排序方式: 共有16条查询结果,搜索用时 15 毫秒
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历史学家说,预测未来无异于撒谎,政治家却常常用“谎言”拉选票。经济学家甚至用“数学模型”来精确论证“谎言”不是吗?10年前谁预言亚洲会成立自由贸易区?谁预言2015年的今天,最大的贸易区已不是北美也不是区盟,而是亚盟?交易量最大的已不是称雄百年的美元,而是刚刚问世的亚元? 相似文献
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为研究干粉组成及粒径对其抑制汽油蒸气与空气混合物爆炸效果的影响,以92号汽油为例,在220 L爆炸罐基础上建立一整套可燃气体(液体蒸气)抑爆研究装置。选取磷酸铵盐、超细磷酸铵盐和钠盐3种干粉为抑爆剂。通过时间继电器调节点火时间,在油气爆燃转爆轰阶段喷射干粉,比较抑爆前后汽油蒸气爆炸的峰值压力、压力上升速率和能量的变化。试验结果表明:铵盐对汽油蒸气的抑爆效果优于钠盐,适当降低磷酸铵盐的粒径有利于提高气体抑爆效果。超细铵盐抑制汽油蒸气爆炸的效果最佳,能降低58.5%的汽油爆炸压力和31.6%的爆炸能量,3种干粉的最佳抑爆质量浓度分别为:超细铵盐0.682 g/L,铵盐0.228 g/L,钠盐0.455 g/L。 相似文献
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提出了一种基于萤火虫改进麻雀搜索算法-支持向量机(FASSA-SVM)的轴承故障诊断方法。首先对轴承工况的振动信号变分模态分解(VMD)得到多个模态分量(IMFs),其次利用排列熵(PE)求解每种工况每个IMF的PE值作为特征参数输入至SVM中,最后利用FASSA方法优化SVM的惩罚因子、核参数并得到最优的轴承故障分类诊断效果。实验结果表明,FASSA-SVM方法的平均测试集诊断准确率高达99.8%,该诊断结果优于传统的萤火虫算法(FA)、优化麻雀搜索算法(SSA)。 相似文献
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Hull-less barley is a special food crop rich in various nutrients in Qinghai-Tibet Plateau. Six-pearling is often used to produce commercial hull-less barley rice in order to improve its rough taste and inferior cooking quality. This study evaluated the differences in the nutritional, cooking, sensory, and storage qualities of hull-less barley rice with different pearling times to obtain suitable processing conditions for the production of high-quality hull-less barley rice. With increasing pearling time, the contents of vitamin B6, vitamin E, dietary fiber, iron, zinc, phenols, and flavonoids significantly decreased to a large extent, protein and vitamin B3 decreased slightly, the contents of total starch and β-glucan increased significantly, and γ-aminobutyric acid (GABA) initially increased and then decreased. The peak, trough, and final viscosity of whole grain barley were 1 860.50 cP, 914.50 cP, and 2 150.00 cP, respectively, and increased after six-pearling to 4 219.00 cP, 2 628.00 cP, and 5 074.00 cP, respectively. At the same time, the water absorption and volume expansion of the pearled hull-less barley increased significantly. The hardness of pearled hull-less barley reduced from 4 708.50 g to 2 282.00 g, its adhesiveness increased from 0.00 to -7.33, and its taste and sensory quality exhibited better. The activities of α-amylase, polyphenol oxidase, lipase, and catalase in pearled hull-less barley slightly decreased. Hull-less bran flour is rich in a variety of nutritional components and could be a potential resource with great developmental value. In general, hull-less barley rice obtained from three-pearling has high nutritional value, high cooking quality, low enzyme activity, and low energy consumption; therefore, it can be used to produce high-quality barley rice. This study provides important information for high-quality pearled hull-less barley and further utilization of barley bran flour. © 2022 Science Press. All rights reserved. 相似文献
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为准确掌握杞麓湖外源入湖污染负荷,进行精准治污,降低水质富营养化程度,采用现场踏勘、实测、同倍比法对杞麓湖流域外源污染物进行了调查,结果显示其外源污染物一是通过5条主要入湖河流的径流携带进入;二是雨后通过农业坡面散流区直接汇入;三是通过湖滨农业排涝区的排涝排入;四是通过湖面降雨降尘的自然输入,入湖途径呈现出相似性和典型性特征。通过调查核算,2018年杞麓湖入湖河流区、湖滨农业排涝区、农业坡面散流区、湖面降雨降尘区总计排入杞麓湖的净污染负荷为:CODCr3632.04t、CODMn776.68t、TN921.96t、TP39.70t。以CODCr为例,湖滨农业排涝区、农业坡面散流区、湖面降雨降尘区、入湖河流区每平方千米入湖CODCr分别为52.07、24.09、11.53、7.54t,表明湖滨农业排涝区的污染治理应该引起高度重视,优先治理。该研究成果可向承担湖泊保护管理主体责任的政府和部门提供从“一湖之治”向“流域之治”转变的治理思路,也为政府在短期内改善杞麓湖富营养化现状和后期保证其得到持续改善提供... 相似文献
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