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   1794篇
  免费   40篇
  国内免费   13篇
教育   1211篇
科学研究   304篇
各国文化   29篇
体育   130篇
综合类   6篇
文化理论   10篇
信息传播   157篇
  2023年   12篇
  2022年   13篇
  2021年   36篇
  2020年   39篇
  2019年   52篇
  2018年   72篇
  2017年   97篇
  2016年   65篇
  2015年   50篇
  2014年   64篇
  2013年   325篇
  2012年   54篇
  2011年   63篇
  2010年   66篇
  2009年   53篇
  2008年   55篇
  2007年   52篇
  2006年   36篇
  2005年   39篇
  2004年   23篇
  2003年   31篇
  2002年   33篇
  2001年   32篇
  2000年   34篇
  1999年   32篇
  1998年   10篇
  1997年   8篇
  1996年   23篇
  1995年   17篇
  1994年   18篇
  1993年   13篇
  1992年   14篇
  1991年   18篇
  1990年   12篇
  1989年   13篇
  1988年   11篇
  1987年   14篇
  1986年   13篇
  1985年   23篇
  1984年   13篇
  1983年   15篇
  1982年   15篇
  1981年   10篇
  1980年   11篇
  1978年   8篇
  1975年   12篇
  1974年   8篇
  1973年   11篇
  1971年   8篇
  1970年   6篇
排序方式: 共有1847条查询结果,搜索用时 15 毫秒
61.
Verbal intelligence, English-language skills, personality, and attitude scales were used as predictors of academic performance in 230 male and female arts students at the University of Hong Kong. A series of bivariate, multiple, and canonical correlation analyses were performed. The results showed that verbal intelligence and attitudes, excepting study orientation, were not predictive of performance. English-language skills had the most predictive value, accounting for about 10% of the variance of performance measures. Personality variables failed to predict performance when composite criterion measures (GPAs) were used; however, they proved to be of predictive value when results of individual academic subjects were used as criterion measures. The study points to the importance of using noncomposite criterion measures in prediction and of considering the cultural context of achievement.  相似文献   
62.
63.
This study was an initial attempt to investigate the relationships among self-efficacy, outcome expectancy, behavioral intention, and actual behavior over time in a beginning weight training class. A total of 109 participants completed questionnaires assessing their self-efficacy, outcome expectancy, and intentions for future weight training. Their attendance and workout logs were calculated as a measure of actual behavior. Correlation analyses revealed significant positive relationships among all the variables during both program periods. Multiple regression analyses indicated that outcome expectancy initially played a more important role than self-efficacy in predicting behavioral intention and actual behavior. However, self-efficacy appeared more influential at midprogram. Findings of this study can enhance our understanding of the determining factors for individuals' motivated behaviors in college physical activity classes.  相似文献   
64.
65.
66.
<正> 全国化工院校情报中心站第四届年会于1988年10月17日-21日在武汉化工学院召开。中心站21个成员单位的代表出席了会议。化工部情报所的有关同志参加了会议。湖北省及武汉市图书馆情报界的知名人士、武汉化工学院领导等均到会致词祝贺。年会的主要议程有:一、就高校情报工作的服务方向、情报有偿服务、情报教学等方面的改革进行了广泛的交流和探讨。华东化工学院和青岛化工学院的代表介绍了图书馆实行定编定岗、优化组合、工资包干和情报实行定额承包、面向企业的改革尝试,引起了代表们的极大兴趣和热烈讨论。  相似文献   
67.
The present work was aimed to study the association of one carbon genetic variants, hyperhomocysteinemia and oxidative stress markers, i.e., serum nitrite, plasma malondialdehyde (MDA) and glutathione (GSH) on intimal medial thickening (IMT) in patients with type 2 diabetes mellitus (T2D). A total number of 76 subjects from ACS Medical College and Hospital, Chennai, India were included in the study, i.e., Group I (n = 42) of T2D and Group II (n = 34) of age- and sex matched healthy controls. The glycated haemoglobin was measured by ion-exchange resin method; plasma homocysteine by Enzyme Linked Immunosorbant Assay method; serum nitrite (nitric oxide, NO), plasma MDA and GSH by spectrophotometric methods; the IMT by high frequency ultrasound. The polymorphisms of one carbon genetic variants were genotyped using polymerase chain reaction-restriction fragment length polymorphism and amplified fragment length polymorphism methods. Results indicate that methyltetrahydrofolate homocysteine methyl transferase (MTR) A2756G allele was found to be protective in T2D and the other variants were not significantly associated with T2D. Glutamate carboxypeptidase II (GCP II) C1561T (r = 0.34; p = 0.05) and methylene tetrahydrofolate reductase (MTHFR) C677T (r = 0.35; 0.04) showed positive correlation with plasma homocysteine in T2D cases. In this study, MTR A2756G allele was found to be protective in T2D; GCP II C1561T and MTHFR C677T showed positive association with plasma homocysteine in T2D cases. Among all the genetic variants, MTR A2756G was found influence IMT. RFC 1 G80A and TYMS 5′-UTR 2R3R showed synergistically interact with MTR A2756G in influencing increase in IMT.  相似文献   
68.
This paper describes a method for the quantitative detection of cells expressing BlaC, a β-lactamase naturally expressed by Mycobacterium tuberculosis, intended for the diagnosis of tuberculosis. The method is based on the compartmentalization of bacteria in picoliter droplets at limiting dilutions such that each drop contains one or no cells. The co-encapsulation of a fluorogenic substrate probe for BlaC allows the quantification of bacteria by enumerating the number of fluorescent drops. Quantification of 10 colony forming units per milliliter is demonstrated. Furthermore, the encapsulation of single cell in drops maintains the specificity of the detection scheme even when the concentration of bacteria that do not express BlaC exceeds that expressing BlaC by one million-fold.  相似文献   
69.
Many self-propelled microorganisms are attracted to surfaces. This makes their dynamics in restricted geometries very different from that observed in the bulk. Swimming along walls is beneficial for directing and sorting cells, but may be detrimental if homogeneous populations are desired, such as in counting microchambers. In this work, we characterize the motion of human sperm cells ∼60 μm long, strongly confined to ∼25 μm shallow chambers. We investigate the nature of the cell trajectories between the confining surfaces and their accumulation near the borders. Observed cell trajectories are composed of a succession of quasi-circular and quasi-linear segments. This suggests that the cells follow a path of intermittent trappings near the top and bottom surfaces separated by stretches of quasi-free motion in between the two surfaces, as confirmed by depth resolved confocal microscopy studies. We show that the introduction of artificial petal-shaped corrugation in the lateral boundaries removes the tendency of cells to accumulate near the borders, an effect which we hypothesize may be valuable for microfluidic applications in biomedicine.  相似文献   
70.
Creating multicellular tumor spheroids is critical for characterizing anticancer treatments since they may provide a better model of the tumor than conventional monolayer culture. Moreover, tumor cell interaction with the extracellular matrix can determine cell organization and behavior. In this work, a microfluidic system was used to form cell-laden core-shell beads which incorporate elements of the extracellular matrix and support the formation of multicellular spheroids. The bead core (comprising a mixture of alginate, collagen, and reconstituted basement membrane, with gelation by temperature control) and shell (comprising alginate hydrogel, with gelation by ionic crosslinking) were simultaneously formed through flow focusing using a cooled flow path into the microfluidic chip. During droplet gelation, the alginate acts as a fast-gelling shell which aids in preventing droplet coalescence and in maintaining spherical droplet geometry during the slower gelation of the collagen and reconstituted basement membrane components as the beads warm up. After droplet gelation, the encapsulated MCF-7 cells proliferated to form uniform spheroids when the beads contained all three components: alginate, collagen, and reconstituted basement membrane. The dose-dependent response of the MCF-7 cell tumor spheroids to two anticancer drugs, docetaxel and tamoxifen, was compared to conventional monolayer culture.  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