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71.
72.
André G. Pernet Hiromasa Nakamoto Naoyasu Ishizuka Masakazu Aburatani Kazuaki Nakahashi Keiji Sakamoto Tadashi Takeuchi 《Tetrahedron letters》1979,20(41):3933-3936
A simplified methodology for the building of prostaglandins substituted at the 10 and 11 positions is presented. 相似文献
73.
Hamao Watanabe Kazuaki Higuchi Tomoko Goto Tsutomu Muraoka Jun Inose Masaaki Kageyama Yasuko Iizuka Masakatsu Nozaki Yoichiro Nagai 《Journal of organometallic chemistry》1981,218(1):27-39
In the presence of a catalytic amount of sodium methoxide, sym-dimethoxytetramethyldisilane was converted into α,ω-dimethoxypermethylpolysilanes, MeO(SiMe2)nOMe where n ? 3, at room temperature. On the other hand, similar treatment of the disilane in THF solution gave cyclic polysilanes, (Me2Si)n where n = 5–7. Decomposition of the disilane in the presence of diphenylacetylene afforded a trisilacyclopentene derivative under similar conditions. This compound was obtained also by the reaction between α,ω-dimethoxypermethylpolysilanes and diphenylacetylene in the presence of sodium methoxide. These cyclic products most likely were formed via permethyl polysilyl anion intermediates derived from α,ω-dimethoxypermethylpolysilanes. Also, the formation of α,ω-dimethoxypermethylpolysilanes could be elucidated in terms of the mechanism involving the base-assisted, concerted nucleophilic substitution or stepwise substitution by silyl anions, rather than the successive dimethylsilylene (Me2Si:) insertion reaction. 相似文献
74.
Photochemical vapor deposition of a-Si films at a high rate using SiH4 and a 185 nm low pressure mercury lamp is described. A maximum rate of 1 nm/sec was attained using the 185 nm lamp. This rate was about ten times higher than that using a 254 nm lamp. Assuming that there is no interaction between the effects of the two wavelengths, the deposition rate per light output power of 184.9 nm light is 160 times larger than that for 253.7 nm light. The absorption cross-section of the 184.9 nm light is ten times greater than that for the 253.7 nm light. 相似文献
75.
[reaction: see text] New Lewis acid-assisted Br?nsted acids (LBAs), tin(IV) chloride-2,6-dialkoxyphenols, serve as artificial cyclases for biomimetic polyene cyclization. For example, the enantioselective cyclization of 4-(homogeranyl)toluene using tin(IV) chloride-2,6-di[(1'R,2'R)-trans-2'-(3' ',5' '-xylyl)cyclohexanoxy]phenol gave a trans-fused tricyclic compound with 85% ee. 相似文献
76.
The purpose of this paper is to provide a careful and accessible exposition of static bifurcation theory for a class of degenerate boundary value problems for diffusive logistic equations with indefinite weights that model population dynamics in environments with spatial heterogeneity. We discuss the changes that occur in the structure of the positive solutions as a parameter varies near the first eigenvalue of the linearized problem, and prove that the most favorable situations will occur if there is a relatively large favorable region (with good resources and without crowding effects) located some distance away from the boundary of the environment.Dedicated to Professor Mitsuru Ikawa on the occasion of his 60th birthday 相似文献
77.
(--)-Muricatacin, a potent cytotoxic (4R,5R)-5-hydroxyheptadecan-4-olide, has been synthesized through alpha-C--H hydroxyalkylation and alpha'-C--H oxidation of tetrahydrofuran. This study presents a novel method for C--H bond functionalization as a means for preparing gamma-(hydroxyalkyl)-gamma-butyrolactones. 相似文献
78.
Takayama H Katakawa K Kitajima M Yamaguchi K Aimi N 《Chemical & pharmaceutical bulletin》2003,51(10):1163-1169
Ten new alkaloids, lycoposerramines-F (1), -G (2), -H (3), -I (4), -J (5), -K (6), -L (7), -M (8), -N (9), and -O (10), having lycopodine-related structures, were isolated from the club moss Lycopodium serratum THUNB. and their structures were elucidated on the basis of spectroscopic analysis and/or chemical transformation. 相似文献
79.
Doke T Hayashi T Kikuchi J Sakaguchi T Terasawa K Yoshihira E Nagaoka S Nakano T Takahashi S 《Radiation measurements》2001,33(3):373-387
Dosimetric measurements on the Space Shuttle Missions STS-84, -89 and -91 have been made by the real-time radiation monitoring device III (RRMD-III). Simultaneously, another dosimetry measurement was made by the Dosimetry Telescope (DOSTEL) on STS-84 and by the tissue-equivalent proportional counter (TEPC) on STS-91. First, the RRMD-III instrument is described in detail and its results summarized. Then, the results of DOSTEL and TEPC are compared with those of the RRMD-III. Also, the absorbed doses obtained by TLD (Mg2SiO4) and by RRMD-III on board STS-84 and -91 are compared. 相似文献
80.
Kazuaki Yanagisawa Deborah E. Cutler 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(3):879-886
Bibliometric analysis was carried out for champion data comparisons among prestigious nuclear research institutes (PNRI) existed
in Japan, the U. S., France, and Germany. The analysis was relied on database INIS (IAEA), ECD (DOE), WOS (Thomson), and SCOPUS
(Elsevier). INIS is advanced, key ex-post evaluating tool for determining general research paper-based champion. Over the
30-year time span of research paper publication, the world champion among 11 PNRI is JAERI confirmed by INIS but ORNL confirmed
by ECD, WOS, and SCOPUS, the latter two collected journal submitted research paper. Five years ago JAERI is the 3rd ranked
institutes following ORNL and ANL. INIS database results revealed that CEA/Grenoble is the French domestic champion regarding
research paper publication. Five years ago it was CEA/Saclay. Results from analytical tools used in bibliometric studies should
be viewed with careful consideration to learn of any influencing factors because different characteristics exhibited by individual
databases can sometimes generate conflicting bibliometric results. This was true among INIS, ECD, WOS, and SCOPUS when looking
at trends especially between 5-year periods. 相似文献