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101.
102.
Hideo Nemoto Hiroshi Kurobe Masataka Ihara Keiichiro Fukumoto Tetsuji Kametani 《Tetrahedron letters》1984,25(29):3095-3098
A convergent and stereoselective synthesis of vitamin D3 was achieved via 3,5-cyclovitamins D3 (20) which were prepared from the chiral aldehyde (2) and the vinyl bromide (12) derived from Grundmann's ketone. 相似文献
103.
Tomoko Hashimoto Reiko Iwase Akira Murakami Tetsuji Yamaoka 《Polymer Degradation and Stability》2009,94(9):1349-1353
Novel biodegradable oligopeptide-type gene carriers composed of cationic residues (KRRRKRKRRRKRKRRC) and oligo leucine segments were developed. The amphiphilic carrier was found to form micelle-like assemblies in aqueous solutions, when the oligo leucine is 12 amino acids length (Pep-L12). NMR, CMC, and GPC analysis revealed their hydrophobic/cationic core/shell morphology. Hydrophobic interaction between leucines is thought to be the major driving force behind formations of assemblies. The transient expression of luciferase introduced to COS-1 cells using Pep-L12 below the CMC is as low as that by the control cationic peptides without leucine residue (Pep-L0), while improved transgene expression was observed in the case of Pep-L12 above CMC. The self-assembly raised the apparent molecular weight and gene transfection ability without loosening their low cytotoxicity. These results indicate that the amphiphilic oligopeptides are very promising materials as highly efficient and less toxic gene carriers. 相似文献
104.
A. Uedono S. Watauchi Y. Ujihira L. Wei S. Tanigawa R. Suzuki H. Ohgaki T. Mikado H. Kametani H. Akiyama Y. Yamaguchi M. Koumaru 《Hyperfine Interactions》1993,79(1-4):621-625
Defects in the separation by implanted oxygen (SIMOX) wafers were studied by monoenergetic positron beams. For the as-implanted specimen, vacancies introduced by ion implantation were found to form vacancy-oxygen complexes. After high temperature annealing, a drastic increase in the formation probability of positronium was observed. This suggests an introduction of open-spaces by the formation of an amorphous SiO2. The present investigation shows that positrons provide a nondestructive probe for the detection of defects in SIMOX wafers and microstructures of SiO2. 相似文献
105.
Vibrational properties of Ba doped Si clathrate are investigated at high pressures up to 20 GPa by Raman spectroscopy. Vibrations related with Ba encaged in the Si cages are observed below 100 cm(-1) by low-frequency Raman measurements of Ba8Si46 and Ba6.6Si46 clathrates. The high-pressure Raman spectra obtained for both compression and decompression processes reveal a new phase transition at 7 GPa, and the reversibility of the phase transition at 15 GPa. We investigate the mechanisms of these phase transitions, the interaction between the guest and host frame, and the volume dependence of the vibrational modes. 相似文献
106.
107.
Tetsuji Kawabe 《Physics letters. [Part B]》1982,114(4):263-265
It is shown that the direct diquark contributions to ν-induced nucleon structure functions vanish in contrast with the case of γ-induced ones if isospin and spin states of diquarks are taken into account seriously. This suggests that higher twist effects of QCD are negligible for ν-induced nucleon structure functions. 相似文献
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