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排序方式: 共有439条查询结果,搜索用时 15 毫秒
1.
Whittum D.H. Ebihara K. Hiramatsu S. Kishiro J.-i. Monaka T. Ozaki T. Takayama K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1993,21(1):136-141
Studies of microwave amplification with an in-focused electron beam drawn from an induction injector are reported. A free-electron laser (FEL) operating at 9.4 GHz and employing ion-focusing within the interaction region has achieved power in excess of 30 MW at 9.4 GHz, with a beam energy of 0.8 MeV and current of 0.7 kA. Peak gain is 20 dB/m, with no saturation after 15 wiggler periods. Also reported are the first evolution and detuning data for an ion-channel laser/maser (ICL). Two shortcomings of the prematurely halted ICL studies are poor frequency discrimination and a large axial plasma gradient. Prospects for operation with an upgraded 1.6 MeV accelerator are discussed 相似文献
2.
Hidenori Hanaoka Yuka Imamoto Takahiro Hino Tetsuya Kohno Kazunori Yanagi Yoshiaki Oda 《Journal of polymer science. Part A, Polymer chemistry》2007,45(16):3668-3676
Chromium catalysts combined with phosphorous‐bridged bisphenoxy ligands were found to be highly active for ethylene polymerization. The most efficient catalyst precursor among them, generated by combining bis[3‐tert‐butyl‐5‐methyl‐2‐hydroxyphenyl](phenyl)phosphine hydrochloride ( 1a ) and CrCl3(THF)3, was characterized. X‐ray analysis of (3‐tert‐butyl‐5‐methyl‐2‐phenoxy)(3‐tert‐butyl‐5‐methyl‐ 2‐hydroxyphenyl)(phenyl)phosphine bis(tetrahydrofuran)chromium dichloride ( 6 ), obtained by the reaction of 1a and CrCl3(THF)3 in the presence of NaH, revealed a unique structure in which one phenol moiety of the bisphenol did not coordinate to the chromium center. Complex 6 showed higher activities than those observed in the in situ catalyst system. Polyethylene of various molecular weights was obtained with differing activators. The highest activity (113.5 kg mmol (cat)?1 h?1) was observed when TIBA/TB was used as a cocatalyst. A medium molecular weight polymer with narrow molecular weight distribution (Mw = 128,700, Mw/Mn = 1.8) was obtained using a 6 ‐TIBA/B(C6F5)3 system. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3668–3676, 2007 相似文献
3.
Various N-sulfenyl heterocycles were synthesized by transamination of sulfenamides using a chlorine gas-free method. The N-sulfenyl heterocycles behaved as sulfenylating reagents of anilines; N-sulfenylbenzimidazoles were the most effective. 相似文献
4.
Tatsuro Ouchi Hirotoshi Fujie Satoshi Jokei Yoshiomi Sakamoto Hidenori Chikashita Takeshi Inoi Otto Vogl 《Journal of polymer science. Part A, Polymer chemistry》1986,24(9):2059-2074
Acryloyl-type polymer fixing 1-β-carbonylethyl-5-fluorouracil residues through D -glucofuranoses via ester bonds was synthesized by means of polymerization of the corresponding monomer and polymer reaction. In order to provide the water-soluble objective polymer, the copolymerization of the acryloyl-type monomer with acrylamide was carried out. The extent of release of 5-FU residues from the copolymer was investigated in the enzyme or nonenzyme system in vitro. Furthermore, the antitumor activities of the water-insoluble homopolymer and water-soluble copolymer obtained were tested in vivo. 相似文献
5.
Masahiro Manabe Asako Tokunaga Hideo Kawamura Hajime Katsuura Masaki Shiomi Koichi Hiramatsu 《Colloid and polymer science》2002,280(10):929-935
In the micellar solution of SDS, the partition coefficient (Kx) of following branched alkanols at infinite dilution was determined by applying a differential conductivity method: the alkanols used were i-CmH2m+1OH (m=4-9, i=1-5) in which the position of OH group (i) shifts from an end to the center of a hydrocarbon chain. The method provides two significant quantities, d!/dXam and dCsf/dCaf in addition to Kx. The following results have been obtained. (1) The dependence of Kx on i indicates that the hydrophobicity of alkanol is weakened with increasing i, whereas the increase in m strengthens the hydrophobicity. (2) The degree of counterion disossiation of micelles (!) is accelerated by the solubilized alkanols in micelles (mole fraction: Xam) and the acceleration rate, d!/dXam (=0.17), depends on neither m nor i. (3) In the bulk water, the monomerically dissolved alkanols (concentration: Caf) depresses the concentration of free monomer surfactant (Csf), and the depressing rate, dCsf/dCaf, in micellar solution is identical with the corresponding quantity, ((CMC/(Ca)o at CMC. 相似文献
6.
[reaction: see text] An aqueous biphasic reaction system enables the direct use of allyl alcohol in the Tsuji-Trost reaction without the help of any activating reagents for allyl alcohol. The reaction conditions are neutral to basic, allowing the use of amines as the nucleophile. Theoretical calculations have elucidated the importance of hydration of the hydroxy group for the smooth generation of pi-allylpalladium species. 相似文献
7.
Hidenori Somei 《Tetrahedron letters》2004,45(9):1841-1844
A new concept of dual activation catalysis in homolytic coupling reaction of 2-naphthol derivatives is described. The dinuclear vanadium(IV) catalyst (R,S,S)-1a promotes the oxidative coupling reaction of 2-naphthol derivatives with high reactivity and enantioselectivity. This dual activation mechanism is supported by the fact that the reaction rate of oxidative coupling of 2-naphthol promoted by the (R,S,S)-1a is 48 times faster than that of the mononuclear complex (S)-3 and a lower catalyst loading of (R,S,S)-1a shows higher catalyst efficiency both in enantioselectivity and chemical yield. 相似文献
8.
N-[2-(D-Glucos-3-O-yl)propionyl]-L-alanine ( 7a ) was synthesized, which has a glucose residue instead of N-acetylglucosamine residue in the muramyl peptide. N-[(D-Glucos-3-O-yl)acetyl]-L-alanine ( 7b ) was also synthesized as a glycolyl analog of 7a in order to determine the relationship between the structure of propionyl moiety in the carbohydrate analog ( 7a ) and the adjuvant activity. These simple analogs are compounds prepared for the purpose of introduction into a synthetic polymer with the view of producing polymeric drugs. 相似文献
9.
Takahiro Makino Kimihiko Kato Hiroyuki Lyozumi Hiroe Honzawa Yoshiaki Tachiiri Mitsuo Hiramatsu † 《Photochemistry and photobiology》1996,64(6):953-956
Abstract— Ultraweak luminescence generated by sweet potato and nonpathogenic Fusarium oxysporum interactions associated with a defense response was detected by a photoncounting method using ultrahigh-sensitive photodetectors. The time-dependent intensity variation, the spectrum and the two-dimensional imaging of the ultraweak luminescence are indicative of the defense response of the sweet potato to F. oxysporum. The production of ipomeamarone as a phytoalexin means that F. oxysporum induced the defense response in the sweet potato. 相似文献
10.
Ohno H Wakayama R Maeda S Iwasaki H Okumura M Iwata C Mikamiyama H Tanaka T 《The Journal of organic chemistry》2003,68(15):5909-5916
Alkyl radicals generated by treatment of thiocarbamates of conformationally favorable 3-alkyl-3-arylpropan-1-ols with tris(trimethylsilyl)silane and AIBN efficiently undergo intramolecular ipso substitution of the methoxy group, yielding the corresponding cyclized products. In contrast, either conformationally favorable or flexible 1-arylalkan-3- or 4-ones easily cyclize into five- or six-membered condensed rings by treatment with SmI(2) via ketyl radical intermediates. The addition of HMPA as cosolvent dramatically changes the cyclization mode of the SmI(2)-induced reaction, and the para-cyclization products are exclusively formed. This "HMPA effect" can be rationalized by the strong chelating ability of HMPA with the samarium atom. 相似文献