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为进一步推进射钉紧固器材的发展,特别是射钉器的改进和开发,需要进行射钉器的打击力测定及其基础研究.射钉器打击力的测定采用钢柱法.钢柱法即特制一些标准钢柱放置于特制的试验装置中,通过材料试验压力机分别测出不同压力后标准钢柱的高度,绘制出P-H曲线图,再通过各型射钉器在实验装置中打压标准钢柱,测出相应高度,最后通过对比压力与高度曲线图来确定射钉器打击力值.通过采用钢柱法测定的打击力值,可以合理优化设计影响射钉器威力的相关零件的结构及尺寸. 相似文献
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Pengbao Lian Huipeng Zhao Jianlong Wang Lizhen Chen Yong Xiang Qinghua Ren 《中国化学工程学报》2019,27(5):1149-1158
In this study, the solubility of m-phenylenediamine in four pure solvents(methanol, ethanol, acetonitrile and water) and three binary solvent(methanol + water),(ethanol + water) and(acetonitrile + water) systems were determined in the temperature ranging from 278.15 K to 313.15 K by using the gravimetric method under atmospheric pressure. In the temperature range of 278.15 K to 313.15 K, the mole fraction solubility values of m-phenylenediamine in water, methanol, ethanol, and acetonitrile are 0.0093–0.1533, 0.1668–0.5589,0.1072–0.5356, and 0.1717–0.6438, respectively. At constant temperature and solvent composition, the mole fraction solubility of o-phenylenediamine in four pure solvents was increased as the following order:water b ethanol b methanol b acetonitrile; and in the three binary solvent mixtures could be ranked as follows:(ethanol + water) b(methanol + water) b(acetonitrile + water). The relationship between the experimental temperature and the solubility of m-phenylenediamine was revealed as follows: the solubility of mphenylenediamine in pure and binary solvents could be increased with the increase of temperature. The experimental values were correlated with the Jouyban–Acree model, van't Hoff–Jouyban–Acree model, modified Apelblat–Jouyban–Acree model, Sun model and Ma model. The standard dissolution enthalpy, standard dissolution entropy and the Gibbs energy were calculated based on the experimental solubility data. In the binary solvent mixtures, the dissolution of m-phenylenediamine could be an endothermic process. The solubility data,correlation equations and thermodynamic property obtained from this study would be invoked as basic data and models regarding the purification and crystallization process of m-phenylenediamine. 相似文献
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对浓香型大曲制曲过程中吡嗪类物质合成的阶段特征与微生物菌群之间的相关性进行解析,探究制曲过程中微生物相互作用对吡嗪类物质合成的影响。通过顶空固相微萃取-气相色谱-质谱联用技术和高通量测序获得制曲过程中吡嗪类物质和微生物菌群结构的阶段性变化,利用主成分分析和线性判别分析寻找制曲过程中的差异微生物。基于Spearman相关系数构建差异微生物与吡嗪类物质的相关性,及这些吡嗪类代谢相关微生物与浓香型大曲微生物菌群之间的相关性网络图。结果显示,在制曲过程中共检测到9种吡嗪类物质,在1~5 d和7~28 d阶段吡嗪类物质的数量和种类存在显著差异,且制曲过程中微生物群落演替可分为两个阶段:A阶段(1~5 d)和B阶段(7~28 d)。在A阶段,差异真菌主要为奥默柯达属(Kodamae)、念珠菌属(Candida),差异细菌主要为考萨考氏菌属(Kosakonia)、泛菌属(Pantoea)、嗜甲基菌属(Methylophilus);B阶段差异真菌主要为嗜热子囊菌属(Thermoascus)、嗜热丝孢菌属(Thermomyces),差异细菌主要为高温放线菌属(Thermoactinomyces)、糖多孢... 相似文献
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采用肉汤微量稀释法,对203 株源于2006—2011年四川牛乳源金黄色葡萄球菌(Staphylococcus aureus,Sa)进行10 种常用抗生素药敏性检测,多重聚合酶链式反应(multiplex polymerase chain reaction,M-PCR)法对其耐甲氧西林基因(mecA)和β-内酰胺类药物耐药基因(blaZ)进行分析,了解Sa耐药性变迁。结果表明:牛乳源Sa菌株对青霉素、氨苄西林耐药率一直居高不下;对阿莫西林/克拉维酸、红霉素、甲氧苄啶/磺胺甲噁唑耐药率有增强趋势;对林可霉素、四环素耐药率呈降低趋势;对环丙沙星耐药率不定;对苯唑西林和头孢噻呋敏感;Sa分离株多重耐药率介于72.1%~100.0%,显示出不尽相同的耐药谱,却呈现出不断增宽的趋势。M-PCR检测显示,2006—2011年分离Sa菌株未从基因水平扩增出mecA基因;不同年度分离株均不同程度携带blaZ基因,不同年度分离株blaZ+检出率介于49.1%~87.5%。药敏实验结果与相关耐药基因检测结果存在对应关系,部分菌株的耐药性与耐药基因的检出率不一致,推测还存在其他耐药机制。结论:四川地区牛乳源金黄色葡萄球菌耐药性不容乐观。 相似文献
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