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   65746篇
  免费   2606篇
  国内免费   31篇
  2020年   629篇
  2019年   788篇
  2018年   1073篇
  2017年   1139篇
  2016年   1164篇
  2015年   876篇
  2014年   996篇
  2013年   4770篇
  2012年   1848篇
  2011年   1931篇
  2010年   1243篇
  2009年   1200篇
  2008年   1740篇
  2007年   1654篇
  2006年   1487篇
  2005年   1352篇
  2004年   1256篇
  2003年   1245篇
  2002年   1207篇
  2001年   2194篇
  2000年   2132篇
  1999年   1564篇
  1998年   717篇
  1997年   604篇
  1992年   1430篇
  1991年   1344篇
  1990年   1346篇
  1989年   1188篇
  1988年   1175篇
  1987年   1148篇
  1986年   1137篇
  1985年   1258篇
  1984年   1004篇
  1983年   856篇
  1982年   631篇
  1981年   614篇
  1979年   1064篇
  1978年   723篇
  1977年   700篇
  1976年   660篇
  1975年   931篇
  1974年   1003篇
  1973年   1096篇
  1972年   922篇
  1971年   829篇
  1970年   825篇
  1969年   830篇
  1968年   1061篇
  1967年   929篇
  1966年   904篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Suicides among older adults in the United States and Canada in the last decade have accounted for an increasing share of all suicides. In both countries the use of firearms among older adults has steadily increased. Despite these trends, little is known about the extent to which crisis centers are prepared to prevent elder suicide. A survey of AAS-listed crisis prevention centers examined the training, knowledge, and current practices relevant to elder suicide among personnel in 321 crisis prevention centers in both countries. Results revealed insufficient training, a lack of familiarity with recent suicide trends, and limited outreach to older adults.  相似文献   
82.
Cancellation tests are commonly used in the clinical assessment of visuospatial function, but there has been little study of task characteristics influencing performance. This study was designed to assess factors which affect cancellation performance. Sixteen healthy subjects sequentially performed four random-array letter cancellation tasks. The forms contained 50 and 100 stimuli and target:distractor (T/D) ratios of 1:4 and 1:9 with target letter “A” and randomly selected letter distractors. The primary performance measure was calculated as the number of correctly cancelled targets divided by the time to complete the task, corrected for accuracy. This measure revealed a strong effect of T/D ratio (p< .0001), with performance adversely affected by higher proportion of distractors. There was no effect of stimulus number. This suggests that T/D ratio should be considered in cancellation test design and interpretation.  相似文献   
83.
84.
85.
86.
87.
88.
Three experiments examined the relationships among plan complexity, access to planned actions, and verbal fluency while pursuing a persuasion goal. Consistent with theoretical expectations, complex planners were less fluent than less complex planners under high access conditions. Persons whose access was raised were less fluent than those whose access was not raised. A second experiment showed that reduced fluency was not induced by lowering of self-confidence. The third experiment replicated the findings of the second experiment and demonstrated that the questioning procedure used to raise access in the first two experiments produced increases in plan complexity as suggested by theory. These findings are discussed in terms of their implications for the study of strategic communication.  相似文献   
89.
90.
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