with a 60–80% yield. Thus, D-glucal and D-galactal can be converted into the corresponding 2-deoxy-1,5-thioanhydro-L-hexitols, while L-rhamnal gives 3,4-di-O-benzyl-2,6-dide-oxy-1,5-thioanhydro-D-xylo-hexitol. This straightforward chemistry is shown to be useful for the synthesis of glycosyl derivatives of 2-deoxy-1,5-thioanhydro-L-hexitol, starting from glycosyl glycals such as D-lactal, D-cellobial, D-maltal, D-melibial and D-gentiobial, thus avoiding the usually lengthy glycosylation procedures
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
A vertebral artery coursing tortuosly below the posterior arch of the atlas (without passing through the trasverse foramen): anatomical report and clinical significance
No full textMichael Type Addition Reactions of O,S and N-nucleophiles on Hex-1-en-2-diethoxyphosphoryl-3-uloses Derived from Glycals
No full textChronic subdural haematoma: a possible relationship with tamoxifen
No full textFive patients operated on between 6 months and 7 years earlier for breast cancer were surgically treated for chronic subdural haematoma. This unusual association may be explained on the basis of known factors such as coagulative impairment subsequent to chemotherapy, a degree of cerebral atrophy or mild trauma. On the other hand, since four of the patients were taking antioestrogen therapy to control the disease, it is speculated that the oestrogenic properties of tamoxifen may have contributed to subdural bleeding. (C) 1998 Published by Elsevier Science B.V. AU rights reserved
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