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排序方式: 共有218条查询结果,搜索用时 171 毫秒
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Qian Zhang Corinna Harms Jens Mitzel Pawel Gazdzicki K. Andreas Friedrich 《Current Opinion in Electrochemistry》2022
The durability of polymer electrolyte membrane fuel cells (PEMFCs) needs to be further improved to cope with application requirements and economic competitiveness. This article highlights the challenges in the reliable determination of degradation rates and lifetime. The reliable evaluation of performance degradation rates is fundamental to quantify and benchmark durability and to allow comparisons between PEMFC durability tests performed using different materials or in different laboratories. The use of efficient recovery procedures enables the discrimination of reversible and irreversible voltage losses and facilitates the understanding of recovery mechanisms. In the end, recent contributions about lifetime diagnoses and prediction are presented, which are promising to be implemented in PEMFC applications. 相似文献
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Corinna Elsenbroich Maria Xenitidou 《Computational & Mathematical Organization Theory》2012,18(1):113-127
We present an analysis for modelling social norms. In social psychology three different normative behaviours have been identified:
obedience, conformity and compliance. We show that this triad is a useful conceptualisation of normative behaviour and that
current models only ever deal with conformity and obedience two, neglecting compliance. We argue that this is a result from
modelling having so far focussed too much on agent behaviour rather than agent knowledge and that cognitive models of normative
behaviour are needed to capture this third and arguably most interesting normative behaviour. 相似文献
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Stefanie?Platz Ann?Liza?Piberger Julia?Budnowski Corinna?Herz Monika?Schreiner Michael?Blaut Andrea?Hartwig Evelyn?Lamy Laura?Hanske Sascha?RohnEmail author 《Analytical and bioanalytical chemistry》2015,407(7):1819-1829
The food-related isothiocyanate sulforaphane (SFN), a hydrolysis product of the secondary plant metabolite glucoraphanin, has been revealed to have cancer-preventive activity in experimental animals. However, these studies have often provided inconsistent results with regard to bioavailability, bioaccessibility, and outcome. This might be because the endogenous biotransformation of SFN metabolites to the structurally related erucin (ERN) metabolites has often not been taken into account. In this work, a fully validated liquid chromatography tandem mass spectrometry (LC–MS–MS) method was developed for the simultaneous determination of SFN and ERN metabolites in a variety of biological matrices. To reveal the importance of the biotransformation pathway, matrices including plasma, urine, liver, and kidney samples from mice and cell lysates derived from colon-cancer cell lines were included in this study. The LC–MS–MS method provides limits of detection from 1 nmol L?1 to 25 nmol L?1 and a mean recovery of 99 %. The intra and interday imprecision values are in the range 1–10 % and 2–13 %, respectively. Using LC–MS–MS, SFN and ERN metabolites were quantified in different matrices. The assay was successfully used to determine the biotransformation in all biological samples mentioned above. For a comprehensive analysis and evaluation of the potential health effects of SFN, it is necessary to consider all metabolites, including those formed by biotransformation of SFN to ERN and vice versa. Therefore, a sensitive and robust LC–MS–MS method was validated for the simultaneous quantification of mercapturic-acid-pathway metabolites of SFN and ERN. 相似文献
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This paper is intended to be a first step towards the continuous dependence of dynamical contact problems on the initial data as well as the uniqueness of a solution. Moreover, it provides the basis for a proof of the convergence of popular time integration schemes as the Newmark method. We study a frictionless dynamical contact problem between both linearly elastic and viscoelastic bodies which is formulated via the Signorini contact conditions. For viscoelastic materials fulfilling the Kelvin-Voigt constitutive law, we find a characterization of the class of problems which satisfy a perturbation result in a non-trivial mix of norms in function space. This characterization is given in the form of a stability condition on the contact stresses at the contact boundaries. Furthermore, we present perturbation results for two well-established approximations of the classical Signorini condition: The Signorini condition formulated in velocities and the model of normal compliance, both satisfying even a sharper version of our stability condition. 相似文献
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Pascal Hubert Samuel Lelièvre Luca Marchese Corinna Ulcigrai 《Israel Journal of Mathematics》2018,225(2):553-607
Lagrange spectra have been defined for closed submanifolds of the moduli space of translation surfaces which are invariant under the action of SL(2, R). We consider the closed orbit generated by a specific covering of degree 7 of the standard torus, which is an element of the stratum H(2). We give an explicit formula for the values in the spectrum, in terms of a cocycle over the classical continued fraction. Differently from the classical case of the modular surface, where the lowest part of the Lagrange spectrum is discrete, we find an isolated minimum, and a set with a rich structure right above it. 相似文献
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Gottschalk Corinna Koster Arie M. C. A. Liers Frauke Peis Britta Schmand Daniel Wierz Andreas 《Mathematical Programming》2018,168(1-2):55-61
Mathematical Programming - The problem of finding a zero of the sum of two maximally monotone operators is of central importance in optimization. One successful method to find such a zero is the... 相似文献
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Babushkin DE Naundorf C Brintzinger HH 《Dalton transactions (Cambridge, England : 2003)》2006,(38):4539-4544
Zirconocenium cations of the type [(MeC5H4)2ZrMe]+, formed by excess methylalumoxane (MAO) from (MeC5H4)2ZrCl2 or (MeC5H4)2ZrMe2 with 13C-labelled ring ligands, are found to form ion pairs with two types of anions, Me-MAO(A)- and Me-MAO(B)-, which differ in their coordinative strengths: More strongly coherent ion pairs [(MeC5H4)2ZrMe+...Me-MAO(B)-] are converted to more easily separable ion pairs [(MeC5H4)2ZrMe+...Me-MAO(A)-] by a sufficient excess of MAO. These react with Al2Me6 to form outer-sphere ion pairs containing the cationic AlMe3 adduct [(MeC5H4)2Zr(mu-Me)2AlMe2]+; formation of the more easily separable ion pairs might be required also for polymerisation catalysis. 相似文献