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21.
三七的傅里叶变换红外光谱鉴别技术 总被引：1，自引：0，他引：1
[目的]寻找简便快捷的中药材品质分级方法。[方法]利用傅里叶变换红外光谱法对5种不同等级的三七（Radix notoginseng）和三七花进行测定。[结果]三七和三七花的光谱在1 800~700 cm-1范围差别明显;在特定吸光度比值上也表现出明显差异,吸光度比A1 242/A2 928、A1 080/A2 928、A1 020/A2 928三七比三七花大,而A1 643/A2 928、A1 416/A2 928、A1 372/A2 928三七比三七花小。不同等级三七的红外光谱峰形和峰位基本相同,但在特征吸收峰上的吸光度比值上存在着差别。不同头数的三七,其吸光度比A1 640/A2 928、A1 240/A2 928、A1 080/A2 928、A1 022/A2 928、A928/A2 928表现出的规律为20头〉40头〉60头〉80头〉100头。[结论]各样品的红外光谱,主要特征吸收峰上吸光度比的差异,说明它们中所含主要物质基本相同,但主要物质含量有差异。红外光谱法在鉴别中药材方面具有方便、快速、无损的特点,有望成为三七等级以及产地鉴别的标准方法。 相似文献
22.
康复景观作为风景园林学一个较为新兴的领域,受到了越来越多的关注,研究方向日益分化。为了厘清康复景观近十年来发展的现状及动向,推动后疫情时代国内康复景观研究的深入,基于国内外文献核心数据库,运用可视化软件（CiteSpace）进行分析,从康复景观健康效益,影响机制以及研究对象等热点方面进行了疏理,总结了康复景观实证研究的主要方法和前沿技术手段,提出研究的不足以及未来可能的发展方向。 相似文献
23.
基于光谱技术的褐壳血斑蛋鉴别方法研究 总被引：2，自引：0，他引：2
血斑蛋是一种带有血丝的异常蛋。通过自制的鸡蛋内部品质光谱检测系统,采集40个正常蛋和60个人工注射血样的血斑蛋的可见/近红外光谱,研究比较了3种不同的血斑蛋判别方法:传统的血值判别法、偏最小二乘判别法(DPLS)以及融合光谱信息与蛋壳颜色信息的最小二乘支持向量机(LS-SVM)判别法,结果表明基于颜色信息融合的最小二乘支持向量机的判别结果明显优于传统的血值判别法,正常蛋的判别正确率为90%,血斑蛋的判别正确率为91.7%,证明了此方法可用于褐色蛋的血斑检测。 相似文献
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25.
提出了一种快速、准确鉴别茶饮料的新思路。采用美国ASD公司的可见-近红外光谱仪对3种茶原料（龙井茶、乌龙茶和铁观音茶）的饮料进行光谱分析。采用多元散射校正（MSC）方法对样本数据进行预处理,再用主成分分析法提取光谱数据的特征值。通过交互验证确定最佳主成分数为5,作为BP神经网络的输入变量,不同原料茶饮料作为输出变量,建立3层人工神经网络鉴别模型,并用模型对20个预测样本进行预测。模型的回判鉴别率达到100%,模型的预测鉴别率达到98.33%。结果表明,基于BP神经网络的近红外光谱鉴别不同原料茶饮料的方法是可行的。 相似文献
26.
王厚天 《东北林业大学学报》1988,(4)
本文通过计算分析给出了一个判别钢筋砼偏心受压构件大、小偏心受压的方法。该法简单实用,且较为准确。它适用于按新的公路桥涵设计规范(JTJ023-85)计算钢筋砼偏心受压构件。 相似文献
27.
The appearance, taste, aroma and texture of food products, including gluten-free bakery products, is very important predictors for whether or not such products would be acceptable for consumers. Food companies that manufacture and supply gluten-free food and beverage products need to utilise a variety of sensory tools for decision making during product development, evaluation of ingredients, processes and products. The six steps to Sensory Evaluation process is a simple to use, stepwise approach to select the right tools to answer questions. Different sensory evaluation tools are used to address questions of the three different types (1) Are two or more products the same or different? (2) What is the nature and size of differences among products? and (3) What are consumers' opinions about a product/s? It is the intention that the discussion in this review would stimulate ideas for application of more advanced sensory tools to further understanding to enhance development of gluten-free foods and ingredients. Some suggestions for future sensory studies on gluten-free bakery products are presented. These include: more research on the acceptance and perception of the sensory properties of gluten-free product options by both coeliac and non-coeliac consumers at different life stages; and evaluation of the sensory properties of gluten-free products in combination with other products, accompaniments and within meals. Also, sensory profiling of the unique properties of naturally gluten-free bakery products, as well as studies to optimize acceptance of these in wider consumer markets. The application of the tools in a systematic manner based on the six steps to sensory testing process presented here will assist researchers to obtain powerful results to answer research questions. 相似文献
28.
以＂歧视经济学＂的分析框架为基础,建立了一个农村劳动力向城市转移的模型,研究农村劳动力转移对城乡收入的影响。结果表明,农村劳动力向城市的转移能够提高城乡收入并在一定程度上缩小城乡收入差距,但由于我国城市资本存量远大于农村资本存量,农村劳动力转移并不能完全消除城乡收入差距。要提高我国农村的收入水平,缩小城乡收入的差距,政府必须双管齐下：一方面大力推动农村劳动力向城市的转移,改变目前城乡二元劳动力市场结构的状况;另一方面,加大对农村地区的投入,促进农村资本存量的增长,以便在劳动力转移的过程中进一步提高农村居民收入。 相似文献
29.
Temporal and spatial changes in parameters of fast chlorophyll fluorescence kinetics (ground fluorescence, Fo and maximal
fluorescence, Fm) and red/NIR reflectance were assessed with a Pulse-Amplitude-Modulated (PAM)-Imaging system on a daily basis
over a period of 2 weeks following inoculation of wheat leaves with powdery mildew and leaf rust. The early detection of these
infections by means of fluorescence imaging was possible 2–3 days before visual symptoms or significant changes in normalised-differenced-vegetation
index (NDVI) became apparent. The initial infection of both fungi caused an increase in Fo and decrease in photochemical efficiency
(Fv/Fm, Fv/Fo). The appearance and development of fungal pustules was accompanied by reduction in Fo and Fm. This resulted
mainly from lower absorption of fluorescence exciting light by the leaf mesophyll due to the shielding effect of fungal mycelium,
and to lesser extent from the chlorophyll breakdown underneath pustules. Among the evaluated fluorescence parameters, Fv/Fo
displayed the most pronounced response to both kinds of infection. Mildew infection influenced chlorophyll fluorescence neither
in the direct vicinity of mycelium nor in the apparently healthy leaf regions. Rust infected plants, in contrast, displayed
significantly reduced photochemical efficiency Fv/Fm and Fv/Fo in chlorotic tissue around pustules. The same, but less pronounced
tendency was found in the apparently healthy regions of rust infected leaves in the last days of the experiment. Dark adaptation
of leaves proved to be necessary for accurate detection of both pathogen infections by means of fluorescence imaging. Additional
experiments are needed to estimate the potential of this technique for remote sensing under field conditions. 相似文献
30.
In this study, the seeds of open-pollinated winter rapeseed cultivars, hybrid winter rapeseed cultivars, open-pollinated spring rapeseed cultivars and hybrid spring rapeseed cultivars were investigated. The physical, optical, mechanical, geometric and image texture properties of rapeseeds were compared. Statistical models were developed based on the analyzed parameters to discriminate between seed groups. Most parameters effectively discriminated between cultivars of winter and spring rapeseed, including true density, porosity, L*, a*, b*, and spectral values at 400 nm, 470 nm, 500–530 nm, 560–620 nm, 640–650 nm and 690 nm. Four homogeneous groups were identified based on linear dimensions: F (surface area), S (width) and shape factors W6 (circularity ratio), Rb (Blair-Bliss coefficient) and W13 (roundness). No statistically significant differences in the mean values of hardness or area under the force-displacement graph were observed between seed groups. The model developed based on image texture variables from channel Y (luminance) was characterized by the highest discrimination accuracy of 82–87%. The experimental groups were classified with 89–92% accuracy in the model combining the best variables from each group of physical parameters. Total classification accuracy in neural networks reached 75% for a validation set comprising geometric properties and 91–92% for a validation set containing physical characteristics. 相似文献