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   56166篇
  免费   2194篇
  国内免费   24篇
  2020年   589篇
  2019年   750篇
  2018年   1036篇
  2017年   1129篇
  2016年   1160篇
  2015年   833篇
  2014年   995篇
  2013年   4460篇
  2012年   1776篇
  2011年   1795篇
  2010年   1151篇
  2009年   1089篇
  2008年   1548篇
  2007年   1604篇
  2006年   1402篇
  2005年   1274篇
  2004年   1196篇
  2003年   1158篇
  2002年   1194篇
  2001年   1746篇
  2000年   1684篇
  1999年   1311篇
  1998年   570篇
  1997年   547篇
  1996年   539篇
  1995年   518篇
  1992年   1105篇
  1991年   1014篇
  1990年   1045篇
  1989年   939篇
  1988年   996篇
  1987年   912篇
  1986年   931篇
  1985年   867篇
  1984年   761篇
  1983年   709篇
  1982年   527篇
  1979年   858篇
  1978年   626篇
  1977年   532篇
  1975年   694篇
  1974年   807篇
  1973年   841篇
  1972年   654篇
  1971年   634篇
  1970年   590篇
  1969年   620篇
  1968年   768篇
  1967年   697篇
  1966年   609篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
981.
The effects of gonadectomy on amphetamine-induced rotational behavior were studied in male and female rats. Different systemic doses were used to produce equivalent brain concentrations of the drug in each group, thereby controlling for sex differences in the metabolism of amphetamine. Ovariectomy of female rats significantly attenuated amphetamine-induced rotation, whereas castration of males was without effect. The results support the idea that in females, the endogenous gonadal hormones facilitate functional activity in the mesostriatal dopamine system.  相似文献   
982.
Saline-treated and amphetamine-treated (7 mg/kg, ip, immediate) male rats from a Sprague-Dawley substrain were observed in two test environments designed to elicit different investigative responses in normal rats. Snout contact with the substrate was generated by placing the rat in a small enclosed cage. Absence of snout contact was induced by placement of the rat on a square elevated platform. Detailed ethological records were kept of locomotion, rearing, sitting, grooming, gnawing, and sleeping throughout the 90-min session. Amphetamine-treated rats incorporated environmentally contingent bodily postures into their forms of stereotyped behavior. The postures were characteristic of those evinced initially by the saline-treated rats in the same test environment. The control rats showed appropriate changes in their investigative behavior when the apparatus was changed at 10 and at 30 min postinjection. The amphetamine-treated rats, however, were completely unresponsive to such changes at 30 min and only partially so at 10 min postinjection. It was concluded that there is a temporal gradient of decreasing readiness to modify repetitive behavior after a single, large dose of amphetamine.  相似文献   
983.
This paper compares LD and non-LD peers on eight variants of the oddity task. This study is part of a larger programmatic research effort aimed at the development of a screening test to detect preschool children who currently pass existing screening tests but, nonetheless, subsequently experience school failure. The theoretical orientation of this approach is to assess active, ongoing cognitive processing ability. The oddity task, which can be structured to assess such processing ability, was evaluated in the present study as a potential component of this screening test. Consistent with a priori predictions, the data resulted in strong group and developmental differences. Oddity performance increased over age, with the non-LD children performing consistently better than their LD peers at each age. Perceptual and conceptual factors were manipulated across the oddity variations, and both factors contributed to group differences. These results were discussed in relationship to early diagnosis and prognosis for learning disabilities that might result from deficiencies in abstract processing ability.The authors would like to express their thanks to the schools, teachers, and students who participated in this study. This research was supported in part by the Mailman Foundation and FDLRS/MAILMAN, a specialized university center of the Florida Diagnostic Learning Resources System, funded through State General Revenue appropriation to provide multidisciplinary evaluation services in exceptional student education programs.  相似文献   
984.
Two basic assumptions of the Circumplex Model of family systems were evaluated: (1) Healthy families evidence balanced degrees of cohesion and adaptability, whereas problem families evidence extreme degrees, and (2) families with balanced degrees of cohesion and adaptability possess more positive communication skills than families with extreme degrees. Subjects were 58 mother-son dyads from father-absent families. In 29 of the families the adolescent was a juvenile offender, while in the remaining families there was no history of arrest or psychiatric referral. The dyads completed the Family Adaptability and Cohesion Scales (FACES) and an unrevealed differences interaction task. FACES was highly proficient at differentiating delinquent from nondelinquent families. Moreover, in families with balanced degrees of cohesion and adaptability, the mothers' communication was significantly more supportive and explicit, and the dyads evidenced significantly greater warmth and affection than dyads with extreme degrees.This research was supported by funding to the Department of Psychology at Memphis State University granted through the Centers of Excellence Program of the State of Tennessee. We thank the staff of the Memphis-Metro Youth Diversion Project for their consideration and assistance.  相似文献   
985.
In partial replication of an earlier study, 35 children at high risk for schizophrenia, 25 children at high risk for affective disorder, and 53 normal control children from a new sample of 7- to 12-year-old subjects were tested with two new visual continuous performance tests. Response levels and intrasubject variability were analyzed separately. Multivariate analyses on factor scores derived from response levels indicate that "groups" is a significant predictor for a factor reflecting discriminability (or sensitivity) for the more difficult of these tests but not for the less difficult one, and that high risk for schizophrenia is associated with lower performance. Factor scores and multiple regression analyses were used to dichotomize subjects as to whether or not they are low performance outliers. A significantly larger proportion of subjects from the high risk for schizophrenia group than from the control groups were low performance outliers. Among subjects that developed psychopathology in adolescence, subjects at high risk for schizophrenia were more likely to have contributed low performance outliers early during childhood.  相似文献   
986.
987.
Quality-of-life measures: hospital interview versus home questionnaire   总被引:2,自引:0,他引:2  
Measures adapted from social survey research were used to assess the quality of life of 33 end-stage renal disease (ESRD) patients in a 2-week test-retest design that varied both location and format of administration (hospital interview vs. home self-administered questionnaire). The measures were found to have substantial consistency over time, location, and format. These results indicate that quality of life is a stable construct and support the usefulness of questionnaire quality-of-life measures for evaluating medical interventions.  相似文献   
988.
Medicaid proposals increasingly focus on cost-saving strategies that restrict clients' control over where and when they may receive services. This study used a field experiment in an urban welfare office to examine the possible effects of two aspects of restrictive policies: the loss of choice of providers and adverse patient mix (i.e., when the majority of a provider's clients are Medicaid beneficiaries). Results indicate that health care presented within the context of not having a choice is derogated and that choice and patient mix combine to influence intentions to seek care. Persons who did not choose the health plan in a simulated choice, who had fewer choices than expected, and who did not accept restricted choice also had negative perceptions.  相似文献   
989.
Male and female volunteers (N = 144) answered the Reactivity Scale (RS) and underwent testing for their perceived intensity and tolerance for finger-pressure pain. Half the Ss were randomly assigned to a low-intensity treatment (1150 g) and half to a high-intensity treatment (2300 g). Pain was rated at 30 and 60 sec., and Ss were asked to endure it as long as possible up to 5 min. The major findings were as follows: (1) women outscored men on reactivity; (2) the three pain measures intercorrelated highly; (3) high-intensity stimulation produced higher pain ratings and shorter tolerance than did low-intensity stimulation; (4) men gave lower intensity ratings than women and tolerated the pain longer; (5) reactivity related positively to judged pain at 30 and 60 sec, and negatively to pain tolerance; (6) there were no significant interaction effects among stimulus intensity, sex and reactivity for any pain measure; (7) the variance in the pain measures accounted for by stimulus intensity, sex and reactivity ranged from 26 to 32%. The implications were briefly discussed for the validity of the RS and factors explaining responses to experimentally-induced pain.  相似文献   
990.
Twenty-six previous studies were reviewed which demonstrated a consistent link between children's smoking uptake and exposure at home to an actively smoking older family member. The present study included another variable: the family model of smoking cessation. The smoking practices, intentions, and attitudes of 344 children aged 10–14 in Western Australia were anonymously assessed. Those with ex-smokers but no active smokers at home resembled children who had never been exposed to a smoking family model in being less likely to smoke now or intend to in the future, having fewer smoking chums, and believing that cigarettes had more personal and social disadvantages than their peers who shared households with active smokers. This suggested that any pro-smoking modeling while the ex-smoker was active had been counteracted by modeling of quitting. Implications for intervention were discussed.  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