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排序方式: 共有150条查询结果,搜索用时 46 毫秒
1.
The aim of this work is to study the dynamic formation and dissociation of trions and excitons in double barrier resonant tunneling diodes. We propose a system of rate equations that takes into account the formation, dissociation and annihilation of these complexes inside the quantum well. From the solutions of the coupled equations, we are able to study the modulation of excitons and trions formation in the device as a function of the applied bias. The results of our model agree qualitatively with the experiments showing the viability of these rate equations system to study the dynamics of complex systems. 相似文献
2.
The synthesis and properties of perchlorobi-9-fluorenylidene, a highly twisted ethylene, are reported. It is a diamagnetic chlorocarbon. 相似文献
3.
Villorbina G Roura L Camps F Joglar J Fabriàs G 《The Journal of organic chemistry》2003,68(7):2820-2829
The formation of methylenecyclopropanes by enzymatic desaturation of 11-cyclopropylundecanoic acid (1) and its disubstituted derivatives cis- and trans-3-5 has been investigated using the Delta(11) desaturase of Spodoptera littoralis as model enzyme. Gas chromatography coupled to mass spectrometry analyses of methanolyzed lipidic extracts from tissues incubated with each probe revealed that all the cyclopropyl fatty acids were transformed into the corresponding 11-cyclopropylidene acids, except for compound trans-5 (5b), which was not desaturated at C11. The formation of methylenecyclopropane 9 as the only reaction product from 1 indicates that a potential radical intermediate is too short-lived to allow rearrangement reactions. Information on the Delta(11) desaturase substrate binding domain is provided considering the cyclopropyl probes 3-5 as conformationally restricted analogues of the straight-chain substrates. 相似文献
4.
A study of the trapping of highly pyramidalized tricyclo[3.3.0.03,7]oct-1(5)-ene derivatives (generated from a 1,2-diiodo precursor on reaction with t-BuLi, 0.45% sodium amalgam and molten sodium) with different dienes (11,12-dimethylene-9,10-dihydro-9,10-ethanoanthracene, 1,3-diphenylisobenzofuran, 2,5-dimethylfuran and furan) is presented. Byproducts from the trapping of pentacyclo[6.4.0.02,10.03,7.04,9]dodeca-5,8,11-triene with 1,3-diphenylisobenzofuran have been synthesized and fully characterized, including an X-ray diffraction analysis. Also, the above triene has been cross coupled with 3,7-dimethyltricyclo[3.3.0.03,7]oct-1(5)ene to give a tetrasecododecahedratetraene derivative. 相似文献
5.
6.
The NMR spectra of anemonin, tetrahydroanemonin and cis-bicyclo[3.3.0]octane-3,7-dione, rigid compounds with two identical functional groups, in the presence of Eu(FOD)3 are studied. The additivity of the lanthanide induced chemical shifts due to “coordination” of europium atoms at both functions is shown, while the trans configuration of the lactone rings of anemonin and the cis ring fusion in bicyclo[3.3.0]octane-3,7-dione is confirmed. 相似文献
7.
Pelayo Camps 《Tetrahedron》2004,60(25):5423-5431
Two diastereomeric pairs of rationally designed huprines additionally substituted at position 13 with a formamido or an acetamido group have been synthesized as potential high affinity acetylcholinesterase inhibitors. The synthetic sequence involves hydrolysis of two diastereomeric 13-methanesulfonamido-huprines, followed by acylation of the resulting diastereomeric amines. In the hydrolysis reaction, carried out with PPA under harsh conditions, significant amounts of cyclized or rearranged by-products were also formed, depending on the stereochemistry of the starting compound. 相似文献
8.
Preparation of potential insect antijuvenile hormone agents 2,2-dimethyl-7-(2,2,2-trifluoroethoxy)-2H-chromene (), 6-methoxy-2,2-dimethyl-7-(2,2,2-trifluoroethoxy)-2-chromene () and 7-methoxy-2,2-dimethyl-6--(2,2,2-trifluoroethoxy)-2-chromene () and the corresponding 3,4-epoxides and is reported. 相似文献
9.
F. Camps O. Colomina A. Conchillo A. Messeguer 《Journal of heterocyclic chemistry》1985,22(5):1421-1423
Treatment of 2,2-dimethyl-2H-1-benzopyrans 5 with a m-chloroperoxybenzoic acid-trifluoroacetic acid mixture and subsequent short path bulb to bulb vacuum distillation of the crude 3,4-hydroxyesters 6 formed afforded title compounds in good yields. Suppression of trifluoroacetic acid was required when using 2,2-di-methyl-2H-1-benzopyrans with electron donating substituents such as precocenes, as starting compounds. 相似文献
10.
Zghal Imen Farjas Jordi Camps Jaume Sánchez-Rodríguez D. Dammak Mohamed Roura-Grabulosa Pere 《Journal of Thermal Analysis and Calorimetry》2020,140(5):2087-2096
Journal of Thermal Analysis and Calorimetry - Thermal energy storage (TES) has been identified as a breakthrough concept in development of renewable technologies. However, the main challenges are... 相似文献