首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3549篇
  免费   65篇
  国内免费   1篇
教育   2548篇
科学研究   221篇
各国文化   43篇
体育   443篇
文化理论   65篇
信息传播   295篇
  2023年   29篇
  2022年   57篇
  2021年   84篇
  2020年   145篇
  2019年   250篇
  2018年   285篇
  2017年   283篇
  2016年   218篇
  2015年   156篇
  2014年   132篇
  2013年   812篇
  2012年   121篇
  2011年   113篇
  2010年   76篇
  2009年   65篇
  2008年   56篇
  2007年   66篇
  2006年   67篇
  2005年   44篇
  2004年   33篇
  2003年   42篇
  2002年   27篇
  2001年   41篇
  2000年   27篇
  1999年   31篇
  1998年   20篇
  1997年   24篇
  1996年   16篇
  1995年   28篇
  1994年   14篇
  1993年   13篇
  1992年   18篇
  1991年   16篇
  1990年   19篇
  1989年   13篇
  1988年   11篇
  1987年   15篇
  1986年   11篇
  1985年   12篇
  1984年   10篇
  1983年   8篇
  1982年   14篇
  1981年   19篇
  1980年   7篇
  1979年   9篇
  1978年   9篇
  1977年   7篇
  1976年   10篇
  1974年   4篇
  1970年   4篇
排序方式: 共有3615条查询结果,搜索用时 31 毫秒
961.
Understanding nature of science (NOS) is considered critical to the development of students’ scientific literacy. However, various studies have shown that a large number of elementary and secondary science teachers do not possess an adequate understanding of NOS. This study investigated how elementary teachers’ understanding of NOS was impacted through a 1-year professional development program in Chile that included NOS instruction as a theme throughout two types of mini-courses in the program. Twelve teachers attended a 1-year development program focused on improving teacher content knowledge and included the instruction of NOS embedded in two self-contained NOS mini-courses (36 h) and two lessons (3 h each) within five science content mini-courses (30 h). The Views of NOS (version D+) questionnaire and interviews were used to assess teachers’ understanding of NOS at the beginning (January) and end of the program (December). Elementary teachers’ understanding of the creative, inferential, and tentative aspect of NOS showed improvement. According to the teachers’ perceptions, the most significant activities for improving their NOS understanding were decontextualized activities in both types of mini-courses (self-contained NOS and science content mini-courses). The implications for professional development programs are also discussed.  相似文献   
962.
Research on elites (that is, on status groups that occupy dominant positions) is characterized by the lack of connection between studies that focus on elite recruitment and those that focus on the exercise of power by elites. As underlined by Giddens (Elites and power in British society, 1974), both types of approach are important and should complement each other in the analysis of mediations between the class structure, the organizational structure and the power structure in a given society. Giddens also insists on the need for recruitment studies to take account of two different dimensions: the types of channel that are privileged by elite groups to reproduce their social position, and the degree of social closure or openness of these channels to other groups (Parkin, The social analysis of class structure, 1974). This distinction is used to organize the present chapter, which focuses on a single channel that has come to play a crucial role in post-industrial societies, that is schools and, more precisely, upper secondary and higher education institutions, and on their influence in three different national contexts: France, the United Kingdom and the United States. In the first section, the specific features of elite education are examined. The second section explores the extent and modes of institutional and social closure.  相似文献   
963.
Academic accommodations for students experiencing disabilities are increasingly available at postsecondary institutions. More studies of the efficacy of accommodations for student success are warranted, however. Given the increased gender gap in university participation, more focus on the unique impact of gender is also needed. Using a sample of students registered with Access and Inclusion Services with learning disabilities (LD), attention-deficit/hyperactivity disorder (ADHD), and combined LD/ADHD at a Canadian undergraduate university (N = 661), we explored the impact of gender on academic performance and accommodation usage. Next, we examined how gender intersected with the impact of academic accommodations on academic performance. Women, on average, demonstrated better academic performance. Academic strategies and assistive technologies were not associated with higher academic performance. However, testing accommodations (extended time and environmental accommodations) were positively associated with academic performance for men with LD or ADHD, but not for the combined group LD/ADHD. For the former two, the more tests accommodated, the higher the academic performance. Furthermore, this gender association was most prominent for students experiencing ADHD. Interpretations and policy recommendations related to these findings are presented.  相似文献   
964.
The global popularity of test-based accountability appears to signal political trust in standardised assessments as valid and relevant measures of education quality. Nonetheless, research shows that educators' perceptions of standardised testing and test-based accountability can vary significantly, as do their responses to accountability demands. Considering the key influence of teachers' beliefs on the way in which they respond to education reforms, in this article we examine teachers' beliefs and opinions about standardised tests and test-based accountability. We analyse a comparative study on interpretations and experiences of standardised testing and test-based accountability demands of compulsory education teachers in Chile and Norway. These cases were selected following a most-different-systems design approach. The data was derived from an electronic survey (n = 2,531) and in-depth interviews (n = 41). The analysis shows how in both contexts, teachers are relatively critical about the validity, usefulness and fairness of standardised tests. This indicates lacking teacher trust in standardised testing and test-based accountability. Still, despite similar trends, some key differences in the beliefs of Chilean and Norwegian teachers are found, which highlight the influence of the sociocultural context in shaping teachers' beliefs. By illuminating how teachers in different contexts make sense of test-based accountability, our analysis contributes to the understanding of why the often-reported mismatch between policy expectations and policy outcomes might occur.  相似文献   
965.
We develop a new transmission scheme for additive white Gaussian noisy (AWGN) channels based on Fuchsian groups from rational quaternion algebras. The structure of the proposed Fuchsian codes is nonlinear and nonuniform, hence conventional decoding methods based on linearity and symmetry do not apply. Previously, only brute force decoding methods with complexity that is linear in the code size exist for general nonuniform codes. However, the properly discontinuous character of the action of the Fuchsian groups on the complex upper half-plane translates into decoding complexity that is logarithmic in the code size via a recently introduced point reduction algorithm.  相似文献   
966.
This paper aims at identifying the factors influencing the implementation of Web accessibility (WA) by European banks. We studied a database made up of 49 European banks whose shares are included in the Dow Jones EURO STOXX® TMI Banks [8300] Index. Regarding the factors for the implementation, we considered three feasible reasons. Firstly, WA adoption can be motivated by operational factors, as WA can aid in increasing operational efficiency. Secondly, we expect large banks to have higher WA levels, as small firms face competitive disadvantages with regard to technology adoption. Lastly, WA can also be understood as a part of the Corporate Social Responsibility (CSR) strategy, so, the more committed a bank is to CSR, the more prone it will be to implement WA. Our results indicate that neither the operational factors nor the firm size seem to have exerted a significant influence on WA adoption. Regarding CSR commitment, results indicate a significant influence on WA adoption. However, the effect of the influence is contrary to that hypothesized, since more CSR-committed banks have less accessible Web sites. A possible reason for this result is that banks not included in the CSR indexes try to overcome this drawback by engaging in alternative CSR activities such as WA.  相似文献   
967.
This paper leverages the concept of absorptive capacity to explore whether similar configurations of intellectual capital (IC) are associated with the performance of relational capital in firms. It proposes a novel implementation of graph theory to analyse similarities in knowledge assets. We use Community Innovation Survey data to examine 5813 manufacturing firms in 13 business sectors and 13 European countries. While firms rely on external relations to compensate for a lack of internal assets, we find that a company’s propensity to cooperate in innovation is associated with its own IC profile. In particular, firms with common knowledge assets are more likely to benefit from business relational capital. The main contribution of this study lies in a holistic approach to understanding how similarities in knowledge assets are linked to gains in business relational capital.  相似文献   
968.
Cancer heterogeneity has received considerable attention for its role in tumor initiation and progression, and its implication for diagnostics and therapeutics in the clinic. To facilitate a cellular heterogeneity study in a low cost and highly efficient manner, we present a microfluidic platform that allows traceable clonal culture and characterization. The platform captures single cells into a microwell array and cultures them for clonal expansion, subsequently allowing on-chip characterization of clonal phenotype and response against drug treatments. Using a heterogeneous prostate cancer model, the PC3 cell line, we verified our prototype, identifying three different sub-phenotypes and correlating their clonal drug responsiveness to cell phenotype.  相似文献   
969.
We present a microfluidic device designed for maintenance and culture of non-adherent mammalian cells, which enables both recirculation and refreshing of medium, as well as easy harvesting of cells from the device. We demonstrate fabrication of a novel microfluidic device utilizing Braille perfusion for peristaltic fluid flow to enable switching between recirculation and refresh flow modes. Utilizing fluid flow simulations and the human promyelocytic leukemia cell line, HL-60, non-adherent cells, we demonstrate the utility of this RECIR-REFRESH device. With computer simulations, we profiled fluid flow and concentration gradients of autocrine factors and found that the geometry of the cell culture well plays a key role in cell entrapping and retaining autocrine and soluble factors. We subjected HL-60 cells, in the device, to a treatment regimen of 1.25% dimethylsulfoxide, every other day, to provoke differentiation and measured subsequent expression of CD11b on day 2 and day 4 and tumor necrosis factor-alpha (TNF-α) on day 4. Our findings display perfusion sensitive CD11b expression, but not TNF-α build-up, by day 4 of culture, with a 1:1 ratio of recirculation to refresh flow yielding the greatest increase in CD11b levels. RECIR-REFRESH facilitates programmable levels of cell differentiation in a HL-60 non-adherent cell population and can be expanded to other types of non-adherent cells such as hematopoietic stem cells.  相似文献   
970.
The capability of 3D printing technologies for direct production of complex 3D structures in a single step has recently attracted an ever increasing interest within the field of microfluidics. Recently, ultrafast lasers have also allowed developing new methods for production of internal microfluidic channels within the bulk of glass and polymer materials by direct internal 3D laser writing. This review critically summarizes the latest advances in the production of microfluidic 3D structures by using 3D printing technologies and direct internal 3D laser writing fabrication methods. Current applications of these rapid prototyped microfluidic platforms in biology will be also discussed. These include imaging of cells and living organisms, electrochemical detection of viruses and neurotransmitters, and studies in drug transport and induced-release of adenosine triphosphate from erythrocytes.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号