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   82489篇
  免费   3409篇
  国内免费   39篇
  2020年   963篇
  2019年   1144篇
  2018年   1650篇
  2017年   1715篇
  2016年   1742篇
  2015年   1267篇
  2014年   1480篇
  2013年   7052篇
  2012年   2735篇
  2011年   2804篇
  2010年   1738篇
  2009年   1739篇
  2008年   2453篇
  2007年   2371篇
  2006年   2168篇
  2005年   1840篇
  2004年   1811篇
  2003年   1769篇
  2002年   1662篇
  2001年   2768篇
  2000年   2646篇
  1999年   1956篇
  1998年   934篇
  1997年   779篇
  1996年   851篇
  1995年   770篇
  1994年   773篇
  1993年   755篇
  1992年   1624篇
  1991年   1515篇
  1990年   1501篇
  1989年   1414篇
  1988年   1382篇
  1987年   1314篇
  1986年   1273篇
  1985年   1371篇
  1984年   1109篇
  1983年   928篇
  1979年   1133篇
  1978年   847篇
  1977年   739篇
  1975年   948篇
  1974年   1038篇
  1973年   1105篇
  1972年   915篇
  1971年   825篇
  1969年   743篇
  1968年   935篇
  1967年   799篇
  1966年   834篇
排序方式: 共有10000条查询结果,搜索用时 250 毫秒
101.
102.
103.
104.
105.
106.
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   
107.
This study examined information communication technologies and workplace friendship dynamics. Employees reported factors that influenced their initiation of friendship with a coworker and reported patterns and perceptions of communication with their workplace friend via different communication methods. Results indicated that personality, shared tasks, and perceived similarity are the most important factors to coworker friendship initiation, and the importance of physical proximity to workplace friendship is diminishing in the electronically connected workplace. Results confirm the primacy of face‐to‐face interaction for workplace friendship initiation and maintenance. E‐mail, phone, and texting were also central to communication among workplace friends. The amount of time spent telecommuting affected workplace friendship initiation and communication. Finally, generational differences were identified with respect to Internet‐based communication methods.  相似文献   
108.
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   
109.
110.
Indiana statute allows police to seize firearms without a warrant if the officer believes a person meets the law's definition of “dangerous.” Review of the use of this law in Marion County (Indianapolis), Indiana, showed that prosecutors filed petitions in court to retain weapons seized by police under this law 404 times between 2006 and 2013. Police removed weapons from people due to identification of a risk of suicide (68%) or violence (21%), or the presence of psychosis (16%). The firearm seizures occurred in the context of domestic disputes in 28% of cases and intoxication was noted in 26% of cases. There were significant demographic differences in the circumstances of firearm seizures and the firearms seized. The seized firearms were retained by the court at the initial hearing in 63% of cases; this retention was closely linked to the defendant's failure to appear at the hearing. The court dismissed 29% of cases at the initial hearing, closely linked to the defendant's presence at the hearing. In subsequent hearings of cases not dismissed, the court ordered the destruction of the firearms in 72% of cases, all when the individual did not appear in court, and dismissed 24% of the cases, all when the individual was present at the hearing. Overall, the Indiana law removed weapons from a small number of people, most of whom did not seek return of their weapons. The firearm seizure law thus functioned as a months-long cooling-off period for those who did seek the return of their guns. Copyright © 2015 John Wiley & Sons, Ltd.  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