全文获取类型
收费全文 | 1747篇 |
免费 | 31篇 |
国内免费 | 1篇 |
专业分类
教育 | 1250篇 |
科学研究 | 162篇 |
各国文化 | 39篇 |
体育 | 87篇 |
综合类 | 4篇 |
文化理论 | 14篇 |
信息传播 | 223篇 |
出版年
2024年 | 5篇 |
2023年 | 16篇 |
2022年 | 16篇 |
2021年 | 43篇 |
2020年 | 57篇 |
2019年 | 88篇 |
2018年 | 114篇 |
2017年 | 122篇 |
2016年 | 107篇 |
2015年 | 81篇 |
2014年 | 103篇 |
2013年 | 356篇 |
2012年 | 78篇 |
2011年 | 91篇 |
2010年 | 63篇 |
2009年 | 68篇 |
2008年 | 47篇 |
2007年 | 48篇 |
2006年 | 54篇 |
2005年 | 18篇 |
2004年 | 31篇 |
2003年 | 31篇 |
2002年 | 25篇 |
2001年 | 14篇 |
2000年 | 14篇 |
1999年 | 14篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 6篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1779条查询结果,搜索用时 15 毫秒
81.
82.
83.
This study explores the impact of governmental support policies on the innovation of SMEs in the regional strategic industries in South Korea. We use the technological development assistance funds as a proxy for governmental support policies for SMEs in the regional industries in Korea. The innovation of SMEs is measured by technological innovation: patent, utility model, trademark, and new design registrations. Before empirically testing the impact of governmental support policies on the innovation of SMEs, this study reviews the literature concerning the innovation and the governmental support policies of SMEs in regional industries. Results from empirical models, which simultaneously control for factors which were thought to affect the innovation of regional SMEs, indicate that a positive relationship exists among the technological development assistance by the Korean government and patent acquisitions and new design registrations of regional SMEs. Networks with universities also have a positive relationship with patent acquisitions and new design registrations of regional SMEs. This study suggests there is an importance to governmental financial aids for regional SME innovations, and there is an importance to the need to build a strong social relationship in today's networked economy. 相似文献
84.
This paper reports a method to control the fluid flow in paper-based microfluidic devices simply by pressing over the channel surface of paper, thereby decreasing the pore size and permeability of a non-woven polypropylene sheet. As a result, fluid resistance is increased in the pressed region and causes flow rate to decrease. We characterize the decrease of flow rate with respect to different amounts of pressure applied, and up to 740% decrease in flow velocity was achieved. In addition, we demonstrate flow rate control in a Y-shaped merging paper and sequential delivery of multiple color dyes in a three-branched paper. Furthermore, sequential delivery of multiple fluid samples is performed to demonstrate its application in multi-step colorimetric immunoassay, which shows a 4.3-fold signal increase via enhancement step. 相似文献
85.
We present an optofluidic microvalve utilizing an embedded, surface plasmon-enhanced fiber optic microheater. The fiber optic microheater is formed by depositing a titanium thin film on the roughened end-face of a silica optical fiber that serves as a waveguide to deliver laser light to the titanium film. The nanoscale roughness at the titanium-silica interface enables strong light absorption enhancement in the titanium film through excitation of localized surface plasmons as well as facilitates bubble nucleation. Our experimental results show that due to the unique design of the fiber optic heater, the threshold laser power required to generate a bubble is greatly reduced and the bubble growth rate is significantly increased. By using the microvalve, stable vapor bubble generation in the microchannel is demonstrated, which does not require complex optical focusing and alignment. The generated vapor bubble is shown to successfully block a liquid flow channel with a size of 125 μm × 125 μm and a flow rate of ∼10 μl/min at ∼120 mW laser power. 相似文献
86.
Kim Schildkamp Jan Vanhoof Peter van Petegem Adrie Visscher 《British Educational Research Journal》2012,38(1):125-152
This article presents the results of two studies on the use of school self‐evaluation in the Netherlands and Flanders. It focuses on which forms of instrumental use of school self‐evaluation results can be found in schools, and how differences in self‐evaluation use between schools can be explained. Results show that the instrumental use of self‐evaluation results in both contexts was limited. Results further show that differences in the use of school self‐evaluation results can be explained by differences in school organizational characteristics, implementation characteristics, and the characteristics of the school self‐evaluation itself. Implications for theory, policy, and practice are discussed. 相似文献
87.
With the increasing use of international survey data especially in cross-cultural and multinational studies, establishing measurement invariance (MI) across a large number of groups in a study is essential. Testing MI over many groups is methodologically challenging, however. We identified 5 methods for MI testing across many groups (multiple group confirmatory factor analysis, multilevel confirmatory factor analysis, multilevel factor mixture modeling, Bayesian approximate MI testing, and alignment optimization) and explicated the similarities and differences of these approaches in terms of their conceptual models and statistical procedures. A Monte Carlo study was conducted to investigate the efficacy of the 5 methods in detecting measurement noninvariance across many groups using various fit criteria. Generally, the 5 methods showed reasonable performance in identifying the level of invariance if an appropriate fit criterion was used (e.g., Bayesian information criteron with multilevel factor mixture modeling). Finally, general guidelines in selecting an appropriate method are provided. 相似文献
88.
Elvira Haezendonck Kim Willems Jenny Hillemann 《International Journal of Inclusive Education》2017,21(1):31-47
Universities, and higher education institutions in general, are ever more influenced by output-driven performance indicators and models that originally stem from the profit-organisational context. As a result, universities are increasingly considering management tools that support them in the (decision) process for attaining their strategic goals. The growth-share matrix is one of these tools that has proven its value in diverse business and competitive contexts in the past few decades. The present study’s contribution is twofold. First, we apply and interpret the growth-share matrix as part of a strategic positioning analysis in a strategic university context. Second, we extend this tool by incorporating social inclusion as a third dimension in the analysis. In recent years, discussions on the rising social disparity among adolescents in higher education have increased and different types of actors have raised the motivation to create more equal opportunities for prospective students who rank among the group of socially disadvantaged adolescents. The findings of an empirical case of the proposed model for a particular Belgian academic programme show that increased social inclusion and higher performance parameters, such as growth in student enrolments and diplomas, can be reached simultaneously. 相似文献
89.
Chai?Ming-liang?Email author Wang?Bing-liang Kim?Jae-yeoul Lee?Jong-min Kim?Doo-hwan 《浙江大学学报(A卷英文版)》2003,4(3):346-351
Embryogenic calli were induced from the seeds of creeping bentgrass (Agrostis palustris Huds.) cv. Regent and colonial bentgrass (Agrostis Tenuis Sibth. Fl. Oxen.) cv. Tiger. The embryogenic calli were precultured on fresh medium for 4–7 days and then co-cultivated withAgrobacterium tumefaciens, LBA4404. which contains plasmid vector-pSBGM harboring bar coding region, synthetic green fluorescent protein (sGFP) coding
region and matrix attachment region (MAR). After 3 days of co-cultivation, the calli were washed thoroughly and transferred
to MS medium containing 2 mg/L of 2, 4-D, 12–15 mg/L phosphinothricin (PPT) and 250 mg/L of cefotaxime. After 2–3 months of
selection, the actively growing calli of ‘Regent’ and ‘Tiger’ were transferred to MS medium with 12–15 mg/L PPT and 250 mg/L
cefotazime for regeneration. The putative transformants were maintained on MS medium with 3 mg/L PPT for long period but control
died within 1 month. After establishing in greenhouse, the transformants also showed strong resistance to 0.4% of herbicide
Basta but control plants died within 2 weeks. Under confocal microscope, both young leaves and roots showed significant GFP
expression. PCR analysis revealed the presence of a DNA fragment of GFP gene at the expected size (380 bp) in the transformants
and its absence in a randomly selected control plant. 相似文献
90.
Carol McDonald Connor Beth M. Phillips Young–Suk Grace Kim Christopher J. Lonigan Michael P. Kaschak Elizabeth Crowe 《Scientific Studies of Reading》2018,22(6):462-484
Testing a component model of reading comprehension in a randomized controlled trial, we evaluated the efficacy of 4 interventions that were designed to target components of language and metacognition that predict children’s reading comprehension: vocabulary, listening comprehension, comprehension of literate language, academic knowledge, and comprehension monitoring. Third- and 4th-graders with language skills falling below age expectations participated (N = 645). Overall, the component interventions were only somewhat effective in improving the targeted skills, compared to a business-as-usual control (g ranged from ?.14 to .33), and no main effects were significant after correcting for multiple comparisons. Effects did not generalize to other language skills or to students’ reading comprehension. Moreover, there were Child Characteristic × Treatment interaction effects. For example, the intervention designed to build sensorimotor mental representations was more effective for children with weaker vocabulary skills. Implications for component models of reading and interventions for children at risk of reading comprehension difficulties are discussed. 相似文献