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11.
12.
Potassium salts of aziridine-2-carboxylic acid derivatives are efficiently converted into esters of amides by reactions with alkyl halides, alkyl dihalides or by acylation with trimethylacetyl chloride followed by aminolyses. 相似文献
13.
Results are presented for potentiometric ammonia gas-sensors which show that the response times increase significantly with age of the sensor when ammonium picrate is used as internal electrolyte and the samples have greater osmolarities than the internal electrolyte solution. A build-up of ammonium picrate crystals on the inner side of the gas-permeable membrane is responsible for this increasein response time. The use of ammonium chloride as internal electrolyte provides constant response times indepent of sample osmotic strength, and is recommended as a means of ensuring that optimal dynamic response characteristics are maintained. 相似文献
14.
H. W. Sarkas S. T. Arnold J. H. Hendricks L. H. Kidder C. A. Jones K. H. Bowen 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,26(1):46-50
We present preliminary evidence for catalytic activity by unsupported mixed metal oxide nanocrystalline materials. The results of this study show that a nanophase form of Li-MgO has begun to exhibit catalytic activity by 300 °C. This is at least 200 degrees below the temperature at which conventional Li-MgO catalysts exhibit comparable activity. Furthermore, at higher temperatures, the same nanophase composition shows enhanced activities and somewhat improved hydrocarbon selectivities over conventional Li-MgO catalysts. 相似文献
15.
The new monoterpenoid 5-isobutyl-3-methyl-2-furancarbaldehyde was isolated from Tagetes glandulifera Schrank and its structure confirmed by synthesis. 相似文献
16.
54Mn is analyzed in complex food ash of high cationic environment. The initial step is an extraction atpH 2.7 with hexane containing di(2-ethylhexyl) phosphoric acid (HDEHP) to complex the54Mn and other nuclides. The manganese is reextracted into an alkaline EDTA buffer which is washed with 1% 8-hydroxyquinoline
in chloroform containing 5% isoamyl alcohol. The54Mn is determined by gamma spectrometry with recoveries ranging from 96.6 to 99.4%. 相似文献
17.
F. E. Arnold 《Journal of polymer science. Part A, Polymer chemistry》1970,8(8):2079-2089
A new fused aromatic heterocyclic tetraamine 2,3,11,12-tetraaminodiquinoxal [2,3-e,2′,3′-1] pyrene has been prepared and polymerized with 1,4,5,8-naphthalenetetracarboxylic acid and pyromellitic dianhydride. The resulting ladder polymers with inherent viscosities ranging from 0.5 to 1.0 dl/g in methanesulfonic acid exhibited thermal stabilities near 600°C in nitrogen and near 450°C in air. 相似文献
18.
Thyagarajan S Shay DT Incarvito CD Rheingold AL Theopold KH 《Journal of the American Chemical Society》2003,125(15):4440-4441
Reaction of TpR,MeCo(I) dinitrogen complexes (R = iPr, tBu) with trimethylsilyl azide yields structurally characterized compounds that imply the formation of reactive intermediates of the type TpR,MeCo=NSiMe3. These cobalt imido species apparently abstract hydrogen from the 3-substituent of the Tp-ligand, leading to the formation of amido complexes accompanied by either Co-C bond formation (R = tBu) or C-C bond formation (R = iPr). 相似文献
19.
Condensation of o-phenylenediamine with 2-, 3- and 4-nitronaphthalene-1,8-dicarboxylic anhydrides gives, in each case, an isomer mixture. Separation of the mixtures into the six isomeric mononitro-7H-benzimidazo[2,1-a]benz[de]isoquinolin-7-ones is described and the isomers characterised in respect of previously reported data on some isomers; ir and mass spectrum data are reported, the latter showing fragmentation ions which may be used in characterising dyes based on this chromophore. Other new derivatives of 7H-benzimidazo[2,1-a]benz[de]isoquinolin-7-one are also described. 相似文献
20.
K. -P. Arnold K. -P. Döring M. Gladisch N. Haas D. Herlach W. Jacobs M. Krauth S. Liebke H. Metz H. Orth H. -E. Schaefer A. Seeger 《Hyperfine Interactions》1984,17(1-4):219-224
We have measured the transverse spin relaxation of positive muons
+ in Al single crystals after irradiation at 150 K with 3 MeV electrons. The relaxation functions agree with those expected for diffusion-limited trapping of the
+ in monovacancies. Between 215 K and 60 K the
+ diffusivity is well described by the Flynn-Stoneham law (multi-phonon incoherent tunnelling between ground states) with an activation enthalpyH
a = (30±2) meV. At lower temperatures, few-phonon (in particular one-phonon) processes become important. The decrease of the vacancy concentration by a factor of 100 during annealing between 227 K and 267 K has been studied. 相似文献