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1.
Three methods of standardizing magnitude estimation data, external calibration, modulus normalization, and equalization were examined using a sensory evaluation data set arising from an incomplete block experiment testing five gels of varying firmness. Both the original data and a logarithmic transformation of the data were analyzed. Instrumental data were also collected. When untransformed data were analyzed the method of standardization profoundly affected tests of significance, coefficients of variation (%CV), and estimation of the power function relating the sensory data to the concentration of the underlying gel. The logarithmically transformed data lead to results independent of the standardizing technique and with higher F-ratios, lower %CV's and normally distributed errors.  相似文献   

2.
Analysis of variance was applied to 3,107 magnitude estimations (ME) obtained upon 173 panelists (16 panels) evaluating the areas of 18 geometric figures. As Butler et al. (1987) pointed out, if a full ANOVA is applied to the values transformed to logarithms, there is no need to re-scale, i.e., normalize the values as is usually done. In fact, even with re-scaling, total variability is not accounted for adequately unless all the sources of variation are partitioned out in the analysis. Under some circumstances, re-scaling is needed: some laboratories re-scale to the arithmetic mean, others to the geometric one. The error was somewhat greater when the data were re-scaled to the arithmetic mean. The residuals of the ME values transformed to logarithms conformed essentially to a normal distribution. Kurtosis was greater, 5.30; otherwise the distribution was close to a log normal one. The average coefficient of variation was <10%.  相似文献   

3.
Contextual shifts were observed for sweetness of a fruit beverage and for estimated tactile roughness of sandpapers. Midrange stimuli were judged to be less intense in the context of stronger items and more intense in the context of weaker items, a contrast effect. The use of a reference standard decreased the size of the contrast shift for the labeled magnitude scale but not for magnitude estimation.  相似文献   

4.
Recent studies comparing magnitude estimation to other scaling methods have been criticized for failure to submit the data to logarithmic transformation before statistical analysis, a procedure which can improve the ability of magnitude estimation scaling to differentiate among products. Data from one of these studies was available for re-analysis, which was conducted both with and without logarithmic transformation of magnitude estimation, category scales and line scales. The ability of magnitude estimation to differentiate among products was improved by log transformation, while the other methods were not. Improvements were associated in pan with reductions in positive skew and improved approximation of the normal distribution. In spite of this improvement, magnitude estimation remained slightly inferior to the other methods especially in the hands of an untrained consumer sample.  相似文献   

5.
Judges rated the intensity of NaCl solutions using magnitude estimation and the labeled magnitude scale. They performed under four response conditions that varied in reliance on memory: (1) verbal response, (2) written response with no retasting and the response sheet removed, (3) written response with a single response sheet which allowed past scores to be reviewed and amended but with no retasting, (4) the same as '3' but with retasting. Discrimination errors tended to decrease from conditions '1' through '4' yet the major and significant effect was allowing judges to retaste stimuli. The effects of how forgetting lowered discrimination were discussed in the context of experimental design and the absolute versus relative cognitive models of scaling.  相似文献   

6.
利用水稻冠层光谱特征诊断土壤氮素营养状况   总被引:6,自引:0,他引:6       下载免费PDF全文
系统测定了不同秸秆还田和氮肥处理下水稻(Oryza sativa)关键生育期的冠层反射光谱及土壤速效氮含量,并对两者之间的关系进行了详尽的分析。结果表明: 土壤速效氮含量在整个水稻生育期内均与可见光波段反射率呈负相关,与近红外波段反射率呈正相关。归一化及比值植被指数与土壤速效氮含量有更好的相关性,分蘖期要优于其它生育时期,以870、1 220 nm波段与560和710 nm波段的组合最佳,但两者的关系易受土壤等背景的干扰。而转换型土壤调节植被指数TSAVI能较好地消除分蘖期土壤背景的影响,两生态点可用统一的方程来拟合,用该研究中所筛选出的最佳波段组合计算出的TSAVI的表现更好,尤其是870 nm波段和710 nm波段的组合,决定系数(R2)由0.46提高到0.60。抽穗期和灌浆期由1 220和760 nm计算的比值指数R(1 220, 760)和新土壤调节植被指数SAVI(1 220,760)与土壤速效氮含量的关系则不受生态点的影响,可用统一回归方程来拟合。这说明水稻冠层反射光谱可以用来评价稻田土壤肥力状况,但仍需进一步研究。  相似文献   

7.
本文介绍了一个在微机(IBM PC)上实现的、用于核酸顺序分析的计算机程序系统.该系统由三个层次和18个功能块构成,菜单及人机对话使得用户能较快地掌握和使用它.在编程中,采用了树结构、先进后出栈和稀疏矩阵等数据结构技巧,运用了Bayes法等统计分析方法,Kruskal算法和Floyd算法等一系列图论方法也被得到应用,这个软件系统的推出对于分子生物学研究具有一定的积极作用.  相似文献   

8.
野大豆叶绿体在低温(77K)时出现三条荧光发射谱带,它们来源于不同的色素蛋白复合体。 在纳秒脉冲激光激发下,捕光天线色素的相对荧光量子产额,随激光强度的增加有明显下降现象。用激子理论和动力学方程讨论和计算了激子扩散参量。指出激子转移是随机的,非相干的。  相似文献   

9.
林分生长量估测模型的研究   总被引:2,自引:1,他引:2  
本文用ARIMA(2,2,0)序列模拟了林分的平均生长过程,给出了落叶松(LarixolgensisHenry)人工林林分在树高、胸径、材积三个指标上平均总生长量的2阶求和自回归滑动平均模型,经模型残量的自相关检验及预测效果检验,估测效果良好.  相似文献   

10.
削偶合今祖法的提出   总被引:8,自引:4,他引:4  
李靖炎 《动物学研究》1992,13(4):387-396
以低等真核生物的5.8S rRNA为材料进行研究。发现在用今祖法消除了进化速度之差的影响所得到的差异矩阵d'中,各组理应彼此相等的数值会因核苷酸偶合的影响而成为不等值的。取各组中各自的的最大值作为受偶合的影响最小者,以之对今祖法所得到的分枝型式进行校正,即可得到更为正确的结果。在此基础上提出了对差异矩阵d'进行最大值成聚以代替原法中的平均值成聚的削偶合今祖法。新法在结果的正确性、稳定性和一致性上都优于原法。  相似文献   

11.
柑桔基因转化新方法的研究   总被引:14,自引:0,他引:14  
尽管应用基因转化进行果树品种改良已日益引起重视,但是在受体的应用和转化方法上还存在着诸多困难。一方面,大多数果树尚不能从细胞或原生质体再生成完整植株,即使少数已可以再生的果树树种,也并非众多品种都能再生成功,而是存在着明显的基因型差异性。同时,还有再生植株童期过长的问题。另一方面,目前在植物基因转化中常用的两种方法即DNA直接吸入法和农杆菌介导的载体法,若以细胞或原生质体为受体,不仅存在再生困难的问题,而且再生过程费时长;若以叶盘、愈伤组织或珠心组织等为受体,既需要在转化后除去农杆菌,又需要排除转化与非转化组织的嵌合性。这些因素都大大地限制了基因转化在果树中的应用。因此,根据多年生果树的生长特点,建立一种适用的基因转化技术已成当务之急。本文采用农杆菌介导的附体腋芽转化-离体扩繁鉴定的方法,成功地将GUS基因转入沙田柚。结果证明这是一种简单、快速、高效的基因转化方法。  相似文献   

12.
13.
14.
Previously proposed methods of determining physical condition of game animals are discussed. A total of 286 African ungulates of ten species were collected and autopsied, and several indices of physical condition were calculated. Selected indices were correlated with total fat or total lean percentages or both. Of the methods discussed and evaluated, those based upon fat deposited in particular areas were more accurate or feasible than those based upon blood constituents, adrenal weights, or body weight/skeletal measurement ratios.  相似文献   

15.
A METHOD FOR THE QUANTITATIVE ESTIMATION OF CYTOPLASMIC STRUCTURES   总被引:1,自引:0,他引:1       下载免费PDF全文
A sampling procedure and calculations are described by which electron micrographs of cytoplasmic structures may be quantitatively analyzed. The relative areas occupied by formed bodies and by the "membrane space," the remainder of the cytoplasm, are evaluated. A method for making a measurement of the quantity of endoplasmic reticulum or other membrane profiles is described. The technic and results are illustrated with normal rat liver cells.  相似文献   

16.
The following statement regarding requests for transfer of patients from one county to another for certain types of therapy not available locally, was prepared by the Cancer Commission of the California Medical Association.  相似文献   

17.
A method is described, which is applicable to cell renewal systems with an anatomical structure in which all cell locations may be uniquely mapped. Its use is demonstrated on the rat incisor inner enamel epithelium, which forms a one cell thick column in the sagittally sectioned tooth. Cells born in the apical part of the column migrate toward the distal end of the tooth, where they mature. As the cells migrate along the column, they traverse the various cell cycle phases. The present study has been designed to estimate the probability of a cell being in a given phase; all cells touching the basement membrane were numbered, and the number of cells separating any two cells was taken as a measure of distance. Since generally all cells move in one direction (lateral cell migration may occur), it is possible to solve the problem with the aid of functions describing the renewal counting stochastic process in which cell distance serves as an independent variable. The method predicts labelled cell and mitotic rates which agree with those estimated in the usual way. It was then utilized to estimate the fraction of cells in G2.  相似文献   

18.
The most widely used scale for assessing food liking or disliking is the 9‐pt hedonic scale. Unfortunately, this affective scale suffers from problems related to unequal scale intervals and the underuse of end categories, which results in a reduced ability to differentiate among extremely well liked or extremely disliked foods. Magnitude estimation avoids these problems while enabling ratio statements to be made about the data. However, it does not provide absolute ratings of liking/disliking and can be difficult for some consumers to use. We report here on the development of a labeled affective magnitude scale (LAM) scale that has advantages over both the 9‐pt hedonic scale and magnitude estimation. Forty‐four semantic labels were scaled for their affective meaning by subjects using modulus‐free magnitude estimation. The geometric mean magnitude estimates obtained for each semantic label were used to construct a series of labeled affective magnitude scales by spacing the labels along a visual analogue scale according to their obtained semantic values. Reliability and sensitivity studies were conducted to assess the effects of alternative semantic and numeric labels. The results of these studies led to the choice of a scale format that uses verbal labels that are consistent with the 9‐pt hedonic scale. The labeled affective magnitude (LAM) scale was compared to the hedonic scale and magnitude estimation in several food preference and acceptability tests. The LAM was shown to have equal reliability and sensitivity to the hedonic scale, provided somewhat greater discrimination among highly liked foods, and resulted in data that were similar to magnitude estimation in terms of the obtained ratios among rated stimuli. The LAM scale was also judged by consumers to be as easy to use as the 9‐pt hedonic scale and significantly less difficult than magnitude estimation.  相似文献   

19.
 本文根据植物群落主成分分析三维排序与植物群落类型的关系,应用多元线性模型理论建立了江苏省盐城珍禽自然保护区盐土植物群落类型与环境的多元线性模型。研究结果表明该模型较好地描述了该保护区植物群落分布的格式,同时,也有助于更明确地揭示植物群落主成分分析各排序轴所反映的环境梯度。  相似文献   

20.
南京汤山直立人颅容量的推算   总被引:4,自引:4,他引:0       下载免费PDF全文
张银运  刘武 《人类学学报》2003,22(3):201-205
以耳上颅高推算现代人颅容量的公式可适用于汤山直立人1号头骨的颅容量的推算。汤山直立人1号头骨的颅容量推算值为871ml,与周口店直立人3号头骨的颅容量值相近,提示了汤山直立人的年代“早于40万年或更早”的看法更可取些。  相似文献   

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