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   16103篇
  免费   621篇
  国内免费   4篇
  2019年   213篇
  2018年   258篇
  2017年   219篇
  2016年   257篇
  2015年   169篇
  2014年   261篇
  2013年   1274篇
  2012年   434篇
  2011年   485篇
  2010年   290篇
  2009年   312篇
  2008年   414篇
  2007年   442篇
  2006年   421篇
  2005年   344篇
  2004年   372篇
  2003年   335篇
  2002年   329篇
  2001年   451篇
  2000年   510篇
  1999年   343篇
  1998年   205篇
  1997年   154篇
  1996年   166篇
  1995年   165篇
  1992年   276篇
  1991年   285篇
  1990年   296篇
  1989年   276篇
  1988年   267篇
  1987年   234篇
  1986年   246篇
  1985年   259篇
  1984年   191篇
  1983年   207篇
  1982年   158篇
  1980年   156篇
  1979年   248篇
  1978年   216篇
  1977年   150篇
  1975年   215篇
  1974年   242篇
  1973年   268篇
  1972年   225篇
  1971年   210篇
  1970年   162篇
  1969年   195篇
  1968年   248篇
  1967年   239篇
  1966年   209篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
861.
862.
863.
Sleep in the dove Zenaida asiatica   总被引:1,自引:0,他引:1  
Electrographic and behavioral observations were made in five adult birds of the genus Zenaida asiatica. Five different vigilance states were quantitated: (1) Active waking (Aw) was characterized by constant behavioral activity; the nuchal electromyogram was tonically active with bursts associated to movements. The electroencephalographic pattern was low voltage and high frequency. (2) Quiet waking (Qw) was characterized by diminished behavioral activity and the EEG pattern was similar to that of Aw. (3) Drowsiness (D) was characterized by behavioral calm. Frequency of cerebral activity diminished progressively, but there were short periods of desynchronization corresponding to brief awakenings. (4) Slow wave sleep (SWS); during this period there was behavioral rest and EEG pattern of continuous slow waves and the nuchal EMG was tonically reduced. Spindles of sleep were not observed. (5) Paradoxical sleep (SP), behaviorally characterized by phasic manifestations consisting of noddings originated by rapid falling down of head and bursts of rapid eye movements. EEG activity was like that of waking state. EMG activity was maintained at the same level as during SWS but sometimes it decreased lightly. Total atonie was not observed. Sleep percentages were higher when recordings were done during the nocturnal period.  相似文献   
864.
ABSTRACT

In the religiously pluralized Western world, a trend called ‘Multiple Religious Belonging’ (MRB) has been identified. Although it is a much theologically debated concept, empirical research on the practice of MRB is limited. The present research project therefore explores the phenomenon of MRB among visitors of Dominican spiritual centers in the Netherlands (n=472). It investigates to what extent and in which ways such visitors combine elements from more than one religious tradition in their lives and what they perceive to be the benefits of combining elements. It links this information to their views on religion, the resources they draw from, their (religiously diverse) networks, and their motivations for attending spiritual activities. The results indicate that respondents who combine elements from more than one religious tradition (‘combiners’) are more likely than ‘non-combiners’ to: a) see religion as something that is constantly changing during the life course; b) have networks which are religiously diverse; c) place importance on nature, in-depth conversations, personal rituals or practices, and theological, philosophical, and spiritual texts as resources; d) be motivated to attend spiritual centers because of a focus on self-exploration.  相似文献   
865.
866.
Scopolamine effects on memory retention in mice: a model of dementia?   总被引:4,自引:0,他引:4  
Scopolamine-treated normal young human subjects exhibit memory dysfunctions analogous to those observed in demented patients. The dysfunctions are reversible by physostigmine but not by d-amphetamine which suggests that the memory impairment is specifically related to reduced cholinergic transmission caused by scopolamine. Scopolamine-induced amnesia has been proposed as a model for dementia where reduced cholinergic function is the suspected cause. We report seven experiments in young adult mice which examine scopolamine's effects on memory retention and whether its amnestic effects are specifically blocked by cholinergic agonists or cholinomimetics. Young adult mice were trained to avoid footshock in a T maze and their retention tested 1 week after training. Pretraining subcutaneous injection of scopolamine improved retention scores of "undertrained" mice at a dose of 0.01 mg/kg but impaired at a dose of 0.1 mg/kg. Post-training injection showed no effect at 0.01 mg/kg, enhanced retention scores at 0.1 mg/kg, and impaired at 1.0 mg/kg. The impairment by 1.0 mg/kg was blocked by injection 45 min post-training of each of two cholinergic drugs but was also counteracted by six drugs which act upon five other neural systems (catecholamine, serotonin, glycine, GABA, and hormonal). When scopolamine was injected 40 min pretraining, and each of eight drugs was injected immediately after training, the amnestic effect of scopolamine was only partially counteracted. This suggests that scopolamine impaired acquisition, in addition to some impairment of memory processing. This was confirmed by a direct study of acquisition rates of the avoidance response; 0.1 mg/kg of scopolamine impaired acquisition. The overall results indicate that pretraining administration of scopolamine impairs learning and to some degree memory processing. Counteracting scopolamine-induced amnesia, by either pretraining or post-training drug administration, is not specific to the cholinergic system.  相似文献   
867.
868.
Objective: To evaluate an intervention programme based on the Health Action Process Approach and designed to increase the intake of fruit and vegetables (F&V) among Iranian adolescents aged 13 to 18.

Design: A randomised controlled trial with three arms examined the short- (1 month) and long-term (6 months) effects of the intervention. There were two intervention groups (one included adolescents only [A group; n = 510]; the second included mothers and adolescents [M + A group; n = 462]) and a control group (n = 483). All participants were recruited from schools.

Main outcome measures: Social cognitions, self-regulatory processes and F&V intake.

Results: The intervention led to an increase in F&V intake for adolescents in the short and long terms. Adolescents in the M + A group increased their F& V intake more than adolescents in the A group. Outcome expectancies, self-monitoring, intentions, action and coping planning, perceived social support and behavioural automaticity mediated the effect of the intervention on F&V intake.

Conclusion: The theory-based intervention led to an increase in F&V intake and promoted more positive social cognitions and self-regulatory processes among Iranian adolescents. The findings also provide evidence that involving mothers in an intervention can confer additional benefit.  相似文献   

869.
870.
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