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151.
152.
Roland Jakob‐Roetne Helmut Jacobsen 《Angewandte Chemie (International ed. in English)》2009,48(17):3030-3059
Mind how you go : The current strategies for the development of therapies for Alzheimer's disease are very diverse. Particular attention is given to the search for inhibitors (see picture for two examples) of the proteolytic enzyme β‐ and γ‐secretase, which inhibits the cleavage of the amyloid precursor proteins into amyloid β peptides, from which the disease‐defining deposits of plaque in the brains of Alzheimer's patients originates.
153.
154.
Pratibha Srivastava Inder Pal Singh Kapoor Gurdip Singh Roland Fröhlich 《Journal of Thermal Analysis and Calorimetry》2010,100(1):233-238
Phenylenediammonium dibromide (PDADBr) salts have been prepared and characterized by X-ray crystallography. The thermal decomposition of PDADBr has been studied by thermogravimetry (TG) and differential thermal analysis (DTA). Kinetic parameters have been evaluated using model fitting and isoconversional methods. The thermolytic pathways have also been suggested which involve proton transfer as a primary step to regenerate parent amine and HBr. Interaction between amine and HBr at higher temperature yields gaseous products. 相似文献
155.
Bauer RE Enkelmann V Wiesler UM Berresheim AJ Müllen K 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(17):3858-3864
A series of first-generation polyphenylene dendrimers based on three different cores were prepared by Diels-Alder cycloaddition and their single-crystal structures were determined. Consisting exclusively of interlocked, twisted phenyl rings, these polyphenylene nanostructures have exciting structural and dynamic properties. Single crystals of dendrimers, suitable for X-ray structure analysis, were grown from different solvent mixtures by slow evaporation at room temperature. It should be pointed out that one of the described polyphenylene dendrimers represents up to now the biggest oligophenylene nanostructure from which crystallographic data is available. 相似文献
156.
Roland S. Gohlke Fred W. McLafferty 《Journal of the American Society for Mass Spectrometry》1993,4(5):367-371
Spectroscopy Laboratory, The Dow Chemical Company, Midland, Michigan, USA In December 1955 or thereabouts, the authors coupled a homemade gas chromatograph to a research time-of-flight mass spectrometer constructed by W. C. Wiley, I. H. McLaren, and D. B. Harrington. This unique gas chromatography/mass spectrometry (GC/MS) instrument generated mass spectra at a lo-kHz rate for display on an oscilloscope; eluted gas chromate graphic components, such as methanol, acetone, benzene, toluene, and carbon tetrachloride, could be visually identified immediately from the oscilloscope display. Many years of further research and development in many laboratories worldwide were necessary, however, to make continuous on-line GC/MS the uniquely valuable analytical tool that it is today. 相似文献
157.
Roland A. Obermüller Christoph Etzlstorfer Heinz Falk 《Monatshefte für Chemie / Chemical Monthly》2002,133(1):89-96
Summary. A hypericin derivative was synthesized in which instead of the methyl groups two benzene rings were condensed to the chromophoric
system in order to extend its conjugation. This derivative showed lowered fluorescence and concomitantly enhanced sensitized
production of active oxygen species as compared to hypericin. However, in contrast to intuition its long wavelength band remained
unshifted in comparison to its parent compound hypericin. Geometry and absorption properties were also investigated by means
of semiempirical calculations.
Received July 27, 2001. Accepted August 9, 2001 相似文献
158.
Roland BK Selby HD Carducci MD Zheng Z 《Journal of the American Chemical Society》2002,124(13):3222-3223
Ligand substitution of [Re(6)(mu(3)-Se)(8)(PEt(3))(5)(CH(3)CN)](SbF(6))(2) (1) with pyridyl-based ligands, 2,4,6-tri-4-pyridyl-1,3,5-triazine (L1) and 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (L2), produced respectively the star-shaped tricluster (T1) and tetracluster (T2) arrays, wherein three (T1) and four (T2) units of the [Re(6)(mu(3)-Se)(8)](2+) core-containing clusters are interconnected by the corresponding bridging ligands. These novel supramolecular assemblies were characterized by a combination of NMR ((1)H and (31)P) spectroscopy, ESI-MS, and microanalysis. The molecular and solid-state structures of T1 have also been established by single-crystal X-ray diffraction. 相似文献
159.
Anthony J. Arduengo III Fredric Davidson Roland Krafczyk William J. Marshall Reinhard Schmutzler 《Monatshefte für Chemie / Chemical Monthly》2000,131(3):251-265
Summary. Synthesis, characterization, and solid state X-ray crystallographic structures for 12-Pn-6 complexes derived from carbene 4,5-dichloro-1,3-dimesitylimidazol-2-ylidene and phosphorus, arsenic, or antimony pentafluoride
are reported. The adducts show octahedral geometries at the pnictogen centers with C-Pn bond distances of 189.8 (P), 199.9 (As), and 217.5 (Sb) pm. The structures are those of internal zwitterions with imidazolium
ion character in the heterocyclic ring and a pentafluoropnictanide anion bonded to C2. Adducts of BF3 with 1,3-dimesitylimidazol-2-ylidene and 4,5-dichloro-1,3-dimesitylimidazol-2-ylidene are also reported for comparison. Although
the reactivity of chlorinated and non-chlorinated carbenes varies considerably, the spectroscopic and structural properties
of analogous adducts are remarkably similar.
Received September 6, 1999. Accepted (revised) October 20, 1999 相似文献
160.