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21.
Bedford RB Fey N Haddow MF Sankey RF 《Chemical communications (Cambridge, England)》2011,47(12):3649-3651
Palladium-catalysed dearomatisation reactions allow access to a previously unknown class of indoloindole heterocycle: 5,10b-dihydroindolo[2,3-b]indoles. The highly reactive nature of these compounds is demonstrated by their facile reactions with water and with hydride, alkyl, aryl and allyl-based organometallic nucleophiles. 相似文献
22.
Bradshaw R Wolstenholme R Blackledge RD Clench MR Ferguson LS Francese S 《Rapid communications in mass spectrometry : RCM》2011,25(3):415-422
An increase in the use of condoms by sexual offenders has been observed. This is likely to be due both to the risk of sexually transmitted diseases and to prevent the transfer of DNA evidence. In this scenario the detection of condom lubricants at a crime scene could aid in proving corpus delicti. Here we show a novel application of Matrix-Assisted Laser Desorption/Ionisation Mass Spectrometry Imaging (MALDI MSI) for mapping the fingermark ridge pattern simultaneously to the detection of the condom lubricant within the fingermark itself. Two condom brands have been investigated to prove the concept. Condoms were handled producing lubricant-contaminated fingermarks. Images of the ridge pattern were obtained simultaneously to the detection of two lubricants, even several weeks after the fingermark deposition. The results therefore show the potential of MALDI MSI to link the suspect (identification through fingermark ridge pattern) to the crime (detection of condom lubricant) in one analysis. This would enable forensic scientists to provide evidence with stronger support in alleged cases of sexual assault. 相似文献
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We study a simple quasispecies model for evolution in two different habitats, with different fitness landscapes, coupled through one-way migration. Our key finding is a dynamical phase transition at a critical value of the migration rate, at which the time to reach the steady state diverges. The genetic composition of the population is qualitatively different above and below the transition. Using results from localization theory, we show that the critical migration rate may be very small-demonstrating that evolutionary outcomes can be very sensitive to even a small amount of migration. 相似文献
25.
Alan P. Bashall John Crowder Hagen Dronia Gerhard Hgele Harry R. Hudson Rosalind J. Lee Mary McPartlin Ray W. Matthews Johannes Ollig 《Heteroatom Chemistry》2010,21(5):314-325
X‐ray structural data for α‐aminopropanephosphonic acid (APPA), together with 1H NMR spectroscopy including PANIC and WIN‐DAISY spectral simulation, and theoretical calculations using the programs VAMP 4.4 (PM3) and GAUSSIAN 92 (3–21G**), confirm an antistaggered relationship between the methyl and phosphonic acid groups in this zwitterionic compound, both in the solid state and in aqueous solution. 31P{1H} and 13C{1H}‐NMR controlled titrations provide information on pKa values, proton exchange, ion‐specific chemical shifts, and coupling constants in solution. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:314–325, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20609 相似文献
26.
Modern methods for sampling rugged landscapes in state space mainly rely on knowledge of the relative probabilities of microstates, which is given by the Boltzmann factor for equilibrium systems. In principle, trajectory reweighting provides an elegant way to extend these algorithms to non-equilibrium systems, by numerically calculating the relative weights that can be directly substituted for the Boltzmann factor. We show that trajectory reweighting has many commonalities with Rosenbluth sampling for chain macromolecules, including practical problems which stem from the fact that both are iterated importance sampling schemes: for long trajectories the distribution of trajectory weights becomes very broad and trajectories carrying high weights are infrequently sampled, yet long trajectories are unavoidable in rugged landscapes. For probing the probability landscapes of genetic switches and similar systems, these issues preclude the straightforward use of trajectory reweighting. The analogy to Rosenbluth sampling suggests though that path-ensemble methods such as PERM (pruned-enriched Rosenbluth method) could provide a way forward. 相似文献
27.
A new procedure is presented for the preparation of N-trifluoroethylanilines by reaction of the appropriate aniline with ethyl trifluoroacetate or trifluoroacetic anhydride, followed by reduction with diborane in tetrahydrofuran. Yields are high unless the aniline carriers a carboyxl, carbonyl, olefin, or o-nitro substituent. several new N-substituted trifluoroacetamides and trifluoroethylanilines are reported. 相似文献
28.
Wakata A Cahill SM Blumenstein M Gunby RH Jockusch S Marti AA Cimbro B Gambacorti-Passerini C Donella-Deana A Pinna LA Turro NJ Lawrence DS 《Organic letters》2008,10(2):301-304
A new mechanistic principle for reporting the phosphorylation of tyrosine is described, which should prove applicable to even the most fastidious of protein tyrosine kinases, as demonstrated by the acquisition of a fluorescent sensor for the extraordinarily demanding anaplastic lymphoma kinase. 相似文献
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The algebra of many-valued quantities 总被引:6,自引:0,他引:6
Rosalind Cecily Young 《Mathematische Annalen》1931,104(1):260-290