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   6906篇
  免费   395篇
  国内免费   12篇
  7313篇
  2023年   76篇
  2022年   65篇
  2021年   105篇
  2020年   166篇
  2019年   205篇
  2018年   290篇
  2017年   300篇
  2016年   308篇
  2015年   186篇
  2014年   229篇
  2013年   789篇
  2012年   400篇
  2011年   433篇
  2010年   239篇
  2009年   258篇
  2008年   356篇
  2007年   368篇
  2006年   288篇
  2005年   253篇
  2004年   240篇
  2003年   240篇
  2002年   220篇
  2001年   110篇
  2000年   80篇
  1999年   88篇
  1998年   79篇
  1997年   71篇
  1996年   60篇
  1995年   65篇
  1994年   60篇
  1993年   51篇
  1992年   45篇
  1991年   34篇
  1990年   30篇
  1989年   34篇
  1988年   35篇
  1987年   28篇
  1986年   28篇
  1985年   37篇
  1984年   28篇
  1983年   25篇
  1982年   25篇
  1981年   20篇
  1980年   22篇
  1979年   29篇
  1978年   35篇
  1977年   23篇
  1976年   19篇
  1974年   20篇
  1973年   16篇
排序方式: 共有7313条查询结果,搜索用时 8 毫秒
51.
The policies related to COVID-19 pandemic such as stay at home orders and social distancing increased daily stress and associated impairments in mental health. This study examines the association between COVID-related stress and cognitive functioning by examining two different types of daily memory lapses, those related to prospective memory (i.e., memory for future plans) and retrospective memory (i.e., memory for past information) as well as the perceived emotional and functional consequences of daily memory problems. As part of a larger study, 58 adults (18 men; 22 ± 3 years) completed a web-based version of the daily inventory of stressful events including stress related to COVID-19 and positive/negative affect for eight consecutive days between 8 September 2020 and 11 November 2020. Findings showed that prospective lapses were positively correlated with COVID-19 stressors (r = 0.41, p = 0.002). At the within-person level, daily COVID-19 stressors were significantly associated with the number of prospective lapses (b = 0.088, SE = 0.040). COVID-19-related stressors were not significantly related to retrospective lapses (all ps > 0.05). Our findings suggested that more daily COVID-19 stressors were related to greater numbers of prospective lapses in daily life even among healthy younger adults. Thus, future research should address long term relations of COVID-19 stress and cognitive functioning in addition to the specific cognitive impairments related to COVID-19 infection.  相似文献   
52.
Despite evidence of the safety and effectiveness of COVID-19 vaccines and their wide availability, many in the U.S. are not vaccinated. Research demonstrates that prosocial orientations predict COVID-19 health behaviors (e.g., social distancing) and vaccination intentions, however, little work has examined COVID-19 vaccination willingness in the U.S. since vaccines were approved. Findings from two U.S. samples show that, in contrast to other COVID-19 health behaviors, vaccine willingness in unvaccinated people is unrelated to prosocial orientation. Study 2 demonstrates that the lack of association between vaccine willingness and prosocial orientation in unvaccinated participants was specific to those with stronger beliefs that COVID-19 vaccines are ineffective. Thus, in prosocial people, perceptions of vaccines' ineffectiveness may undermine COVID-19 vaccine willingness.  相似文献   
53.
The plastic barrel suit provides complete protection of chronically implanted fistulas and electrical connectors. The lost time, expense, and the frustrations of having these devices damaged was avoided.  相似文献   
54.
Wayne Lee 《Psychometrika》1966,31(3):397-412
A method of design symbolization (DS) is given for a class of designs in which all factors are related by complete crossing or by nesting. Characterization of acceptable DS's, and logical relational properties are given. It is shown how the design model can be obtained from the DS.The preparation of this article was supported by NIH Grant GM-11128, and by grants to the Institute of Human Learning by NSF and NIH.  相似文献   
55.
56.
The 3RT Test consists of a simple, a choice, and a conditional reaction time (RT) task. The three tasks involve comparable visual stimuli and require identical manual responses, but they differ in the complexity of cognitive processing required. The nonverbal stimuli convey commonly known meanings. Responses can be made either on the keyboard or on response keys connected to the computer’s serial port. The computer’s internal timer/counter is used for millisecond timing. The test administration program allows flexible setting of the test conditions. The data analysis program provides summary data not only for each RT task as a whole, but also for separate trial types within each task. Summary statistics include measures of variation and central value that are not affected by extreme scores. In addition to laboratory studies with normal adults, the 3RT Test is suitable for life-span developmental studies, cross-cultural comparisons, and other uses in various clinical settings.  相似文献   
57.
This paper is concerned with the processing of informal arguments, that is, arguments involving probable truth. A model of informal argument processing is presented that is based upon Hample's (1977) expansion of Toulmin's (1958) model of argument structure. The model postulates that a claim activates an attitude, the two components forming a complex that in turn activates reasons. Furthermore, the model holds occurrence of the reason, or possibly the claim and the reason, activates values. Three experiments are described that provide support for the model.This research was supported by the Mellon Foundation and by the Office of Educational Research and Improvement of the Department of Education via an award for the Center for the Study of Learning to the Learning Research and Development Center. The contents of the paper are not necessarily the position of any of these organizations.  相似文献   
58.
To determine the frequency and correlates of nonsuicidal physically self-damaging acts in 12–14 year olds, a two stage epidemiologic survey with a self-administered questionnaire (N=3283) followed by a psychiatric interview of a subsample of the adolescents and their parents (N=444) was used. Prevalence estimates of interview validated nonsuicidal physically self-damaging acts were 2.46% in males and 2.79% in females. Significant relationships were found between nonsuicidal physically self-damaging acts and suicidal ideation, major depression and undesirable life events. Data suggest that physically self-damaging acts occur at substantial rates during early adolescence. The strong correlation between nonsuicidal self-destructive acts and both suicidal ideation and major depression clarifies prior conflicting reports in the literature and suggests that a history of self-damaging acts should be taken into consideration when evaluating for possible depression and suicide risk.  相似文献   
59.
Direct-observation procedures were used to objectively and efficiently assess several classes of service provided for individuals residing at two state facilities for the developmentally disabled. Time samples were taken of the condition of the clients' physical environment and of the clients themselves. The ongoing behavior of both clients and staff also was recorded. Each residence was observed at least three times during both regular work hours and evening/weekend hours. Results showed that both facilities scored high in the categories regarding the physical condition of the living areas, as well as the categories concerning the condition of the clients. Greater variability was seen in the data on client and staff behavior. More generally, the results indicate that time-sampling procedures can be used efficiently to collect data on multiple aspects of service delivery for large numbers of individuals.  相似文献   
60.
Tolbutamide has previously been shown to amplify the pressor effects of “exogenous” catecholamines in conscious dogs, possibly due to sensitization of the α1-adrenoreceptor-mediated vasoconstriction. The objective of this study was to examine if tolbutamide also amplifies the pressor effects of “endogenous” catecholamines released during psychological stress (classical Pavlovian aversive conditioning). Experiments were conducted in β-adrenoreceptor-blocked (propranolol, 1 mg/kg, i.v.) conscious dogs (n=4) trained in classical aversive conditioning. Conditioning was accomplished by following a tone (CS+) with a 1/2 second shock; another tone (CS-) was not followed by any shock and served as control. With saline pretreatment, aversive conditioning (i.e., CS+) increased mean arterial pressure (MAP) only by approximately 4.7% when compared to CS-, whereas with tolbutamide (45 mg/kg, i.v.) pretreatment, the increase in MAP induced by CS+ beyond what was induced by the CS- (approximately 6.2%) was significantly (p<0.05) larger than that with saline pretreatment. In isolated canine femoral arterial segments (n=4), the vasoconstrictor effect of phenylephrine (an α1-agonist) at 5×10?6M (which was the EC50 value) was amplified by 2×10?2M of tolbutamide from 54.0±2.0% to 66.9±2.1%. In conclusion, tolbutamide amplifies the pressor effects of “endogenous” catecholamines in conscious dogs, possibly by sensitization of the α1-adrenoreceptor-mediated vasoconstriction. This mechanism of action is novel and has not been reported with other agents.  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