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Susanne Prediger 《ZDM》2008,40(2):277-286
This article explores the idea that theoretical approaches might be usefully compared in terms of the ways in which they lead researchers to construe commonsense classroom problems. It reports an experience when one such problem was posed to a range of researchers with different theoretical backgrounds. They were invited to propose an answer, and to reframe the classroom problem as a research problem. As anticipated, responses adopted particular theoretical perspectives that “privileged” certain objects of study and modes of explanation. Nevertheless, where responses did appeal to a common theoretical perspective, sometimes used in combination with others, there could be quite sharp differences in conceptualisation, proposed action, and research intention. 相似文献
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Identification of Structure–Activity Relationships from Screening a Structurally Compact DNA‐Encoded Chemical Library
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Dr. Raphael M. Franzini Dr. Torun Ekblad Dr. Nan Zhong Moreno Wichert Willy Decurtins Angela Nauer Mauro Zimmermann Dr. Florent Samain Dr. Jörg Scheuermann Dr. Peter J. Brown Prof. Dr. Jonathan Hall Dr. Susanne Gräslund Prof. Dr. Herwig Schüler Prof. Dr. Dario Neri 《Angewandte Chemie (International ed. in English)》2015,54(13):3927-3931
Methods for the rapid and inexpensive discovery of hit compounds are essential for pharmaceutical research and DNA‐encoded chemical libraries represent promising tools for this purpose. We here report on the design and synthesis of DAL‐100K, a DNA‐encoded chemical library containing 103 200 structurally compact compounds. Affinity screening experiments and DNA‐sequencing analysis provided ligands with nanomolar affinities to several proteins, including prostate‐specific membrane antigen and tankyrase 1. Correlations of sequence counts with binding affinities and potencies of enzyme inhibition were observed and enabled the identification of structural features critical for activity. These results indicate that libraries of this type represent a useful source of small‐molecule binders for target proteins of pharmaceutical interest and information on structural features important for binding. 相似文献
107.
Konstantin Dirian Susanne Backes Claudia Backes Volker Strauss Fabian Rodler Frank Hauke Andreas Hirsch Dirk M. Guldi 《Chemical science》2015,6(12):6886-6895
A water soluble naphthalenebisimide derivative (NBI) was synthesized and probed to individualize, suspend, and stabilize single wall carbon nanotubes (SWCNTs). Besides a comprehensive photophysical and electrochemical characterization of NBI, stable suspensions of SWCNTs were realized in buffered D2O. Overall, the dispersion efficiency of the NBI surfactant was determined by comparison with naphthalene based references. Successful individualization of SWCNTs was corroborated in several microscopic assays. In addition, emission spectroscopy points to the strong quenching of SWCNT centered band gap emission, when NBIs are immobilized onto SWCNTs. The origin of the quenching was found to be strong electronic communication, which leads to charge separation between NBIs and photoexcited SWCNTs, and, which yields reduced NBIs as well oxidized SWCNTs. Notably, electrochemical considerations revealed that the energy content of these charge separated states is one of the highest reported for SWCNT based electron donor–acceptor hybrids so far. 相似文献
108.
Per Martin Björemark Dr. Susanne Olsson Dr. Theonitsa Kokoli Prof. Mikael Håkansson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(24):8750-8753
Even though the isolation of tetrahedral stereoisomers usually presents a synthetic challenge, a highly enantioenriched tetrahedral silver complex could be easily accessed by either crystallization or Viedma ripening. The overall preparation may be regarded as an example of absolute asymmetric synthesis. Experimental results indicate that both crystallization and Viedma ripening follow a similar cluster‐controlled mechanism. 相似文献
109.
Godau T Bleifuss SM Müller AL Roth T Hoffmann S Heinemann FW Burzlaff N 《Dalton transactions (Cambridge, England : 2003)》2011,40(24):6547-6554
One-pot syntheses of three new enantiopure heteroscorpionate ligands derived from (+)-camphor or (-)-menthone are described. The ligands are obtained by reacting pyrazoles derived from (+)-camphor or (-)-menthone with sodium hydride and thionyl chloride. Subsequent reactions with pyridine and various aldehydes afford the tripod ligands in multi-gram amounts. Especially the menthopyrazole based ligand 6 showed encouraging ee values up to 69% in the Cu(I) catalysed enantioselective cyclopropanation of styrene with ethyl diazoacetate. 相似文献
110.
Harrison S Fraser K Lane G Hughes D Villas-Boas S Rasmussen S 《Analytical and bioanalytical chemistry》2011,401(9):2955-2963
The main water-soluble carbohydrates in temperate forage grasses are polymeric fructans. Fructans consist of fructose chains
of various chain lengths attached to sucrose as a core molecule. In grasses, fructans are a complex mixture of a large number
of isomeric oligomers with a degree of polymerisation ranging from 3 to >100. Accurate monitoring and unambiguous peak identification
requires chromatographic separation coupled to mass spectrometry. The mass range of ion trap mass spectrometers is limited,
and we show here how monitoring selected multiply charged ions can be used for the detection and quantification of individual
isomers and oligomers of high mass, particularly those of high degree of polymerization (DP > 20) in complex plant extracts.
Previously reported methods using linear ion traps with low mass resolution have been shown to be useful for the detection
of fructans with a DP up to 49. Here, we report a method using high-resolution mass spectrometry (MS) using an Exactive Orbitrap
MS which greatly improves the signal-to-noise ratio and allows the detection of fructans up to DP = 100. High-sugar (HS) Lolium perenne cultivars with high concentrations of these fructans have been shown to be of benefit to the pastoral agricultural industry
because they improve rumen nitrogen use efficiency and reduce nitrous oxide emissions from pastures. We demonstrate with our
method that these HS grasses not only contain increased amounts of fructans in leaf blades but also accumulate fructans with
much higher DP compared to cultivars with normal sugar levels. 相似文献