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   2896篇
  免费   608篇
  国内免费   211篇
  3715篇
  2024年   65篇
  2023年   43篇
  2022年   54篇
  2021年   94篇
  2020年   116篇
  2019年   89篇
  2018年   101篇
  2017年   118篇
  2016年   77篇
  2015年   84篇
  2014年   77篇
  2013年   233篇
  2012年   168篇
  2011年   220篇
  2010年   188篇
  2009年   192篇
  2008年   207篇
  2007年   295篇
  2006年   277篇
  2005年   244篇
  2004年   160篇
  2003年   117篇
  2002年   72篇
  2001年   57篇
  2000年   41篇
  1999年   63篇
  1998年   34篇
  1997年   32篇
  1996年   26篇
  1995年   27篇
  1994年   18篇
  1993年   22篇
  1992年   9篇
  1991年   7篇
  1990年   9篇
  1989年   9篇
  1988年   10篇
  1987年   4篇
  1986年   11篇
  1985年   8篇
  1984年   10篇
  1983年   7篇
  1982年   6篇
  1981年   5篇
  1980年   6篇
  1979年   3篇
排序方式: 共有3715条查询结果,搜索用时 0 毫秒
821.
张华  庞丽娟  董奇  陈瑶 《心理科学》2004,27(6):1333-1336
数数能力是儿童用于建构其数学知识系统的重要工具,是儿童早期获得的最基本的数认知能力之一。本研究以234名3、4岁儿童为被试,采用个别测查法对儿童数数的规则及其策略运用进行了考察。研究发现:(1)随着数列数目的增大,3、4岁儿童数数精确性呈下降趋势,但4岁儿童在各项任务上的数数精确性显着高于3岁儿童;(2)3、4岁儿童在数7、10、15、30任务上的错误表现有显着差别;(3)3、4岁儿童数数策略运用存在显着差别.协方差分析显示。策略使用在数7和数10任务上具有显着效应。  相似文献   
822.
In this study, the authors validated the 3-factor, 8-facet model of Hood's Mysticism Scale and explored mean differences in mysticism with 330 indigenous Chinese Christian and 323 non-Christian participants. Confirmatory factor analysis demonstrated good fit for the overall Chinese sample and established measurement invariance of the instrument across the 2 groups. Both groups scored above the midpoint on the total Mysticism Scale, whereas Christians scored significantly higher in the mystical interpretation factor than did non-Christians. Controlling for demographic variables, multiple regression procedures revealed that a high intrinsic religious orientation mediated the association of Christian religious affiliation with mysticism. These results yielded patterns consistent with those found in the West and suggested that the Mysticism Scale was a valid quantitative measure for exploring spirituality issues in Chinese society.  相似文献   
823.
It is generally assumed that “perceptual object” is the basic unit for processing visual information and that only a small number of objects can be either perceptually selected or encoded in working memory (WM) at one time. This raises the question whether the same resource is used when objects are selected and tracked as when they are held in WM. In two experiments, we measured dual-task interference between a memory task and a Multiple Object Tracking task. The WM tasks involve explicit, implicit, or no spatial processing. Our results suggest there is no resource competition between working memory and perceptual selection except when the WM task requires encoding spatial properties.  相似文献   
824.
    
This study examined the relationship between family context of middle school students on their educational and occupational ideals. Middle school students (N = 2000) responded to questions assessing family location, family structure, parental educational level and family economic status, as well as to the Middle School Students' Ideals Questionnaire. Multivariate analysis of variance indicated that life, educational and occupational ideals of female students and students in lower grades were higher than that of male students and students in higher grades. Regression analysis indicated that paternal education level have a positive association with educational and occupational ideals, but not life ideals, and family economic status have a positive relation to life ideals, but not educational and occupational ideals. Moreover, the interaction between family economic status and family location has a negative association with students' life, educational and occupational ideals. These results suggest that different factors predicted different ideals of adolescents, and that family economic status had a negative moderating effect on the relationship between family location and ideals of students.  相似文献   
825.
    
Recent research has shown that poverty directly impeded cognitive functions because the poor could be easily distracted by monetary concerns. We argue that this effect may be limited to functions relying on working memory. For functions that rely on proceduralized processes however, monetary concerns elicited by reminding of financial demands would be conducive rather than harmful. Our results supported this hypothesis by showing that participants with lower income reached the learning criterion of the information‐integration categorization task faster than their more affluent counterparts after reminding of financial demands.  相似文献   
826.
    
  相似文献   
827.
    
Tungsten (W) is cited as a candidate first-wall material in fusion reactors owing to its outstanding thermal properties and erosion resistance. An important issue is that the energetic isotopes of hydrogen, tritium (T) and deuterium (D) and helium (He) particles damage the surface of W in fusion reactors. He particles cause more notable damage than D or T because the binding energy of defects and He is larger than that of defects and D or T. In this study, well-annealed W specimens were implanted with 5 keV He ions at room temperature and irradiation dosages of 1.0 × 1020 and 2.5 × 1021 ions/m2. Then, thermal desorption spectroscopy analysis was performed by heating the samples to 1973 K at a ramping rate of 0.5 K/s. Thermal desorption of He in the sample irradiated with a low dosage occurred at 1400 and 1960 K, whereas that in the sample irradiated with a high dosage occurred at 740, 1050 and 1500 K. According to the microstructures observed using transmission electron microscopy, both peaks in the former case were attributed to He de-trapping from irradiation to nduced helium-vacancy clusters of different sizes, whereas the peaks in the latter case were attributed to He de-trapping from surface defects, irradiation-induced dislocation loops and tiny helium-vacancy clusters, respectively.  相似文献   
828.
829.
    
A pectin lyase gene pnlzj5b from Aspergillus niger ZJ5 was identified and overexpressed successfully in Pichia pastoris. Recombinant PNLZJ5B exhibited high activity towards citrus pectin (150 U ml−1). Through further codon optimization, the expression efficiency of PNLZJ5B in P. pastoris increased to 3·5-fold (532/150 U ml−1). PNLZJ5B was purified by ultrafiltration, anion exchange and gel chromatography. It showed optimal activity and good stability at 58°C and pH 4·5. PNLZJ5B activity improved with increasing degrees of methyl esterification of pectin. The Km and Vmax values were 0·81 mg ml−1 and 372·8 μmol min−1 mg−1, respectively. In addition, PNLZJ5B effectively decreased the viscosity of apple juice. Compared with commercial pectin lyase, PNLZJ5B obtained a higher juice volume. These favourable enzymatic properties of PNLZJ5B show potential utility in juice-processing applications and other food-related fields.  相似文献   
830.
    
The aim of this study is to examine the mediating role of life events in the relation between Internet addiction and depression using an adolescent sample in China. A total of 3507 urban adolescent students were asked to complete the questionnaires including Young's Internet Addiction Scale, Adolescent Self‐Rating Life Events Checklist, and Center for Epidemiologic Studies Depression Scale, Parent–Child Conflict Tactics Scales, and demographic characteristics. Path analyses demonstrated that life events fully mediated the relationship between Internet addiction and adolescent depression. Specificity for the mediating role of life events was demonstrated in comparison to alternative competing mediation models. The findings support our hypothesis that the effect of Internet addiction on adolescent depression is mediated by the life events. Further research is required to test the temporal relationship between Internet addiction and adolescent depression and explore mechanisms underlying the pathways leading to adolescent depression.  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