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   34856篇
  免费   655篇
  国内免费   2篇
  35513篇
  2019年   450篇
  2018年   587篇
  2017年   610篇
  2016年   611篇
  2015年   448篇
  2014年   550篇
  2013年   2486篇
  2012年   1023篇
  2011年   1081篇
  2010年   639篇
  2009年   645篇
  2008年   944篇
  2007年   929篇
  2006年   879篇
  2005年   787篇
  2004年   774篇
  2003年   703篇
  2002年   745篇
  2001年   1039篇
  2000年   954篇
  1999年   737篇
  1998年   401篇
  1997年   331篇
  1996年   333篇
  1992年   569篇
  1991年   558篇
  1990年   544篇
  1989年   553篇
  1988年   549篇
  1987年   510篇
  1986年   534篇
  1985年   585篇
  1984年   471篇
  1983年   451篇
  1982年   372篇
  1981年   361篇
  1979年   536篇
  1978年   396篇
  1977年   330篇
  1976年   366篇
  1975年   447篇
  1974年   499篇
  1973年   515篇
  1972年   409篇
  1971年   387篇
  1970年   382篇
  1969年   411篇
  1968年   491篇
  1967年   422篇
  1966年   423篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.

In the present study, we investigated whether parents’ beliefs about their high school aged adolescents’ spatial abilities (i.e., spatial visualization, mental manipulation, and navigation abilities) differed based on their child’s gender. We also examined whether these beliefs related to parents’ encouragement of their child to pursue a Science, Technology, Engineering, or Mathematics (STEM) career as well as students’ actual STEM major and career intentions. Data were collected from 117 pairs of U.S. high school students and one of their parents. We found that parents of young men thought their child had higher mental manipulation and navigation abilities than did parents of young women, even after statistically controlling for adolescents’ actual spatial abilities. Parents who perceived that their child had higher mental manipulation ability were more likely to encourage their child to pursue a STEM career, and those students were more likely to report that they intended to pursue a STEM career. These findings suggest that parents’ beliefs about how good their child is at spatial tasks may be based more strongly on gender stereotypes than on their child’s actual spatial abilities. Helping to make parents aware of these beliefs could be a potential lever of intervention to increase women’s participation in STEM careers.

  相似文献   
992.
Motivation and Emotion - Parents’ level of involvement in children’s schooling is related to children’s academic success; yet, few studies have considered factors that may play a...  相似文献   
993.
Only recently has determining the child-rearing concerns of parents been considered an important research objective. Existing efforts have, for the most part, either employed small sample sizes or surveyed parents already in the process of seeking help or advice. It was, therefore, felt that additional, more representative data were needed. In the present study, 583 mothers with children aged 59 months or younger were surveyed regarding their concerns about their children's development. On the „Specific Needs Assessment Report”︁ (SNAR) (copyright © 1975, by Karl F. Riem, J. Jeffrey Crisco, and Kathy Willms), mothers rated their concerns for 60 developmental-behavioral items about their children's health, attending skills, problem behaviors, communication skills, motor skills, cognitive skills, self-help skills, and social skills. Mothers were most frequently concerned to a moderate or major degree about at least one item of the problem behavior category. For this category, parent-child management, crying-whining, and temper tantrums were the individual items of greatest concern. Mothers of girls more frequently indicated health concerns than mothers of boys. These results support those of previous investigations, which suggested the need for parent education programs to help parents manage their children.  相似文献   
994.
Data from experimental animals suggest that 5-hydroxytryptamine (5HT) may have an inhibitory effect on aggression, while clinical studies have found a correlation between pathological aggression and low brain 5HT. To investigate this relationship further we used amino acid mixtures designed to raise or lower the levels of the 5HT precursor, tryptophan. Normal male subjects were given tryptophan-depleted, balanced, or tryptophan-supplemented ammo acid mixtures and tested for aggression 5 hours later. The balanced amino acid mixture served as a control for the tryptophan depletion and supplementation. Testing for aggression was done using the Buss paradigm in which subjects deliver electric shocks to a (nonexistent) partner in response to stimulus tones. Duration and intensity of shock delivered were the measures of aggression, while responsivity to the stimulus tones was the measure of perceptual sensitivity. Neither tryptophan supplementation nor tryptophan depletion had any effect on these measures of aggression or perceptual sensitivity. We conclude that raising or lowering the synthesis of brain 5HT through alterations in tryptophan availability does not influence aggression in normal males as measured by the Buss task.  相似文献   
995.
The experiments were performed on adult male cats selected initially as good mousekillers. Cats were tested in pairs and each pair was introduced separately to the experimental compartment. The attitude toward the partner before and during the predatory competition test as well as superiority in catching and killing the mice, considered as an index of dominance, were registered. In the course of experiment five types of relations between the predatory dominance and aggressive behavior were observed. The concept of dominance as an outcome of several factors was discussed. It was concluded that predatory dominance is not based exclusively on aggressive mechanisms, as it may be formed and sustained without overt aggression.  相似文献   
996.
997.
998.
999.
Abstract— This article compares studies that use event-related brain potential (ERP) and eye movement data to examine changes in reading behavior when a text is read twice. Although the types of information provided by these methodologies are different, both indicate that rereading a text facilitates many aspects of processing. ERPs provide a method for measuring comprehension and memory processes separately, while eye movements provide a continuous record of performance and allow changes in reading behavior to be localized to specific words. The results from these studies are compatible. However, converging evidence is not always found when different paradigms are contrasted, and diverging results can provide important information. To facilitate comparison across experiments, we suggest using a common set of materials for both paradigms. We conclude that comparing the results of research based on more than one paradigm provides a more complete understanding of the processes involved in reading.  相似文献   
1000.
STATED WILLINGNESS TO PAY FOR PUBLIC GOODS:   总被引:3,自引:0,他引:3  
Abstract— In the contingent valuation method for the valuation of public goods, survey respondents are asked to indicate the amount they are willing to pay (WTP) for the provision of a good. We contrast economic and psychological analyses of WTP and describe a study in which respondents indicated their WTP to prevent or to remedy threats to public health or to the environment, attributed either to human or to natural causes. WTP was significantly higher when the cause of a harm was human, though the effect was not large. The means of WTP for 16 issues were highly correlated with the means of other measures of attitude, including a simple rating of the importance of the threat. The responses are better described as expressions of attitudes than as indications of economic value, contrary to the assumptions of the contingent valuation method.  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