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911.
Marwa Elsbaey Bai Jie Chiaki Tanaka Hikaru Kato Sachiko Tsukamoto Kazuteru Usui Go Hirai Tomofumi Miyamoto 《Tetrahedron letters》2019,60(33):150948
Two novel epimers, named nuciferols A (1) and B (2), possessing a unique 6.9′, 9.6′, 7′.8″-cyclosesquineolignan skeleton, were isolated from the ethyl acetate fraction of the endocarp of Cocos nucifera. Their planar structure was elucidated by 1D-, 2D-NMR, HRESIMS and their absolute configuration was determined by ECD. Nuciferols A and B showed radical scavenging activity using DPPH assay, and only nuciferol B showed neuroprotective effects against t-BHP induced cell death in N2a cells. 相似文献
912.
Naonari Sakamoto Yutaro Hirai Tsunenobu Onodera Takuma Dezawa Yutaka Shibata Hitoshi Kasai Hidetoshi Oikawa Hiroshi Yabu 《Particle & Particle Systems Characterization》2019,36(1)
Janus particles, particles that have two distinct aspects on their surface or interiors, have attracted much attention due to their potential for application. For the application of Janus particles to high‐resolution displays, and as light sources for optical circuits and fluorescent probes, the Janus particles should be nanosize to ensure high‐resolution display and analysis, responsive to external stimuli, and highly fluorescent. However, it is still a challenging issue to develop such highly fluorescent nanoscale Janus particles and control their alignment. Magnetoresponsive Janus particles, of which the orientation can be controlled by an external magnetic field, are prepared by the simple introduction of polymer‐coated magnetic nanoparticles (NPs) into the hemispheres of Janus particles. If these magnetoresponsive Janus particles can be combined with a strong fluorescence system, then they could be ideal candidates as components of the previously mentioned applications. In the present study, Janus particles are prepared with a fluorescent dye and gold nanoparticles (Au NPs) on one side. The optical properties of the resulting particles are assessed and discussed. Furthermore, the response of composite Janus particles containing dyes, Au NPs, and iron oxide NPs to an external magnetic field is discussed. 相似文献
913.
Cr-Si binary oxide prepared by a sol-gel method, when activated by visible light, catalyses highly selective oxidation of cyclohexane to cyclohexanone with molecular oxygen. 相似文献
914.
Hiroshi Hirai 《Annals of Combinatorics》2006,10(1):111-128
A characterization is given to the distance between subtrees of a tree defined as the shortest path length between subtrees.
This is a generalization of the four-point condition for tree metrics. For this, we use the theory of the tight span and obtain
an extension of the famous result by Dress that a metric is a tree metric if and only if its tight span is a tree.
Received July 13, 2004 相似文献
915.
T. Nagatomo K. Matsuta Y. Nakashima T. Sumikama M. Ogura K. Akutsu T. Iwakoshi H. Fujiwara T. Minamisono M. Fukuda M. Mihara T. Miyake K. Minamisono S. Momota Y. Nojiri A. Kitagawa M. Sasaki M. Torikoshi M. Kanazawa M. Suda M. Hirai S. Sato S. Y. Zhu J. Z. Zhu Y. J. Xu Y. N. Zheng J. R. Alonso G. F. Krebs T. M. Symons 《Hyperfine Interactions》2004,159(1-4):273-276
The momentum dependences of the nuclear spin polarization P and alignment A of 13B(, T
1/2 = 17.36 ms) produced in the 100A MeV 15N + Be collisions have been measured by detecting β-ray asymmetry. Because both the P and A were significantly smaller than the prediction from a simple kinematical model, some relaxation mechanisms must be take into
account. Comparing the signs of the observed alignment of 12B, the sign of the quadrupole coupling constant eqQ of 13B in TiO2 was determined to be positive. 相似文献
916.
A simple device consisting of two ion-exchange columns, two alumina-based filters, and a pump (Figure 1) was assembled to form the C8-C14 polycyclic ring system present in the halichondrin B class of marine natural products. The effectiveness of this device was tested for three substrates. In each case, the desired polycyclic ketal 3, 5, or 7 was obtained almost quantitatively in a single operation. 相似文献
917.
X.?P.?Zhu Tomiyuki?Yukawa Takehiro?Kishi Makoto?Hirai Hisayuki?Suematsu Weihua?Jiang Kiyoshi?YatsuiEmail author 《Journal of nanoparticle research》2005,7(6):669-673
Synthesis of photoluminescent Si nanoparticles has been successfully prepared using an intense pulsed ion-beam evaporation
(IBE) technique in vacuum. Si nanoparticles are produced by the IBE method without any post-annealings. Photoluminescence
(PL) mainly in blue range with a peak of 455 nm and a shoulder near 510 nm is observed in as-deposited Si nanoparticles at
room temperature. The blue light emission is relatively stable with no noticeable change, as the samples have already stored
in air more than 4 months. The observed PL does not fit the quantum confinement model, since a majority of particle size is
around ~20 nm, estimated by SEM and XRD measurements. Moreover, hydrofluoric acid (HF) corrosion tests on the Si nanoparticles
also indicate a correlation between the presence of the surface oxide layers and the PL. Oxide-related luminescence is likely
the source of this blue light emission. 相似文献
918.
Kosuke Ono 《Journal of Mathematical Analysis and Applications》2003,286(2):540-562
Consider the initial boundary value problem for the linear dissipative wave equation (□+∂t)u=0 in an exterior domain . Using the so-called cut-off method together with local energy decay and L2 decays in the whole space, we study decay estimates of the solutions. In particular, when N?3, we derive Lp decays with p?1 of the solutions. Next, as an application of the decay estimates for the linear equation, we consider the global solvability problem for the semilinear dissipative wave equations (□+∂t)u=f(u) with f(u)=|u|α+1,|u|αu in an exterior domain. 相似文献
919.
[reaction: see text] Photoirradiation of benzene solutions containing 1-diarylvinylidene-2,2,3,3-tetramethylcyclopropanes (2a--d) afforded rearranged products 1,2,3-butatrienes (3a-d) in good to high yields. Photorearrangement from 2,2,3-trimethyl and 2,2- and 2,3-dimethyl derivatives 2e--g also proceeded, but the rates of the rearrangement were lower than those of 2a--d. A singlet mechanism is proposed for this photorearrangement, where alkyl migration occurs from 1,3-biradical intermediates generated via the homolysis of the C1-C2 bond. Generation of diarylvinylidene carbenes from 1,3-biradicals might be competitive with the formation of 3. 相似文献