探讨独立重复试验及其概率公式

独立重复试验,也叫做贝努里（Ber—noulli,瑞士数学家和物理学家）试验,是在同样的条件下重复地,各次之间相互独立地进行的一种试验．这种试验在理论上和实践上都十分有用．然而,笔者在教学中发现很多学生对独立重复试验及其概率公式缺乏深入理解,教科书和很多参考资料对此也未深入全面阐述,故很多学生处理这类问题,容易程式化,硬套公式,条件稍作变化便不知所措．     

食物中维生素E含量的快速荧光测定

本文用正交试验方法探讨了粮食、食品、饲料、蔬菜、水果等食物中维生素E荧光测定过程中的各种条件,用0.1M盐酸—乙醇混合溶液代替常规的有机溶剂如乙醚或石油醚(30—60℃)进行样品处理,且用分析纯的石油醚(30—60℃)代替常用的乙烷作萃取剂,在λ_(ex)295nm/λ_(eM)340nm处测定维生素E。经多次试验,结果满意,测定食物中维生素E的相对偏差为2.0—5.0％,维生素E的平均回收率为99.2％。     

双酶法水解寻氏肌蛤蛋白制备抗氧化肽的研究

文章以寻氏肌蛤为原料制备抗氧化肽,研究木瓜蛋白酶—复合蛋白酶双酶法酶解寻氏肌蛤的工艺条件。以1,1-二苯基-2-苦肼基(DPPH)自由基清除率为测定指标,通过单因素和正交试验确定双酶法制备抗氧化肽的最佳条件。结果显示:pH6.0,酶比例1∶1,[E]/[S]8%,酶解温度60℃,酶解时间6.5h为最佳酶解条件。验证试验表明,在此条件下,抗氧化肽对DPPH自由基清除率为68.70%。     

对独立重复试验概率问题的探讨

独立重复试验,也叫做贝努里（Ber—noulli,瑞士数学家和物理学家）试验,是在同样的条件下重复地、各次之间相互独立地进行的一种试验．在这种试验中,每一次试验只有两种结果,即某事件要么发生,要么不发生,并且任何一次试验中发生的概率都是一样的,这种情况在实际问题中是很多的．例如,在产品的抽样检验中,要么抽到合格品,要么抽到不合格品;在一定条件下,种子要么发芽,要么不发芽,等等．笔者在教学中发现很多学生对独立重复试验及其概率公式缺乏深入理解,     

催化湿式氧化技术在有机化工废水中的试验研究

有机化工废水普遍具有COD浓度高、含盐量高、难生物降解等特点,本试验主要针对高浓度有机化工废水进行研究,结果表明催化湿式氧化技术对高浓度有机化工废水有较好的处理效果。在270℃、8MPa条件下反应时间40—60min,原水COD浓度在20000—100000mg/l,COD去除率可达85%以上。     

木屑—硫酸浸出软锰矿工艺实践

研究了木屑—硫酸法直接浸出软锰矿的新工艺方法,并对该法的原理和工艺条件进行了较详细的探讨。通过单因素实验找出软锰矿浸出的最佳条件,以推进我国锰矿浸出率的实验研究。通过此次单因素实验我们可以从试验的结果得出：软锰矿中锰的浸出率受到软锰矿与木屑用量之比、软锰矿质量与硫酸体积之比、硫酸浓度、浸出温度及浸出时间等因素的影响。木屑—硫酸法直接浸出软锰矿的方法在较佳的工艺条件下,锰的浸出率可达93%以上。     

大型实对称特征值问题的块Jacobi-Davidson方法的不精确求解

块Jacobi—Davidson方法是计算大型实对称矩阵特征值问题的有效方法,可解决矩阵存在重特征值和密集特征值情况时的计算问题．块Jacboi—Davidson算法分为内外两层迭代,外层迭代计算矩阵特征对,内层迭代求解校正方程组,计算量主要花费是校正方程组的求解．针对校正方程的不精确求解,提出了几种构造预条件子的块不完全分解方法,并通过数值试验,对多种预条件子的效果进行比较．     

癸酸酰基甘氨酸钠的合成

以樟树籽仁油为原料,提取天然中碳链脂肪酸癸酸与甘氨酸在碱性条件下,采用肖顿—鲍曼法合成癸酸酰基甘氨酸钠。通过单因素试验和正交试验,优选合成癸酸酰基甘氨酸钠表面活性剂的最佳工艺条件。重点考察反应温度、投料比、丙酮用量、反应时间对缩合反应的影响。结果表明:癸酸酰基甘氨酸钠最佳合成工艺条件为反应时间3 h,投料比为2:1,反应温度15℃,丙酮与水体积比为2.5:1,在此反应条件下,产物的收率可达到68%,同时通过红外、质谱等分析手段对所合成的化合物进行结构分析鉴定。     

探讨独立重复试验及其概率公式

独立重复试验,也叫做贝努里（Ber—noulli,瑞士数学家和物理学家）试验,是在同样的条件下重复地、各次之间相互独立地进行的一种试验．这种试验在概率论中占有相当重要的地位,因为随机现象的统计规律性只有在大量独立重复试验中才能显示出来．其次,在n次独立重复试验中某事件恰好发生k（k=0,1,2,…,n）次的概率,组成离散型随机变量的一种相当重要的概率分布——二项分布．在这种试验中,     

在溴化十六烷基三甲基铵存在下碘化钾——结晶紫体系浮选分离镉的研究

研究了在溴化十六烷基三甲基铵存在下碘化钾—结晶紫体系浮选分离镉的行为及其与常见离子分离的条件。试验表明,在一定条件下,能使Cd(Ⅱ)与常见离子Zn(Ⅱ)、Fe(Ⅲ)、Co(Ⅱ)、Ni(Ⅱ)、Mn(Ⅱ)、Al(Ⅲ)分离。     

影响冬枣贮藏保鲜的关键环境因子

从贮藏温度、环境湿度、气体成分和微生物作用等四个环境因子出发,探讨了影响冬枣保鲜的关键问题并提出了相应的解决办法.     

Processing errors in conditional and biconditional problem solving behavior

Students (N = 237) in each of grades 8, 10, 12, and 14 were randomly divided into three groups and administered either a 16-item multiple-choice test of conditional syllogisms, or a 16-item test of biconditional syllogisms, or a 32-item test with both conditional and biconditional syllogisms. Results provided within experiment and within-subjects comparison of responses on conditional and biconditional syllogisms. A comparison of response patterns on conditional items with responses on actual biconditional items provided a direct test of the previously hypothesized biconditional misinterpretation of conditional problems. These analyses confirmed the strong tendency of subjects (across grades) to interpret conditional syllogisms biconditionally. Surprisingly, performance on biconditional problems does not improve systematically with age; in fact, college sophomores perform only slightly better than eighth graders. With regard to conditional syllogisms, results confirmed previously described performance variations across forms of both major and second premises and also replicated an unusual reversed developmental trend on the problem which involves denying the consequent.     

Conditional Standard Errors of Measurement for Scale Scores

Standard errors of measurement of scale scores by score level (conditional standard errors of measurement) can be valuable to users of test results. In addition, the Standards for Educational and Psychological Testing (AERA, APA, & NCME, 1985) recommends that conditional standard errors be reported by test developers. Although a variety of procedures are available for estimating conditional standard errors of measurement for raw scores, few procedures exist for estimating conditional standard errors of measurement for scale scores from a single test administration. In this article, a procedure is described for estimating the reliability and conditional standard errors of measurement of scale scores. This method is illustrated using a strong true score model. Practical applications of this methodology are given. These applications include a procedure for constructing score scales that equalize standard errors of measurement along the score scale. Also included are examples of the effects of various nonlinear raw-to-scale score transformations on scale score reliability and conditional standard errors of measurement. These illustrations examine the effects on scale score reliability and conditional standard errors of measurement of (a) the different types of raw-to-scale score transformations (e.g., normalizing scores), (b) the number of scale score points used, and (c) the transformation used to equate alternate forms of a test. All the illustrations use data from the ACT Assessment testing program.     

Processing of identity and conditional relations in monkeys (Cebus apella) and pigeons (Columba livid)

Learning & Behavior - As a test of differential processing of identity and conditional relations, subjects were first highly trained on 0-sec delay identity matching (IM) and conditional...     

Stepping Up Test Score Conditional Variances

In Woodruff (1990), I derived estimates for the conditional standard error of measurement in prediction (CSEMP), the conditional standard error of estimation (CSEE), and the conditional standard error of prediction (CSEP). My original estimates assume that the conditional residual error score variances and the conditional residual true score variances, obtained from the regression of an observed score onto a parallel observed score, obey the same step-up rules as do the marginal error score variance and the marginal true score variance. The present article derives alternative estimates for the various test score conditional variances that do not depend on these assumptions.     

Generalization of the Lord‐Wingersky Algorithm to Computing the Distribution of Summed Test Scores Based on Real‐Number Item Scores

With known item response theory (IRT) item parameters, Lord and Wingersky provided a recursive algorithm for computing the conditional frequency distribution of number‐correct test scores, given proficiency. This article presents a generalized algorithm for computing the conditional distribution of summed test scores involving real‐number item scores. The generalized algorithm is distinct from the Lord‐Wingersky algorithm in that it explicitly incorporates the task of figuring out all possible unique real‐number test scores in each recursion. Some applications of the generalized recursive algorithm, such as IRT test score reliability estimation and IRT proficiency estimation based on summed test scores, are illustrated with a short test by varying scoring schemes for its items.     

The harmful aspect of teacher conditional support on students’ self-perception of school competence

When children perceive a conditional support, they only feel loved and encouraged for their ability to meet others’ standards. This may lead them to develop high sensitivity to errors and anxiety and low perception of competence. In this study, we examined the relationship between the perceived conditional support from teacher and children’s self-perception of school competence. We tested the mediating effect of sensitivity to errors and test anxiety in the relationship between teacher conditional support and children’s perception of school competence. Participants were 524 elementary school students (aged 9–10 years). The results showed that the greater the extent to which the children perceived conditional support from their teacher, the lower their self-perceived scholastic competence. They also confirm that this relationship was mediated by sensitivity to errors and test anxiety.     

中国股市价格的波动性研究——基于沪深300指数的GARCH族模型

本文运用GARCH族模型,以中国A股市场较有代表性的沪深300指数作为研究对象,对中国股市价格波动中存在的条件异方差性和正负冲击对股价波动影响的不对称性进行检验,结果表明在样本期（2005年4月8日至2009年5月22日）内,我国股价波动存在明显的条件异方差性,但是并未发现正负冲击对股价波动影响的不对称性。     

Dubious Sovereignty: Federal Conditions of Aid and the No Child Left Behind Act

The No Child Left Behind Act (NCLB) represents the greatest extension to date of Federal authority over public school governance. In NCLB, Congress used its conditional spending power to push states and localities into enacting particular kinds of testing and accountability policies. This article places NCLB in the context of Congress's generally increasing willingness to exert itself via conditions attached to federal financial aid. It also analyzes the implications of NCLB for federalism and intergovernmental relationships in education governance.     

Feature-positive discriminations during a spatial-search task with humans

During feature-positive operant discriminations, a conditional cue, X, signals whether responses made during a second stimulus, A, are reinforced. Few studies have examined how landmarks, which can be trained to control the spatial distribution of responses during search tasks, might operate under conditional control. We trained college students to search for a target hidden on a computer monitor. Participants learned that responses to a hidden target location signaled by a landmark (e.g., A) would be reinforced only if the landmark was preceded by a colored background display (e.g., X). In Experiment 1, participants received feature-positive training (+←YB/ XA→+/A?/B?) with the hidden target to the right of A and to left of B. Responding during nonreinforced transfer test trials (XB?/YA?) indicated conditional control by the colored background, and spatial accuracy indicated a greater weighting of spatial information provided by the landmark than by the conditional cue. In Experiments 2a and 2b, the location of the target relative to landmark A was conditional on the colored background (+←YA/ XA→+/ ZB→+/ +←C /A?/B?). At test, conditional control and a greater weighting for the landmark’s spatial information were again found, but we also report evidence for spatial interference by the conditional stimulus. Overall, we found that hierarchical accounts best explain the observed differences in response magnitude, whereas spatial accuracy was best explained via spatial learning models that emphasize the reliability, stability, and proximity of landmarks to a target.