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排序方式: 共有1116条查询结果,搜索用时 15 毫秒
1.
2.
Enantiomeric Cyclic Peptides with Different Caco‐2 Permeability Suggest Carrier‐Mediated Transport
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B. Sc. Eduard Puig Prof. Dr. Beat Ernst Prof. Dr. Horst Kessler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8023-8027
Recently, oral absorption of cyclic hexapeptides was improved by N‐methylation of their backbone amides. However, the number and position of N‐methylations or of solvent exposed NHs did not correlate to intestinal permeability, measured in a Caco‐2 model. In this study, we investigate enantiomeric pairs of three polar and two lipophilic peptides to demonstrate the participation of carrier‐mediated transporters. As expected, all the enantiomeric peptides exhibited identical lipophilicity (logD7.4) and passive transcellular permeability determined by the parallel artificial membrane permeability assay (PAMPA). However, the enantiomeric polar peptides exhibited different Caco‐2 permeability (Papp) in both directions a–b and b–a. The same trend was observed for one of the lipophilic peptide, whereas the second lipophilic enantiomer pair showed identical Caco‐2 permeability (within the errors). These findings provide the first evidence for the involvement of carrier‐mediated transport for peptides, especially for those of polar nature. 相似文献
3.
Eduard Feireisl Antonín Novotný Hana Petzeltov 《Mathematical Methods in the Applied Sciences》2002,25(12):1045-1073
We prove a general compactness result for the solution set of the compressible Navier–Stokes equations with respect to the variation of the underlying spatial domain. Among various corollaries, we then prove a general existence theorem for the system in question with no restrictions on smoothness of the spatial domain. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
4.
This paper solves the problem of the duration of the total eclipseof a satellite of a body, provided that (a) the body is sphericalin shape and the mass distribution inside the body is sphericallysymmetrical; (b) the satellite is a very small object; (c) thesatellite's orbit around a body is circular and the satellitecan pass through the centre of its shadow; (d) a source of lightis the source of the conical body's shadow (umbra) and it doesnot change its apparent position in the sky; (e) there are noperturbations on the satellite's orbit. The solution presentedrepresents the general discussion of the problem based on utilizationof some parts of the theory of contraction mappings. 相似文献
5.
Eduard Prugovečki 《Foundations of Physics》1991,21(1):93-124
The issue of the intrinsic nonlocality of quantum mechanics raised by J. S. Bell is examined from the point of view of the recently developed method of geometro-stochastic quantization and its applications to general relativistic quantum theory. This analysis reveals that a distinction should be made between the topological concept of locality used in formulating relativistic causality and a type of geometric locality based on the concept of fiber bundle, which can be used in extending the strong equivalence principle to the quantum domain. Both play an essential role in formulating a notion of geometro-stochastic propagation based on quantum diffusions, which throws new light on the EPR paradox, on the origin of the arrow of time, and on other fundamental issues in quantum cosmology and the theory of measurement. 相似文献
6.
7.
In this paper we construct a positive doubly power bounded operator
with a nonpositive inverse on an AL-space. 相似文献
8.
The derivative expansion of the effective action is a perturbative development in derivatives of the fields. The expansion breaks down when some of the derivatives are too large. We show how to sum exactly the first and second derivatives and treat perturbatively derivatives higher than second. 相似文献
9.
Non-additivity effects in coupled dynamic-stochastic systems are investigated. It is shown that there is a mapping of the
replica approach to disordered systems with finite replica indexn on Tsallis non-extensive statistics, if the average thermodynamic entropy of the dynamic subsystem differs from the information
entropy for the probability distribution in the stochastic subsystem. The entropic indexq is determined by the entropy difference ΔS. In the case of incomplete information, the entropic indexq=1−n is shown to be related to the degree of lost information. 相似文献
10.
O. V. Dementienko O. P. Kuznetsova A. P. Tikhonov E. V. Prut 《Polymer Science Series A》2007,49(11):1218-1225
The influence of dynamic vulcanization on the amount of the sol fraction, the crosslink density, the melt flow index, and the mechanical properties of ternary (isotactic polypropylene-rubber-crumb rubber) and binary (rubber-crumb rubber) blends was studied. Two types of ethylene-propylene-diene terpolymer (elastomer) were used as the rubber component, the oil-free elastomer and the elastomer extended with paraffin oil during its synthesis. The blends were vulcanized in the presence of a sulfur accelerating system. It was shown that blends with crumb rubber having a particle size of less than 0.1 mm exhibited the best mechanical and rheological characteristics. The introduction of crumb rubber into thermoplastic elastomers that contain the oil-free ethylene-propylene-diene terpolymer leads, at a certain ratio of the components, to a rise in the melt flow index, regardless of the crumb-rubber particle size and of whether the rubber component was vulcanized. 相似文献