排序方式: 共有25条查询结果,搜索用时 78 毫秒
1.
Ohne Zusammenfassung 相似文献
2.
3.
H. Strache 《Fresenius' Journal of Analytical Chemistry》1924,64(1-4):113-136
Ohne Zusammenfassung 相似文献
4.
In this paper, we report on modifications in structural and optical properties of CdS thin films due to 190 keV Mn-ion implantation at 573 K. Mn-ion implantation induces disorder in the lattice, but does not lead to the formation of any secondary phase, either in the form of metallic clusters or impurity complexes. The optical band gap was found to decrease with increasing ion fluence. This is explained on the basis of band tailing due to the creation of localized energy states generated by structural disorder. Enhancement in the Raman scattering intensity has been attributed to the enhancement in the surface roughness due to increasing ion fluence. Mn-doped samples exhibit a new band in their photoluminescence spectra at 2.22 eV, which originates from the d-d (4T1 → 6A1) transition of tetrahedrally coordinated Mn2+ ions. 相似文献
5.
6.
7.
H. Strache und H. Löffler 《Fresenius' Journal of Analytical Chemistry》1931,83(7-8):294-295
Ohne Zusammenfassung 相似文献
8.
Ohne Zusammenfassung 相似文献
9.
Dr. Friederike Ratsch Joss Pepe Strache Dr. Waldemar Schlundt Dr. Jörg-Martin Neudörfl Andreas Adler Sarwar Aziz Prof. Dr. Bernd Goldfuss Prof. Dr. Hans-Günther Schmalz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(14):4640-4652
The Ir-catalyzed conversion of prochiral tert-cyclobutanols to β-methyl-substituted ketones proceeds under comparably mild conditions in toluene (45–110 °C) and is particularly suited for the enantioselective desymmetrization of β-oxy-substituted substrates to give products with a quaternary chirality center with up to 95 % ee using DTBM-SegPhos as a chiral ligand. Deuteration experiments and kinetic isotope effect measurements revealed major mechanistic differences to related RhI-catalyzed transformations. Supported by DFT calculations we propose the initial formation of an IrIII hydride intermediate, which then undergoes a β-C elimination (C−C bond activation) prior to reductive C−H elimination. The computational model also allows the prediction of the stereochemical outcome. The Ir-catalyzed cyclobutanol cleavage is broadly applicable but fails for substrates bearing strongly coordinating groups. The method is of particular value for the stereo-controlled synthesis of substituted chromanes related to the tocopherols and other natural products. 相似文献
10.
H. Strache und S. Iritzer 《Fresenius' Journal of Analytical Chemistry》1893,32(1):479-481
Ohne Zusammenfassung 相似文献