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41.
42.
This article focuses on educational enterprises outside the formal sector, such as museums, botanical gardens and interactive
science centres. International research is drawn on to illuminate how design, culture, educational strategies and settings
combine to affect the way in which young people respond to experiences on offer, leading to analysis of the impact of such
settings in promoting learning, and the likely implications for those who staff such venues. Aikenhead’s concept of the educator
as ‘culture broker’ is developed to suggest ways in which learning might be best supported. It envisages a shift from ‘delivery’
strategies targeted at large groups towards approaches which focus on what learners choose to know about using dialogue between
children and ‘known and trusted people’. Analysis of observed responses in various settings is undertaken from a sociocultural
perspective using the notion of communities of practice. Implications for the roles of education managers and their staff
in further research are developed. 相似文献
43.
Formal models for service composition have been proposed with the variation of the requirements of service developers. Some
famous models have provided checking and verification techniques and tools for the behavior of service composition. These
models generally focus much on the message flow of web services and neglecting the data contained in the exchanged messages
among services, which restrict the application range of these models and also the web service techniques. As new kind of services
with different protocols and communication methods have appeared, it is needed to model service composition from a new view
which is adapted to the new development in service area. In this paper we offer a function oriented model of service composition
which treats the composite service as a software system and specify the function of services which can be directly used to
the realization by service providers. 相似文献
44.
The author articulates key stressors in the lives of families who are homeless. These stresses often combine with barriers such as lack of job opportunities and/or insensitive professionals. Strategies for helping homeless families overcome these barriers and related issues are presented. 相似文献
45.
Pigeons' keypecking was reinforced by food on baseline schedules of multiple variable interval (VI) x VI x and on contrast schedules of multiple VI x VI y. Deprivation of food was varied by maintaining subjects at 75%, 85%, and 95% (+/- 2%) of their free-feeding weights. Positive and negative behavioral contrast were observed. The size of the contrast was not systematically altered by changes in deprivation. Positive and negative contrast were both larger later in the session than they were earlier. Within-session decreases in responding were steeper for the baseline than for the contrast schedules for positive contrast. Within-session decreases were steeper for the contrast than for the baseline schedules for negative contrast. These results were predicted by the idea that different amounts of habituation to the reinforcer during the baseline and contrast schedules contribute to behavioral contrast. The results show that contrast occurs under conditions that reduce the effect of the following component. The results support the assumption that positive and negative contrast are produced by symmetrical theoretical variables. 相似文献
46.
In five conditioned taste aversion experiments with rats, summation, retardation, and preference tests were used to assess the effects of extinguishing a conditioned saccharin aversion for three or nine trials. In Experiment 1, a summation test showed that saccharin aversion extinguished over nine trials reduced the aversion to a merely conditioned flavor (vinegar), whereas three saccharin extinction trials did not subsequently influence the vinegar aversion. Experiment 2 clarified that result, with unpaired controls equated on flavor exposure prior to testing; the results with those controls suggested that the flavor extinguished for nine trials produced generalization decrement during testing. In Experiment 3, the saccharin aversion reconditioned slowly after nine extinction trials, but not after three. Those results suggested the development of latent inhibition after more than three extinction trials. Preference tests comparing saccharin consumption with a concurrently available fluid (water in Experiment 4, saline in Experiment 5) showed that the preference for saccharin was greater after nine extinction trials than after three. However, saccharin preference after nine extinction trials was not greater, as compared with that for either latent inhibition controls (Experiments 4 and 5) or a control given equated exposures to saccharin and trained to drink saline at a high rate prior to testing (Experiment 5). Concerns about whether conditioned inhibition has been demonstrated in any flavor aversion procedure are discussed. Our findings help explain both successes and failures in demonstrating postextinction conditioned response recovery effects reported in the conditioned taste aversion literature, and they can be explained using a memory interference account. 相似文献
47.
石敏俊 《浙江大学学报(A卷英文版)》2004,5(12):1533-1542
Land degradation is one of the severe environmental problems in China. In order to combat land degradation, a soil conservation program was introduced since 2000 to reduce soil erosion by converting slope-cultivated land into forestry and pasture. This paper represents the first systematic attempt to investigate the impact of the soil conservation program on land degradation in the loess plateau. The results indicate that the soil conservation program to convert slope fields into forest or pasture is an effective way to combat soil erosion. However, a subsidy that is higher than profit of land use activity of slope fields before their conversion into forest and pasture is needed to encourage farmers to join the conservation program. A policy measure to encourage and assist farmers to develop sedentary livestock by using crops produced from fields as well as fodder and forage grass from the converted slope fields might contribute to combat soil erosion. Increase in off-farm job opportunities may encourage households to reduce cultivation in slope fields. That implies a policy measure to encourage rural urbanization might contribute to combat soil erosion. 相似文献
48.
49.
Yangxueqingnao particles inhibit rat vascular smooth muscle cell proliferation induced by lysophosphatidic acid 总被引:1,自引:0,他引:1
Cai W Xu Y Chen JZ Huang SR Lu ZY Wang ZK 《Journal of Zhejiang University. Science. B》2005,6(9):892-896
Objective: To observe the effect of Yangxueqingnao particles on rat vascular smooth muscle cell (VSMC) proliferation induced by lysophosphatidic acid (LPA). Methods: The amount of3H-TdR (3H-thymidine) admixed in cultured rat VSMC was measured and mitogen-activated protein kinase (MAPK) activity and lipid peroxidation end product malondialdehyde (MDA)content of the VSMC were assayed. Results: 1×10-9, 1×10-8, 1×10-7 mol/L LPA in a concentration dependent manner, induced the amount of 3H-TdR admixed, MAP kinase activity, and MDA content of the cultured rat VSMC to increase. However, 5%, 10%,and 15% Yangxueqingnao serum preincubation resulted in a decrease of 23.0%, 42.0%, and 52.0% (P<0.01) respectively in the amount of 3H-TdR admixed, a decline in VSMC MAP kinase activity of 13.9% (P<0.05), 29.6% (P<0.01), and 48.9% (P<0.01)respectively, and also, a decrease in MDA content of VSMC of 19.4%, 24.7%, and 43.2% (P<0.01) respectively, in the 1×10-7mol/L LPA-treated VSMC. Conclusions: LPA activates the proliferation and lipid peroxidation of VSMC in a concentration dependent manner. The LPA-induced VSMC proliferation is related to the activity of MAP kinases, enzymes involved in an intracellular signalling pathway. The results of the present study showed that Yangxueqingnao particles can effectively inhibit LPA-induced VSMC proliferation, MAP kinase activation, and reduce lipid peroxidative lesion. 相似文献
50.
This investigation analyzed goals from the Individual Educational Programs (IEPs) of 54 high school students with diagnosed
reading disabilities in basic skills (decoding and/or word identification). Results showed that for 73% of the students, the
IEPs written when they were in high school failed to specify any objectives regarding their acute difficulties with basic
skills. IEPs from earlier points in the students’ educations were also reviewed, as available. For 23 of the students, IEPs
were present in the students’ files for three time points: elementary school (ES), middle school (MS), and high school (HS).
Another 20 students from the sample of 54 had IEPs available for two time points (HS and either MS or ES). Comparisons with
the IEPs from younger years showed a pattern of decline from ES to MS to HS in the percentage of IEPs that commented on or
set goals pertaining to weaknesses in decoding. These findings suggest that basic skills deficits that persist into the upper
grade levels are not being sufficiently targeted for remediation, and help explain why older students frequently fail to resolve
their reading problems. 相似文献