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611.
This essay examines how the ideograph <freedom> was crafted through dialectical struggles between Euro-Americans and American Indians over federal Indian policy between 1964 and 1968. For policymakers, <freedom> was historically sutured to the belief that assimilation was the only pathway to American Indian liberation. I explore the American Indian youth movement's response to President Johnson's War on Poverty to demonstrate how activists rhetorically realigned <freedom> in Indian policy with the Great Society's rhetoric of “community empowerment.” I illustrate how American Indians orchestrated counterhegemonic resistance by reframing the “Great Society” as an argument for a “Greater Indian American.” This analysis evinces the rhetorical significance of ideographic transformation in affecting policy change.  相似文献   
612.
613.
An important objective in science education is for students to understand the nature of science. Therefore, it is important that science textbooks, which are key resources in elementary science curricula, convey an accurate conception of the nature of science. This study examined first- to fifth-grade elementary science textbooks with regard to their presentations of the nature of science.  相似文献   
614.
Leadership demands in American public schools have changed dramatically in the past 20 years. Whether–or how–the practice of leadership will change to meet those demands is an open question. The change in demands is largely a consequence of the introduction of performance-based accountability—policies that evaluate, reward, and sanction schools on the basis of measured student performance. While the merits of these policies are debatable, the fact that they have changed—probably fundamentally—the demands placed on school leaders is not.  相似文献   
615.
The use of kits in elementary science classes is a growing trend in some countries. Kits provide materials and inquiry lessons in a ready-to-teach format for teachers to use in their science instruction. This study examined elementary teachers' instructional strategies, classroom practices, and assessment types in relation to the frequency of science kit use. A total of 503 elementary teachers from an urban school district received professional development, implemented kits in their classrooms for a year, and then completed a survey about science kit use and teaching practices. Despite similarities in demographic characteristics (gender, ethnicity, certification/educational level), there were significant differences in teachers' use of inquiry-based teaching and assessment practices by kit use. Teachers who reported using kits the most often were significantly more likely to report that their students designed and implemented laboratory investigations as well recorded, represented, and analyzed data. In addition, the high kit users indicated that they were more likely to use student groups, require students to use evidence to support claims, and use alternative assessments of student work including portfolios, notebooks, and long-term projects than those teachers who used kits less frequently. Those teachers who reported using kits the least often were significantly more likely to report having students practice for standardized tests. The role of kits in promoting reform-based teaching practices is discussed.  相似文献   
616.
This study sought to identify specific types of discussion-based strategies that two successful high school physics teachers using a model-based approach utilized in attempting to foster students' construction of explanatory models for scientific concepts. We found evidence that, in addition to previously documented dialogical strategies that teachers utilize to engage students in effectively communicating their scientific ideas in class, there is a second level of more cognitively focused model-construction-supporting strategies that these teachers utilized in attempting to foster students' learning. A further distinction between macro and micro strategy levels within the set of cognitive strategies is proposed. The relationships between the resulting three levels of strategies are portrayed in a diagramming system that tracks discussions over time. The study attempts to contribute to a clearer understanding of how discussion-leading strategies may be used to scaffold the development of conceptual understanding.  相似文献   
617.
Different methods of ball carrying can be used when a player runs with the ball in rugby union. We examined how three methods of ball carrying influenced sprinting speed: using both hands, under the left arm and under the right arm. These methods were compared with running without the ball. Our aim was to determine which method of ball carrying optimizes sprinting speed. Altogether, 48 rugby union players (age 21±2 years, height 1.83±0.1?m, body mass 85.3±12?kg, body fat 14?±?5%; mean±s) were recruited. The players performed twelve 30-m sprints in total (each player performed three trials under each of three methods of carrying the ball and sprinting without the ball). The design of the study was a form of Latin rectangle, balanced across the trial order for each of the methods and for pairwise combinations of the methods in blocks of four per trial. Each sprint consisted of a 10-m rolling start, followed by a 20-m timed section using electronic timing gates. Compared with sprinting 20?m without the ball (2.58±0.16?s), using both hands (2.62±0.16?s) led to a significantly slower time (P?<0.05). Sprinting 20?m with the ball under the left arm (2.61±0.15?s) or under the right arm (2.60± 0.17?s) was significantly quicker than when using ‘both hands’ (P?<0.05), and both these methods were significantly slower than when running without the ball (P?<0.05). Accordingly, running with the ball in both hands led to the greatest decrement in sprinting performance, although carrying the ball under one arm also reduced the players' sprinting ability. Our results indicate that to gain a speed advantage players should carry the ball under one arm.  相似文献   
618.
Abstract

The swim section of Sprint- and Olympic-distance triathlon race formats is integral to the success of subsequent cycle and running disciplines, and to overall race performance. The current body of swimming-based triathlon research suggests that the energy used, and the positioning gained among competitors during the swim, is important in determining the success of an athlete's race, especially professional athletes in draft-legal settings. Furthermore, by swimming at a reduced intensity, it has been shown that the performance of the subsequent disciplines may be enhanced. However, reductions in energy output can be obtained without compromising swimming speed. This review highlights the importance of swimming intensity during a triathlon and how it impacts on the ensuing cycle and run. Furthermore, consideration is given to current methods used to manipulate swimming performance.  相似文献   
619.
Abstract

This study is a meta-analysis of 109 reports of the performance of children and adolescents on the 20-m shuttle run test (20-mSRT). The studies were performed in 37 countries and included data on 418,026 children, tested between 1981 and 2003. Results were expressed as running speed (km · h?1) at the final completed stage of the 20-mSRT. Raw data were combined with pseudodata using Monte Carlo simulation. The 20-mSRT performances were expressed as z-scores relative to all children of the same age and sex from all countries. An overall “performance index” was derived for each country as the average of the age- and sex-specific z-scores for all children from that country. Factorial analysis of variance was used to compare scores among countries and regions, and between boys and girls of the same age. There was wide and significant (P < 0.0001) global variability in the performance of children. The best performing children were from the Northern European countries Estonia, Iceland, Lithuania, and Finland (0.6 – 0.9 standard deviations above the global average). The worst performing children were from Singapore, Brazil, USA, Italy, Portugal, and Greece (0.4 – 0.9 standard deviations below the global average). There is evidence that performance was negatively related to being overweight, as well as to a country's average temperature.  相似文献   
620.
Abstract

In this study, we investigated the effect of ingesting carbohydrate alone or carbohydrate with protein on functional and metabolic markers of recovery from a rugby union-specific shuttle running protocol. On three occasions, at least one week apart in a counterbalanced order, nine experienced male rugby union forwards ingested placebo, carbohydrate (1.2 g · kg body mass?1 · h?1) or carbohydrate with protein (0.4 g · kg body mass?1 · h?1) before, during, and after a rugby union-specific protocol. Markers of muscle damage (creatine kinase: before, 258 ± 171 U · L?1 vs. 24 h after, 574 ± 285 U · L?1; myoglobin: pre, 50 ± 18 vs. immediately after, 210 ± 84 nmol · L?1; P < 0.05) and muscle soreness (1, 2, and 3 [maximum soreness = 8] for before, immediately after, and 24 h after exercise, respectively) increased. Leg strength and repeated 6-s cycle sprint mean power were slightly reduced after exercise (93% and 95% of pre-exercise values, respectively; P < 0.05), but were almost fully recovered after 24 h (97% and 99% of pre-exercise values, respectively). There were no differences between trials for any measure. These results indicate that in experienced rugby players, the small degree of muscle damage and reduction in function induced by the exercise protocol were not attenuated by the ingestion of carbohydrate and protein.  相似文献   
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