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991.
Hiryu S Hagino T Fujioka E Riquimaroux H Watanabe Y 《The Journal of the Acoustical Society of America》2008,124(2):EL51-EL56
Echolocation pulses emitted by wild Pipistrellus abramus were investigated while foraging for insects in the field. Similar to other European pipistrelles, the frequency structure during foraging varied. During the search phase, the bats emitted long shallow frequency-modulated pulses 9-11 ms in duration, whereas the maximum pulse duration of the bats approaching a large target wall in the laboratory was 3 ms. No significant difference was observed between decreases in the interpulse interval during these two approach flights. It is concluded that the bats use a long quasi-constant frequency pulse to find a weak echo from a small prey target. 相似文献
992.
Mamoru Furuta Takahiro Hiramatsu Tokiyoshi Matsuda Chaoyang Li Hiroshi Furuta Takashi Hirao 《Journal of Non》2008,354(17):1926-1931
Zinc oxide (ZnO) film was deposited on a glass substrate by rf magnetron sputtering with O2/Ar as working gases. Structural properties of the films were characterized by XRD. Average crystallite size in the films was strongly dependent on both the gas flow ratio of O2/Ar and rf-power at a constant deposition pressure. During the deposition, energetic species in the plasma were in situ monitored using optical emission spectroscopy. An inverse correlation was observed between the average crystallite size and the emission intensity ratio of IO∗/IAr. Bombardment of atomic oxygen to the growing surface played an important role in determining the average crystallite size in the films. The average crystallite size could be controlled by the emission intensity ratio of IO∗/IAr. 相似文献
993.
994.
Dr. Hajime Kameo Tatsuya Kawamoto Prof. Shigeyoshi Sakaki Prof. Didier Bourissou Prof. Hiroshi Nakazawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(7):2370-2375
Si?F bond cleavage of fluoro‐silanes was achieved by transition‐metal complexes under mild and neutral conditions. The Iridium‐hydride complex [Ir(H)(CO)(PPh3)3] was found to readily break the Si?F bond of the diphosphine‐ difluorosilane {(o‐Ph2P)C6H4}2Si(F)2 to afford a silyl complex [{[o‐(iPh2P)C6H4]2(F)Si}Ir(CO)(PPh3)] and HF. Density functional theory calculations disclose a reaction mechanism in which a hypervalent silicon species with a dative Ir→Si interaction plays a crucial role. The Ir→Si interaction changes the character of the H on the Ir from hydridic to protic, and makes the F on Si more anionic, leading to the formation of Hδ+???Fδ? interaction. Then the Si?F and Ir?H bonds are readily broken to afford the silyl complex and HF through σ‐bond metathesis. Furthermore, the analogous rhodium complex [Rh(H)(CO)(PPh3)3] was found to promote the cleavage of the Si?F bond of the triphosphine‐monofluorosilane {(o‐Ph2P)C6H4}3Si(F) even at ambient temperature. 相似文献
995.
996.
A biphenyl-based amino sulfonamide was designed to improve the intrinsic low catalytic activity of amine organocatalysts. The newly synthesized amino sulfonamide catalyst promoted the Mannich reaction in a highly enantioselective fashion and a remarkable catalyst turnover number was achieved. 相似文献
997.
The effects of drying temperature on the structural evolution of alkoxy-derived silica gel prepared using various catalysts have been investigated. The dependence of specific surface area, Sg, reflecting the structure, on the temperature of drying was remarkable for a non-catalyzed xerogel. The effect of drying temperature on the Sg of an ammonia-catalyzed xerogel was also found but was not very large. The Sg of xerogels obtained by drying at 60°C was always higher by 50% than the gels dried at 30°C without regard to the aging temperature. The Sg of xerogels from HCl-catalyzed solution was of the order of several m2/g, however, the Sg of the aerogel obtained by hypercritical drying of the wet gel from a similar solution was about 800 m2/g. These phenomena were understood on the basis of SAXS measurements on both wet gels and aerogels. 相似文献
998.
Ikuma Shiota Arihiro Iwasaki Shimpei Sumimoto Hiroshi Tomoda Kiyotake Suenaga 《Tetrahedron letters》2018,59(13):1261-1263
A new polyketide with a cis-fused decalin ring scaffold, caldorin, was isolated from the marine cyanobacterium Caldora penicillata. The gross structure and relative configuration were elucidated by spectroscopic analyses. We also clarified that caldorin is a weak SOAT inhibitor and moderate osteoblast differentiation inhibitor. On the other hand, caldorin did not exhibit cytotoxicity against either HeLa or HL60 cells. 相似文献
999.
Kazuma Shimoda Takahiro Mitsuoka Kenta Ueda Hiroshi Suemune Go Hirai Mariko Aso 《Tetrahedron letters》2018,59(51):4528-4531
A dendritic bisphosphonate carrying three bisphosphonate (BP) units in close proximity was designed as a ligand to conjugate large therapeutic molecules for their bone selective delivery. The Bu3P-catalyzed conjugate addition of nitromethane to vinylidene bisphosphonate was effective to construct a quaternary carbon center carrying BP units. Owing to multivalent interactions, the dendritic bisphosphonate showed considerable affinity for the bone mineral hydroxyapatite even in the presence of a competitor, demonstrating potential as a bone targeting ligand. 相似文献
1000.
The Electronic State of Hydrogen in the α Phase of the Hydrogen‐Storage Material PdH(D)x: Does a Chemical Bond Between Palladium and Hydrogen Exist? 下载免费PDF全文
Shun Dekura Prof. Hirokazu Kobayashi Prof. Ryuichi Ikeda Prof. Mitsuhiko Maesato Haruka Yoshino Prof. Masaaki Ohba Prof. Takayoshi Ishimoto Dr. Shogo Kawaguchi Prof. Yoshiki Kubota Dr. Satoru Yoshioka Prof. Syo Matsumura Prof. Takeharu Sugiyama Prof. Hiroshi Kitagawa 《Angewandte Chemie (International ed. in English)》2018,57(31):9823-9827
The palladium–hydrogen system is one of the most famous hydrogen‐storage systems. Although there has been much research on β‐phase PdH(D)x, we comprehensively investigated the nature of the interaction between Pd and H(D) in α‐phase PdH(D)x (x<0.03 at 303 K), and revealed the existence of Pd?H(D) chemical bond for the first time, by various in situ experimental techniques and first‐principles theoretical calculations. The lattice expansion, magnetic susceptibility, and electrical resistivity all provide evidence. In situ solid‐state 1H and 2H NMR spectroscopy and first‐principles theoretical calculations revealed that a Pd?H(D) chemical bond exists in the α phase, but the bonding character of the Pd?H(D) bond in the α phase is quite different from that in the β phase; the nature of the Pd?H(D) bond in the α phase is a localized covalent bond whereas that in the β phase is a metallic bond. 相似文献