全文获取类型
收费全文 | 91686篇 |
免费 | 1912篇 |
国内免费 | 7篇 |
专业分类
93605篇 |
出版年
2020年 | 866篇 |
2019年 | 1094篇 |
2018年 | 1455篇 |
2017年 | 1504篇 |
2016年 | 1638篇 |
2015年 | 1204篇 |
2014年 | 1409篇 |
2013年 | 6495篇 |
2012年 | 2629篇 |
2011年 | 2767篇 |
2010年 | 1767篇 |
2009年 | 1678篇 |
2008年 | 2446篇 |
2007年 | 2442篇 |
2006年 | 2214篇 |
2005年 | 1996篇 |
2004年 | 1862篇 |
2003年 | 1765篇 |
2002年 | 1866篇 |
2001年 | 2814篇 |
2000年 | 2752篇 |
1999年 | 2077篇 |
1998年 | 1019篇 |
1997年 | 895篇 |
1996年 | 890篇 |
1992年 | 1829篇 |
1991年 | 1718篇 |
1990年 | 1714篇 |
1989年 | 1557篇 |
1988年 | 1531篇 |
1987年 | 1461篇 |
1986年 | 1555篇 |
1985年 | 1626篇 |
1984年 | 1343篇 |
1983年 | 1236篇 |
1982年 | 859篇 |
1981年 | 849篇 |
1979年 | 1437篇 |
1978年 | 1006篇 |
1977年 | 865篇 |
1975年 | 1210篇 |
1974年 | 1343篇 |
1973年 | 1434篇 |
1972年 | 1233篇 |
1971年 | 1156篇 |
1970年 | 1081篇 |
1969年 | 1089篇 |
1968年 | 1429篇 |
1967年 | 1274篇 |
1966年 | 1115篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
201.
A multivariate hierarchical model of specific cognitive abilities was fitted to data from 7-year-old adopted and nonadopted sibling pairs in the Colorado Adoption Project in order to assess differential genetic influence on specific mental abilities. Model fitting results and Schmid-Leiman (Schmid & Leiman, 1957) transformations reveal significant heritable variation for verbal, spatial, and memory factors independent of general cognitive ability for the eight ability tests examined. In contrast, environmental influences are primarily measure-specific. The results suggest genetic effects in middle childhood that differentially influence mental ability scores. 相似文献
202.
Reminder treatments have been shown to facilitate the retrieval of a variety of conditioned responses. Whether or not similar results would occur with an experimental paradigm which involves primarily memory for a stimulus, i.e., where no particular response is specified, is unclear. Accordingly, using Sprague-Dawley rats, we employed a latent inhibition paradigm with a long (10 days) retention interval between sucrose (CS) preexposure and sucrose-illness pairing (training). The results demonstrated a loss of latent inhibition following the 10-day retention interval suggesting "forgetting" of the CS preexposure. However, placing a single reminder exposure to the CS within the preexposure-to-training interval reinstated the preexposure effect. Controls indicated that in the absence of the initial preexposure the reminder per se did not produce latent inhibition. Thus, a reminder can reinstate a stimulus attribute (flavor representation) and explicit conditioned responses. 相似文献
203.
From previous research, the ultrasonic vocalizations of male mice (Mus domesticus) to female mouse urine were hypothesized to be learned as a result of classical conditioning during adult heterosexual encounters. According to this interpretation, a previously neutral conditioned stimulus in female urine comes to elicit vocalizations as a result of its association with some other unknown unconditioned stimulus associated with adult females. However, the research from which this hypothesis was derived utilized urine collected from females housed in metabolic cages. Three experiments further examined the classical conditioning hypothesis using two types of female urine: (i) metabolic-cage-collected urine and (ii) freshly voided urine. Experiment 1 demonstrated that, in contrast to vocalizations to metabolic-cage-collected urine, adult heterosexual experience was not necessary for males to vocalize to freshly voided female urine. In addition, unlike metabolic-cage-collected urine (Experiment 3), freshly voided urine remained a potent stimulus for eliciting vocalizations during repeated testing (Experiments 2 and 3). Finally, freshly voided urine appeared to cause a previously neutral stimulus (cotton swab) to acquire ultrasound eliciting properties (Experiment 2). We suggest from these findings that two chemosignals that elicit vocalizations from males may exist in female mouse urine: (i) a potent, but volatile or easily degraded, unconditioned stimulus to which males vocalize without sexual experience and (ii) a nonvolatile, chemically stable conditioned stimulus. 相似文献
204.
Patterns of coping with cancer. 总被引:12,自引:0,他引:12
We identified five patterns of coping in a sample of 603 cancer patients: "seeking or using social support," "focusing on the positive," "distancing," "cognitive escape-avoidance," and "behavioral escape-avoidance." Relationships of these coping patterns to sociodemographic characteristics, medical factors, stress appraisals, psychotherapeutic experience, and emotional distress were tested using correlational and regression techniques. Type of cancer, time since diagnosis, and whether a person was currently in treatment had few or no relationships to coping. The specific cancer-related problem (e.g., pain, fear of future) was also not associated with how individuals coped. Perceptions of its stressfulness, however, were related to significantly more coping through social support and more of both forms of escape-avoidance. Coping through social support, focusing on the positive, and distancing was associated with less emotional distress, whereas using cognitive and behavioral escape-avoidance was associated with more emotional distress. Implications of the results for understanding coping processes and intervention with cancer patients are discussed. 相似文献
205.
Anterior cerebral asymmetry and the nature of emotion. 总被引:14,自引:0,他引:14
R J Davidson 《Brain and cognition》1992,20(1):125-151
This article presents an overview of the author's recent electrophysiological studies of anterior cerebral asymmetries related to emotion and affective style. A theoretical account is provided of the role of the two hemispheres in emotional processing. This account assigns a major role in approach- and withdrawal-related behavior to the left and right frontal and anterior temporal regions of two hemispheres, respectively. Individual differences in approach- and withdrawal-related emotional reactivity and temperament are associated with stable differences in baseline measures of activation asymmetry in these anterior regions. Phasic state changes in emotion result in shifts in anterior activation asymmetry which are superimposed upon these stable baseline differences. Future directions for research in this area are discussed. 相似文献
206.
207.
Fernand R. Gobet 《Psychological research》1992,54(1):38-43
Summary The effects of noncontingency between subjects' responses and outcomes were examined with respect to treatment-and-posttest similarity and skill in the task. The experimental design consisted of three groups. The first group had to solve chess problems with objective solutions and received veridical feedback; each member of the second group faced problems with no objective solutions, and received the same feedback as the member of the first group he was yoked with, but without any control on it; the control group received a waiting task. It was found at the end of the experiment that the group with unsolvable problems was more depressed than the two other groups. The mid-strength players were the most sensitive to the manipulation, and the weakest players showed little effect of learned helplessness. It was also found that the effects were proportional to the degree of similarity between the treatment and the posttest. The results limit the domain of applicability of the learned-helplessness model. 相似文献
208.
209.
N J Osgood 《Suicide & life-threatening behavior》1992,22(1):98-106
One major purpose of this study was to identify environmental factors related to suicide in long-term care facilities. Questionnaires were mailed to a random sample of administrators at 1,080 facilities. Information was collected on facility characteristics, overt suicide, and intentional life-threatening behavior. Chi-square analyses revealed 4 environmental characteristics related to suicidal behavior and deaths from suicide: staff turnover, size, auspices, and per diem cost. More suicides occurred in larger facilities and facilities with higher staff turnover. Religious or "other" facilities experienced more suicidal deaths than public or private facilities; facilities charging less experienced more deaths. 相似文献
210.
Mark R. Wiederanders 《Behavioral sciences & the law》1992,10(1):141-148
Postinstitutional arrests and state hospitalizations of 191 patients placed on conditional release (CONREP group) were compared to those of 44 patients released from the same California state hospital with no aftercare due to expiration of commitment terms (MAXOUT group). The two groups were not randomly determined but were comparable in demographic characteristics and rates of preprogram arrest. The CONREP group had a significantly lower community-period arrest rate than did the MAXOUT group (p <.001). Survival rate analyses, using time until arrest and time until revocation as dependent variables, suggested that revocations during the first 240 days of community re-entry reduced the potential arrest rate within the CONREP group. Results were discussed in terms of the “criminalization hypothesis” as well as the crime-preventive possibilities of the conditional release mechanism. 相似文献