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1.
由于种种原因,硅质挂钩砖在烤窑过程中经常出现炸裂,给窑炉的安全使用留下重大隐患.结合在烤窑过程中的体会对此进行一些简要的分析探讨,并提出预防措施和出现问题后的补救办法. 相似文献
2.
通过实地考察,介绍美国、日本和欧洲的液晶显示技术,着重叙述有源矩阵液晶显示技术、制备关键工艺、新型液晶显示器件的开发以及夏普公司在LCD领域中的领先水平. 相似文献
3.
利用边界条件,推导出SH波在多层介质系统中的转移矩阵,利用移矩阵法研究了SH波在一维声子晶体中禁带和缺陷模的特征。得出了SH波的禁带中心频率和频率宽度随入射角和周期厚度的变化规律。得出了SH波的缺陷模中心频率和频率宽度随入射角和杂质厚度的变化规律。 相似文献
4.
《Journal of the European Ceramic Society》2014,34(16):4383-4388
Homogeneous transparent optical glass–ceramics precipitated with unique nonlinear crystals are promising materials for photonic applications. We have utilized heat treatment method to prepare transparent ZnO–Bi2O3–B2O3 glass–ceramic containing Bi2ZnB2O7 nonlinear nanocrystals. A large third-order nonlinear susceptibility χ(3) of glass–ceramic is measured by Z-scan technique, which mainly attributed to unique [BiO6] and [B2O5] units in Bi2ZnB2O7 crystal structure and the quantum size effect of nanoparticles. The discovery is of great potential in the application of nonlinear optical integrated devices. 相似文献
5.
1,1?-Diamino-4,4?,5,5?-tetranitro-2,2?-biimidazole (DATNBI) was synthesized, by employing one-pot facile method, from 4,4?,5,5?-tetranitro-2,2?-biimidazole. The crystal structure was determined by X-ray diffraction for the first time. DATNBI crystallized in monoclinic system P21/c, with a crystal density of 1.934 g cm?3 at 293(2) K and 2.019 g cm?3 at 130(2) K, respectively. Its crystal parameters at 293 K are a = 4.8833(15) Å, b = 6.960(2) Å, c = 6.928(4) Å, α = γ = 90°, β = 93.418(6)°, V = 591.1(3) ?3, Z = 2, μ = 0.178 mm?1, and F(000) = 348. The thermal stability and non-isothermal kinetics of DATNBI were studied by differential scanning calorimeter (DSC) with heating rates of 5, 10, 15, and 20 K min?1. The apparent activation energy (Ea) at the first decomposition peak calculated by Kissinger, Ozawa, and Starink equations were 85.50, 89.67, and 86.10 kJ mol?1, respectively. For the second peak, these were 116.49, 119.82, and 117.45 kJ mol?1, respectively, with individual pre-exponential factors lnA = 18.40 s?1 and lnA = 25.11 s?1. The thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) analysis of thermal decomposition products reveals that the main decomposition gas products are H2O, N2O, CO2, and NO2. Based on the new crystalline densities, the detonation velocity and pressure predicted by EXPLO5 are 9062 m s?1 and 36.4 GPa, respectively. 相似文献
6.
Cytochrome P450 3A4 (CYP3A4) is a major human drug-metabolizing enzyme, notoriously known for its extreme substrate promiscuity, allosteric behavior, and implications in drug–drug interactions. Despite extensive investigations, the mechanism of ligand binding to CYP3A4 is not fully understood. We determined the crystal structure of CYP3A4 complexed with fluorol, a small fluorescent dye that can undergo hydroxylation. In the structure, fluorol associates to the substrate channel, well suited for the binding of planar polyaromatic molecules bearing polar groups, through which stabilizing H-bonds with the polar channel residues, such as Thr224 and Arg372, can be established. Mutagenesis, spectral, kinetic, and functional data confirmed the involvement but not strict requirement of Thr224 for the association of fluorol. Collectively, our data identify the substrate channel as a high-affinity ligand binding site and support the notion that hydrophobic ligands first dock to the nearby peripheral surface, before migrating to the channel and, subsequently, into the active site. 相似文献
7.
Pradeep Subedi Hackwon Do Jun Hyuck Lee Tae-Jin Oh 《International journal of molecular sciences》2022,23(21)
Cytochrome P450 enzymes (CYPs) are heme-containing enzymes that catalyze hydroxylation with a variety of biological molecules. Despite their diverse activity and substrates, the structures of CYPs are limited to a tertiary structure that is similar across all the enzymes. It has been presumed that CYPs overcome substrate selectivity with highly flexible loops and divergent sequences around the substrate entrance region. Here, we report the newly identified CYP101D5 from Sphingomonas echinoides. CYP101D5 catalyzes the hydroxylation of β-ionone and flavonoids, including naringenin and apigenin, and causes the dehydrogenation of α-ionone. A structural investigation and comparison with other CYP101 families indicated that spatial constraints at the substrate-recognition site originate from the B/C loop. Furthermore, charge distribution at the substrate binding site may be important for substrate selectivity and the preference for CYP101D5. 相似文献
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用铝酸钠溶液合成4A沸石的研究 总被引:9,自引:0,他引:9
研究了用氧化铝生产过程中的铝酸钠溶液采用水热合成法制备洗涤剂用4A沸石的合成条件,并介绍了结晶导向剂在合成4A沸石中的应用.用该方法合成4A沸石可以简化生产流程,降低生产成本,能取得较好的经济效益. 相似文献