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111.
1,3-Oxazolidin-4-ones and 1,3-oxazin-4-ones were synthesized by formal cyclocondensation of imines with α- or β-hydroxy acids. 相似文献
112.
The gas-phase decomposition of diallylvinylphosphine 1 into C5H5P 12 is studied by DFT/6-311+G(d,p) calculations with the B3LYP functional, followed by single-point energy-only calculations at the CCSD(T)/6-311+G(d,p) level. According to these calculations, the first step involves a retro-ene elimination that yields 3-phosphahexatrienes 2Z and 2E. Both compounds equilibrate through the formation of 1,2- and 3,4-dihydrophosphetes 3 and 4, and it is shown that the formation of 2Z is favored by the exothermic formation of the 3,4-dihydrophosphinine 5 through a 6pi-electrocyclization. Though 5 can easily isomerize into 2,3- (6) and 1,2-diyhydrophosphinines (7) by successive 1,5-hydrogen shifts, the formation of 12 from 5, 6, or 7 through an elimination of H2 is found to be a high energy process. It is also shown that the elimination of H2 from lambda5-phosphinine 8 following a C2v pathway is a symmetry-forbidden process. Finally, 1,4-dihydrophosphinine 9, which can be formed through a 1,4-hydrogen shift from lambda5-phosphinine 8, is found to be a convenient precursor of 12 through a 1,4-elimination of H2. The formation of 9 from 5 involves the intermediary formation of 3-phosphabicyclo[3.1.0]hex-2-ene 10. The mechanism eventually proposed for the formation of 12 from 2Z is given in Scheme 16 at the CCSD(T) level. 相似文献
113.
The synthesis of alkylarylphosphines is easily carried out by hydrophosphination of unactivated alkenes under mild thermal activation; gram scale amounts of products can be prepared by this simple methodology. 相似文献
114.
Magnani A Marchettini N Ristori S Rossi C Rossi F Rustici M Spalla O Tiezzi E 《Journal of the American Chemical Society》2004,126(37):11406-11407
The present work deals with the spatially extended oscillatory Belousov Zhabotinsky reaction-diffusion system carried out in an anisotropic environment of phosphatidylcholines/water binary system, which presents layered aqueous domains separated by lipid bilayers. We report the occurrence of stable Turing patterns, spiral waves, and other exotic structures in phospholipids bilayers that are generally used as a models for cell plasma membranes. 相似文献
115.
116.
We propose a physical interpretation of the so-called van der Waals equation of state for rubbers, which gives a relation between the force and the deformation. On a phenomenological basis this equation takes the finite extensibility and a non-defined interaction into account. Here the fininte extensibility is discussed for the dilute case (no entanglements) and the highly entangled limit. The intramolecular interactions are described by orientational effects. The resulting equation of state for the force shows the same features as the van der Waals equation.Dedicated to Prof. H.-G. Kilian on the occasion of his 60th birthday. 相似文献
117.
The aim of the paper is the simplification of calibration procedures in the investigation of multi-element-systems by calculating
calibration curves. This requires, as well as taking into account the measuring geometry and the detector properties, above
all the calculation of the number of the characteristic X-rays emitted by the sample per incident particle. For the calculation
of the thick target yield a computer programme has been developed which makes possible a simple exchange of subroutines describing
the stopping power of the sample, the cross-section of K-shell ionization, the fluorescence yield and the matrix absorption
for the resulting K-X-rays of the elements contained in the sample. The agreement between experiment and calculation is discussed,
when various approximations for the functions mentioned are used, as well as the possible influence of the grain size and
surface roughness of the samples on the measurements, on which the calculations are based.
相似文献
118.
An automated sample pretreatment of human blood plasma for liquid chromatographic determination of three antidepressant drugs, dibenzepine; a tricyclic antidepressant (TCA), reboxetine; a selective noradrenaline reuptake inhibitor (SNRI) and fluvoxamine; a selective serotonin reuptake inhibitor (SSRI), based on supported liquid membrane (SLM) for unsurpassed sample clean-up and analyte enrichment, has been developed. The chromatograms after enrichment of plasma blank and aqueous blank are virtually indistinguishable. The entire analytical procedure revealed good linearity and low detection limits of 5, 15 and 20 ng mL–1 for dibenzepine, reboxetine and fluvoxamine, respectively. No carry-over effects were noted. The repeatability of extraction at three concentrations in the range 40–150 ng mL–1 for the three drugs was between ca. 3% and 7% as relative standard deviation. The reproducibility relative standard deviation during three different days (replacing the membrane each day) was not significantly higher. 相似文献
119.
Zusammenfassung Durch den Einsatz zweiwertiger Ionen in der wäßrigen Subphase kann die Packungsdichte gespreiteter Monoschichten wasserunlöslicher Tenside pH-abhän-gig erhöht werden. Ergebnisse für Octadecylamin auf einer Lösung von Natriumhydrogensphosphat werden angegeben.
Mit 2 Abbildungen 相似文献
Summary The packing density of spread monolayers of waterinsoluble surface-active agents can be increased by use of bivalent ions in the aqueous subphase. Results for octadecyl amine spread on a solution of sodium hydrogen phosphate are given.
Mit 2 Abbildungen 相似文献
120.
Th. Kartnig 《Mikrochimica acta》1963,51(1):88-92
Zusammenfassung Eine Bestimmung von HCH und DDT aus Pulvergemischen und Streupudern wird beschrieben. Die beiden Insektizide werden über einer Säule, die mit Aluminiumoxyd neutral beschickt ist, mit Äther oder n-Hexan eluiert und das Eluat im Vakuum vorsichtig getrocknet. Aus der Schmelze des Rückstandes wird mit Hilfe der Glaspulvermethode die prozentuelle Zusammensetzung an Hand von Eichkurven ermittelt.
Summary A method is described for determining HCH and DDT obtained from mixed powders and dusting powders. The two insecticides are passed through a column packed with neutral aluminium oxide, and then eluted with ether or n-hexane, and the eluate then carefully dried in vacuo. The percentage composition is found by means of standard curves when the glass powder method is applied to the melt of the residue.
Résumé On décrit un dosade de HCH et de DDT sur le mélange des poudres et sur des poudres d'épandage. On réalise l'élution des deux insecticides avec l'éther ou le n-hexane, sur une colonne remplie d'oxyde d'aluminium neutre et l'on sèche avec prudence l'éluat dans le vide. On obtient la composition en pour-cent sur la partie fondue du résidu, au moyen de la méthode à la poudre de verre et en se servant de courbes d'étalonnage.相似文献