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991.
Fukuhara K Nakanishi I Kansui H Sugiyama E Kimura M Shimada T Urano S Yamaguchi K Miyata N 《Journal of the American Chemical Society》2002,124(21):5952-5953
A catechin analogue in which the geometry was constrained to be planar was synthesized. The planar catechin showed excellent radical-scavenging ability, comparable to that of quercetin, and efficient protection against DNA strand breakage induced by the Fenton reaction. 相似文献
992.
Solvable vertex models in statistical mechanics give rise to soliton cellular automata at q=0 in a ferromagnetic regime. By means of the crystal base theory we study a class of such automata associated with non-exceptional quantum affine algebras U′ $_q$ ( $\widehat {\mathfrak{g}}$ $_n$ ). Let B $_l$ be the crystal of the U′ $_q$ ( $\widehat {\mathfrak{g}}$ $_n$ )-module corresponding to the l-fold symmetric fusion of the vector representation. For any crystal of the form B = $B_{l_1 }$ ? ...? $B_{l_N }$ , we prove that the combinatorial R matrix B $_M$ ?B $\widetilde \to$ B?B $_M$ is factorized into a product of Weyl group operators in a certain domain if M is sufficiently large. It implies the factorization of certain transfer matrix at q=0, hence the time evolution in the associated cellular automata. The result generalizes the ball-moving algorithm in the box-ball systems. 相似文献
993.
Real-time measurement of low-energy-range neutron spectra on board the space shuttle STS-89 (S/MM-8)
Matsumoto H Goka T Koga K Iwai S Uehara T Sato O Takagi S 《Radiation measurements》2001,33(3):321-333
We have developed a real-time, Bonner Ball-type (neutron energy range is from thermal to 15 MeV) neutron spectral measurement system (Bonner Ball Neutron Detector (BBND)) for use on board the International Space Station (ISS). From measurements taken inside STS-89 (S/MM-8), we successfully distinguished neutrons from protons and other particles in a mixed radiation field; a task hitherto considered difficult. Although the experimental period was short, only 3.5 days (January 24-27, 1998), we were able to obtain energy spectral data and the Earth's neutron dose-equivalent map for the ISS orbital conditions (altitude 400 km, orbit inclination angle 51.6 degrees). A method for calculating the neutron energy spectrum and compensating for the particle interaction with the sensors is also described in detail. 相似文献
994.
S. J. Blundell I. M. Marshall B. W. Lovett F.L. Pratt W. Hayes M. Kurmoo S. Takagi T. Sugano 《Hyperfine Interactions》2001,133(1-4):169-177
Positive muons can be implanted into organic and molecular magnets in order to study their internal magnetic field distribution and any associated dynamics. The muon behaves essentially as a microscopic magnetometer, sensitive to local magnetic order and magnetic fluctuations. We describe some recent experiments using this technique which were performed on a variety of organic systems, including nitronyl nitroxide magnets and materials with spin-Peierls ground states, MEM(TCNQ)2 and DEM(TCNQ)2, and demonstrate how the technique can give information concerning their ground states. 相似文献
995.
Hitotsuyanagi Y Hasuda T Aihara T Ishikawa H Yamaguchi K Itokawa H Takeya K 《The Journal of organic chemistry》2004,69(5):1481-1486
Three analogues of RA-VII (1), an antitumor bicyclic hexapeptide from Rubia plants, were synthesized. Three analogues, [Gly-1]RA-VII (4), [Gly-2]RA-VII (5), and [Gly-4]RA-VII (6), in which one of the three alanine residues in 1 was replaced by a glycine residue, were prepared by linking of the cycloisodityrosine unit, obtained by degradation of 1, to three different glycine-containing tetrapeptides followed by macrocyclization. Of these three analogues, analogue 4 showed the highest cytotoxic activity. The NMR study revealed that in solution the conformer structures and their ratios of analogue 4 were very similar to those of natural peptide 1, suggesting that the methyl groups at Ala-2 and Ala-4 should be essential for producing the bioactive conformation, whereas that at D-Ala-1 is not essential. 相似文献
996.
997.
Reaction of gamma-silyl-beta,gamma-epoxybutanenitrile with a base generates an alpha-nitrile carbanion derivative of 4-siloxybut-3-enenitrile, which undergoes reaction with bis-electrophiles such as 1,omega-dihaloalkanes, omega-bromo-alpha,beta-unsaturated esters, and bisenoates to provide highly functionalized carbocycles. 相似文献
998.
999.
DNA duplex regions of the spots on a DNA microarray were successfully visualized by scanning electrochemical microscopy (SECM) in the electrolyte containing ferrocenyl naphthalene diimide as a hybridization indicator. 相似文献
1000.
Fujita N Biradha K Fujita M Sakamoto S Yamaguchi K 《Angewandte Chemie (International ed. in English)》2001,40(9):1718-1721