5,8-Methanoquinazolines fused with imidazoles 4a-4b , thiadiazoles 5–6 , pyrimidines 7, 9, 11 and 12 , and 1,3,5-triazine 13 were prepared starting from (5R,8S)-2-amino-8,9,9-trimethyl-5,6,7,8-tetrahydro-5,8-methanoquinazoline 3 . Most compounds possessed central nervous system stimulant activities. 相似文献
Differential scanning calorimetry on the two-component system of dioctadecyldimethylammonium chloride (DOAC)–water was carried out in the temperature region from 80 °C down to -100 °C. As the result, a new type of glassy state was found around at -40 °C for the supercooled complete gel phase. 相似文献
In this paper, we study large deviation properties for countable to one Markov systems associated to weak Gibbs measures for non-Hölder potentials. Furthermore, we establish multifractal large deviation laws for countable to one piecewise conformal Markov systems, which are derived systems constructed over hyperbolic regions for certain nonhyperbolic systems exhibiting intermittency. We apply our results to higher-dimensional number theoretical transformations. 相似文献
Metal-insulator-metal system was prepared using the single-crystalline Cu-9at.% Al(1 1 1) support. Oxidation of the substrate under well-controlled conditions at elevated temperature leads to the formation of well-ordered aluminium oxide layer. The Pd-Au topmost layer was prepared by a step-by-step deposition of both metals afterwards on the oxide layer at room temperature. Low energy electron diffraction (LEED) measurement did not confirm epitaxial growth of the metal overlayer and gave only a rise of diffuse background after each deposition step. The growth of Pd-Au overlayer exhibited Stranski-Krastanov mode influenced by intermetallic interaction between those metals. No binding energy shifts were visible for the core-level photoelectron peaks of the substrate and the oxide using X-ray photoelectron spectroscopy (XPS). In contrast, the binding energy shifts of Pd 3d and Au 4f photoelectron levels in both directions were observed during all depositions. Bimetallic interactions between the metals as well as size effects are further discussed. 相似文献
The catalytic asymmetric alkylation of α-cyanocarboxylates and acetoacetates with an alkyl halide was performed under phase-transfer conditions to afford compounds which have a chiral quaternary carbon with up to 97% and 94% ee, respectively. As applications of this method, chiral 2-oxindole derivatives and a β-lactam derivative were synthesized. 相似文献
The dimensions of nanocelluloses are important factors in controlling their material properties. The present study reports a fast and robust method for estimating the widths of individual nanocellulose particles based on the turbidities of their water dispersions. Seven types of nanocellulose, including short and rigid cellulose nanocrystals and long and flexible cellulose nanofibers, are prepared via different processes. Their widths are calculated from the respective turbidity plots of their water dispersions, based on the theory of light scattering by thin and long particles. The turbidity‐derived widths of the seven nanocelluloses range from 2 to 10 nm, and show good correlations with the thicknesses of nanocellulose particles spread on flat mica surfaces determined using atomic force microscopy.
(19)F NMR/MRI probe is expected to be a powerful tool for selective sensing of biologically active agents owing to its high sensitivity and no background signals in live bodies. We have recently reported a unique supramolecular strategy for specific protein detection using a protein ligand-tethered self-assembling (19)F probe. This method is based on a recognition-driven disassembly of the nanoprobes, which induced a clear turn-on signal of (19)F NMR/MRI. In the present study, we conducted a systematic investigation of the relationship between structure and properties of the probe to elucidate the mechanism of this turn-on (19)F NMR sensing in detail. Newly synthesized (19)F probes showed three distinct behaviors in response to the target protein: off/on, always-on, and always-off modes. We clearly demonstrated that these differences in protein response could be explained by differences in the stability of the probe aggregates and that "moderate stability" of the aggregates produced an ideal turn-on response in protein detection. We also successfully controlled the aggregate stability by changing the hydrophobicity/hydrophilicity balance of the probes. The detailed understanding of the detection mechanism allowed us to rationally design a turn-on (19)F NMR probe with improved sensitivity, giving a higher image intensity for the target protein in (19)F MRI. 相似文献
A catalytic asymmetric allylation of 3,4-dihydroisoquinoline was carried out with allyltrimethoxylsilane-Cu as the nucleophile in the presence of DTBM-SEGPHOS as the chiral ligand to afford corresponding chiral 1-allyltetrahydroisoquinoline derivatives in good yield and stereoselectivity. The allyl adduct thus obtained was applied to the synthesis of several isoquinoline alkaloids such as crispine A and homolaudanosine. The reaction was further used for the synthesis of the isoquinoline moiety of schulzeine A. 相似文献