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151.
Despite the recent advance in C-H bond functionalization chemistry, the C-H bonds in the acridine ring system, which is an important scaffold in medicinal and material science, have met with limited success, due, in part, to the lack of activated C-H bonds adjacent to the ring nitrogen atom. Herein, several protocols that can effect the regioselective arylation and alkylation of acridines at the C-4 and C-9 positions are described. 相似文献
152.
Noguchi M Nakamura M Ohno A Tanaka T Kobayashi A Ishihara M Fujita M Tsuchida A Mizuno M Shoda S 《Chemical communications (Cambridge, England)》2012,48(45):5560-5562
An efficient chemo-enzymatic process for construction of the α-linked disaccharide unit (GlcNAcα1-4Gal) found in gastric mucin has been developed. The process consists of a one-step preparation of a novel triazine type glycosyl donor in water and the subsequent transglycosylation to a galactose derivative catalysed by α-N-acetylglucosaminidase. 相似文献
153.
Mamoru Tobisu Ayaka Yasutome Ken Yamakawa Toshiaki Shimasaki Naoto Chatani 《Tetrahedron》2012,68(26):5157-5161
Ni(0)/NHC-based catalyst system can promote the amination of N-heteroaryl methyl ethers via the cleavage of normally unreactive carbon–oxygen bonds. Electron-deficient N-heteroarenes including pyridine, quinoline, isoquinoline, and quinoxaline undergo amination to afford aminopyridine and related heteroarenes, which constitute an important class of compounds. 相似文献
154.
S Kurimoto K Suzuki M Okasaka Y Kashiwada OK Kodzhimatov Y Takaishi 《Chemical & pharmaceutical bulletin》2012,60(7):913-919
Seven new sesquiterpene lactone glycosides (1-7) were isolated from the H2O-soluble fraction from the MeOH extract of the roots of Ferula varia. Their structures were elucidated by extensive spectroscopic analyses. The absolute configurations of compounds 1 and 2 were determined by modified Mosher's method. 相似文献
155.
Pravin Sawant Mamoru Ishii Michitsugu Mori 《International Journal of Heat and Fluid Flow》2009,30(4):715-728
Prediction of amount of entrained droplets or entrainment fraction in annular two-phase flow is essential for the estimation of dryout condition and analysis of post dryout heat transfer in light water nuclear reactors and steam boilers. In this study, air–water and organic fluid (Freon-113) annular flow entrainment experiments have been carried out in 9.4 and 10.2 mm diameter test sections, respectively. Both the experiments covered three distinct pressure conditions and wide range of liquid and gas flow conditions. The organic fluid experiments simulated high pressure steam–water annular flow conditions. In each experiment, measurements of entrainment fraction, droplet entrainment rate and droplet deposition rate have been performed by using the liquid film extraction method. A simple, explicit and non-dimensional correlation developed by Sawant [Sawant, P.H., Ishii, M., Mori, M., 2008. Droplet entrainment correlation in vertical upward co-current annular two-phase flow. Nucl. Eng. Des. 238 (6), 1342–1352] for the prediction of entrainment fraction is further improved in this study in order to account for the existence of critical gas and liquid flow rates below which no entrainment is possible.Additionally, a new correlation is proposed for the estimation of minimum liquid film flow rate at the maximum entrainment fraction condition. The improved correlation successfully predicted the newly collected air–water and Freon-113 entrainment fraction data. Furthermore, the correlations satisfactorily compared with the air–water, helium–water and air–genklene experimental data measured by Willetts [Willetts, I.P., 1987. Non-aqueous annular two-phase flow. D.Phil. Thesis, University of Oxford]. However, comparison of the correlations with the steam–water data available in literature showed significant discrepancies. It is proposed that these discrepancies might have been caused due to the inadequacy of the liquid film extraction method used to measure the entrainment fraction or due to the change in mechanism of entrainment under high liquid flow conditions. 相似文献
156.
Naoko Asakuma Toshimi Fukui Mamoru Aizawa Motoyuki Toki Hiroaki Imai Hiroshi Hirashima 《Journal of Sol-Gel Science and Technology》2000,19(1-3):333-336
Structural changes stimulated by ultraviolet (UV) laser irradiations of sol-gel derived inorganic oxide films were investigated. Dried gel films of TiO2, Nb2O5, Ta2O5, SrTiO3 and Pb(Zr
x
Ti1–x
)O3 (PZT) were found to be crystallized by the laser irradiation. On the other hand, the photo-induced change in gel films of BaTiO3, LiNbO3 and LiTaO3 was not observed although the laser beams were absorbed in the films. These sol-gel films were thermally crystallized at almost the same temperature around 600–700°C except TiO2. Thus, the UV-laser-induced crystallization is not directly ascribed to a simple thermal effect with the irradiation. Photochemical properties of the cations are assumed to be important for the change in sol-gel films. 相似文献
157.
Takeo Tomita Mamoru Takahashi Masaki Sasaki Hiroshi Sakamoto Masahiro Takahashi Hiroshi Tamura 《Shock Waves》2009,19(3):213-228
During development tests of the LE-7A prototype engine, severe side-loads were observed. The side-load peaks appeared only
in certain limited conditions during start-up and shut-down transients. To investigate phenomena causing those severe side-loads
observed in the LE-7A prototype engine nozzle, series of cold-flow tests and hot-firing tests as well as CFD analyses were
conducted. As a result of the hot-firing tests, two different phenomena were found to cause severe side-loads in the LE-7A
prototype engine nozzle. One was a restricted shock separation (RSS) flow structure and the other was a phenomenon termed
“separation jump,” the rapid movement of the separation location in the vicinity of the step. A step was installed in the
LE-7A prototype to supply film-cooling gas. Hot-firing test results showed that RSS can occur for a limited mixture ratio.
Detailed flow structure of RSS on the nozzle surface was revealed by the cold-flow tests. Measured pressures and visualized
images of cold-flow tests clarified the mechanism causing the separation jump. The key phenomenon ruling the separation jump
was found to be the base flow behind the step. Based on the results of the present study, the latest LE-7A engine nozzle design
has been changed to eliminate the severe side-load.
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158.
159.
160.
Precipitation temperature-total polymer concentration diagrams for toluene solutions of two styrene-acrylonitrile copolymers different in chemical composition and their mixtures were determined and then triangular phase diagrams of this system were constructed from these diagrams. It is speculated from the triangular phase diagrams and experimentally shown that the copolymer may be effectively fractionated by chemical composition in this system. 相似文献