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81.
82.
Ni76Cr19AlTi合金的热变形行为 总被引:1,自引:0,他引:1
在Gleeble-1500热模拟机上对Ni76Cr19AlTi合金棒材进行恒温和恒速压缩变形实验,变形温度范围为80m-1150℃,应变速率范围为10^-3—10^0S^-1.结果表明,实验合金在800和850℃热压缩时变形抗力较大,容易发生开裂;而在950—1150℃温度范围内热变形由于发生动态再结晶,合金变形抗力减小,变形容易进行,不会发生开裂.研究了合金在高温塑性变形过程中流变应力的变化规律,确定了合金在950-1150℃范围内的变形激活能Q为376.84kJ/mol,应力指数n为4.15.对合金的热压缩变形真应力-真应变曲线及变形机制的分析表明,合理的变形条件为105m-1150℃及10^-1-10^0s^-1. 相似文献
83.
84.
《国际聚合物材料杂志》2012,61(8):562-575
In this study, we fabricated PHB scaffolds by solid/liquid phase separation method. The properties of fabricated scaffolds were investigated using SEM, DMTA, and DSC. Our studies noticed that for an approach to scaffolds that contain tubular morphology and better mechanical properties, the solution should be frozen near crystallization temperature. For in vitro evaluation, the P19 mouse embryonal cell line was used as a model system. Results notice that cells attach and differentiate to the nerve cell. In vitro assay shows that it is a suitable model for use as a platform for neural tissue engineering applications. 相似文献
85.
ZHAO Wenyu ZHANG Qingjie GUAN Jianguo 《武汉理工大学学报(材料科学英文版)》2006,21(2):36-40
The dried gel of SrFe12O19, prepared by citrate approach, was investigated by means of infrared spectroscopy ( IR ), thermogravimetric analysis ( TG ), differential scanning calorimetry ( DSC ), X- ray diffraction( XRD ) techniques, energy dispersive spectroscopy( EDS ), and transmission electron microscopy( TEM ). The thermal instability and the thermal decomposition of low-temperature strontium M-type hexaferrite crystallized at about 600℃ were confirmed for the first time by XRD method. The decomposition of the low-temperature strontium M-type hexaferrite took place at about 688.6℃ determined by DSC investigation. The low-temperature strontium M-type hexaferrite nanopartieles were decomposed into SrFeO2.5 with an orthorthombic cell and Fe2O3 with a tetragonal cell as well as possibl α-Fe2O3 . The agglomerated particles with sizes less than 200 nm obtained at 800℃ were plesiomorphous to strontium M-type hexaferrite. The thermally stable strontium M-type hexaferrite nanopartieles with sizes less than 100um cotdd take place at 900 ℃ . Up to 1000 ℃ , the phose transformotion to form strontium M-type hexaferrite was ended, the calcinations with the sizes more than 1μm were composed of α-Fe2O3 and strontium M-type hexaferrite. The method of distinguishing γ-Fe2O3 with a spinel structure from Fe2O3 with tetragonal cells by using powder XRD method was proposed. Fe2O3 with tetragonal cells to be crystallized before the crystallization of thermally stable strontium M-type hexaferrite was confirmed for the first time. The reason why α- Fe2O3 as an additional phase appears in the calcinations is the cationic vacancy of stroutium M-type hexaferrite , SrFe12-x□O19 (0≤x ≤0.5). 相似文献
86.
David Kahn 《Cryptologia》2013,37(4):273-294
American codebreakers achieved remarkable success in solving Japanese codes, but could not prevent the surprise attack on Pearl Harbor because the Japanese never transmitted anything about the attack on the airwaves. 相似文献
87.
Sueva Cantalupo Vito Alessandro Lasorsa Roberta Russo Immacolata Andolfo Giuseppe DAlterio Barbara Eleni Rosato Giulia Frisso Pasquale Abete Gian Marco Cassese Giuseppe Servillo Ivan Gentile Carmelo Piscopo Matteo Della Monica Giuseppe Fiorentino Giuseppe Russo Pellegrino Cerino Carlo Buonerba Biancamaria Pierri Massimo Zollo Achille Iolascon Mario Capasso 《International journal of molecular sciences》2021,22(10)
Genome-wide association studies (GWAS) found locus 3p21.31 associated with severe COVID-19. CCR5 resides at the same locus and, given its known biological role in other infection diseases, we investigated if common noncoding and rare coding variants, affecting CCR5, can predispose to severe COVID-19. We combined single nucleotide polymorphisms (SNPs) that met the suggestive significance level (P ≤ 1 × 10−5) at the 3p21.31 locus in public GWAS datasets (6406 COVID-19 hospitalized patients and 902,088 controls) with gene expression data from 208 lung tissues, Hi-C, and Chip-seq data. Through whole exome sequencing (WES), we explored rare coding variants in 147 severe COVID-19 patients. We identified three SNPs (rs9845542, rs12639314, and rs35951367) associated with severe COVID-19 whose risk alleles correlated with low CCR5 expression in lung tissues. The rs35951367 resided in a CTFC binding site that interacts with CCR5 gene in lung tissues and was confirmed to be associated with severe COVID-19 in two independent datasets. We also identified a rare coding variant (rs34418657) associated with the risk of developing severe COVID-19. Our results suggest a biological role of CCR5 in the progression of COVID-19 as common and rare genetic variants can increase the risk of developing severe COVID-19 by affecting the functions of CCR5. 相似文献
88.
澳门特区政府总部办公室最初是一座民宅,回归前是总督府。它是澳门19世纪豪宅代表之一,见证了澳门葡式民宅由内敛到张扬的转变。同时,作为不同时期的最高权力所在地,建筑对社会及政局的发展作出相应的嬗变,影响了澳门建筑的发展。 相似文献
89.
0Cr19Ni9N中由于含有氮元素 ,使锻造性能大幅下降 ,通过多火次 (5~ 10次 )锻造 ,使 8件产品一次性锻造成功。经检验各项性能指标完全符合要求 相似文献
90.
生物降解混源油混合比例估算方法 总被引:13,自引:2,他引:11
研究生物降解混源油的混合比例时的关键是根据研究对象的降解程度,选择既能抗该降解程度又能有效区分烃源岩贡献的生物标志化合物,作为估算原油生物降解前的混合比例的参数,并通过配比实验检验估算结果的可靠程度。在研究渤海PL19—3油田生物降解混源油的混合比例时,选用源自沙河街组三段和东营组下段烃源岩的典型油样,以三芳甾烷/三芳甲藻甾烷作为参数,用估算法计算了PL19—3—4井(最靠近渤中凹陷)生物降解原油混合比例,东营组下段烃源岩的贡献约占30%,该井以南的PLl9—3—2井、PL19—3-8井和PL19—3—5井东营组下段烃源岩的贡献逐步下降,最低约占10%。图4表3参15 相似文献