全文获取类型
收费全文 | 4540篇 |
免费 | 57篇 |
国内免费 | 7篇 |
专业分类
教育 | 3536篇 |
科学研究 | 230篇 |
各国文化 | 84篇 |
体育 | 308篇 |
综合类 | 1篇 |
文化理论 | 61篇 |
信息传播 | 384篇 |
出版年
2021年 | 30篇 |
2020年 | 58篇 |
2019年 | 89篇 |
2018年 | 105篇 |
2017年 | 139篇 |
2016年 | 103篇 |
2015年 | 87篇 |
2014年 | 102篇 |
2013年 | 1132篇 |
2012年 | 74篇 |
2011年 | 99篇 |
2010年 | 76篇 |
2009年 | 104篇 |
2008年 | 109篇 |
2007年 | 102篇 |
2006年 | 101篇 |
2005年 | 95篇 |
2004年 | 90篇 |
2003年 | 99篇 |
2002年 | 85篇 |
2001年 | 78篇 |
2000年 | 75篇 |
1999年 | 70篇 |
1998年 | 62篇 |
1997年 | 70篇 |
1996年 | 68篇 |
1995年 | 64篇 |
1994年 | 53篇 |
1993年 | 57篇 |
1992年 | 56篇 |
1991年 | 61篇 |
1990年 | 54篇 |
1989年 | 61篇 |
1988年 | 46篇 |
1987年 | 41篇 |
1986年 | 46篇 |
1985年 | 56篇 |
1984年 | 31篇 |
1983年 | 46篇 |
1982年 | 43篇 |
1981年 | 44篇 |
1980年 | 32篇 |
1979年 | 65篇 |
1978年 | 31篇 |
1977年 | 50篇 |
1976年 | 35篇 |
1975年 | 33篇 |
1974年 | 38篇 |
1973年 | 24篇 |
1972年 | 22篇 |
排序方式: 共有4604条查询结果,搜索用时 359 毫秒
121.
Externalities as conventionally defined miss many of the spillovers that are both causes and consequences of the technological changes that underlie economic growth. We introduce a much wider concept called technological complementarities. New general purpose technologies (GPTs) rejuvenate the growth process by creating technological complementarities, which are adequately measured neither by total factor productivity (TFP) nor by externalities. There would be major gains from technological change even if the returns on capital invested in innovation never exceeded the returns on investing in existing technologies so that there were neither externalities nor positive changes in TFP. 相似文献
122.
Professorial entrepreneurship has recently attracted much attention. This paper draws upon historical research, a survey of faculty, and an Internet-based methodology for identifying professorial affiliations with entrepreneurial firms at two of the premier electrical engineering and computer science departments in the US, The University of California, Berkeley and Stanford. We employ the concept of “nested embeddedness” to explain why the faculty members in these two institutions have different levels of entrepreneurship and corporate involvement. EE&CS faculty at both universities were found to be socially embedded in departments and disciplines that supported and placed value on entrepreneurial activities. However, while being embedded in a university environment with a history of success and high level of support for entrepreneurship, EE&CS faculty at Stanford had a significantly greater level of corporate involvement, including the founding of start-ups. Although significantly less than Stanford, the level of corporate involvement among EE&CS faculty at Berkeley was also substantial. This suggests that being embedded in an academic department and disciplines with cultures that are supportive of entrepreneurial activity can help counteract the disincentives created by a university environment that is not strongly supportive of these activities. 相似文献
123.
This study used semistructured interviews and grounded theory to look for characteristics among college undergraduates that predicted persistence into Ph.D. and M.D./Ph.D. training. Participants in the summer undergraduate and postbaccalaureate research programs at the Mayo Clinic College of Medicine were interviewed at the start, near the end, and 8–12 months after their research experience. Of more than 200 themes considered, five characteristics predicted those students who went on to Ph.D. and M.D./Ph.D. training or to M.D. training intending to do research: 1) Curiosity to discover the unknown, 2) Enjoyment of problem solving, 3) A high level of independence, 4) The desire to help others indirectly through research, and 5) A flexible, minimally structured approach to the future. Web-based surveys with different students confirmed the high frequency of curiosity and/or problem solving as the primary reason students planned research careers. No evidence was found for differences among men, women, and minority and nonminority students. Although these results seem logical compared with successful scientists, their constancy, predictive capabilities, and sharp contrast to students who chose clinical medicine were striking. These results provide important insights into selection and motivation of potential biomedical scientists and the early experiences that will motivate them toward research careers. 相似文献
124.
Teachers' education, classroom quality, and young children's academic skills: results from seven studies of preschool programs 总被引:10,自引:0,他引:10
Early DM Maxwell KL Burchinal M Alva S Bender RH Bryant D Cai K Clifford RM Ebanks C Griffin JA Henry GT Howes C Iriondo-Perez J Jeon HJ Mashburn AJ Peisner-Feinberg E Pianta RC Vandergrift N Zill N 《Child development》2007,78(2):558-580
In an effort to provide high-quality preschool education, policymakers are increasingly requiring public preschool teachers to have at least a Bachelor's degree, preferably in early childhood education. Seven major studies of early care and education were used to predict classroom quality and children's academic outcomes from the educational attainment and major of teachers of 4-year-olds. The findings indicate largely null or contradictory associations, indicating that policies focused solely on increasing teachers' education will not suffice for improving classroom quality or maximizing children's academic gains. Instead, raising the effectiveness of early childhood education likely will require a broad range of professional development activities and supports targeted toward teachers' interactions with children. 相似文献
125.
126.
Reconsidering the Character and Role of Inquiry in School Science: Analysis of a Conference 总被引:2,自引:1,他引:1
We summarize a conference on scientific inquiry bringing together science educators, cognitive scientists and philosophers
of science with three goals:
This research was supported by NSF grant ESIE #0343196 awarded to the authors. The opinions expressed in this article are
those of the authors and do not necessarily reflect the views of the National Science Foundation. Paper presented at the International
History and Philosophy of Science and Science Teaching Group meeting in Leeds, England July 15–18, 2005. 相似文献
1. | to establish how much consensus exists about scientific inquiry, |
2. | to discuss implications of that consensus for teaching science, |
3. | to identify areas where consensus is lacking to establish where further research and discussion would be most valuable. |
127.
Alazne Aizpitarte Olivia E. Atherton Lucy R. Zheng Itziar Alonso-Arbiol Richard W. Robins 《Child development》2019,90(1):117-126
Relational aggression—a psychological form of aggression—has numerous negative consequences for physical and emotional health. However, little is known about the risk factors that lead youth to engage in relational aggression. Using multimethod data from a longitudinal research of 674 Mexican-origin youth, this study examined the influence of parents, siblings, and peers on the development of relational aggression. Increases in relational aggression from age 10 to 16 were associated with: (a) low levels of parental monitoring and (b) increased association with deviant peers and siblings. These results held across gender and nativity status. The findings suggest that multiple socialization agents contribute to the development of relational aggression. We discuss the practical implications for reducing relational aggression during adolescence. 相似文献
128.
Richard Spoth Linda Trudeau Cleve Redmond Chungyeol Shin Mark E. Feinberg Mark T. Greenberg 《Child development》2019,90(6):1847-1855
This study examines crossover effects of adolescent substance misuse preventive interventions on academic success in college. It evaluates pathways of influence on college grades, via effects on school engagement, problem-solving skills, and substance misuse in high school. Data were collected as part of an Randomized Controlled Trial (RCT) evaluating a multicomponent intervention conducted in 28 school districts with middle school students. At age 19, study participants (N = 1,488) enrolled in college reported on college grades. The model fit the data, supporting hypothesized pathways of intervention impacts. Inclusion of a significant direct effect on college grades further improved model fit. Results support the potential for universal substance misuse preventive interventions delivered by community partnerships during middle school to yield effects on long-term academic success. 相似文献
129.
Although widely touted as important, there is little evidence regarding the influence of teaching experience on elementary teachers' science subject matter knowledge (SMK). To better understand this phenomenon, we administered an assessment of science topics taught in the fifth and sixth grades to 169 preservice teachers, 231 fifth-grade teachers, and 208 sixth-grade teachers. We then compared the mean scores of teachers at different stages in the career cycle using one-way and two-way ANOVA and explored the relationship between SMK scores and years of teaching experience using regression analysis. Findings indicate that (i) being assigned to a specific grade level had an impact on teachers' SMK for topics included in the grade level, (ii) teachers' SMK scores were lower later in their careers for both science topics they had never taught and for science topics they were responsible for teaching, and (iii) results differed for fifth and sixth grades. This study adds to the existing literature through the examination of a large sample of elementary teachers, with teachers of varying years of experience, while focusing on the science topics these teachers are responsible for teaching. The results of this study provide strong evidence that (i) years of experience teaching specific science topics is associated with the development of teachers' knowledge of these topics, and (ii) teaching experience, what teachers do in the context of their everyday practice, can be an effective means of self-directed learning for teachers. There is also evidence that this influence is not uniform across years of teaching experience or science topics taught. These findings raise important implications about future research into the mechanism of SMK development through teaching experience and teacher grade-level assignments. 相似文献
130.
Magdalena M. Apanasionok Richard P. Hastings Corinna F. Grindle Richard C. Watkins Andreas Paris 《科学教学研究杂志》2019,56(7):847-880
A comprehensive review of the literature was conducted to identify current practice on teaching science to students with intellectual disability (ID) and/or Autism Spectrum Disorder (ASD) in relation to two review questions—students' science outcomes and students' and teachers' experiences of the interventions. Six databases related to education, psychology, and science were systematically searched. A detailed protocol can be viewed on PROSPERO (registration number: CRD42017057323). Thirty studies were identified that reported on science interventions and 20 on student/teacher experiences of the interventions. The majority of the studies targeted science vocabulary and concepts. Other targets included inquiry skills and comprehension skills. The majority of the interventions used components of systematic instruction (n = 23). Five studies focused on self-directed learning and two on comprehension-based instruction. Students and teachers reported positive experiences of the interventions. The findings suggest that components of systematic instruction in particular might be effective in teaching science content to students with ID and/or ASD. Further research is needed to explore the effectiveness of identified interventions on teaching more complex science skills and with students with severe disabilities. Some limitations related to the search strategy are highlighted. 相似文献