全文获取类型
收费全文 | 891篇 |
免费 | 90篇 |
国内免费 | 131篇 |
出版年
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.
David Schultz Archana Ambike Sean Kevin Logie Katherine E. Bohner Laura M. Stapleton Holly VanderWalde Christopher B. Min Jennifer A. Betkowski 《Journal of abnormal child psychology》2010,38(5):601-613
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.
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