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91.
M. Hoshino M. Takai K. Fukuda K. Imura J. Hayashi 《Journal of polymer science. Part A, Polymer chemistry》1989,27(6):2083-2092
The application of NMR for natural organic compounds has been carried out from the early history of NMR. But they reported on the liquid state NMR and the samples were limited to the materials which dissolved in proper solvents. It has been possible to measure the samples in the solid state in 1970s and is widely used as a familiar analytical method in 1980s. Whereas some of the data is inadequate, concerning cellulose derivatives, in particular, only nitrate and acetate were reported by Patterson1 and Doyle,2 respectively. In this paper, the 13C CP/MAS solid state NMR spectra of several cellulose derivatives are shown and the relationship between the structure and spectrum is discussed. 相似文献
92.
M. Takai Y. F. Lu T. Koizumi S. Namba S. Nagatomo 《Applied Physics A: Materials Science & Processing》1988,46(3):197-205
Single crystal ferrite has been etched by focused Ar+ laser irradiation in a CCl4 gas atmosphere. The etched groove showed cracks due to thermal stresses when samples were etched by a laser vaporization process in a vacuum, while in a CCl4 atmosphere, such cracks were not observed. An etching rate of 68 /s obtained for a thermochemical process by laser irradiation was four orders of magnitude higher than that for a wet chemical etching process. A high aspect (depth-to-width) ratio of up to 10 was obtained for etched grooves. Under specific conditions, bending of the groove and orientation dependence in etching rate were observed. 相似文献
93.
Dr. Kosuke Ono Shunsuke Shimo Dr. Kohei Takahashi Dr. Nobuhiro Yasuda Dr. Hidehiro Uekusa Prof. Nobuharu Iwasawa 《Angewandte Chemie (International ed. in English)》2018,57(12):3113-3117
Dynamic interconversion between large covalent organic cages was achieved simply by heating or acid/base treatment. A mixture of the boroxine cages 12‐mer and 15‐mer was cleanly converted into a pyridine adduct of the 9‐mer boroxine cage upon treatment with pyridine, and the geometry of N‐coordinated boron atoms changed from trigonal to tetrahedral. The reverse reaction was achieved by heating or acid treatment. In this process, the larger boroxine cages 12‐mer and 15‐mer were found to be entropically favored owing to the release of free pyridine molecules from 9‐mer ?6 Py. 相似文献
94.
Utilization of Donor–Acceptor Interactions for the Catalytic Acceleration of Nucleophilic Additions to Aromatic Carbonyl Compounds
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Tatsuhiro Uchikura Dr. Kosuke Ono Dr. Kohei Takahashi Prof. Nobuharu Iwasawa 《Angewandte Chemie (International ed. in English)》2018,57(8):2130-2133
A conceptually new method for the catalytic electrophilic activation of aromatic carbonyl substrates, by utilizing donor–acceptor interactions between an electron‐deficient macrocyclic boronic ester host ( [2+2] BTH‐F ) and an aromatic carbonyl guest substrate, was realized. In the presence of a catalytic amount of [2+2] BTH‐F , dramatic acceleration of the nucleophilic addition of a ketene silyl acetal towards either electron‐rich aromatic aldehydes or ketones was achieved. Several control experiments confirmed that inclusion of the aromatic substrates within [2+2] BTH‐F , through efficient donor–acceptor interactions, is essential for the acceleration of the reaction. 相似文献
95.
96.
Barrette J Bellwied R Braun-Munzinger P Cleland WE David G Duek E Fatyga M Fox D Gavron A Greene SV Hall J Hemmick TK Heifetz R Herman M Herrmann N Hogue RW Ingold G Jayananda K Kraus D Lissauer D Llope WJ Legault A Ludlam T Majka R Makowiecki D Mark SK Mitchell JT Muthuswamy M O'Brien E Olsen L Polychronakos V Rawool-Sullivan M Rotondo F Sandweiss J Shivakumar B Simon J Sonnadara U Sullivan JP Stachel J Sunier J Takai H Throwe T Van Hecke H Waters L Woody C Wolf K Wolfe D 《Physical review letters》1990,64(11):1219-1222
97.
The martensitic phase of 301 stainless steel has been locally transformed into the austenitic phase by irradiating it with a focused Ar-ion laser beam in order to investigate the local change of magnetic properties accompanying the phase transformation. The intensity of the magnetic signal was found to locally reduce at a laser power of 350 mW and almost extinguish at 550 mW with a beam spot size of 13.2 m (at 1/e intensity), indicating the local austenitic phase transformation of the irradiated stainless steel.On leave from Ltd., Shimoteno, Himeji, Hyogo 670, Japan 相似文献
98.
Iida A Takai K Okabayashi T Misaki T Tanabe Y 《Chemical communications (Cambridge, England)》2005,(25):3171-3173
We have developed a practical crossed Claisen condensation between ketene silyl acetals and methyl esters using catalytic NaOH to obtain alpha-monoalkylated beta-keto esters and inaccessible alpha,alpha-dialkylated beta-keto esters. 相似文献
99.
A method for measuring specific activities of 14C-labelled compounds by gas chromatography-mass spectrometry-computer system (GC-MS-CPU) was developed. This method was proved to provide practically precise and accurate specific activities of various 14C-labelled compounds with such merits as requirement of small amount of samples, being applicable to volatile compounds, and convenience. The C.V. percent obtained for tested compounds was within 3.9 and the reliable sensitivity should be over 37 MBq/mM (1 mCi/mM). This method was also useful for obtaining information on the labelling pattern and the synthetic procedures applied. 相似文献
100.
The separation of cold drugs and neuroleptics by high-performance liquid chromatogarphy with the porous polymer resin DVB-MCL-O (or 11-30-0), which is a styrene-divinylbenzene-methyl methacrylate copolymer substituted with hydroxymethyl groups, was studied. This copolymer was compared with the commercial porous polymers Hitachi gel 3011, 3011-0 and 3030. A very small theoretical plate height was obtained by using DVB-MCL-O and methanol-ammonia solution (99:1) as the stationary and mobile phases, respectively. This combination was found to be the most suitable for the rapid separation of condensed aromatic ring compounds. 相似文献