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   45454篇
  免费   1751篇
  国内免费   14篇
  2019年   495篇
  2018年   774篇
  2017年   694篇
  2016年   774篇
  2015年   574篇
  2014年   670篇
  2013年   4109篇
  2012年   1162篇
  2011年   1223篇
  2010年   775篇
  2009年   714篇
  2008年   1115篇
  2007年   1012篇
  2006年   944篇
  2005年   795篇
  2004年   756篇
  2003年   769篇
  2002年   749篇
  2001年   1512篇
  2000年   1429篇
  1999年   1062篇
  1996年   565篇
  1995年   542篇
  1994年   523篇
  1993年   502篇
  1992年   1060篇
  1991年   976篇
  1990年   967篇
  1989年   859篇
  1988年   865篇
  1987年   846篇
  1986年   826篇
  1985年   820篇
  1984年   727篇
  1983年   587篇
  1982年   490篇
  1981年   488篇
  1979年   698篇
  1978年   510篇
  1976年   464篇
  1975年   640篇
  1974年   648篇
  1973年   736篇
  1972年   675篇
  1971年   609篇
  1970年   544篇
  1969年   533篇
  1968年   685篇
  1967年   554篇
  1966年   559篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
961.
To test the idea that scopolamine provides a suitable pharmacological model of the memory defects associated with cortical or subcortical dementias, we assessed memory on a battery of tasks in healthy young normal subjects who received 0.5 mg scopolamine, 0.1-0.2 mg glycopyrrolate or physiological saline, once each on three separate occasions, and compared the pattern of memory failure induced by scopolamine to that observed on the same tasks in patients with Alzheimer's disease (AD) or Huntington's disease (HD). In agreement with previous reports, scopolamine impaired acquisition and delayed recall of a 14-word list and disrupted retention on the Brown-Peterson distractor task, whereas the peripherally active anticholinergic glycopyrrolate was without effect. However, under scopolamine the pattern of errors made on these memory tasks was quite different from that seen in patients with AD. Scopolamine did not increase the number of false positive errors on delayed recognition of the word list and also failed to increase the number of prior-item intrusions on the Brown-Peterson task. Also, scopolamine did not impair learning of a symbol-digit paired-associate task, and did not reduce the number of words retrieved or increase the number of words repeated on a standardized verbal fluency test. When the effects of scopolamine on memory were compared to the pattern of impairments observed in demented patients with HD, several differences were found. Although scopolamine clearly produces deficits on some measures of anterograde memory, the present findings question whether anticholinergic drugs adequately mimic the full range of memory impairments observed in cortical or subcortical dementias.  相似文献   
962.
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   
963.
The psychometric properties of the State-Trait Anxiety Inventory for Children (STAIC) and relationships between STAIC T-Anxiety scores and standardized measures of achievement were determined for 948 kindergarten and first-and second-grade children. The T-anxiety scores of kindergarten children were lower than those of first-and second-graders. Internal consistency of the STAIC scales was higher in individual testing sessions than in small group administrations. Small but significant negative correlations were found between STAIC T-Anxiety scores and measures of school achievement. It was concluded that the STAIC is a potentially useful measure of state and trait anxiety in kindergarten through sixth-grade children, but it must be administered individually at the kindergarten and first-grade levels.The research was performed while the senior author was a senior research scientist at the Dallas Independent School District.  相似文献   
964.
Despite speculation that sucrose consumption affects behavior, little empirical information is available. Accordingly, this study investigated the effect of sucrose consumption on the behavior of eight preschool children. Children were tested individually using a double-blind, crossover design. On separate mornings each child received 6 ounces of juice, sweetened on one morning with sucrose and on the other with an artificial sweetener. Children were observed for 90 minutes following the drinks, alternating between 15-minute sessions of work on structured tasks and 15-minute sessions of free play. Following the sucrose drink the children showed a decrement in performance in the structured testing situation, and they demonstrated more inappropriate behavior during free play. These differences in behavior were most pronounced approximately 45 to 60 minutes after the drinks. Thus, the study provides objective evidence in young children of a rather subtle, yet significant, time-dependent behavior effect of sucrose ingestion.This research was funded in part by grants from the General Research Grants Committee, University Hospital, Boston University Medical Center, and from the University of Connecticut Research Foundation. The project was conducted at the Clinical Research Center, Massachusetts Institute of Technology (National Institute of Health/General Clinical Research Center Grant 5M01-RR00088-20). We would like to express our appreciation to the many staff members of the Clinical Research Center for their extensive cooperation in helping us to plan and carry out this study, and to the director and staff of Technology Children's Center for their assistance in helping us to reach interested families. We also would like to thank the parents and children who participated in the study. Portions of this paper were presented at the annual meeting of the American Psychological Association, Toronto, August 1984.  相似文献   
965.
Attitudes toward posthumous organ donation and commitment to donate   总被引:4,自引:0,他引:4  
The medical need for human organs suitable for use as transplants far exceed the supply, and is growing. More favorable attitudes about organ donation would increase people's willingness to sign posthumous donation pledges. But effective educational programs require information about the public's present views. Verbal attitude scales were constructed and administered to 110 adults, resulting in reliable measurement of two independent dimensions, prodonation and antidonation (r = .003). Cluster analysis of the instrument revealed that the positive dimension involves belief in the humanitarian benefits of organ donation and feelings of pride experienced by the donor. The negative dimension reflects fears of body mutilation and of receiving inadequate medical treatment when one's life is at risk. Pro and anti scores in combination predicted willingness to sign a donor card. A 2 X 2 analysis of variance (High-Low Positive X High-Low Negative) revealed significant main effects for both positive and negative attitude. Also, a significant interaction effect was obtained. Those subjects who had both strong positive attitudes and weak negative attitudes were especially willing to sign donor cards. Suggestions for designing educational campaigns to promote organ donation are offered.  相似文献   
966.
J D Morrison  J Reilly 《Perception》1986,15(5):541-552
The possibility that changes in decision-making may contribute to the age-related decline in contrast sensitivity has been investigated in nineteen young subjects (ages 21-38 years) and twenty-seven old subjects (ages 55-92 years). A signal detection paradigm was employed in which the detection of stationary sinusoidal grating patterns was measured at 3 and 15 cycles deg-1 for a range of contrasts which were psychophysically equivalent for each subject. A decline in contrast sensitivity with age at the spatial frequencies studied was confirmed for contrast thresholds obtained both by the ascending method and from the 50% hit rate for detection of the grating pattern. The criterion adopted for decision-making, expressed as both beta and percentage bias, did not change significantly between young and old subjects at 15 cycles deg-1. At 3 cycles deg-1, criterion beta did not change significantly at X0.8, X1.0, or X1.2 contrast threshold, but at contrast giving 50% hit rate there was a significant increase with age. The percentage bias increased significantly at contrast threshold but not at 50% hit rate. It is inferred from the results that the loss of contrast sensitivity was not accountable in terms of the adoption of a more conservative criterion by older subjects. Hence visual loss in ageing is attributed to changes within the visual pathway rather than within higher decision-making centres.  相似文献   
967.
A field study of 28 residents in family practice was conducted. Physicians' self-reports of empathy, self-monitoring ability, and affective communication skill as well as their objectively measured nonverbal communication skills were examined as predictors of patient satisfaction, appointment noncompliance, and physician workload (schedule density). Physicians completed the Hogan Empathy Scale, Snyder Self-Monitoring Scale, Affective Communication Test, short form of the Profile of Nonverbal Sensitivity, and a nonverbal encoding task. Patient satisfaction with communication, affective care, and technical care was assessed using a 25-item, visit-specific satisfaction scale. Appointment records were used to determine the number of patients seen by each physician and the compliance of patients with scheduled appointments. Results indicated that the three self-report measures were unrelated to the measures of patient noncompliance and patient satisfaction, but self-reported affective communication ability was significantly correlated with physician workload. Objectively measured physician sensitivity to audio communication predicted patient compliance: More sensitive physicians experienced fewer unrescheduled appointment cancellations. Nonverbal encoding skill was significantly related to patient satisfaction with affective care and to physician workload.  相似文献   
968.
969.
Self-disclosure patterns of Anglo-Americans and Mexican Americans were analyzed according to overall frequency of reported self-disclosure and preferred targets (i.e., mother, father, male friend, female friend). Administrator sex and ethnicity were systematically varied so that the interaction of these variables with participant sex and ethnicity could be investigated. Results revealed that Anglo-Americans reported the most disclosure and Mexican-American men the least. Some suggestions are provided for counselors working with Mexican-American men.  相似文献   
970.
Psychopathology and symptom patterns were studied in 60 former prisoners-of-war (POWs) by administering standardized tests including the Minnesota Multiphasic Personality Inventory (MMPI), an adjustment problem checklist, and a structured clinical interview. Most POWs showed marked psychological impairment, but modal profile analysis identified two prototypic MMPI patterns, which differed in pervasiveness and type of psychopathology. Profile subtypes were defined by unique clusters of clinical symptoms and differed in confinement stress severity. The typology of symptoms argues against a homogeneous conceptualization of stress-induced disorders and suggests the need for definition of the severity and subtype of stress phenomena and individual difference factors in responding to trauma.  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