从野生植物中提取黄酮类药物的探索

本实验对黄酮提取方法进行了研究比较,研究证明,煮沸法优于索氏提取法;所用提取剂,乙酸乙酯优于乙醇,并提出了进一步改进的设想.     

REIMERS,Fernando, and McGINN,Noel. 1997. Informed Dialogue: Using Research to Shape Educational Policy Around the World

International Review of Education -     

Social skills training with early adolescents: Effects on social skills, well-being, self-esteem and coping

This study discusses the educational effects of a social skills training on adolescents’ social skills, self-esteem, well-being and coping. A group of 14- to 16-year-old normal adolescents followed a social skills training based on social learning principles. A pre-test — experiment — post-test design was used and the group’s performance was compared with that of a non-intervention control-group. The training was given at school, and the data were collected by means of self-report measures. The results show that the training was successful in several respects: the adolescents’ social anxiety decreased, their social activity increased, their self-esteem improved, and they made more use of adequate coping-strategies. The implications of the results for different sub-groups of adolescents are discussed. Critical attention is also given to two other issues: the type of assessment used and the short-term nature of the evaluation.     

Comparing Teacher Assessment and Standard Task Results in England: the relationship between pupil characteristics and attainment

This study examines the 1992 National Curriculum assessment data from one large LEA in England in order to address the issue of equity. For comparison purposes we also present additional data obtained front the same sample of pupils on an NFER standardised word recognition test. The report focuses on the relative performance of gender, low income, linguistic, and special needs groups on a standardised reading test and the teacher (TA) and standard task (ST) performance assessments administered in 1992 to 7‐year‐olds as part of the national curriculum (NC) in England and Wales. The impact of schools and teacher effectiveness on student attainments scores is also examined and discussed. Briefly, the findings show that irrespective of the method of assessment, differences in attainment were found between most pupil groups investigated. However, importantly, only very modest evidence was found that particular methods of assessment appeared either to reduce or increase the differences in attainment and overall no clear patterns emerged. The findings are discussed in the context of various factors that may have an impact on the assessment of student attainment.     

A Canadian Perspective on Portfolio Use in Student Assessment

Portfolios can serve as a means of collecting information that can be seen as evidence for evaluating the achievement of students in classrooms. The use of portfolios has a long history although their general use in classroom assessment is a recent phenomenon. Portfolios are not widely used in large‐scale assessments; they are a classroom‐based phenomenon in Canadian schools. In this paper, we explore three themes related to portfolio use in the Canadian context. First, we consider examples of policies and procedures as recommended by Ministries of Education to illustrate the range of statements provided. Next, we review surveys of portfolio use and acceptance by teachers and, to a lesser degree, administrators. Finally, we describe and discuss three studies that have begun to investigate the use and interpretation of portfolios.     

Competition and the quality of public schools

A growing body of empirical research has provided provocative evidence that competition from private schools improves student achievement in neighboring public schools. However, this uniform conclusion has been based on fundamentally different empirical specifications. This study examines the importance of these different specifications by presenting new evidence on the relationship between public school quality and competition from private schools. This evidence is based on a unique data set that contains consistently defined high school graduation rates for the unified school districts in 18 states. The results indicate that empirical strategies which rely exclusively on ordinary least-squares (OLS) can lead to misleading inferences because of omitted variables bias and the simultaneous determination of the demand for private schools and public school quality. Nonetheless, two-stage least-squares (2SLS) estimates indicate that competition from private schools does have a positive and statistically significant impact on the high school graduation rates of neighboring public schools.     

Can Examinees Use a Review Option to Obtain Positively Biased Ability Estimates on a Computerized Adaptive Test?

Part of the controversy about allowing examinees to review and change answers to previous items on computerized adaptive tests (CATs) centers on a strategy for obtaining positively biased ability estimates attributed to Wainer (1993) in which examinees intentionally answer items incorrectly before review and to the best of their abilities upon review. Our results, based on both simulated and live testing data, showed that there were instances in which the Wainer strategy yielded inflated ability estimates as well as instances in which it yielded deflated ability estimates. The success of the strategy in inflating ability estimates depended on the ability estimation method used (maximum likelihood versus Bayesian), the examinee's true ability level, the standard error of the ability estimate, the examinee's ability to implement the strategy, and the type of decision made from the ability estimate. We discuss approaches to dealing with the Wainer strategy in operational CAT settings.