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991.
The conversion of 23-nor-5,20(22)E-choladienic acid-3β-ol and other intermediates of the putative norcholanic acid pathway of cardenolide biosynthesis by recombinant 3β-hydroxysteroid dehydrogenase from Digitalis lanata in dehydrogenation and reduction reactions was investigated. 23-nor-4,20(22)E-choladienic acid-3-one was found to be a substrate of recombinant progesterone 5β-reductases from D. lanata and Arabidopsis thaliana. The role of various substrates in cardenolide biosynthesis is discussed. 相似文献
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With great interest we read the recent publication of Sohn et al. [Sohn, S.Y., Chang, I.S., Moon, T.H., 2007. Random effects Weibull regression model for occupational lifetime. European Journal of Operational Research 179, 124–131] on a Weibull regression model with random effects for modelling occupational lifetime. We congratulate Sohn and colleagues on their comprehensive and clearly written paper. Nevertheless, we would like to comment on two points, the first regarding the moments of the underlying Weibull distribution, the second regarding the relations of Sohn’s model to the class of frailty models. 相似文献
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Andreas Mautner Xiaohua Qin Harald Wutzel Samuel C. Ligon Barbara Kapeller Doris Moser Guenter Russmueller Juergen Stampfl Robert Liska 《Journal of polymer science. Part A, Polymer chemistry》2013,51(1):203-212
Monomers for radical photopolymerization based on vinyl esters (VEs) have recently been identified as suitable alternatives to (meth)acrylates on account of their low irritancy and cytotoxicity. The drawback of most VEs with abstractable hydrogens is their relatively low reactivity compared with (meth)acrylates. Within this article, we proved by photo‐differential scanning calorimetry measurements and real‐time Fourier transform infrared spectroscopy that the thiol‐ene concept is able to improve the photoreactivity of these VEs to a large extent to a level between those of acrylates and methacrylates. Other VEs have now a reactivity of at least the level of similar acrylates. Mechanical properties as determined by Dynamic Mechanical Analysis and Charpy impact tests showed significant toughening of these materials. Furthermore, we were able to confirm low toxicity of all components by osteoblast cell culture experiments. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
999.
Feichtinger Gustav Andreas J. Novak 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(3):197-211
In this paper we present a simple time-continuous behavioural model of habit formation. Addictive behaviour is damped by a threshold which adapts itself to the habit. This adaptive behaviour of the threshold may lead to periodic fluctuations of the consumption rate, the habit and the threshold. It turns out that both a low adjustment rate of the threshold as well as a steep consumption function favour oscillatory patterns. 相似文献
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Peter Medley Andreas Bollhöfer Paul Martin 《Journal of Radioanalytical and Nuclear Chemistry》2013,296(2):1155-1162
Low-level measurements of 210Po using alpha spectrometry with a 209Po tracer have been conducted at the Environmental Research Institute of the Supervising Scientist (eriss) for many years, on samples with a range of activity concentrations spanning several orders of magnitude. These samples originated from a wide range of research and monitoring projects, and included a wide variety of traditional foods consumed by the indigenous population in Australia’s Northern Territory. Assessment of instrument blank and analyte blank data from these measurements collected over a period of 8 years was conducted. Instrumental blank data for 210Po and 209Po generally followed a normal distribution, whereas analyte blank data for 210Po followed a lognormal distribution. Instrumental blank data for 209Po indicated an increasing trend, indicative of a low level of polonium volatilisation from prepared sources. Lower limits of detection, including the critical limit, detection limit and quantification limit have been calculated. The critical limit ranges from 12 to 37 counts per day. Detection and quantification limits range from 0.18 to 0.33 mBq and 2.3 to 3.6 mBq for a 4-day count, with an assumed mean chemical recovery of 53 %. These limits are relatively high for alpha spectrometric techniques due to the high variability of the analyte blank signal and non-normal distribution for 210Po. Native plant species have relatively low activity concentrations of 210Po in their edible fruits and the amount of sample that should be used for analysis to ensure 90 % of fruit samples analysed reach the specified quantification limit was 11 g. 相似文献