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排序方式: 共有84条查询结果,搜索用时 31 毫秒
1.
Meinhard Wlaschek Gudrun Heinen Arndt Poswig Agatha Schwarz Thomas Krieg Karin Scharffetter-Kochanek 《Photochemistry and photobiology》1994,59(5):550-556
Abstract— Previous work has shown that fibroblast-derived collagenase/matrix-metalloproteinase-1(MMP–1), responsible for the breakdown of dermal interstitial collagen, was dose-dependently induced in vitro and in vivo by UVA irradiation and this induction was at least partly mediated byinterleukin–6(IL–6). We here provide evidence that UVA-inducedIL–1α andIL–1β play a central role in the induction of the synthesis both ofIL–6 and collagenase/MMP–1. In contrast to the late increase ofIL–1α andIL–1β mRNA levels at 6 h postirradiation, bioactivity ofIL–1 is already detectable at 1 h postirradiation. This early peak ofIL–1 bioactivity appears to be responsible for the induction ofIL–6 synthesis and together withIL–6 lead to an increase of the steady-state mRNA level of collagenase/MMP–1 as deduced from studies usingIL–1α andIL–1β antisense oligonucleotides or neutralizing antibodies againstIL–1α andIL–1β Besides the early posttranslationally controlled release of intracellularIL–1, a latter pretranslationally controlled synthesis and release ofIL–1 perpetuates the UV response. From these data we suggest a UV-induced cytokine network consisting ofIL–1α,IL–1β andIL–6, which via interrelated autocrine loops induce collagenase/MMP–1 and thus may contribute to the loss of interstitial collagen in cutaneous photoaging. 相似文献
2.
S. R. de Miguel J. C. Heinen A. A. Castro O. A. Scelza 《Reaction Kinetics and Catalysis Letters》1989,40(2):331-335
The enhancement of the activity of a carbon treated with HF is due to the drastic diminution of its inorganic impurities, which produces an increase of the surface area of the carbon, a stronger Pt-C interaction and a higher Pt dispersity.
, HF, , , Pt-C Pt.相似文献
3.
4.
P.M. Heinen J.J. Engelen E.W. Kittel W.J. Metzger M.M. Schouten J.S.M. Vergeest R.T. Van De Walle B. Jongejans H. Voorthuis M. Cerrada R.J. Hemingway S.O. Holmgren M.J. Losty 《Nuclear Physics B》1977,122(3):443-463
A partial-wave analysis of the low-mass (π+π?p) system produced in the reaction K?p → K?(π+π?p) at 4.2 GeV/c incident momentum is performed in order to study the two (π+π?p) enhancements around 1500 and 1700 MeV. It is found that the low-mass (π+π?p) system can be described using the spin-parity states and only. In the 1500 MeV region contributions are observed from the wave decaying into p? and the wave decaying into Δ++π?; in the 1700 MeV region contributions are found from the wave decaying into Δ++π?, the wave decaying into p?, and the wave decaying into p?. 相似文献
5.
Übersicht Für einige statische und kinetische Stabilitätsfälle des geraden Stabes werden die kritischen Lasten unter Berücksichtigung der genauen, nichtlinearen Verformungen des Grundzustandes ermittelt. Bei den kinetischen Stabilitätsfällen wird zusätzlich die äußere Dämpfung beachtet.
About the influence of non-linear deformations of the fundamental state on static and kinetic stability in the theory of rods
Summary For some conditions of static and kinetic stability of the straight rod the critical loads are determined with special regard to the exact, non-linear deformations of the fundamental state. In case of kinetic stability the external damping is additionally taken into account.相似文献
6.
Prof. Dr.-Ing. A. Heinen 《Archive of Applied Mechanics (Ingenieur Archiv)》1988,58(2):103-108
Übersicht Auf der Grundlage des kinetischen Stabilitätskriteriums wird das räumliche Knicken gerader Stäbe unter Streckendrillmomenten behandelt. Hierbei wird auch der Einfluß der äußeren Dämpfung auf die kritischen Lasten berücksichtigt.
Some more solutions to the problem of spatial buckling caused by nonconservative torsion
Summary The spatial buckling of straight rods, twisted by uniformly distributed moments, is treated on the basis of the criterion of kinetic stability. In this connexion the influence of external damping on the critical loads is also taken into account.相似文献
7.
Zusammenfassung Bei der kurzzeitigen Hochtemperaturbeaufschlagung nichtrostender Stähle (z.B. Durchlaufglühen, Schweißen) in Atmosphären mit verschiedenen O2-Partialdrucken können oxidische Deckschichten entstehen, die eine solche Dicke erreichen, daß sie optisch wahrgenommen werden. Zusammenhängende Schichten sind häufig farbig. Dies ist überwiegend auf Interferenz, z.T. aber auch auf Absorption des Lichts zurückzuführen. Bei nicht zusammenhängenden inselförmigen Schichten entsteht der Eindruck eines Grauschleiers. Die Zusammensetzung der Schichten ist je nach Werkstoff, Temperatur und Atmosphäre sehr unterschiedlich nd kann im Detail nicht vohergesagt werden. Analytische Untersuchungen erfolgten mit ESCA und Mikro-AES. Wo es auf die Analyse farblich differenzierter Bereiche ankam, die sich im Kontrast im REM-Bild nicht unterschieden, wurde zusätzlich LAMMA eingesetzt. Diese Methode gestattet darüber hinaus den empfindlichen Nachweis auch der leichten Elemente bei hohem räumlichen Auflösungsvermögen.
Herrn Professor Dr. H. Hartmann zum 70. Geburtstag gewidmet 相似文献
Surface analysis on stainless steels exhibiting annealing colours
Summary When stainless steels are exposed for short periods to high temperatures (as in welding and continuous annealing), oxide layers sufficiently thick to be visible may be formed in atmospheres with various O2 partial pressures. Continuous layers are often coloured. This arises mainly from interference, but to some extent from absorption of the light also. Non-continuous layers consisting of islands give the surface an appearance of grey haze. The composition of the layers differs very much according to the material, temperature, and atmosphere, and cannot be accurately predicted. We investigated the layers analytically by ESCA and micro-AES. Where it was necessary to investigate differently coloured areas that could not be distinguished in the SEM picture, LAMMA was used also. This method additionally enables even the light elements to be detected very sensitively and gives high spatial resolution.
Herrn Professor Dr. H. Hartmann zum 70. Geburtstag gewidmet 相似文献
8.
9.
M. Pinterić M. Miljak N. Biškup O. Milat I. Aviani S. Tomić D. Schweitzer W. Strunz I. Heinen 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,11(2):217-225
We report a detailed characterization of the magnetism and AC transport in single crystals of the organic conductor -(BEDT-TTF)2Cu[N(CN)2]Cl by means of magnetic anisotropy measurements and low-frequency dielectric spectroscopy. Magnetic anisotropy obeys Curie-Weiss
law with negative Curie-Weiss temperature in the temperature range 300 K-70 K. An antiferromagnetic transition with concomitant
canted antiferromagnetic state is established at 22 K. A large hysteresis in the spin-flop transition and magnetic field reversal
of the weak ferromagnetic magnetization are documented for the first time. A broad dielectric relaxation mode of moderate
strength () emerges at 32 K, and weakens with temperature. The mean relaxation time, much larger than that expected for single-particle
excitations, is thermally activated in a manner similar to the DC conductivity and saturates below 22 K. These features suggest
the origin of the broad relaxation as an intrinsic property of the weak ferromagnetic ground state. We propose a charged domain
wall in a random ferromagnetic domain structure as the relaxation entity. We argue that the observed features might be well
described if Dzyaloshinsky-Moriya interaction is taken into account. A Debye relaxation with similar temperature dependence
was also observed and seems to be related to an additional ferromagnetic-like, most probably, field-induced phase. We tentatively
associate this phase, whose tiny contribution was sample dependent, with a Cu2+ magnetic subsystem.
Received 15 June 1998 and Received in final form 1 February 1999 相似文献
10.
Martin Müller Susanne Heinen Ulrich Oertel Klaus Lunkwitz 《Macromolecular Symposia》2001,164(1):197-210
We report on the deposition and properties of multilayers composed of reactive polymers on planar surfaces. As reactive polymers the poly cations poly(ethylene‐imine), poly(L‐lysine) (PLL), poly(allylamime) (PAA) and the polyanions poly(acrylate) (PAC), poly(vinylsulfate), poly(maleate‐co‐olefines) were used. ATR‐FTIR Spectroscopy was adopted to study deposition, binding and stimulation properties of polymer multilayers. The binding of charged species of different molecular size such as rhodanide anions and sodium oleate from solution was examined, whereby binding was found to be dependent on the charge of the outermost layer. For these two analytes a selectivity parameter Q, defined as the ratio between the adsorbed amount obtained at the negatively charged and that at the positively charged surface, respectively, was determined. Furthermore, swelling experiments on multilayer assemblies of PLL and PAC exposed to mixtures of ethanol/water (10–70% EtOH content) were carried out. Our experiments gave evidence, that the PLL layers showed a more significant increase in density than the PAC layers. The conformation of PLL incorporated into multilayers could be changed by pH variation. 相似文献