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排序方式: 共有1006条查询结果,搜索用时 15 毫秒
1.
Yuxi Guo Xuefeng Chen Pin Gong Fuxin Chen Dandan Cui Mengrao Wang 《International Journal of Food Science & Technology》2021,56(10):4970-4982
In vitro digestion models are widely used to study the structural changes, digestion and release of food components under simulated gastrointestinal conditions. As compared to the in vivo digestion tests, the in vitro digestion reflects the digestion and utilisation of food after ingestion and has the advantages of being time consuming, inexpensive, reproducible and free from moral and ethical restrictions. This study reviewed the current research studies on the in vitro simulated digestion of polysaccharides conducted in the last 5 years and focused on the oral, gastric and intestinal digestion models, with the aim of providing a basis for the further testing of changes in the content, structure and active ingredients of polysaccharides before and after digestion. 相似文献
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水文过程相依性是水文变异的主要表现形式之一,应用自回归模型对其进行拟合时合理确定模型阶数是一个难点问题。本文在分析AIC和BIC准则的基础上,提出了一种以原序列与其相依成分的相关系数作为拟合度指标,同时借用信息熵形式的函数式,作为模型不确定性度量指标的自回归模型定阶准则(简称RIC准则)。以AR(1)、AR(2)、AR(3)和AR(4)模型为例进行统计试验,将不同序列长度下该准则的定阶准确率与其他定阶准则进行比较,试验结果表明,RIC准则对于上述模型均具有较好的适应性,且定阶准确率远高于AIC准则,其中对于前三阶模型RIC准则优于BIC准则,但四阶模型略低于BIC准则。RIC准则的优势是可以同时满足模型定阶、相依程度分级与模型检验的需求,将其应用于实测水文序列分析,结果显示,该准则能较准确地识别自回归模型的阶数,且符合提出的"相依有变异而残差无变异的最小阶数"的检验标准。 相似文献
3.
Mi Thxi 《计算机科学技术学报》1997,12(5):425-440
The original interpretation of the constructive set theory CZF in Martin-Loef‘s type theory uses the‘extensional identity types’.It is generally believed that these‘types’do not belong to type theory.In this paper it will be shown that the interpretation goes through without identity types.This paper will also show that the interpretation can be given in an intensional type theory.This reflects the computational nature of the interpretation.This computational aspect is reinforced by an ω-Set moel of CZF. 相似文献
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Jiang Hongzhi Li Yuxi Zhao Huijie Li Xudong Xu Yang 《International Journal of Computer Vision》2021,129(5):1787-1787
International Journal of Computer Vision - In the original publication of the article, the name of the last author should be Yang Xu, instead of Xu Yang. “Xu” is the family name, and... 相似文献
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Boron-based metal-free catalysts for oxidative dehydrogenation of propane (ODHP) have drawn great attention in both academia and industry due to their impressive activity and olefin selectivity. Herein, the SiO2 and B2O3 sequentially coated honeycomb cordierite catalyst is designed by a two-step wash-coat method with different B2O3 loadings (0.1%-10%) and calcination temperatures (600, 700, 800 ℃). SiO2 obtained by TEOS hydrolysis acts as a media layer to bridge the cordierite substrate and boron oxide via abundant Si-OH groups. The welldeveloped straight channels of honeycomb cordierite make it possible to carry out the reactor under high gas hourly space velocity (GHSV) and the thin wash-coated B2O3 layer can effectively facilitate the pore diffusion on the catalyst. The prepared B2O3/SiO2@HC monolithic catalyst exhibits good catalytic performance at low boron oxide loading and achieves excellent propylene selectivity (86.0%), olefin selectivity (97.6%, propylene and ethylene) and negligible CO2 (0.1%) at 16.9% propane conversion under high GHSV of 345,600 ml·(g B2O3)-1·h-1, leading to a high propylene space time yield of 15.7 g C3H6·(g B2O3)-1·h-1 by suppressing the overoxidation. The obtained results strongly indicate that the boron-based monolithic catalyst can be properly fabricated to warrant the high activity and high throughput with its high gas/surface ratio and straight channels. 相似文献
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Boron-based metal-free catalysts for oxidative dehydrogenation of propane (ODHP) have drawn great attention in both academia and industry due to their impressive activity and olefin selectivity. Herein, the SiO2 and B2O3 sequentially coated honeycomb cordierite catalyst is designed by a two-step wash-coat method with different B2O3 loadings (0.1%–10%) and calcination temperatures (600, 700, 800 °C). SiO2 obtained by TEOS hydrolysis acts as a media layer to bridge the cordierite substrate and boron oxide via abundant SiOH groups. The well-developed straight channels of honeycomb cordierite make it possible to carry out the reactor under high gas hourly space velocity (GHSV) and the thin wash-coated B2O3 layer can effectively facilitate the pore diffusion on the catalyst. The prepared B2O3/SiO2@HC monolithic catalyst exhibits good catalytic performance at low boron oxide loading and achieves excellent propylene selectivity (86.0%), olefin selectivity (97.6%, propylene and ethylene) and negligible CO2 (0.1%) at 16.9% propane conversion under high GHSV of 345,600 ml·(g B2O3)−1·h−1, leading to a high propylene space time yield of 15.7 g C3H6·(g B2O3)−1·h−1 by suppressing the overoxidation. The obtained results strongly indicate that the boron-based monolithic catalyst can be properly fabricated to warrant the high activity and high throughput with its high gas/surface ratio and straight channels. 相似文献
10.
考虑到色噪声或低快条件下噪声特征值发散,导致基于特征分解的信源数估计方法得到的信号判据值和噪声判据值区分不明显,提出了一种基于加权特征投影的信源数估计方法;首先,为了使该方法可适用于低信噪比条件,对阵列接收数据的协方差矩阵进行降噪处理,并利用降噪后协方差矩阵所有特征值和特征向量构造了一个用来区分信号和噪声的加权空间矩阵;然后,将降噪后的协方差矩阵在该加权空间矩阵上投影,从而增大了信号判据值与噪声判据值的差异;最后,结合幂函数的缩放性构建了判决函数,进而实现信源数估计;通过理论分析和实验验证,该方法不仅适用于白噪声和色噪声条件,而且在低快拍和低信噪比条件下优势明显,在快拍数为10,信噪比分别为0 dB的白噪声和6 dB的色噪声条件下,该方法的成功检测概率均达到90%以上,同时该算法在信源数较多时效果鲁棒. 相似文献