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排序方式: 共有433条查询结果,搜索用时 9 毫秒
41.
Hisayasu Ishibashi Dr. Manuel Rondelli Hiroki Shudo Prof. Dr. Takehisa Maekawa Prof. Dr. Hideto Ito Prof. Dr. Kiichi Mizukami Prof. Dr. Nobuo Kimizuka Prof. Dr. Akiko Yagi Prof. Dr. Kenichiro Itami 《Angewandte Chemie (International ed. in English)》2023,62(44):e202310613
The active metal template (AMT) strategy is a powerful tool for the formation of mechanically interlocked molecules (MIMs) such as rotaxanes and catenanes, allowing the synthesis of a variety of MIMs, including π-conjugated and multicomponent macrocycles. Cycloparaphenylene (CPP) is an emerging molecule characterized by its cyclic π-conjugated structure and unique properties. Therefore, diverse modifications of CPPs are necessary for its wide application. However, most CPP modifications require early stage functionalization and the direct modification of CPPs is very limited. Herein, we report the synthesis of a catenane consisting of [9]CPP and a 2,2′-bipyridine macrocycle as a new CPP analogue that contains a reliable synthetic scaffold enabling diverse and concise post-modification. Following the AMT strategy, the [9]CPP-bipyridine catenane was successfully synthesized through Ni-mediated aryl-aryl coupling. Catalytic C−H borylation/cross-coupling and metal complexation of the bipyridine macrocycle moiety, an effective post-functionalization method, were also demonstrated with the [9]CPP-bipyridine catenane. Single-crystal X-ray structural analysis revealed that the [9]CPP-bipyridine catenane forms a tridentated complex with an Ag ion inside the CPP ring. This interaction significantly enhances the phosphorescence lifetime through improved intermolecular interactions. 相似文献
42.
Iridium-chiral diphosphine complex catalyzes an enantioselective intramolecular Pauson-Khand-type reaction to give various chiral bicyclic cyclopentenones. The enantioselective reaction proceeds more smoothly and enantioselectively under a lower partial pressure of carbon monoxide. Moreover, aldehyde can be used as a CO source in the enantioselective carbonylative coupling. 相似文献
43.
Liu SQ Kuroda-Sowa T Konaka H Suenaga Y Maekawa M Mizutani T Ning GL Munakata M 《Inorganic chemistry》2005,44(4):1031-1036
Three luminescent silver(I)-oligo(phenylenevinylene) complexes, [Ag2(bmsb)(ClO4)2] (1), [Ag2(bmsb)(H2O)4](BF4)2 (2), and [Ag2(bdb)(CF3SO3)2] (3) (bmsb = 1, 4-bis(methylstyryl)benzene, bdb = 4,4'-bis(2, 5-dimethylstryryl)biphenyl), have been synthesized and structurally characterized. Complexes 1 and 2 are 2D networks with unique metallocyclophane motifs. Complex 3 affords a 2D zigzag sheet, in which silver triflates form tubelike double chains and bdb molecules act as linkages. Complex 2 exhibits high electric conductivity because of columnar aromatic stackings formed through intra- and intermolecular pi-pi interactions. Complexes 1-3 in the solid state exhibit luminescence, of which excitation and emission maxima are shifted to longer wavelength as compared to those of the corresponding metal-free ligands. 相似文献
44.
Images are very useful to obtain diagnostic informations in medical fields. Also by superimposing two or three images obtained from the same patient, various informations, for example a degree of overlapping and anatomical land mark, which can not be found in only one image, can be often found. In this paper characteristics of our trial color television system for the purpose of superimposing X-ray images and/or radionuclide images are described. This color television system, superimposing two images in each different color consists of two monochromatic vidicon cameras and 20 inches conventional color television in which only two simple video amplifier circuits are added. Signals from vidicon cameras are amplified about 40 dB and are directly applied to cathode terminals of color CRT in the television. This system is very simple and economical color displays, and enhance a degree of overlapping and displacement between images. As one of typical clinical applications, pancreas images were superimposed in color by this method. As a result, size and position of pancreas was enhanced. Also X-ray image and radionuclide image were superimposed to find exactly the position of tumors. Furthermore this system was very useful for color display of multinuclides scintigraphy. 相似文献
45.
Yasunori Maekawa 《Journal of Mathematical Fluid Mechanics》2011,13(4):515-532
We study a linearized operator of the equation for the axisymmetric Burgers vortex which gives a stationary solution to the
three dimensional Navier–Stokes equations with an axisymmetric background straining flow. It is numerically known that the
Burgers vortex obtains better stabilities as the circulation number (or the vortex Reynolds number) is increasing. Although
the global stability of the axisymmetric Burgers vortex is already proved rigorously, mathematical understanding of this numerical
observation has been lacking. In this paper we study a linearized operator that includes the circulation number as a parameter,
and prove that if the operator is restricted on a suitable invariant subspace, then its spectrum moves to the left as the
circulation number goes to infinity. As an application, we show that the axisymmetric Burgers vortex with a high rotation
has a better stability, in the sense that the non-radially symmetric part of solutions to the associated evolution equation
decays faster in time if the circulation number is sufficiently large. 相似文献
46.
I. Ogawa T. Idehara S. Maekawa W. Kasparek G. F. Brand 《International Journal of Infrared and Millimeter Waves》1999,20(5):801-821
A compact system to convert gyrotron output into an intense gaussian beam has been designed by introducing an intermediate focusing element into the quasi-optical system. The design is significantly simplified by applying gaussian optics and confirmed by application of the Huygens equation. The beam quality is improved by truncating the sidelobes of the far-field. In spite of the beam truncation, only a small fraction (11 %) of the beam power is sacrificed. 相似文献
47.
Masako Maekawa Haruko Nagai Kayoko Magara 《Colloids and surfaces. A, Physicochemical and engineering aspects》2000,170(2-3):191-198
Mixture diffusion of two dyes (C.I. Direct Blue 15 (DB15) and C.I. Direct Yellow 12 (DY12)) with different affinity onto the substrate into cellulose membrane from the binary solution was studied at 55°C. Uptake curves and concentration–distance profiles were measured experimentally in the ratios (DB15:DY12) 1:0.5, 1:1 and 1:2. It was examined whether the diffusion of the dyes could be analyzed based on the parallel diffusion theory of surface and pore diffusion. It was revealed that the diffusion of DB15 with higher affinity could be analyzed based on the model in the ratios 1:0.5 and 1:1, although the theoretical value deviated slightly from the data in the concentration–distance profile in the ratio 1:1. On the other hand, the diffusion of DY12 with smaller affinity could not be described by the model, because the diffusivity of the dye changed during the adsorption process against the assumption of the model. 相似文献
48.
49.
50.
Satoshi Hashimoto Yukihiko Fujiwara Yasuko Kitahara Yasuo Tsuchiya Toshiyasu Nishimura 《X射线光谱测定》2001,30(2):116-122
A novel technique for determining the chemical states of elements with a heterogeneous distribution in samples involving EPMA line analysis is proposed. LLS (linear least squares) calculation was applied to a set of reduced spectra measured in the line analysis. The reduced spectra which have several energy points (including two points for backgrounds) were measured in order to save measuring time. The LLS calculation gives the mole fraction of each chemical state. We applied this method to the analysis of corrosion products formed on Cr-containing steel after corrosion tests. EPMA mapping revealed that Cr is enriched only in the inner layer of the corrosion products. From the results of the LLS calculation, it was determined that Cr in the corrosion products exists in the trivalent Cr state whereas in the steel Cr is in the metallic state. This result corresponds to the spectra of characteristic x-rays from the corroded steel. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献