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   891篇
  免费   90篇
  国内免费   131篇
  2024年   2篇
  2023年   14篇
  2022年   20篇
  2021年   27篇
  2020年   48篇
  2019年   41篇
  2018年   30篇
  2017年   39篇
  2016年   39篇
  2015年   35篇
  2014年   34篇
  2013年   77篇
  2012年   50篇
  2011年   65篇
  2010年   65篇
  2009年   64篇
  2008年   66篇
  2007年   84篇
  2006年   76篇
  2005年   50篇
  2004年   24篇
  2003年   18篇
  2002年   10篇
  2001年   14篇
  2000年   8篇
  1999年   9篇
  1998年   7篇
  1997年   3篇
  1996年   9篇
  1995年   7篇
  1994年   10篇
  1993年   2篇
  1992年   5篇
  1991年   3篇
  1990年   4篇
  1989年   5篇
  1988年   5篇
  1987年   4篇
  1986年   7篇
  1985年   4篇
  1983年   1篇
  1982年   3篇
  1981年   5篇
  1980年   3篇
  1979年   3篇
  1978年   3篇
  1977年   5篇
  1976年   2篇
  1975年   1篇
  1973年   1篇
排序方式: 共有1112条查询结果,搜索用时 15 毫秒
61.
Besides the well-known cube-on-cube orientation relationship (OR) between M23C6 carbide and matrix, we have determined a new OR named as the twin-related OR in a long-term ageing Ni-based superalloy on the basis of the extensive and detailed electron diffraction analyses. Furthermore, by means of atomic-resolution high angle annular dark-field imaging technique which is implemented in the aberration-corrected scanning transmission electron microscope, we elucidated the interfacial characteristics between M23C6 and matrix for above two types of ORs. Taking into account of the interfacial characteristics, we propose that the twin-related OR possesses a higher total interfacial energy. Thus, its frequency of occurrence is lower than that of the cube-on-cube OR though both ORs are usually seen in the long-term ageing samples.  相似文献   
62.
The directional solidification process of ternary Ag42.4Cu21.6Sb36 eutectic alloy within a wide growth rate range from 2 to 60 μm/s was accomplished at a constant temperature gradient of 50 K/cm. As growth rate increases, the ternary (θ(Cu2Sb) + ε(Ag3Sb) + Sb) eutectic morphology evolves from “lamellar (θ + ε) plus fibrous (Sb)” structure into “(θ + Sb) fibres in continuous ε matrix” structure. The θ and (Sb) phase spacings decrease with the increase of growth rate according to power functions with exponent values of 0.55 and 0.56, respectively. It is also found that the microhardness of directionally solidified Ag42.4Cu21.6Sb36 alloy samples is enhanced with the increase of growth rate, and the decrease of θ and (Sb) phase spacings.  相似文献   
63.
64.
Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used to investigate the factor structure of coping in mothers with high levels of life stress. In Study 1, EFA of the Coping Orientation to Problems Experienced (C. S. Carver, M. F. Scheier, & J. K. Weintraub, 1989) in a sample of mothers of full-term or very low birth weight 2-year-old children yielded 7 reliable coping factors. Each factor accounted for significant variance in at least 1 of 6 outcomes measuring maternal-child well-being. In Study 2, CFA was used to cross-validate the EFA model on the basis of the responses of mothers of 2-year-old children with prenatal polysubstance exposure. CFA results revealed a moderately good fit, confirming the factor structure in a 2nd, independent sample of mothers with high levels of life stress.  相似文献   
65.
Crick and Dodge’s (Psychological Bulletin 115:74–101, 1994) social information processing model has proven very useful in guiding research focused on aggressive and peer-rejected children’s social-cognitive functioning. Its application to early childhood, however, has been much more limited. The present study responds to this gap by developing and validating a video-based assessment tool appropriate for early childhood, the Schultz Test of Emotion Processing—Preliminary Version (STEP-P). One hundred twenty-five Head Start preschool children participated in the study. More socially competent children more frequently attributed sadness to the victims of provocation and labeled aggressive behaviors as both morally unacceptable and less likely to lead to positive outcomes. More socially competent girls labeled others’ emotions more accurately. More disruptive children more frequently produced physically aggressive solutions to social provocations, and more disruptive boys less frequently interpreted social provocations as accidental. The STEP-P holds promise as an assessment tool that assesses knowledge structures related to the SIP model in early childhood.  相似文献   
66.
“多少”概念发展的研究   总被引:1,自引:0,他引:1  
采用数量判定任务,分别用2~30和5~100范围内点子图为刺激,研究个体“多”和“少”概念的发展。结果发现:在5~100点子条件下,随年龄的增长,个体“多”概念的判断值、“少”概念的判断值、“多”“少”概念的临界值均显著增大;7~9岁是个体“多少”概念发展的转折期;个体对“多少”概念的认知具有相对性;在本实验的两种条件下,随年龄增长,个体“多”概念的判断值、“少”概念的判断值、“多”“少”概念的临界值逐渐趋于刺激点子数最大值的2/3、1/3、1/2,“多”概念与“少”概念判断的不确定距离逐渐趋于刺激点子数最大变化范围的1/3或略小于1/3。  相似文献   
67.
人乳头瘤病毒疫苗的问世使宫颈癌的预防进入崭新的时代,自其问世以来便饱受伦理争议.通过分析目前全球医学文献中比较重视和争议的伦理问题,如Gardasil与Cervarix哪种更为有效,能否在发展中国家顺利推广,应当“强制接种”还是“自愿接种”,男性是否应常规接种等.基于伦理学的基本原则,提出正确的宣教是解决的经由之路.  相似文献   
68.
本文在对当前国内外主要心理统计学教材进行比较的基础上,指出与上个世纪八十年代的心理统计学教材内容相比较,在内容上的新探索主要体现在(1)由“假设检验”的内容中发展出“统计检验力”和“效果大小”的统计指标和估计方法;(2)引进一般线性模型来统合方差分析和回归分析这两种统计方法;(3)适度增加一些“多元统计分析”的内容等三个方面.本文对前两个方面的新内容作了简要评述,并对教材内容的编排方面提出了新的思路.  相似文献   
69.
This article highlights the impact of technology on the ability of individuals to be creative within society. The role of computers in the creative act is explored from a broad perspective to allow for the discovery of general principles of creativity. Insight into the barriers that individuals must overcome to function creatively in the information age are then presented. To this end, the process by which creativity occurs is reviewed, and the consequences of the development of technology and the impact of computers on creativity are discussed. Examples of computers used to facilitate creativity are then illustrated. Finally, the necessary conditions for creativity to exist in society are highlighted, and suggestions are offered for the coexistence of creativity and technology in the future.  相似文献   
70.
This is a study of the development trend of creative scientific problem finding (CSPF) ability of a sample of 1,367 elementary, middle, and high school students in two Chinese cities. Students were instructed to generate science related questions in both open and closed conditions with responses scored for Fluency, Flexibility, and Originality. Results suggest that CSPF ability has a developmental trend characterized by a significant leap in the 5th grade, followed by a steady advance until it peaked in the 8th grade, and then declined and stabilized in the high school years (9th–11th grades). No difference between male and female students was found. The type of instruction showed significant differential influence on CSPF and its development.  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