由3-氨基-2-卤代-2-烯亚胺制备3-卤代喹啉     

PedroJ.Campos  谭成权  MiguelA.Rodriguez  ElenaAón 《大连大学学报》1996,(4)

紫外光照射3-氨基-2-卤代-2-烯亚胺生成3-卤代喹啉,该反应对氯代衍生物是定量反应(>95％),溴代和碘代喹啉可以较高产率从反应粗产物中容易地分离出来,由于这一反应温和、简便、干净和快速,我们预期这一反应过程将被广泛应用。  相似文献   

Exploring affiliation network models as a collaborative filtering mechanism in e-learning     

Daniel Rodríguez  Miguel Ángel Sicilia  Salvador Sánchez-Alonso  Leonardo Lezcano  Elena García-Barriocanal 《Interactive Learning Environments》2013,21(4):317-331

The online interaction of learners and tutors in activities with concrete objectives provides a valuable source of data that can be analyzed for different purposes. One of these purposes is the use of the information extracted from that interaction to aid tutors and learners in decision making about either the configuration of further learning activities or the filtering of learning resources. This article explores the use of an affiliation network model for such kind of purposes. Concretely, the use of techniques such as blockmodeling – a technique used to derive meaningful patterns of relationships in the network – and the analysis of m-slices – a technique helpful to study cohesion in relationships – are explored as tools to decide on the configuration of topics and/or learner groups. In particular, the results of the case study show that such techniques can be used to (i) filter participants for rearranging groups; (ii) rearrange topics of interest; and (iii) dynamically change the structure of a course. The techniques presented can be considered a case of collaborative filtering based on social network structure.  相似文献   

The research environment of universities     

Javier Vidal  Miguel Quintanilla 《Tertiary Education and Management》2013,19(3):183-189

Part‐time study is one of the foci of the widening participation agenda in the UK. The experiences of part‐time students, however, have received remarkably little attention from scholars, especially in a comparative context. This paper explores existing historical data going back over a decade to identify the main themes of part‐time experience at a number of UK higher education institutions and how it compares and contrasts with the full‐time experience. The surveys use the Student Satisfaction Approach. The main themes emerging from institutional survey data over time are the work/family/study balance, assessment and feedback, access to learning and catering resources, and students' financial situation. There is sometimes a question of identity, but unlike many studies of part‐time student experience, which focus on aspects of disadvantage, social, and cultural capital, the data for this paper indicate that many part‐time students have a sense of themselves as being ignored or at worst marginalised in contemporary higher education.  相似文献   

Interactive effects of the probability of the cue and the probability of the outcome on the overestimation of null contingency     

Fernando Blanco  Helena Matute  Miguel A. Vadillo 《Learning & behavior》2013,41(4):333-340

Overestimations of null contingencies between a cue, C, and an outcome, O, are widely reported effects that can arise for multiple reasons. For instance, a high probability of the cue, P(C), and a high probability of the outcome, P(O), are conditions that promote such overestimations. In two experiments, participants were asked to judge the contingency between a cue and an outcome. Both P(C) and P(O) were given extreme values (high and low) in a factorial design, while maintaining the contingency between the two events at zero. While we were able to observe main effects of the probability of each event, our experiments showed that the cue- and outcome-density biases interacted such that a high probability of the two stimuli enhanced the overestimation beyond the effects observed when only one of the two events was frequent. This evidence can be used to better understand certain societal issues, such as belief in pseudoscience, that can be the result of overestimations of null contingencies in high-P(C) or high-P(O) situations.  相似文献   

Total Protein of Whole Saliva as a Biomarker of Anaerobic Threshold     

Miguel Sordi Bortolini Junior  Guilherme Gularte De Agostini  Ismair Teodoro Reis  Romeu Paulo Martins Silva Lamounier  Jeffrey B. Blumberg  Foued Salmen Espindola 《Research quarterly for exercise and sport》2013,84(3):604-610

Saliva provides a convenient and noninvasive matrix for assessing specific physiological parameters, including some biomarkers of exercise. We investigated whether the total protein concentration of whole saliva (TPWS) would reflect the anaerobic threshold during an incremental exercise test. After a warm-up period, 13 nonsmoking men performed a maximum incremental exercise on a cycle ergometer. Blood and stimulated saliva were collected during the test. The TPWS anaerobic threshold (PAT) was determined using the Dmax method. The PAT was correlated with the blood lactate anaerobic threshold (AT; r = .93, p < .05). No significant difference (p = .16) was observed between PAT and AT. Thus, TPWS provides a convenient and noninvasive matrix for determining the anaerobic threshold during incremental exercise tests.  相似文献   

Performance analysis of elite men’s and women’s wheelchair basketball teams     

Miguel ángel Gómez  Javier Pérez  Bartosz Molik  Robert J. Szyman  Jaime Sampaio 《Journal of sports sciences》2013,31(11):1066-1075

Abstract

The purpose of the present study was to identify which game-related statistics discriminate winning and losing teams in men’s and women’s elite wheelchair basketball. The sample comprised all the games played during the Beijing Paralympics 2008 and the World Wheelchair Basketball Championship 2010. The game-related statistics from the official box scores were gathered and data were analysed in 2 groups: balanced games (final score differences ≤12 points) and unbalanced games (final score differences >13 points). Discriminant analysis allowed identifying the successful 2-point field-goals and free-throws, the unsuccessful 3-point field-goals and free-throws, the assists and fouls received as discriminant statistics between winning and losing teams in men’s balanced games. In women’s games, the teams were discriminated only by the successful 2-point field-goals. Linear regression analysis showed that the quality of opposition had great effects in final point differential. The field-goals percentage and free-throws rate were the most important factors in men’s games, and field-goals percentage and offensive rebounding percentage in women’s games. The identified trends allow improving game understanding and helping wheelchair basketball coaches to plan accurate practice sessions and, ultimately, deciding better in competition.  相似文献   

Reliability of NIRS portable device for measuring intercostal muscles oxygenation during exercise     

Felipe Contreras-Briceño  Maximiliano Espinosa-Ramirez  Gonzalo Hevia  Diego Llambias  Miguel Carrasco  Francisco Cerda 《Journal of sports sciences》2013,31(23):2653-2659

ABSTRACT

This study assessed the intra-individual reliability of oxygen saturation in intercostal muscles (SmO₂-m.intercostales) during an incremental maximal treadmill exercise by using portable NIRS devices in a test-retest study. Fifteen marathon runners (age, 24.9 ± 2.0 years; body mass index, 21.6 ± 2.3 kg·m^?2; V?O₂-peak, 63.7 ± 5.9 mL·kg^?1·min^?1) were tested on two separate days, with a 7-day interval between the two measurements. Oxygen consumption (V?O₂) was assessed using the breath-by-breath method during the V?O₂-test, while SmO₂ was determined using a portable commercial device, based in the near-infrared spectroscopy (NIRS) principle. The minute ventilation (VE), respiratory rate (RR), and tidal volume (Vt) were also monitored during the cardiopulmonary exercise test. For the SmO₂-m.intercostales, the intraclass correlation coefficient (ICC) at rest, first (VT1) and second ventilatory (VT2) thresholds, and maximal stages were 0.90, 0.84, 0.92, and 0.93, respectively; the confidence intervals ranged from ?10.8% – +9.5% to ?15.3% – +12.5%. The reliability was good at low intensity (rest and VT1) and excellent at high intensity (VT2 and max). The Spearman correlation test revealed (p ≤ 0.001) an inverse association of SmO₂-m.intercostales with V?O₂ (ρ = ?0.64), VE (ρ = ?0.73), RR (ρ = ?0.70), and Vt (ρ = ?0.63). The relationship with the ventilatory variables showed that increased breathing effort during exercise could be registered adequately using a NIRS portable device.  相似文献   

The changing role of international cooperation in developing countries (as they develop): A case study of skills development policies in Peru     

Miguel Jaramillo 《International Journal of Educational Development》2012,32(1):22-30

A focus on the changes in the relationship between international cooperation and local actors in the skills development field in Peru as the country strengthened its financial position in the last two decades allows us to examine the role of the economic factor in these changes. The paper argues that indeed there is an association between the two. Peru's strengthened financial position has limited reliance on IC funding to carry out policy innovations, which has led IC to abandon the top-bottom approach to reform of the early nineties for a bottom-up approach that focuses in key actors at the middle level of the public sector entities and on sub-national governments. However, a second important factor has been institutional reform. Peru has developed a national policy towards IC and thus created a new setting for IC work, producing a more orderly environment for collaboration, while boosting information sharing among local agencies expecting international cooperation. The analysis stresses local factors conditioning changes and identifies lessons for the actors involved, particularly for international cooperation (IC), regarding possible strategies for a more effective role in skills development policies.  相似文献   

Teachers’ scaffolding science reading comprehension in low-income schools: how to improve achievement in science     

Sandra Patricia Rojas Rojas  Alejandra Meneses  Emilio Sánchez Miguel 《International Journal of Science Education》2013,35(13):1827-1847

ABSTRACT

Reading is a tool that promotes the learning of science across schooling. Scientific texts are conceptually and linguistically complex, especially for students from low-income contexts because they have neither the experience with the language nor the literacy skills to face the challenges of scientific knowledge. This study used a mix method approach to compare the cognitive scaffolding practiced by teachers during science reading activities in high- and low-performing schools. Three teachers and 141 fourth grade students from low socioeconomic background schools participated in 48 class sessions. Classes were video-recorded and transcribed. The data were analyzed using Sanchez’ Pedagogic Practice Analysis System. The results show that teachers from both types of schools continuously use reading as a tool for learning. The effective teacher uses reading with non-invasive scaffolding and varied verbal participation to elaborate knowledge, promoting literal and inferential comprehension and more opportunities for the students to construct knowledge. By contrast, less effective teachers use reading with invasive scaffolding and little verbal participation of the students to consolidate knowledge, promoting mainly literal comprehension. This study shed light on different approaches teachers use to foster reading comprehension for science learning.  相似文献   

¿Cómo determinan los niños la concordancia de género?: Refutación de la teoría del género natural     

Miguel Pérez 《Infancia y Aprendizaje》2013,36(50):73-91

Resumen

En este artículo se presentan los datos de un experimento realizado sobre el desarrollo del género con 160 niños hispanoparlantes de 4 a 11 años de edad. Las tres posibles claves (información semántica, morfofonológica, y sintáctica) que los hablantes pueden emplear para determinar el género del nombre y su concordancia con otros elementos variables que lo acompañan, han sido manipuladas experimentalmente para ofrecer las combinaciones posibles. Así se han presentado 1) items en los que solamente estaba presente una clave, 2) items en los que había un efecto combinado de dos de ellas en concordancia (ambas ya sea masculinas, o femeninas), 3) e items en los que las claves estaban en conflicto (una de ellas era masculina y la otra femenina, por ejemplo).

Los resultados hallados (que se comparan con los obtenidos en otras lenguas) dan apoyo a la perspectiva teórica que defiende que los niños prestan más atendón a la información sintáctica y morfofonológica (intralingüística) que a la semántica (extralinguistica).  相似文献