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101.
102.
An aroma chemical emitted from Gerris paludum insularis was analyzed by means of GC and GC-MS. The main constituent was identified as iso amyl alcohol (3-methyl-1-butanol). The chemical showed a characteristic aroma of Gerris paludum insularis. 相似文献
103.
Shirokawa S Kamiyama M Nakamura T Okada M Nakazaki A Hosokawa S Kobayashi S 《Journal of the American Chemical Society》2004,126(42):13604-13605
A highly regio- and diastereoselective TiCl4-mediated vinylogous Mukaiyama aldol reaction using the chiral vinylketene silyl N,O-acetal has been developed. The present vinylogous Mukaiyama aldol reaction provides a unique and effective means of controlling remote asymmetric induction. The methyl group at the alpha-position is important in achieving a high level of stereoselectivity. From a synthetic point of view, this methodology can provide a one-step construction of delta-hydroxy-alpha,gamma-dimethyl-alpha,beta-unsaturated carbonyl unit that is seen in many natural polyketide products. 相似文献
104.
Abe S Fujishima T Tsubone T Fujimura R Ono H Matoba O Oda K Shimura T Kuroda K 《Optics letters》2003,28(6):420-422
The photorefractive effect in a nominally undoped 0.91Pb(Zn1/3Nb2/3)O3-0.09PbTiO3 single crystal is measured. We report what is, to our knowledge, the first observation of the photorefractive effect in Pb-based relaxor ferroelectric crystals. The crystal is grown by the flux solution method. Then it is cut into a 2 mm x 4 mm x 8 mm piece and electrically poled along the [111] direction. The coupling constant of the two-wave mixing is 17 cm(-1), and the normalized time constant under 1-W/cm(2) illumination is 12 s at a wave-length of 476 nm. The effective trap density is calculated as 5 x 10(16) cm(-3) from the Debye screening length under the assumption of Kukhtarev's band-transport model. The dominant carrier is identified to be holes from the direction of two-wave mixing energy transfer. 相似文献
105.
A novel addition reaction of an aromatic hydrazine to the diketone derivative of C60 occurs highly regioselectively with an unusual migration of two hydrogen atoms from the hydrazine to the fullerene and affords a fluorescent product having a methylene carbon along the orifice. 相似文献
106.
Acid-catalyzed oligomerization of 2-(hydroxymethyl)pyrroles bearing C6F5, 2,6-Cl2C6H3, CF3 and CO2Et groups at beta-positions was examined. The reaction of ethyl pyrrole-3-carboxylates gave a mixture of oligomers and type I isomers of porphyrinogens and hexaphyrinogens were isolated when the other beta-substituents were sufficiently bulky, for example, mesityl, 2,6-Cl2C6H3 and C6F5 groups. On the other hand, the pyrroles having other electron-withdrawing groups afforded porphyrinogens as the only isolable products. 相似文献
107.
Russulanorol (1), a new norsesquiterpenoid with a novel carbon skeleton, was isolated from the fruiting bodies of Russula delica FR. (Russulaceae) together with three known sesquiterpenoids. The structure of 1 was elucidated on the basis of spectral data and chemical transformation. Compound 1 is an equilibrium mixture of two stereoisomers (1a, b) on the C-11 acetal carbon. 相似文献
108.
Let p(n) denote the ordinary partition function. Subbarao conjecturedthat in every arithmetic progression r (mod t) there are infinitelymany integers N = r (mod t) for which p(N) is even, and infinitelymany integers M = r (mod t) for which p(M) is odd. We provethe conjecture for every arithmetic progression whose modulusis a power of 2. 2000 Mathematics Subject Classification 11P83. 相似文献
109.
Although it is thought that perfluoro-2,4-dimethyl-3-isopropyl-3-pentyl (PFR-2) is a candidate for electron paramagnetic resonance
(EPR) imaging agents because of its high stability, no study has been made yet on the EPR imaging of PFR-2. In this study,
EPR imaging of a phantom including PFR-2 and mice that had received PFR-2 was performed by an in vivo EPR imaging system operating
at an EPR frequency of 700 MHz equipped with a bridged loop-gap resonator (inner diameter, 41 mm; axial length, 10 mm). Because
PFR-2 is insoluble in water, it was dissolved in perfluorocarbon. The PFR-2 solution was put in cylindrical sample tubes with
various inner diameters, and these sample tubes were placed together in a larger cylindrical sample tube filled with a physiological
saline solution, which was used as a phantom. The spatial resolution was estimated to be about 3 mm on the basis of EPR imaging
of the phantom. EPR images of mice that had received a PFR-2 injection via the intraperitoneal route indicated that PFR-2
remained in the peritoneal cavity even 2 days after the injection. This finding suggests that it is possible to perform EPR
imaging of experimental animals using PFR-2 as an imaging agent which persists in a biological system.
Authors' address: Hidekatsu Yokoyama, National Institute of Advanced Industrial Science and Technology, 2266-98 Anagahora,
Shimoshidami, Moriyama-ku, Nagoya, Aichi 463-8560, Japan 相似文献
110.
Splittings in the variety of residuated lattices 总被引:2,自引:0,他引:2
It is shown that the only algebra that splits the lattice of subvarieties of the variety of residuated lattices is the two element boolean algebra.
Received October 4, 1999; accepted in final form August 11, 2000. 相似文献