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111.
H. Weber K. Braun E. Unsin H. Widey G. Zäpfel Peter F. Heil W. Krämer K. -W. Schulte Th. Fischer G. Fandel 《Mathematical Methods of Operations Research》1980,24(6):B199-B206
Ohne Zusammenfassung 相似文献
112.
Synthesis and Investigation of Aminosulphur Trifluorides and of a Hydrolysis Product 1-(Fluorooxothio)-2,5-dihydropyrrole The reaction of previously unknown (trimethylsilyl)amines with sulphur tetrafluoride gives some new aminosulphurtrifluorides. Experiments to cleaver 1-(Trifluorothio)-2,5-dihydropyrrole and 1-(trifluorothio)pyrrolidin into butadiene and ethylene respectively and NSF3 by way of a chelotrope cycloelimination were unsuccessful. 1H-NMR and 19F-NMR spectra revealed the nitrogen in the aminosulphur trifluorides must be regarded sp3 hybridized rather than sp2. 相似文献
113.
The static vessel pyrolysis of bicyclo[2.2.2]octa-2,5,7-triene (barrelene) has been studied between 483 and 523 K. The products were acetylene and benzene (in equal quantities) with no other detectable C8H8 isomer (down to less than 1% of total). The time dependence fitted first-order kinetics, and the data are consistent with a homogeneous unimolecular reaction close to, if not at, its high-pressure limit at 0.25 torr. The rate constant was fitted to the Arrhenius equation These Arrhenius parameters are shown to imply a concerted single-step process. Alternative mechanisms are discussed and a comparison is made with the retro-Diels—Alder reactions of other bicyclo[2.2.2]octa-olefin systems. 相似文献
114.
115.
Tiberius E. Braun 《Mikrochimica acta》1957,45(1):128-130
Sans résumé 相似文献
116.
H. Braun 《Applied Physics A: Materials Science & Processing》1978,17(2):193-197
The electrical conductivity of a conducting powder is influenced by the properties of the grain surface as well as the grain
core. By appropriate variation of pressure and electric frequency, the two contributions can be separated, as long as the
grains have shapes nearly like spheres. From experimental data on pressed powders one can thus obtain information concerning
carrier density and mobility of bulk material. Results for PbO2 obtained in this way agree well with the properties of bulk PbO2 samples reported in the literature. 相似文献
117.
118.
Experiments using atomic force microscopy for unfolding single multidomain biopolymers cover a broad range of time scales
from equilibrium to non-equilibrium. A master equation approach allows to identify and treat coherently three dynamical regimes
for increasing linear ramp velocity: i) an equilibrium regime, ii) a transient regime where refolding events still occur,
and iii) a saw-tooth regime without any refolding events. For each regime, analytical approximations are derived and compared
to numerically investigated examples. We analyze in the framework of this model also a periodic experimental protocol instead
of a linear ramp. In this case, a major simplification arises if the dynamics can be restricted to an effectively two-dimensional
subspace. For transitions with an intermediate meta-stable state, like Immunoglobulin27, a refined model allows to extract
previously unknown molecular parameters related to this meta-stable state. 相似文献
119.
J.?Bartels M.?Braun G.?P.?VaccaEmail author 《The European Physical Journal C - Particles and Fields》2005,40(3):419-433
We analyze the momentum space triple pomeron vertex in perturbative QCD. In addition to the standard form of this vertex which is used in the context of total cross sections at high energies and in the QCD reggeon field theory, there exists an alternative form which has to be used in the study of high-mass diffraction. We review and analyze the relation between these two versions. We discuss some implications for the BK equation. In the second part of our paper we extend this analysis to the pomeron-odderon-odderon vertex.Received: 11 January 2005, Revised: 24 January 2005, Published online: 3 March 2005 相似文献
120.
Eckhoff DA Sutin JD Clegg RM Gratton E Rogozhina EV Braun PV 《The journal of physical chemistry. B》2005,109(42):19786-19797
Studying the properties and stability of silicon nanoparticles (Si-np) in aqueous environments may lead to novel applications in biological systems. In this work, we use absorption and photoluminescence (PL) spectroscopy to characterize ultrasmall Si-np prepared through anodic etching and ultrasonic fractionation of a crystalline Si wafer. Their behavior is studied over time in 2-propanol and during treatments with water, NaOH, HCl, and H(2)O(2). The observed population is divided into two types of material: bright species consisting of well-etched Si-np, approximately 1 nm in diameter, and dark species derived from partially etched or aggregated Si structures. The dark material is seen by its scattering in the 2-propanol and water solutions and is largely removed via precipitation with the NaOH or HCl treatment. The bright material includes three distinct species with their respective emissions in the UV-B, UV-A, and hard-blue regions of the spectrum. The hard-blue PL is shown to have a simple pH dependence with a pK(a) approximately 3, providing an important insight into its chemical origin and signaling for possible application of Si-np as environmental probes. Our results offer some potential for tailoring the PL properties of ultrasmall Si-np through control of their surface chemistry. 相似文献