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排序方式: 共有90条查询结果,搜索用时 15 毫秒
1.
We report the results of a study of the self-assembly of four minimalist peptide strands with a native beta-barrel structure. Using a soft-well potential to mimic cellular crowding, molecular dynamics simulations were performed in confining spheres of varying radii. By utilizing a previously introduced scaling factor lambda for the non-native hydrophobic interactions (0相似文献
2.
Capon RJ Skene C Liu EH Lacey E Gill JH Heiland K Friedel T 《Natural product research》2004,18(4):305-309
Bioassay directed fractionation of a Raspailia (Raspailia) sp. (Order Poecilosclerida; Family Raspailiidae) collected during scientific trawling operations off the Northern Rottnest Shelf yielded as nematocidal agents the known metabolites, phorboxazoles A (1) and B (2). Further examination revealed the new natural product but known synthetic compound, esmodil (3). The structure for 3 was confirmed by spectroscopic analysis and total synthesis. 相似文献
3.
Anna Rabe Julia Büker Dr. Soma Salamon Adarsh Koul Dr. Ulrich Hagemann Dr. Joachim Landers Dr. Klaus Friedel Ortega Dr. Baoxiang Peng Prof. Dr. Martin Muhler Prof. Dr. Heiko Wende Prof. Dr. Wolfgang Schuhmann Prof. Dr. Malte Behrens 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(68):17038-17048
By using the crystalline precursor decomposition approach and direct co-precipitation the composition and mesostructure of cobalt-based spinels can be controlled. A systematic substitution of cobalt with redox-active iron and redox-inactive magnesium and aluminum in a cobalt spinel with anisotropic particle morphology with a preferred 111 surface termination is presented, resulting in a substitution series including Co3O4, MgCo2O4, Co2FeO4, Co2AlO4 and CoFe2O4. The role of redox pairs in the spinels is investigated in chemical water oxidation by using ceric ammonium nitrate (CAN test), electrochemical oxygen evolution reaction (OER) and H2O2 decomposition. Studying the effect of dominant surface termination, isotropic Co3O4 and CoFe2O4 catalysts with more or less spherical particles are compared to their anisotropic analogues. For CAN-test and OER, Co3+ plays the major role for high activity. In H2O2 decomposition, Co2+ reveals itself to be of major importance. Redox active cations in the structure enhance the catalytic activity in all reactions. A benefit of a predominant 111 surface termination depends on the cobalt oxidation state in the as-prepared catalysts and the investigated reaction. 相似文献
4.
Helmut Friedel 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1969,20(3):329-342
Zusammenfassung In der vorliegenden Arbeit werden schwach konvergierende und schwach divergierende MGD-Strömungen in der Grenzschichtnäherung untersucht. Das Verhalten dieser magnetischen Grenzschicht, charakterisiert durch alleinige Berücksichtigung der magnetischen Viskosität und Vernachlässigung der dynamischen Viskosität, wird durch die starke Kopplung zwischen Magnetfeld und Strömungsfeld bestimmt. Es werden im allgemeinen durch diese Kopplung die MGD-Grenzschichtgleichungen komplizierter, so dass deren analytische Lösung nur mit Hilfe von Ähnlichkeitstransformationen möglich ist. Nur im GrenzfallR
M (magnetische Reynoldszahl sehr gross) erhält man eine analytische Lösung. Mit Hilfe bestimmter Symmetriebedingungen werden die Lösungen auf symmetrische Strömungen eingeschränkt (freier Strahl oder Kanalströmungen). Schliesslich wird noch gezeigt, dass die endliche elektrische Leitfähigkeit die Ursache der freien Turbulenz gewisser Jet-Konfigurationen ist.
This research has been sponsored in part by the United States Government under Contract No. F61052-67-C-0014. 相似文献
This research has been sponsored in part by the United States Government under Contract No. F61052-67-C-0014. 相似文献
5.
P. Schmid K. Uran F. Macherey M. Ebert H.-J. Ullrich D. Sommer F. Friedel 《Analytical and bioanalytical chemistry》2009,393(8):1863-1870
The formation of Fe–Zn intermetallic compounds, as relevant in the commercial product galvannealed steel sheet, was investigated
by scanning electron microscopy and different methods of X-ray diffraction. A scanning electron microscope with high resolution
was applied to investigate the layers of the galvannealed coating and its topography. Grazing incidence X-ray diffraction
(GID) was preferred over conventional Bragg–Brentano geometry for analysing thin crystalline layers because of its lower incidence
angle α and its lower depth of information. Furthermore, in situ experiments at an environmental scanning electron microscope (ESEM)
with an internal heating plate and at an X-ray diffractometer equipped with a high-temperature chamber were carried out. Thus,
it was possible to investigate the phase evolution during heat treatment by X-ray diffraction and to display the growth of
the ζ crystals in the ESEM. 相似文献
6.
7.
The motivations to realize nuclear breeder reactors are developed in the present context of a strong growth in electronuclear power stations in many countries, using mostly moderated and water cooled reactors.The past studies can be of a substantial profit in France and, to a lesser degree, in other countries of the EU. However, to use fully the 238 uranium isotope, the materials for these breeders must withstand much harder radiation than those for water reactors. The power densities and thermal gradients will also be much more intense. The mechanical stresses, both static and dynamic, will be large and will act on materials with altered mechanical properties. Fuel elements will have to be produced with materials already irradiated several times and therefore showing such alterations.A field of studies concerning materials and their mechanical behavior in new and severe conditions is sketched here, both in construction and working conditions, together with proposed necessary instrumentation and research orientations. 相似文献
8.
9.
Dendronized Hyperbranched Macromolecules: Soft Matter with a Novel Type of Segmental Distribution 下载免费PDF全文
Priv.‐Doz. Dr. Albena Lederer Prof. Dr. Walther Burchard Tobias Hartmann Johannes S. Haataja Dr. Nikolay Houbenov Andreas Janke Dr. Peter Friedel Dr. Ralf Schweins Dr. Peter Lindner 《Angewandte Chemie (International ed. in English)》2015,54(43):12578-12583
Dendronization of a hyperbranched polyester with different generation dendrons leads to pseudo‐dendritic structures. The hyperbranched core is modified by the divergent coupling of protected monomer units to the functional groups. Compared to dendrimers, the synthetic effort is significantly less, but the properties are very close to those of high‐generation dendrimers. The number of functional groups, molar mass, and rheology behavior even in the early generation (G1–G4) pseudo‐dendrimers strongly resembles the behavior of dendrimers in higher generations (G5–G8). Comparison of the segmental and internal structure with perfect dendrimers is performed using SANS, dynamic light scattering and viscosity analysis, microscopy and molecular dynamics simulation. The interpretation of the results reveals unique structural characteristics arising from lower segmental density of the core, which turns into a soft nano‐sphere with a smooth surface even in the first generation. 相似文献