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排序方式: 共有2191条查询结果,搜索用时 31 毫秒
11.
Kiyoshi Tanemura Tsuneo Suzuki Takaaki Horaguchi Mikio Sudo 《Journal of heterocyclic chemistry》1991,28(2):305-309
A new heterocycle, furo[4,3,2-de][1]benzopyran ( 2 ), was synthesized. A key step in the sequence was the allylic bromination of 3,4-dihydrofuro[4,3,2-de][1]benzopyran ( 8 ) to give 3-bromo-3,4-dihydrofuro[4,3,2-de][1]-benzopyran ( 10 ) using N-bromosuccinimide under irradiation and high dilution conditions. Bromide 10 was dealt with 1,8-diazabicyclo[5.4.0]undec-7-ene to afford compound 2 . Several reactions of 2 were examined. Protonation of 2 in trifluoroacetic acid occurred at the 2-position to form a pyrylium ion 12 . Catalytic hydrogenation of 2 with palladium on charcoal proceeded smoothly to give 8 . Reduction of 2 by sodium and ethanol afforded 3-ethyl-4-hydroxybenzofuran ( 14 ). Electrophilic substitutions of 2 such as formylation, acetylation, and bromination, occurred easily at the 2-position. The above results show that compound 2 has both properties of benzofuran and 4-methylenepyran. 相似文献
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Pyridine-based, structurally isomeric two macrocyclic compounds displayed a remarkably different complexation nature. The cage-type compound has an ideal structure for spherical cations, especially for the NH4+ ion, but the reaction with some transition metals and Ln3+ produced its protonated species. On the other hand, its isomer formed complexes with alkali metals and lanthanides (1:1) and also with transition metals. Some structures of the complexes were clarified by crystallographic analyses. 相似文献
14.
We have studied the algorithm for the automatic chromatic dispersion compensation using bit error rate (BER) and Q-factor optimization for realization of dynamically reconfigurable all-optical network. We have made sure good performance using the compensation system by laboratory experiments. 相似文献
15.
M. Fukushima H. Tamate N. Fujii Y. Nakano 《Journal of Radioanalytical and Nuclear Chemistry》2003,257(1):105-108
In this work, we determined the levels of trace metals in protein fractions isolated from rock oysters by neutron activation analysis (NAA) and particle induced X-ray emission (PIXE). Proteins were extracted from mantles and hepatopancreases of rock oysters and fractionated by size-exclusion high performance liquid chromatography (HPLC). The protein fractions from mantles and hepatopancreases are found to be abundant in Fe, Cu, Zn, Mn, Pb, and Ag. HPLC profiles of Fe, Cu, Zn, and Ag indicate that those elements are bound to proteins extracted from mantles and hepatopancreases. 相似文献
16.
Kazuhiko Nakano Toshihiro Nakamura Izumi Nakai Akira Kawase Makoto Imai Mikio Hasegawa Yohichi Ishibashi Isamu Inamoto Kazuhuyu Sudou Masaru Kozaki Akira Tsuruta Akihiro Ono Kazutoshi Kakita Mamoru Sakata 《Analytical sciences》2006,22(9):1265-1268
The Japan Society for Analytical Chemistry has developed some new plastic certified reference materials (CRMs) for the analysis of mercury in polyester disks using XRF analysis. These CRMs (named as JSAC 0621-0625) were prepared by casting polyesters including a toluene solution of organometallic compounds as a standard. Concentrations of the five levels of mercury ranged from 0 to 250 mg/kg. Homogeneity tests of prepared disks had shown excellent results. Interlaboratory comparison study for the certification was performed by 15 laboratory participants. The z-scores in robust statistical method was applied for the evaluation of outliers. The certified values were assigned after discarding outliers. The uncertainties of certified values were determined as the confidence levels of 95%. 相似文献
17.
Tomoji Kumano Yoshifumi Ohata Norikazu Fujii Yoshiyuki Ushigami Tetsuro Takeshita 《Journal of magnetism and magnetic materials》2006
All kinds of high-permeability GO are manufactured using AlN as the main inhibitor. From a purely metallurgical viewpoint, three types of inhibitor preparation for high-permeability GO have been shown. They include a complete solution without nitriding, a complete precipitation with nitriding and a partial precipitation with nitriding. In this study, another possibility, i.e., a complete solution method with nitriding, was investigated to avoid the extra high-temperature slab reheating and to examine the effect of nitriding on GO bearing Al. This method can also provide the sharp Goss texture, and nitriding is shown to be very useful for changing the inhibitor intensity, depending on the primary grain size. 相似文献
18.
N Fujii T Watanabe A Otaka K Bessho I Yamamoto T Noda H Yajima 《Chemical & pharmaceutical bulletin》1987,35(12):4769-4776
19.
Stuart D Breedon RE Kim GN Ko W Lander RL Maeshima K Malchow RL Smith JR Imlay R Kirk P Lim J McNeil RR Metcalf W Myung SS Cheng CP Gu P Li J Li YK Ye MH Zhu YC Abashian A Gotow K Hu KP Low EH Mattson ME Piilonen L Sterner KL Lusin S Rosenfeld C Wang AT Wilson S Frautschi M Kagan H Kass R Trahern CG Abe K Fujii Y Higashi Y Kim SK Kurihara Y Maki A Nozaki T Omori T Sagawa H Sakai Y Sugimoto Y Takaiwa Y Terada S Walker R Kajino F Perticone D Poling R Thomas T Ishi Y Miyano K Miyata H Sasaki T 《Physical review letters》1990,64(9):983-986
20.