全文获取类型
| 收费全文 | 225篇 |
| 免费 | 7篇 |
| 国内免费 | 1篇 |
专业分类
| 教育 | 159篇 |
| 科学研究 | 22篇 |
| 各国文化 | 8篇 |
| 体育 | 7篇 |
| 综合类 | 1篇 |
| 文化理论 | 2篇 |
| 信息传播 | 34篇 |
出版年
| 2023年 | 3篇 |
| 2022年 | 4篇 |
| 2021年 | 4篇 |
| 2020年 | 12篇 |
| 2019年 | 11篇 |
| 2018年 | 23篇 |
| 2017年 | 11篇 |
| 2016年 | 17篇 |
| 2015年 | 8篇 |
| 2014年 | 10篇 |
| 2013年 | 37篇 |
| 2012年 | 16篇 |
| 2011年 | 12篇 |
| 2010年 | 10篇 |
| 2009年 | 7篇 |
| 2008年 | 7篇 |
| 2007年 | 9篇 |
| 2006年 | 4篇 |
| 2005年 | 4篇 |
| 2004年 | 2篇 |
| 2003年 | 5篇 |
| 2002年 | 1篇 |
| 2001年 | 4篇 |
| 2000年 | 2篇 |
| 1999年 | 1篇 |
| 1998年 | 2篇 |
| 1997年 | 3篇 |
| 1994年 | 1篇 |
| 1992年 | 1篇 |
| 1977年 | 1篇 |
| 1968年 | 1篇 |
排序方式： 共有233条查询结果，搜索用时 15 毫秒
11.
12.
Applying the Theory of Planned Behavior (TPB), this study examines parents’ attitudes, social norms, self-efficacy, and intentions regarding parental mediation of children’s smartphone use. A survey conducted with parents of young smartphone users aged 10–17 shows that parents tend to perceive discussion-based active mediation to be more desirable, as compared to rule-making restrictive mediation. Findings also indicate that the extent to which parents believe that they have control over their parental mediation practices plays an important role in forming positive intentions to practice parental mediation, regardless of the mediation domain. 相似文献
13.
14.
15.
Soo Jin Lee Jaehong Shin 《International Journal of Science and Mathematics Education》2015,13(2):329-355
In the present study, we describe a participating student’s (Carol’s) distributive partitioning scheme and operations along with Steffe’s and his colleagues’ studies about children’s constructions of fraction knowledge as a particular model of mathematical learning. Analysis of Carol’s mathematical behaviors indicates that an operationally common mathematical behavior (distributive partitioning operation) was revealed in various mathematical problem situations such as fraction multiplication, fraction division, and multiplicative transformation between fractional quantities. It both provides a rationale for why becoming versed in one mathematical subject could facilitate working with another mathematical subject and also implies the necessity of describing and defining students’ mathematical behaviors from an operational view of knowledge, which might lead to building foundations of a substantial cognitive map for students’ mathematical development. 相似文献
16.
The current study took a person-centered approach to examine the heterogeneity of changes in children’s emotions and persistence during a goal-blocking task and examined how different profiles of emotions and persistence related to children’s self-regulation. Children’s anger, sadness, and persistence were rated in a goal-blocking task in toddlerhood (T1; N = 140, 72 boys, Mage = 2.67 years, 90.7% White) and preschool (T2). Children’s self-regulation, specifically sustained attention and engagement, was assessed at T1, T2, and early school-age (T3) from 2005 to 2012. Growth mixture modeling revealed two classes of children at T1 and three classes at T2 with different patterns of anger, sadness, and persistence. Children’s classification at T2, but not T1, significantly predicted their sustained attention and engagement both concurrently and longitudinally. 相似文献
17.
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
18.
The present study examined the motivational correlates and achievement consequences of students’ help-seeking tendencies during sixth grade (N = 217). Students’ grades were collected from school records at the beginning and end of the school year. Midway through the year students reported on their academic self-efficacy and social demonstration goals; teachers reported on students’ help-seeking tendencies. First quarter grades and academic self-efficacy were positively related to adaptive help seeking and negatively related to avoidant help seeking. In addition, a social demonstration-approach goal was negatively related to adaptive help seeking. Help-seeking tendencies predicted 3rd quarter grades, controlling for 1st quarter grades. 相似文献
19.
Oxygen and glucose supply is one of the important factors for the growth and viability of the cells in cultivation of tissues, e.g., spheroid, multilayered cells, and three-dimensional tissue construct. In this study, we used finite element methods to simulate the flow profile as well as oxygen and glucose supply to the multilayered cells in a microwell array chip for static and perfusion cultures. The simulation results indicated that oxygen supply is more crucial than glucose supply in both static and perfusion cultures, and that the oxygen supply through the wall of the perfusion culture chip is important in perfusion cultures. Glucose concentrations decline with time in static cultures, whereas they can be maintained at a constant level over time in perfusion cultures. The simulation of perfusion cultures indicated that the important parameters for glucose supply are the flow rate of the perfusion medium and the length of the cell culture chamber. In a perfusion culture chip made of oxygen-permeable materials, e.g., polydimethylsiloxane, oxygen is hardly supplied via the perfusion medium, but mainly supplied through the walls of the perfusion culture chip. The simulation of perfusion cultures indicated that the important parameters for oxygen supply are the thickness of the flow channel and the oxygen permeability of the walls of the channel, i.e., the type of material and the thickness of the wall. 相似文献
20.
In this article, the authors present the fabrication of an enzyme-entrapped alginate hollow fiber using a microfluidic device. Further use of enzyme-entrapped alginate hollow fibers as a biocatalytic microchemical reactor for chemical synthesis is also deliberated in this article. To ensure that there is no enzyme leaching from the fiber, fiber surfaces were coated with chitosan. To confine the mobility of reactants and products within the porous hollow fibers the entire fibers were embedded into a transparent polydimethylsiloxane (PDMS) matrix which also works as a support matrix. A vanadium-containing bromoperoxidase enzyme isolated from Corallina confusa was used as a model enzyme to demonstrate the use of these alginate hollow-fiber reactors in bromo-oxidation of phenol red to bromophenol blue at different dye flow rates. Stability of the entrapped enzyme at different temperatures and the effect of the chitosan coating on the reaction conversion were also studied. It was observed that molecules as big as 27 kDa can be retained in the matrix after coating with chitosan while molecules with molecular-weight of around 378 Da can still diffuse in and out of the matrix. The kinetic conversion rate in this microfluidic bioreactor was more than 41-fold faster when compared with the standard test-tube procedure. 相似文献