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   22335篇
  免费   1108篇
  国内免费   17篇
  2021年   200篇
  2020年   338篇
  2019年   409篇
  2018年   560篇
  2017年   574篇
  2016年   571篇
  2015年   461篇
  2014年   489篇
  2013年   1912篇
  2012年   853篇
  2011年   957篇
  2010年   570篇
  2009年   552篇
  2008年   725篇
  2007年   705篇
  2006年   608篇
  2005年   521篇
  2004年   513篇
  2003年   491篇
  2002年   482篇
  2001年   776篇
  2000年   756篇
  1999年   516篇
  1998年   248篇
  1997年   234篇
  1996年   203篇
  1995年   181篇
  1994年   176篇
  1993年   182篇
  1992年   400篇
  1991年   363篇
  1990年   394篇
  1989年   360篇
  1988年   345篇
  1987年   319篇
  1986年   334篇
  1985年   340篇
  1984年   270篇
  1983年   218篇
  1979年   227篇
  1978年   192篇
  1975年   218篇
  1974年   262篇
  1973年   223篇
  1972年   222篇
  1971年   187篇
  1969年   205篇
  1968年   208篇
  1967年   170篇
  1966年   189篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
81.
Pigeons can discriminate locations presented in pictures   总被引:3,自引:3,他引:0       下载免费PDF全文
The present experiments were designed to teach pigeons to discriminate two locations represented by color photographs. Two sets of photographs were taken at two distinctive locations on a university campus. These sets represented several standpoints at each location. For the true-discrimination group, pictures from the two locations were differentially associated with reward; for the pseudodiscrimination group, half of the views from each location were arbitrarily but consistently associated with reward. The former group acquired the discrimination much more rapidly. These birds also showed good transfer to new views from the standpoints used in training and to a new standpoint at each location not used in training. In a second experiment, another group of pigeons could terminate any training trial by pecking an “advance” key. Three of 4 subjects used this option to reduce the duration of trials in which pictures from the negative location were presented. These data suggest that pigeons can integrate views shown in pictures into a “concept” of a location. The method used here may be the experimental analogue of a common, natural process by which animals learn to identify locations.  相似文献   
82.
Basing on the author's experiences during his study stay at the Serbsky All-Union Research Institute for General and Forensic Psychiatry in Moscow a report is given about the theoretical foundations and the carrying-out of forensic-psychiatric expert-opinions in the field of penal as well as civil law in the U.S.S.R. Some peculiarities in comparison with the practice in the G.D.R. are taken in special account.  相似文献   
83.
The Rosenberg Self-esteem Scale was administered to 550 14- and 16-yr.-old (+/- 6 mo.) girls. Self-esteem scores were categorized by weight and weight by height. Scores on the Quetelet Index for obesity were correlated with self-esteem scores. Mean self-esteem of the low- and middle-weight by height group was significantly higher than the mean of the high-weight by height group. In analyzing weight alone, the self-esteem of the middle-weight group was significantly higher than the self-esteem of the high-weight group. The correlation of the obesity index and self-esteem indicated that as weight increased self-esteem decreased.  相似文献   
84.
85.
86.
87.
88.
89.
90.
Stress in time     
The goals of this research were to determine whether speakers adjust the stress patterns of words within sentences to create an alternation between strong and weak beats and to explore whether this rhythmic alternation contributes to the characteristics stress differences between two major lexical categories of English. Two experiments suggested that speakers do alter lexical stress in accordance with rhythmic biases. When speakers produced disyllabic pseudowords in sentence contexts, they were more likely to place stress on the first syllable when the pseudoword was preceded by a weak stress and followed by a strong one than when the strong stress preceded and the weak followed. This occurred both when the pseudowords served as nouns and when they served as verbs. Text analyses further revealed that weakly stressed elements precede nouns more often than verbs, whereas such elements follow verbs more often than nouns. Thus, disyllabic nouns are more likely than disyllabic verbs to occupy contexts biased toward trochaic rhythm, a finding consistent with leftward dominant stress in disyllabic English nouns. The history of stress changes in English nouns and verbs also conforms with the view that rhythmic context may have contributed to the evolution of stress differences. Together, the findings suggest that the citation stress patterns of words may to some degree reflect adaptations of lexical knowledge to conditions of language performance.  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