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   38064篇
  免费   547篇
  国内免费   54篇
教育   26700篇
科学研究   4302篇
各国文化   390篇
体育   2817篇
综合类   39篇
文化理论   313篇
信息传播   4104篇
  2021年   350篇
  2020年   562篇
  2019年   830篇
  2018年   1082篇
  2017年   1162篇
  2016年   1065篇
  2015年   666篇
  2014年   891篇
  2013年   7460篇
  2012年   860篇
  2011年   925篇
  2010年   754篇
  2009年   726篇
  2008年   807篇
  2007年   784篇
  2006年   668篇
  2005年   634篇
  2004年   588篇
  2003年   542篇
  2002年   594篇
  2001年   643篇
  2000年   641篇
  1999年   610篇
  1998年   337篇
  1997年   366篇
  1996年   413篇
  1995年   345篇
  1994年   360篇
  1993年   342篇
  1992年   490篇
  1991年   513篇
  1990年   514篇
  1989年   517篇
  1988年   437篇
  1987年   415篇
  1986年   441篇
  1985年   521篇
  1984年   438篇
  1983年   422篇
  1982年   356篇
  1981年   342篇
  1980年   316篇
  1979年   425篇
  1978年   388篇
  1977年   333篇
  1976年   289篇
  1975年   227篇
  1974年   243篇
  1973年   256篇
  1971年   226篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
161.
162.
163.
Indexing consistency in MEDLINE   总被引:3,自引:0,他引:3  
The quality of indexing of periodicals in a bibliographic data base cannot be measured directly, as there is no one "correct" way to index an item. However, consistency can be used to measure the reliability of indexing. To measure consistency in MEDLINE, 760 twice-indexed articles from 42 periodical issues were identified in the data base, and their indexing compared. Consistency, expressed as a percentage, was measured using Hooper's equation. Overall, checktags had the highest consistency. Medical Subject Headings (MeSH) and subheadings were applied more consistently to central concepts than to peripheral points. When subheadings were added to a main heading, consistency was lowered. "Floating" subheadings were more consistent than were attached subheadings. Indexing consistency was not affected by journal indexing priority, language, or length of the article. Terms from MeSH Tree Structure categories A, B, and D appeared more often than expected in the high-consistency articles; whereas terms from categories E, F, H, and N appeared more often than expected in the low-consistency articles. MEDLINE, with its excellent controlled vocabulary, exemplary quality control, and highly trained indexers, probably represents the state of the art in manually indexed data bases.  相似文献   
164.
165.
The present study examined three hypotheses regarding the consequences of early brain damage for academic achievement: First, early brain insults will have a negative impact on achievement, even in children with normal intelligence. Second, underachievement in these children will be at least partially independent of IQ (i.e., not fully accounted for by a lowering of IQ within the average range). Third, normally intelligent children with histories of brain insult will also manifest selective cognitive dysfunctions. To test these hypotheses, we compared two groups of children who had recovered from Haemophilus influenzae type b meningitis. The "complicated" group consisted of children who, as a consequence of having sustained neurologic complications during their illness, were more likely to have had brain insults. Children in the "uncomplicated" group did not have complications with their illness and were regarded as having escaped significant central nervous system (CNS) pathology. Only children with normal hearing and a prorated Full Scale IQ of at least 80 (WISC-R) were considered. Group differences on the Wide Range Achievement Test-Revised were consistent with the first two hypotheses. Although the two groups had similar Verbal IQs, the complicated group also had a lower mean Performance IQ and performed less well on perceptually demanding neuropsychological tasks. Findings suggest that learning disabilities may have selective, brain-related cognitive antecedents; but they challenge the practice of using IQ criteria for clinical diagnosis.  相似文献   
166.
167.
168.
A cooperative acquisition program for monographs for the twelve resource libraries in Region IX of the Regional Medical Library Network is described. Each of the participating libraries has agreed to purchase all books of an assigned publisher which fall within a prescribed subject-format profile. It is hoped that this will help to reduce unnecessary duplication and contribute toward the development of resources in the region.  相似文献   
169.
170.
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