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排序方式: 共有99条查询结果,搜索用时 281 毫秒
1.
Maximiliano A. Burgos Paci Gustavo A. Argüello Plcido García Helge Willner 《国际化学动力学杂志》2003,35(1):15-19
Thermal decomposition of bis(trifluoromethyl) peroxydicarbonate has been studied. The mechanism of decomposition is a simple bond fission, homogeneous first‐order process when the reaction is carried out in the presence of inert gases such as N2 or CO. An activation energy of 28.5 kcal mol?1 was determined for the temperature range of 50–90°C. Decomposition is accelerated by nitric oxide because of a chemical attack on the peroxide forming substances different from those formed with N2 or CO. An interpretation on the influence of the substituents in different peroxides on the O? O bond is given. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 35: 15–19, 2003 相似文献
2.
In this paper, we present experimental data for SIMS analysis of residual gas elements (RGEs) with a Cameca IMS-6f ion microprobe. We considered a simple experimental technique, which provides an effective separation of the secondary ions, sputtered from the bulk of a target, and from the molecules, adsorbed on the analyzed surface from the residual atmosphere. The technique needs the sputtering yield of one monolayer (ML) per second to be applied. The method improves (in more than one order of magnitude) the detection limit for RGEs in SIMS analysis, and simultaneously, provides information about the residual atmosphere at the sample surface and in the main chamber of the experimental instrument. The method provides a calibration method for an ion gauge, and can be used for SIMS analysis with a gas (O2) flooding. 相似文献
3.
L. M. Razo S. Solis M. Asomoza A. Hernandez 《Journal of Thermal Analysis and Calorimetry》1995,45(6):1323-1330
The combination of a DuPont 942 thermomechanical analyzer with a CBM computer allowed the establishment of thermodynamic properties such as isobars, isobaric volumetric expansions, isothermal compressibilities, and the equation of stateV=V(p, T) in a limited region ofpVT space. 相似文献
4.
Fused-silica capillaries chemically derivatized with silane/poly(vinylpyrrolidone) (PVP) or dynamically modified with plexiglas [poly(methyl methacrylate)] were prepared and evaluated with regard to column stability and separation performance for capillary isoelectric focusing of standard proteins. The PVP coating showed the better stability and was good for at least 100 runs while the plexiglas coating started to deteriorate after about 30 runs. The time spent for the plexiglas coating is about 40 minutes while the PVP coating requires two days. The migration time reproducibility was better with the PVP capillary (RSD 0.7-1.6%, n = 5) compared to the plexiglas-coated column (RSD 1.2-2.9%, n = 5) while peak area and height varied over a similar interval (RSD 2-28.1% area; 0.9-22.7% height, n = 5). The two most consistent proteins in this evaluation, viz. myoglobin A and carbonic anhydrase II, showed linear dynamic ranges between 5-150 and 5-50 microg/mL, and limits of detections at 2 and 1 microg/mL, respectively, employing UV detection at 280 nm. 相似文献
5.
The synthesis of CF(3)OC(O)OOC(O)F is accomplished by the photolysis of a mixture of (CF(3)CO)(2)O, FC(O)C(O)F, CO, and O(2) at -15 degrees C using a low-pressure mercury lamp. The new peroxide is obtained in pure form in low yield after repeated trap-to-trap condensation and is characterized by NMR, IR, Raman, and UV spectroscopy. Geometrical parameters were studied by ab initio methods [B3LYP/6-311+G(d)]. At room temperature, CF(3)OC(O)OOC(O)F is stable for many days in the liquid or gaseous state. The melting point is -87 degrees C, and the boiling point is extrapolated to 45 degrees C from the vapor pressure curve log p = 8.384 - 1715/T (p/mbar, T/K). A possible mechanism for the formation of CF(3)OC(O)OOC(O)F is discussed, and its properties are compared with those of related compounds. 相似文献
6.
Eduardo Corts Corts Rafael Sosa Mendoza Maximiliano Santibez Gutirrez Olivia Garca‐Mellado De Corts 《Journal of heterocyclic chemistry》2004,41(2):273-276
The preparation and spectral properties often novel methyl 5‐[(o‐, m‐, and p‐substituted)‐phenylthio]‐2‐benzimidazolecarbamates with possible pharmacological activity as antihelmintics is described; by condensation and cyclization between 5‐methylthioures sulfate chloroformic acid methyl ester and 3,4‐diaminophenyl‐substituted‐phenylthio ether dissolved in ethanol. The structures of all final products were corroborated by ir; 1H‐nmr, 13C‐nmr and ms. 相似文献
7.
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9.
Dr. Michael Peter Mercer Sam Affleck Dr. Edgardo Maximiliano Gavilán-Arriazu Dr. Alana Aragón Zülke Dr. Philip A. Maughan Shivam Trivedi Prof. Maximilian Fichtner Dr. Anji Reddy Munnangi Prof. Ezequiel P. M. Leiva Prof. Harry Ernst Hoster 《Chemphyschem》2022,23(5):e202100748
Sodium-ion batteries (NIBs) utilize cheaper materials than lithium-ion batteries (LIBs) and can thus be used in larger scale applications. The preferred anode material is hard carbon, because sodium cannot be inserted into graphite. We apply experimental entropy profiling (EP), where the cell temperature is changed under open circuit conditions. EP has been used to characterize LIBs; here, we demonstrate the first application of EP to any NIB material. The voltage versus sodiation fraction curves (voltage profiles) of hard carbon lack clear features, consisting only of a slope and a plateau, making it difficult to clarify the structural features of hard carbon that could optimize cell performance. We find additional features through EP that are masked in the voltage profiles. We fit lattice gas models of hard carbon sodiation to experimental EP and system enthalpy, obtaining: 1. a theoretical maximum capacity, 2. interlayer versus pore filled sodium with state of charge. 相似文献
10.
We study the stability of general relativistic static thick disks. As an application we consider the thick disk generated
by applying the “displace, cut, fill and reflect” method, usually known as the image method, to the Schwarzschild metric in
isotropic coordinates. The isotropic Schwarzschild thick disk obtained from this method is the simplest model to describe,
in the context of General Relativity, real thick galaxies. Stability under a general first order perturbation of the disk
energy momentum tensor is investigated. The first order perturbation, when applied to the conservation equations, leads to
a set of differential equations that have fewer equations than unknowns. In this article we search for perturbations in which
the perturbation of the four velocity in a certain direction leads to a pressure perturbation in the same direction. We found
that, in general, the isotropic Schwarzschild thick disk is stable under these kinds of perturbations. 相似文献