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Sample records for alkines

  1. Hydrostannierung funktionalisierter Alkine mit gemischten Zinnhalogenidhydriden, Klärung von Struktur und Mechanismus mittels NMR-Spektroskopie

    OpenAIRE

    Thiele, Christina Marie

    2002-01-01

    Das Knüpfen neuer C-C-Bindungen ist häufig eine Aufgabe des organischen Synthetikers. Eine in letzter Zeit sehr beliebte Methode hierfür ist die Palladium-katalysierte Kupplung organischer Elektrophile mit Tetraorganostannanen (Stille-Kupplung). Diese Methode ist sehr vielseitig und erlaubt zum Beispiel auch die Einführung ungesättigter Fragmente mit definierter Konfiguration durch die Verwendung von Vinylstannanen. Einer der direktesten Wege zur Darstellung von Vinylstannanen ist die Hydrost...

  2. A Bibliometric Analysis of the Academic Influences of and on Evaluation Theorists' Published Works

    Science.gov (United States)

    Heberger, Anne E.; Christie, Christina A.; Alkin, Marvin C.

    2010-01-01

    As is the case with other fields, there is motivation for studying the impact that the body of evaluation theory literature has within and outside the field. The authors used journal articles written by theorists included on the evaluation theory tree by Alkin and Christie (2004; Christie & Alkin, 2008) and published in the Web of Science, an…

  3. Rh- and Ru-complex-catalyzed dimerization of arylethynes in aqueous environment

    Czech Academy of Sciences Publication Activity Database

    Novák, P.; Kotora, Martin

    2009-01-01

    Roč. 74, č. 3 (2009), s. 433-442. ISSN 0010-0765 Grant ostatní: GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40550506 Keywords : dimerizations * terminal alkines * enynes * arylacetylenes Subject RIV: CC - Organic Chemistry Impact factor: 0.856, year: 2009

  4. How Analogue Research Can Advance Descriptive Evaluation Theory: Understanding (and Improving) Stakeholder Dialogue

    Science.gov (United States)

    Campbell, Bernadette; Mark, Melvin M.

    2015-01-01

    Evaluation theories can be tested in various ways. One approach, the experimental analogue study, is described and illustrated in this article. The approach is presented as a method worthy to use in the pursuit of what Alkin and others have called descriptive evaluation theory. Drawing on analogue studies conducted by the first author, we…

  5. Polyglycerol Based Hydrogels for the Immobilization of Catalytically Active Enzymes and as Scaffolds for Cells

    OpenAIRE

    Dey, Pradip

    2015-01-01

    Im Rahmen dieser Doktorarbeit wurden Hydrogele basierend auf dendritischem Polyglycerol (dPG) entwickelt, welche unter Verwendung verschiedener Vernetzungsreaktionen, wie z. B. durch Amidverknüpfung oder durch ringspannungsvermittelte Azid-Alkin Cycloaddition (strain promoted azide alkyne cycloaddition, SPAAC), hergestellt wurden. Das Anwendungsspektrum dieser Hydrogele reicht von der Entwicklung enzymbasierter Biosensoren bis hin zu Trägermaterialien für Knorpelzellen. Enzymbasierte Bios...

  6. Funktionalisierung organischer Verbindungen durch Borylentransfer

    OpenAIRE

    Herbst, Thomas

    2009-01-01

    Im Rahmen dieser Arbeit wurden Gruppe 6 Aminoborylenkomplexe zum Borylentransfer auf Alkine verwendet. Die Bor–Übergangsmetallmehrfachbindung wird gespalten, und die Boryleneinheit (BR) auf die C-C-Dreifachbindung übertragen. Diese formale [2+1]-Cycloaddition macht Borirene (Boracyclopropene) in sehr guten Ausbeuten zugänglich. In früheren Arbeiten ist die Borirensynthese entweder auf geringe Ausbeuten oder auf wenige Beispiele mit schwer zugänglichen Edukten beschränkt. Die entwickelte Metho...

  7. Bibliographie générale

    OpenAIRE

    2016-01-01

    Abensour M., Le procès des maîtres-rêveurs, Arles, Sulliver, 2000. Ackroyd P., Albion, The Origins of the English Imagination, Londres, Chatto and Windus, 2002. Ackroyd P., Notes for a New Culture [1976], Londres, Alkin Books, 1993. Ackroyd P., T.S. Eliot [1984], Harmondsworth, Penguin, 1993. Agamben G., Profanations, Paris, Rivages, 2006. Anderson S., Erb, E., Berührung ist nur eine Randerscheinung. Neue Literatur aus der DDR, Köln, Kiepenhauer und Witsch, 1985. Barthes R., Le bruissement de...

  8. Functionalization and detection of RNA and its modifications

    OpenAIRE

    Kellner, Stefanie

    2012-01-01

    Unterschiedlich substituierte Reagenzien, basierend auf dem Cumarin Körper, wurden untersucht und Struktur-Funktions-Beziehungsstudien zeigten eine Selektivität für ein natürlich vorkommendes, modifiziertes Nukleosid, 4-Thiouridine (s4U). Im Verlauf dieser Experimente, fiel ein multifunktionales Cumarin, namens PBC, aus mehreren Gründen auf. Neben seiner 2000 fachen Selektivität für s4U gegenüber Uridin, besitzt PBC ein zusätzliches terminales Alkin für Konjugationsreaktionen mit Aziden. Es w...

  9. Fast Non-destructive temperature measurement of two-electrons atoms in a magneto-optical trap

    OpenAIRE

    Cristiani, Matteo; Valenzuela, Tristan; Gothe, Hannes; Eschner, Jürgen

    2010-01-01

    We extend the technique originally proposed by Honda et al.to measure the temperature of Ytterbium and alkine-earth atoms confined in a Magneto-Optical Trap (MOT). The method is based on the analysis of excitation spectra obtained by probing the 1S0->3P1 inter-combination line. Thanks to a careful analysis and modeling of the effects caused by the MOT light on the probe transition we overcome the resolution and precision limits encountered in previous works. Ground state light shift and Rabi ...

  10. 1,3-Dipolare Cycloaddition von N2O an hochreaktive Mehrfachbindungen

    OpenAIRE

    Plefka, Oliver

    2011-01-01

    In der vorliegenden Arbeit wird über 1,3-dipolare Cycloadditionen mit Lachgas (N2O) unter milden Reaktionstemperaturen (≈ RT) berichtet. N2O ist ein sehr unreaktives 1,3-dipolares Reagenz. Bisher in der Literatur durchgeführte 1,3-dipolare Cycloadditionen mit N2O benötigten immer sehr drastische und gefährliche Reaktionsbedingungen (bis zu 300°C und 500 atm.). Dabei entstanden nach einer (postulierten) einleitenden 1,3-dipolaren Cycloaddition von N2O an Olefine oder Alkine immer nur sticks...

  11. 1-[2-(4-Methyl-7-coumarinyloxyethyl]-4-(5-{1-[2-(4-methyl-7-coumarinyloxyethyl]-1H-1,2,3-triazol-4-yl}pentyl-1H-1,2,3-triazole

    Directory of Open Access Journals (Sweden)

    Fernando Cidade Torres

    2016-04-01

    Full Text Available Nature often produces compounds with a high degree of symmetry to reduce structural information and complexity. Synthesis of identical twin drugs, through the linkage of two identical pharmacophoric entities, is a classical strategy to produce more potent and/or selective drugs. Herein, two units of the privileged core of the coumarin hymecromone were linked together using “click chemistry”. Synthesis of 1-[2-(4-Methyl-7-coumarinyloxyethyl]-4-(5-{1-[2-(4-methyl-7-coumarinyloxyethyl]-1H-1,2,3-triazol-4-yl}pentyl-1H-1,2,3-triazole was achieved by coupling of two identical units of an azido coumarin with a symmetrical alkine using copper(I-catalyzed alkyne-azide cycloaddition reaction, in good yields and with complete regioselectivity.

  12. A new flavonol glycoside derivative from leaves of Moldenhawera nutans.

    Science.gov (United States)

    do Vale, Ademir E; David, Jorge M; Brandão, Hugo N; David, Juceni P

    2005-01-01

    The ethyl acetate extract of leaves of Moldenhawera nutans Queiroz & Alkin (Leguminosae) furnished, besides methyl gallate and gallic acid, the flavonols named laricetrin, laricetrin 3-glucoside and laricetrin 3-galactoside as well as the new one named laricetrin 5-galloyl-3-beta-D-xylopyranoside. It also was isolated from the hexane extract: beta-sitosterol, lupenone, beta-amyrinone, alpha-amyrinone, lupeol, beta-amyrin, alpha-amyrin and alpha-tocopherol. The antioxidant activities of flavonoids were measured through DPPH radical scavenging and inhibition of auto-oxidation of beta-carotene methods. The structures of the compounds were determined by analyses of spectral data. This is the first report dealing with phytochemical studies of leaves of M. nutans. In addition this current work describes the unequivocal attribution of 1H NMR and 13C NMR data of laricetrin. PMID:15787243

  13. Reversible and Irreversible Binding of Nanoparticles to Polymeric Surfaces

    Directory of Open Access Journals (Sweden)

    Wolfgang H. Binder

    2009-01-01

    Full Text Available Reversible and irreversible binding of CdSe-nanoparticles and nanorods to polymeric surfaces via a strong, multiple hydrogen bond (= Hamilton-receptor/barbituric acid is described. Based on ROMP-copolymers, the supramolecular interaction on a thin polymer film is controlled by living polymerization methods, attaching the Hamilton-receptor in various architectures, and concentrations. Strong binding is observed with CdSe-nanoparticles and CdSe-nanorods, whose surfaces are equipped with matching barbituric acid-moieties. Addition of polar solvents, able to break the hydrogen bonds leads to the detachment of the nanoparticles from the polymeric film. Irreversible binding is observed if an azide/alkine-“click”-reaction is conducted after supramolecular recognition of the nanoparticles on the polymeric surface. Thus reversible or irreversible attachment of the nanosized objects can be achieved.

  14. Fast Non-destructive temperature measurement of two-electrons atoms in a magneto-optical trap

    CERN Document Server

    Cristiani, Matteo; Gothe, Hannes; Eschner, Jürgen

    2010-01-01

    We extend the technique originally proposed by Honda et al.to measure the temperature of Ytterbium and alkine-earth atoms confined in a Magneto-Optical Trap (MOT). The method is based on the analysis of excitation spectra obtained by probing the 1S0->3P1 inter-combination line. Thanks to a careful analysis and modeling of the effects caused by the MOT light on the probe transition we overcome the resolution and precision limits encountered in previous works. Ground state light shift and Rabi broadening are measured and successfully compared with calculated values. This knowledge allows us to properly extract the Doppler contribution to the linewidth, thus obtaining a reliable measurement of the cloud temperature. We finally show how spectroscopy on free-falling atoms provides an alternative method to determine the sample temperature which resembles the standard time-of-flight technique.

  15. Tempo-spatial variation of emission inventories of speciated volatile organic compounds from on-road vehicles in China

    Directory of Open Access Journals (Sweden)

    H. Cai

    2009-05-01

    Full Text Available Emission inventories of sixty-nine speciated non-methane volatile organic compounds (NMVOC from on-road vehicles in China were estimated for the period of 1980–2005, using seven NMVOC emission profiles, which were summarized based on local and international measurements from published literatures dealing with specific vehicle categories running under particular modes.

    Results show an exponential growth trend of China's historical emissions of alkanes, alkenes, alkines, aromatics and carbonyls during the period of 1980–2005, increasing from 63.9, 39.3, 6.9, 36.8 and 24.1 thousand tons, respectively, in 1980 to 2781.4, 1244.9, 178.5, 1350.7 and 403.3 thousand tons, respectively, in 2005, which coincided well with China's economic growth. Emission inventories of alkenes, aromatics and carbonyls were gridded at a high resolution of 40 km×40 km for air quality simulation and health risk evaluation, using the geographic information system (GIS methodology. Spatial distribution of speciated NMVOC emissions shows a clear difference in emission densities between developed eastern and relatively underdeveloped western and inland China. Besides, the appearance and expansion of high-emission areas was another notable characteristic of spatial distribution of speciated NMVOC emissions during the period.

    Emission contributions of vehicle categories to speciated NMVOC groups showed annual variation, due to the variance in the provincial emissions and in the relative fractions of the seven emission profiles adopted at the provincial level. Highly reactive and toxic compounds accounted for high proportions of emissions of speciated NMVOC groups. The most abundant compounds were isopentane, pentane and butane from alkanes; ethene, propene, 2-methyl-2-butene and ethyne from alkenes and alkines; benzene, toluene, ethylbenzene, o-xylene, and m,p-xylene (BTEX and 1,2,4-trimethylbenzene from aromatics and formaldehyde, acetaldehyde

  16. Tempo-spatial variation of emission inventories of speciated volatile organic compounds from on-road vehicles in China

    Directory of Open Access Journals (Sweden)

    H. Cai

    2009-09-01

    Full Text Available Emission inventories of sixty-seven speciated non-methane volatile organic compounds (NMVOC from on-road vehicles in China were estimated for the period of 1980–2005, using seven NMVOC emission profiles, which were summarized based on local and international measurements from published literatures dealing with specific vehicle categories running under particular modes.

    Results show an exponential growth trend of China's historical emissions of alkanes, alkenes, alkines, aromatics and carbonyls during the period of 1980–2005, increasing from 63.9, 39.3, 6.9, 36.8 and 24.1 thousand tons, respectively, in 1980 to 2778.2, 1244.5, 178.7, 1351.7 and 406.0 thousand tons, respectively, in 2005, which coincided well with China's economic growth. Emission inventories of alkenes, aromatics and carbonyls were gridded at a high resolution of 40 km×40 km for air quality simulation and health risk evaluation, using the geographic information system (GIS methodology. Spatial distribution of speciated NMVOC emissions shows a clear difference in emission densities between developed eastern and relatively underdeveloped western and inland China. Besides, the appearance and expansion of high-emission areas was another notable characteristic of spatial distribution of speciated NMVOC emissions during the period.

    Emission contributions of vehicle categories to speciated NMVOC groups showed annual variation, due to the variance in the provincial emissions and in the relative fractions of the seven emission profiles adopted at the provincial level. Highly reactive and toxic compounds accounted for high proportions of emissions of speciated NMVOC groups. The most abundant compounds were isopentane, pentane and butane from alkanes; ethene, propene, 2-methyl-2-butene and ethyne from alkenes and alkines; benzene, toluene, ethylbenzene, o-xylene, and m,p-xylene (BTEX and 1,2,4-trimethylbenzene from aromatics and formaldehyde, acetaldehyde

  17. Role of biology in the air–sea carbon flux in the Bay of Bengal and Arabian Sea

    Indian Academy of Sciences (India)

    M K Sharada; P S Swathi; K S Yajnik; C Kalyani Devasena

    2008-08-01

    A physical-biological-chemical model (PBCM)is used for investigating the seasonal cycle of air –sea carbon flux and for assessing the effect of the biological processes on seasonal time scale in the Arabian Sea (AS)and Bay of Bengal (BoB),where the surface waters are subjected to contrasting physical conditions.The formulation of PBCM is given in Swathi et al (2000),and evaluation of several ammonium-inhibited nitrate uptake models is given in Sharada et al (2005). The PBCM is here first evaluated against JGOFS data on surface pCO2 in AS, Bay of Bengal Process Studies (BoBPS)data on column integrated primary productivity in BoB,and WOCE I1 data on dissolved inorganic carbon (DIC)and alkalinity (ALK)in the upper 500 meters at 9°N in AS and at 10°N in BoB in September –October.There is good qualitative agreement with local quantitative discrepancies. The net effect of biological processes on air –sea carbon flux on seasonal time scale is determined with an auxiliary computational experiment,called the abiotic run,in which the biological processes are turned off.The difference between the biotic run and abiotic run is interpreted as the net effect of biological processes on the seasonal variability of chemical variables.The net biological effect on air –sea carbon flux is found to be highest in southwest monsoon season in the northwest AS, where strong upwelling drives intense new production.The biological effect is larger in AS than in BoB,as seasonal upwelling and mixing are strong in AS,especially in the northeast,while coastal upwelling and mixing are weak in BoB.

  18. 內容探勘技術在教育評鑑研究發展趨勢分析之應用 The Application of Content Mining Techniques to the Analysis of Educational Evaluation Research Trends

    Directory of Open Access Journals (Sweden)

    曾元顯 Yuen-Hsien Tseng

    2011-03-01

    the evaluation methods, the studies conducted by Chen, Weiss, and Rossi are identified as newer ones than those by Cook and Compbell, which coincides with the fact shown in the evaluation theory tree (a sort of topical tree organized by Marvin Alkin, an experienced expert in the field. Besides, with this topic trend analysis, it is also found that the number of papers dealing with the major research topics seems to be decreasing. However, all these results need to be interpreted by domain experts to reveal their true meanings. The methodology presented in this research may be applied not only to improve the efficiency of content analysis, but also to facilitate regular tracing of topic evolution, to spot the positions of important researchers in the field, and therefore to provide relevant clues or materials for further studies.