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931.
K. Horn A. M. Bradshaw K. Doblhofer S. Krause G. Weinberg H. -M. Seidenspinner R. Schulz 《Fresenius' Journal of Analytical Chemistry》1989,333(4-5):590-595
Summary The adhesion of chemically and electrochemically deposited copper films on commercial polyimide foils has been studied using scanning electron microscopy, photoelectron spectroscopy, EDX and IR reflection-absorption spectroscopy. Experiments have been carried out on the bare surface and the deposited layers as well as on surfaces prepared by peeling off the deposits. The results show that, at least for the case considered here, poor adhesion is caused by cohesion failure in the foil itself, and that a thin surface layer of the polyimide foil is important for the interface bond. IR spectroscopy was used to study the molecular nature of this surface layer.
Untersuchung der Adhäsion von Kupfer an Polyimidfolien mit Hilfe von oberflächenanalytischen Verfahren相似文献
932.
933.
934.
We apply a first-principles computational approach to study a light-sensitive molecular switch. The molecule that comprises the switch can convert between a trans and a cis configuration upon photoexcitation. We find that the conductance of the two isomers varies dramatically, which suggests that this system has potential application as a molecular device. A detailed analysis of the band structure of the metal leads and the local density of states of the system reveals the mechanism of the switch. 相似文献
935.
The first precise measurement of the Casimir force between dissimilar metals is reported. The attractive force, between a Cu layer evaporated on a microelectromechanical torsional oscillator and an Au layer deposited on an Al2O3 sphere, was measured dynamically with a noise level of 6 fN/sqrt[Hz]. Measurements were performed for separations in the 0.2-2 micro m range. The results agree to better than 1% in the 0.2-0.5 micro m range with a theoretical model that takes into account the finite conductivity and roughness of the two metals. The observed discrepancies, which are much larger than the experimental precision, can be attributed to a lack of a complete characterization of the optical properties of the specific samples used in the experiment. 相似文献
936.
The use of homopolymer 2a of methyl 5-vinylsalicylate, as well as of statistical copolymers 2b-f, in the diastereoselective protonation of the chiral keto-enolate 1 leads to selectivities of up to 93:7 in favor of product 3. 相似文献
937.
Of all of the organometallic reagents currently used to form carbon–carbon bonds, organocopper reagents rank amongst the most important. Interest in these reagents centers not only on their regioselectivity, but also increasingly on their application in stereoselective transformations (principally Michael additions and SN2′ reactions); the use of suitable substrates or chirally modified cuprates can lead to highly diastereo- and enantioselective reactions. Simultaneously, extensions of methods for the preparation and application of these reagents (for example functionalized organocopper species and Lewis acid catalysis, respectively) have opened up new horizons for organocopper reagents. Mechanistically, the reactions are well-documented and understood, but this aspect of the subject has not kept pace with the many rapid developments in preparative chemistry. Organocopper ragents have proved to be indispensable in the synthesis of complex natural products and pharmaceuticals, chiral auxiliaries, and molecules with interesting structural features. In this review we will discuss some of the more recent important developments in this area; the organization will follow the type of selectivity (regio-, diastereo-, and enantioselectivity). 相似文献
938.
Summary Flavanones ofArachis hypogaea, Hemizonia increscens, Eriodictyon glutinosum andThymus vulgaris extracts have been stereospecifically analysed by gradient elution on a column of cellulose triacetate supported on silica gel diol. The stereochemistry of naringenin, eriodictyol and homoeriodictyol was in favour of the 2S-configurated flavanones. 相似文献
939.
940.
Alfons Krause 《Monatshefte für Chemie / Chemical Monthly》1965,96(1):303-304
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