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排序方式: 共有1797条查询结果,搜索用时 46 毫秒
81.
Pinon A Alexandre V Cupferman S Crozier A Vialette M 《International journal of cosmetic science》2007,29(2):111-119
The influence of ethanol on the behaviour of Pseudomonas aeruginosa and Staphylococcus aureus strains was evaluated throughout this study. Strains of different origin were used: collection, clinical and industrial strains were selected. Concentrations of ethanol from 0 to 20% (v/v) were evaluated by automated optical density measurements and by enumeration. When growth conditions were observed, predictive microbiology models were used to assess quantitatively for the ethanol effect. Primary modelling of kinetics was performed to determine growth rate values; secondary modelling was performed on these growth rates as influenced by ethanol, and minimum inhibitory concentrations of ethanol were determined for each strain. Staphylococcus aureus strains were more resistant to ethanol than P. aeruginosa strains, in growth conditions as well as in inactivation conditions. Furthermore, clinical S. aureus strains were more resistant than the collection strain. The method was promising for management of microbiological safety in cosmetics. 相似文献
82.
通过交通大学和东京大学近代特定时期校门建筑的比较和分析,试图揭示两者之间所体现的文化渊源,同时引发一些思考. 相似文献
83.
Ana I.R.N.A. Barros Fernando M. Nunes Berta Gonçalves Richard N. Bennett Ana Paula Silva 《Food chemistry》2011
In this work the total vitamin C contents (ascorbic acid + dehydroascorbic acid) and antioxidant activity of raw and cooked chestnuts was evaluated. The vitamin C contents of raw chestnuts varied significantly between the different cultivars (cv) studied and it varied from 400 mg/kg dry weight (cv Lada) to 693 mg/kg dry weight (cv Martaínha). The different cultivars behave differently during the cooking process concerning the loss of vitamin C. A significant decrease in the vitamin C content of the chestnuts was observed, 25–54% for the boiling process and 2–77% for the roasting process. Boiled and roasted chestnuts can be good sources of vitamin C since it may represent 22.4%, 16.2%, 26.8% and 19.4%, respectively, of the recommended dietary intake for an adult man and woman. The cooking process significantly changed the antioxidant activity of the chestnuts. A difference was observed between the cultivars during the cooking processes, concerning the antioxidant activity. For the raw chestnuts the variation in vitamin C content of the chestnuts explains 99% of the antioxidant activity variation but for the roasted and boiled chestnuts this percentage significantly decreases to 51% and 88%, respectively. Although a high antioxidant activity is still present in the cooked chestnuts, the cause for this antioxidant activity is less dependent on the vitamin C content of the chestnuts, probably due to the conversion of ascorbic acid to dehydroascorbic acid. The increase in gallic acid during the cooking process, presumably transferred from the peels to the fruit, also contributes to the high antioxidant activity observed for the cooked chestnuts. 相似文献
84.
提出一种基于希尔伯特—黄变换(HHT)—线性判别分析(LDA)的枸杞产地电子舌辨识方法。以宁夏、新疆、甘肃、青海4个产地的枸杞为试验材料,采用伏安电子舌采集不同产地枸杞的"指纹图谱"信息,利用集合经验模态分解(EEMD)对电子舌原始信号进行多尺度分解得到一组本征模态函数(IMF),分别求取其奇异谱熵和Hilbert边际谱作为特征向量。在该基础上,利用LDA建立枸杞产地非线性组合预测模型。试验结果表明,HHTLDA与分别采用特征点提取(FPE)、主成分分析(PCA)和离散小波变换(DWT)的算法相比,具有更好的分类效果。对未知产地枸杞的总体分类精度和kappa系数分别达到98%和0.973,均表明该模型具有较好的鉴别效果。 相似文献
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Ming-Feng Lu Hong-Fang Ji Ting-Xuan Li Shou-Kai Kang Yue-Jie Zhang Jue-Fei Zheng Tian Tian Xi-Shuai Jia Xing-Ming Lin Hong-Yu Zhang 《International journal of molecular sciences》2013,14(6):12843-12852
Primitive proteins are proposed to have utilized organic cofactors more frequently than transition metals in redox reactions. Thus, an experimental validation on whether a protein constituted solely by early amino acids and an organic cofactor can perform electron transfer activity is an urgent challenge. In this paper, by substituting “late amino acids (C, F, M, T, W, and Y)” with “early amino acids (A, L, and V)” in a flavodoxin, we constructed a flavodoxin mutant and evaluated its characteristic properties. The major results showed that: (1) The flavodoxin mutant has structural characteristics similar to wild-type protein; (2) Although the semiquinone and hydroquinone flavodoxin mutants possess lower stability than the corresponding form of wild-type flavodoxin, the redox potential of double electron reduction Em,7 (fld) reached −360 mV, indicating that the flavodoxin mutant constituted solely by early amino acids can exert effective electron transfer activity. 相似文献
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为考察近红外光谱对玉米种子的品种识别与产地识别性能,采集了8个玉米品种波长范围为12 000~4 000 cm-1的近红外光谱数据,并基于此数据研究了基于PCA的光谱数据特征的提取方法,并探讨了神经网络(ANN)和支持向量机模型(SVM)在品种识别上的性能,进一步研究了玉米品种的产地识别技术,且比较了传统可见光图像的品种识别。研究发现:基于近红外的玉米品种识别,在6个主分量的情况下整体上性能达到90%以上;SVM算法较ANN算法稳定可靠,更适合于小样本情况下的光谱分析;基于光谱的品种识别与基于可见光图像的品种识别效果相当;另外发现同一品种在不同产地上其光谱特征差别较大,据此可以应用光谱进行产地鉴别,鉴别力达到95%以上。本研究所构建的方法对玉米品种识别和产地识别具有积极意义。 相似文献
90.