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   129篇
  免费   5篇
教育   72篇
科学研究   7篇
各国文化   1篇
体育   23篇
文化理论   3篇
信息传播   28篇
  2023年   2篇
  2021年   1篇
  2020年   5篇
  2019年   2篇
  2018年   6篇
  2017年   7篇
  2016年   4篇
  2015年   9篇
  2014年   3篇
  2013年   25篇
  2012年   7篇
  2011年   7篇
  2010年   9篇
  2009年   4篇
  2008年   7篇
  2007年   6篇
  2006年   3篇
  2005年   4篇
  2004年   6篇
  2003年   1篇
  2002年   3篇
  2000年   2篇
  1999年   3篇
  1996年   3篇
  1992年   1篇
  1991年   1篇
  1990年   2篇
  1977年   1篇
排序方式: 共有134条查询结果,搜索用时 500 毫秒
101.
102.
High-throughput size-based rare cell enrichment using microscale vortices   总被引:2,自引:0,他引:2  
Cell isolation in designated regions or from heterogeneous samples is often required for many microfluidic cell-based assays. However, current techniques have either limited throughput or are incapable of viable off-chip collection. We present an innovative approach, allowing high-throughput and label-free cell isolation and enrichment from heterogeneous solution using cell size as a biomarker. The approach utilizes the irreversible migration of particles into microscale vortices, developed in parallel expansion-contraction trapping reservoirs, as the cell isolation mechanism. We empirically determined the critical particle∕cell diameter D(crt) and the operational flow rate above which trapping of cells∕particles in microvortices is initiated. Using this approach we successfully separated larger cancer cells spiked in blood from the smaller blood cells with processing rates as high as 7.5×10(6) cells∕s. Viable long-term culture was established using cells collected off-chip, suggesting that the proposed technique would be useful for clinical and research applications in which in vitro culture is often desired. The presented technology improves on current technology by enriching cells based on size without clogging mechanical filters, employing only a simple single-layered microfluidic device and processing cell solutions at the ml∕min scale.  相似文献   
103.
A community-based intervention with specific factors for children and parents exposed to interparental violence (IPV) was compared with a control intervention based on non-specific factors. We hypothesized that participation in an intervention with specific factors, focused on IPV, parenting and coping, would be associated with better recovery. IPV exposed children and parents were group randomized over a specific factors- and control intervention. Baseline, posttest and follow-up measurements of 155 parents and children (aged 6–12 years, 55.5% boys) were fitted in a multilevel model. Outcomes were parent and teacher reported children's internalizing and externalizing problems (CBCL, TRF), child self-reported depressive symptoms (CDI) and parent and child reported children's post-traumatic stress symptoms (TSCYC, TSCC). Based on intention-to-treat and completer analyses, children in the specific factors intervention did not show better recovery than children in the control intervention. Children in both interventions decreased significantly in parent-reported children's internalizing and externalizing problems and post-traumatic stress symptoms. Children reported a decrease in their mean level of depressive and post-traumatic stress symptoms. Teachers reported a decrease in internalizing problems, but not in externalizing problems. No association between time since exposure and level and course of symptoms was found. Treatment differentiation was assessed and both programs were significantly different on hypothesized effective factors. Higher treatment adherence in both programs did not result in a larger difference in recovery. IPV exposed children improve over the course and after participating in a community-based child- and parent program, but specific factors in intervention may not carry additional benefits when implemented in community settings.  相似文献   
104.
In this study, a progressive-learning approach to physics, based on knowledge-building pedagogy, was compared to a content-centered approach in which explanations, experiments, and discussions are centered on the transmission of knowledge. Forty-six students attending the first year of high school participated in this study over a whole school year. Students’ knowledge and mastery of physics concepts were assessed through questionnaires containing both open-ended and multiple-choice questions. Overall, the ‘progressive-learning' group outperformed the content-centered group. Results are discussed in relation to the theoretical background and the experimental teacher's diary of classroom activities. The main conclusion achieved by this study is that the teaching of physics should be slow, cyclic, and developmentally appropriate for the context.  相似文献   
105.
Homework completion has an important impact on the overall academic functioning of students. Consultation requests often center on identifying efficient interventions so that teachers may facilitate the homework process and enhance students' academic achievement. This investigation employed a randomized interdependent group contingency and randomized reinforcers to improve homework completion and accuracy of spelling performance in 21 elementary school students. An ABAB reversal design across all students was employed. Results showed this intervention to have a positive impact on both spelling homework completion and accuracy rates. Limitations, future research, and contributions are addressed.  相似文献   
106.
107.
108.
With the aim of identifying new water dispersed polymers for textile conservation, the structure and properties of three commercial polyacrylates and one commercial polyvinylacetate were analysed. The characteristics of these materials, not previously used in the conservation and restoration fields, were compared with that shown by Primal AC33 and Mowilith DMC2 and SDM5, widely used as consolidating or adhesive agents of ancient textiles. To achieve a thorough characterisation of each polymer, molecular, thermal, structural and mechanical investigation techniques were applied on film samples, obtained from polymer water dispersions through water casting at room temperature and/or compression moulding. The photo-oxidative resistance of these materials was also assessed by artificial weathering of water cast films and by measuring the Yellowing Index (YI) as a function of the exposure time under xenon-arc lamp. Collected data were used to appropriately compare the performances shown by these polymers when applied on artefacts consisting of natural fibres. In particular it was found that, among the products not previously used in the conservation and restoration fields, a high potential for carrying out treatments on textiles is shown by the samples commercialised with the trade names of Acrilem RP6005 and Acrilem 30WA. These products, in fact, exhibit properties that make them suitable as substitutes for Primal AC33 and Mowilith DMC2 and SDM5, respectively, depending upon conservation needs. It was very interesting to note that Acrilem 30WA, also after aging, shows YI values lower than that shown by Mowilith DMC2 and SDM5.  相似文献   
109.
ABSTRACT

The aim of this study was to examine the relationship between the peak velocity derived from the Carminatti Test (T-CAR) (PVT-CAR) and physical match performance in young soccer players. Thirty-three youth soccer players were recruited from 2 non-professional clubs. Friendly matches and small-sided game were performed. Physical match demands were assessed using Global Positioning System (GPS) technology. On a separate occasion, the players were submitted to the T-CAR. Players were categorised into 3 groups based on their T-CAR performance: Low (PVT-CAR ≤ P33), Intermediate (P33 > PVT-CAR < P66) and High (PVT-CAR ≥ P66). The PVT-CAR (15.5 ± 0.7 km·h?1) was significantly related to high-intensity activities (HIA; r = 0.78, P < 0.001), high-intensity running (HIR; r = 0.66, P < 0.001), sprinting (r = 0.62, P < 0.001) and total distance (TD) covered (r = 0.47, P < 0.01) during friendly matches. The PVT-CAR was strongly correlated with the amount of HIA (r = 0.81, P < 0.001), HIR (r = 0.85, P < 0.001) and TD covered (r = 0.81, P < 0.001) during small-sided game. No significant correlation was observed between the PVT-CAR and distance of sprinting (r = 0.49, P = 0.067) during small-side game. Furthermore, players in the High group covered significantly more TD (10%) and did more HIA (42%), sprinting (31%) and HIR (25%) during friendly matches compared to the players classified as having Low performance on the T-CAR. These differences still remained after adjusting for chronological age (CA), maturity and body size. In conclusion, the current study gives empirical support to the ecological and construct validity of this novel field test (T-CAR) as an indicator of match-related physical performance in young soccer players during pubertal years.  相似文献   
110.
This study examined the relations of maternal vicarious emotional responding and child-rearing practices, as well as familial emotional environment, to 5-6 and 8-9-year-old children's vicarious emotional responding. There were some correspondences between mothers' and children's heart rate, facial, and self-reported reactions to a sympathy-inducing film. Maternal sympathy/perspective taking and reinforcement of sympathy/prosocial behavior, as well as negative subordinate emotion in the home, were associated with markers of girls' sympathy; mothers' personal distress (for girls), restrictiveness regarding displays of hurtful negative emotions (particularly for young girls), and negative dominant emotion in the home (for both sexes) were associated with markers of personal distress. Mothers' linking of the film character's experience to children's own experience was associated with children's responsiveness to the film, and mother's verbalizations during the film concerning her own emotional state and role taking were associated with boys' self-reported sympathy.  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