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141.
Michael Winkler Wolfram Sander 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2000,112(11):1945-1945
142.
Wolfram Grimme Joachim Gossel Johann Lex 《Angewandte Chemie (International ed. in English)》1998,37(4):473-475
Intermolecular cycloaddition of the bifunctional tetrachlorotribenzene 1 results in higher Diels–Alder oligomers of benzene ( 2 ), of which the linear and an angular hexamer (n=1) were characterized. The oligomers decompose above 110°C through stepwise extrusion of benzene and tetrachlorobenzene. 相似文献
143.
Astrid M. Müller Stefan Lochbrunner Wolfram E. Schmid Werner Fuß 《Angewandte Chemie (International ed. in English)》1998,37(4):505-507
What is the standard course of the cis – trans isomerization of nonpolar polyenes? Many results support a pathway in which only a central CH group rotates out of the plane, while the remaining parts of the molecule reorient within the plane (“hula-twist” mechanism). The intermediate structure through which the molecule passes corresponds to the geometry predicted for the conical intersection of the S1 and S0 potential energy surfaces (see picture). 相似文献
144.
Wolfram Sander Roman Wrobel Peter Komnick Paul Rademacher Heidi M. Muchall Helmut Quast 《European journal of organic chemistry》2000,2000(1):91-98
The flash vacuum pyrolysis of 3,3,5,5-tetramethylpyrazolin-4-one ( 4 ) with subsequent trapping of the products in argon at 10 K results in the formation of a complex product mixture with tetramethylcyclopropanone ( 5 ) as one of the minor constituents. The 193 nm photochemistry of matrix-isolated 4 is much cleaner, yielding cyclopropanone 5 and allene oxide 9 as the major products. The reaction of tetramethylallene 13 with oxygen atoms yields the same product mixture of 5 and 9 and thus provides an independent route to these species. The experimental IR spectra of 5 and 9 are in good agreement with the results from DFT calculations. 相似文献
145.
Daéid NN Meier-Augenstein W Kemp HF 《Rapid communications in mass spectrometry : RCM》2011,25(13):1812-1816
The analysis of un-dyed spun cotton fibres can be challenging within a forensic science context where discrimination of one fibre from another is of importance. Conventional microscopic and chemical analysis of these fibres is generally unsuccessful because of their similar morphology. In this work we have explored the potential of isotope ratio mass spectrometry (IRMS) as a tool for spun cotton fibre analysis in an attempt to reveal any discriminatory information available. Seven different batches of un-dyed spun cotton fibre from four different countries were analysed. A combination of the hydrogen and oxygen isotopic data facilitated the correct association of the samples, demonstrating, for the first time, the applicability of IRMS to fibre analysis in this way. 相似文献
146.
Fink F Hochrein J Wolowski V Merkl R Gronwald W 《Journal of computational chemistry》2011,32(12):2575-2586
One of the main challenges in protein-protein docking is a meaningful evaluation of the many putative solutions. Here we present a program (PROCOS) that calculates a probability-like measure to be native for a given complex. In contrast to scores often used for analyzing complex structures, the calculated probabilities offer the advantage of providing a fixed range of expected values. This will allow, in principle, the comparison of models corresponding to different targets that were solved with the same algorithm. Judgments are based on distributions of properties derived from a large database of native and false complexes. For complex analysis PROCOS uses these property distributions of native and false complexes together with a support vector machine (SVM). PROCOS was compared to the established scoring schemes of ZRANK and DFIRE. Employing a set of experimentally solved native complexes, high probability values above 50% were obtained for 90% of these structures. Next, the performance of PROCOS was tested on the 40 binary targets of the Dockground decoy set, on 14 targets of the RosettaDock decoy set and on 9 targets that participated in the CAPRI scoring evaluation. Again the advantage of using a probability-based scoring system becomes apparent and a reasonable number of near native complexes was found within the top ranked complexes. In conclusion, a novel fully automated method is presented that allows the reliable evaluation of protein-protein complexes. 相似文献
147.
Continuous-flow isotope ratio mass spectrometry (CF-IRMS) was used to compare (2)H isotopic composition at natural abundance level of human scalp hair and fingernail samples collected from subjects worldwide with interpolated delta(2)H precipitation values at corresponding locations. The results showed a strong correlation between delta(2)H values of meteoric water and hair (r(2) = 0.86), while the corresponding correlation for nails was not as strong (r(2) = 0.6). Offsets of -180 per thousand and -127 per thousand were observed when calculating solutions of the linear regression analyses for delta(2)H vs. delta(18)O correlation plots of hair and nail samples, respectively. Compared with the +10 per thousand offset of the global meteoric water line equation these findings suggested that delta(18)O data from hair and nail would be of limited diagnostic value. The results of this pilot study provide for the first time tentative correlations of (2)H isotopic composition of human hair and nails with local water. Linear regression analyses for measured delta(2)H values of human hair and nails vs. water yielded delta(2)H(hair) = 0.49 x delta(2)H(water) - 35 and delta(2)H(nails) = 0.38 x delta(2)H(water) - 49, respectively. The results suggest that (2)H isotopic analysis of hair and nail samples can be used to provide information regarding an individual's recent geographical life history and, hence, location. The benefit of this technique is to aid identification of victims of violent crime and mass disasters in circumstances where traditional methods such as DNA and fingerprinting cannot be brought to bear (or at least not immediately). 相似文献
148.
149.
A rigorous three-dimensional linear analysis of the electrohydrodynamic instability in nematic liquid crystals including the flexoelectric effect is presented for the case of an applied d.c. voltage. The flexoelectric effect leads to an appreciable reduction of the threshold and to the appearance of oblique rolls at threshold for the standard material MBBA. We discuss the influence of a magnetic field and test several approximations against the rigorous results 相似文献
150.