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排序方式: 共有374条查询结果,搜索用时 15 毫秒
81.
Thermally‐Activated Pentanol Delivery from Precursor Poly(p‐phenylenevinylene)s for MEMS Lubrication
Ross S. Johnson Cody M. Washburn Alan W. Staton Matthew W. Moorman Ronald P. Manginell Michael T. Dugger Shawn M. Dirk 《Macromolecular rapid communications》2012,33(16):1346-1350
The synthesis of two new polyphenylene vinylene (PPV) precursor polymers which can be thermally induced to eliminate pentanol is presented. Pentanol has recently been discovered to be a very useful lubricant in MicroElectroMechanical Systems. The utilization of the elimination reaction of precursor polymers to PPV as a small molecule delivery platform has, to the best of our knowledge, not been previously reported. The elimination reactions were examined using thermal gravimetric analysis, gas chromatography, and UV–Vis spectroscopy. Using PPV precursors allows for (1) a high loading of lubricant (one molecule per monomeric unit), (2) a platform that requires relatively high temperatures (>145 °C) to eliminate the lubricant, and (3) a non‐volatile, mechanically and chemically stable by‐product of the elimination reaction (PPV). 相似文献
82.
R Kobayashi K Hanaya M Shoji K Umezawa T Sugai 《Chemical & pharmaceutical bulletin》2012,60(9):1220-1223
In order to synthesize the potent nuclear factor (NF)-κB inhibitor, (2S,3S,4S)-dehydroxymethylepoxyquinomycin (DHMEQ), in a large scale, a new route for its corresponding racemic precursor, dihexanoyl (2R*,3R*,4R*)-DHMEQ, was developed. By employing both hydroquinone and benzoquinone intermediates, the total yield, reproducibility, and synthetic steps were improved and the synthetic cost was reduced. 相似文献
83.
Advanced high-pressure plasma diagnostics with hairpin resonator probe surrounded by film and sheath
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The hairpin probe using microwave resonance in plasma is applicable to high pressure 1.33×10 3-1.01×10 5 Pa)) as developed recently.In this work,an analytic model of the hairpin resonator probe surrounded by a thin dielectric layer and a sheath layer is proposed.The correction factor due to these surroundings is analytically found and confirmed by electromagnetic field finite difference time domain simulation,thus enabling the accurate measurement of electron density in a high-pressure non-equilibrium uniform discharge. 相似文献
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William F. Cody 《Archiv der Mathematik》1985,44(6):493-502
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88.
Kenji Mori Takeshi Sugai Yukari Maeda Tomomi Okazaki Tadashi Noguchi Hiroshi Naito 《Tetrahedron》1985,41(22):5307-5311
The racemate and both the (R)- and (S)-forms of gizzerosine [2-amino-9-(4-imidazolyl)-7-azanonanoic acid] were synthesised, and the (S)-isomer was identified as the toxic substance in fish meal causing severe gizzard erosion (black vomit) in chicks. 相似文献
89.
Cody Timmons Dianjun Chen C. Elizabeth Barney Sameer Kirtane Guigen Li 《Tetrahedron》2004,60(52):12095-12099
A new nitrogen source combination was found for the regio- and stereoselective diamination of α,β-unsaturated ketones. This combination employs the readily available and inexpensive combination of NCS and 2-NsNH2 as the electrophilic nitrogen source, and acetonitrile as the nucleophilic nitrogen source, respectively. The reaction is easily performed by mixing olefin, 2-NsNH2, NCS and 4 Å molecular sieves in freshly distilled acetonitrile at room temperature. The reaction is chemoselective without the formation of any haloamine side products. A new aziridinium ion formed from enones and 2-NsNHCl is suggested to exist and to react with nitrile via a [2+3] cycloaddition mechanism, which is responsible for the excellent regio-, stereoselectivity of the resulting diamination products. 相似文献
90.
We report changes in optical absorption and Raman spectra of a-Ge:H when H content is increased from 0 to 16 atomic %. Increasing H content increases the optical gap by 0.4eV, sharpens the absorption tail by a factor of two and decreases bond angle fluctuations by 20. We conclude that H can affect the optical edge by decreasing network disorder. 相似文献