全文获取类型
收费全文 | 10538篇 |
免费 | 196篇 |
国内免费 | 189篇 |
出版年
2017年 | 27篇 |
2016年 | 26篇 |
2015年 | 37篇 |
2014年 | 29篇 |
2013年 | 36篇 |
2012年 | 957篇 |
2011年 | 1060篇 |
2010年 | 272篇 |
2009年 | 151篇 |
2008年 | 835篇 |
2007年 | 808篇 |
2006年 | 786篇 |
2005年 | 610篇 |
2004年 | 575篇 |
2003年 | 509篇 |
2002年 | 466篇 |
2001年 | 318篇 |
2000年 | 371篇 |
1999年 | 178篇 |
1998年 | 72篇 |
1997年 | 28篇 |
1996年 | 54篇 |
1995年 | 38篇 |
1994年 | 79篇 |
1993年 | 90篇 |
1992年 | 99篇 |
1991年 | 114篇 |
1990年 | 95篇 |
1989年 | 97篇 |
1988年 | 103篇 |
1987年 | 122篇 |
1986年 | 89篇 |
1985年 | 114篇 |
1984年 | 113篇 |
1983年 | 138篇 |
1982年 | 94篇 |
1981年 | 84篇 |
1980年 | 77篇 |
1979年 | 84篇 |
1978年 | 74篇 |
1966年 | 50篇 |
1965年 | 131篇 |
1964年 | 106篇 |
1963年 | 126篇 |
1962年 | 54篇 |
1958年 | 104篇 |
1957年 | 94篇 |
1956年 | 58篇 |
1955年 | 34篇 |
1952年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
Meilán JJ Martínez-Sánchez F Carro J Sánchez JA Pérez E 《The Spanish journal of psychology》2012,15(2):487-494
This study broaches in a novel way the analysis of cognitive impairment characteristic of the early stages of Alzheimer's Disease (AD). Specifically, we attempt to determine the acoustic speech parameters that are sensitive to the onset of the disease, and their association with the language deficit characteristic of AD. Speech analysis was carried out on 21 elderly patients with AD using Praat software, which analyzes the acoustic components of speech. The data obtained were subjected to stepwise regression, using the overall scores obtained in the test as the criterion variable, and the scores on the frequency, amplitude and periodicity variables as predictors of performance. We found that the percentage of voiceless segments explains a significant portion of the variance in the overall scores obtained in the neuropsychological test. This component seems to be related mainly to the patient's ability in phonological fluency. This finding could permit the creation of a diagnostic test for AD through analysis of the acoustic speech parameters at very low cost in terms of both time and resources. 相似文献
943.
Together with the completion of the Human Genome Project, biomedical research has marched into the "Post-Genomic Era." In order to take advantage of this extracted gene related information extensively and precisely so as to realize man's biological phenomena as well as the mechanism of pathogenesis, consequentially, a large scale sample collection of different geological areas and/or ethnic groups becomes necessary for the future population based genetic research of a country and, in turn, the construction of population-based genetic database (Biobank). In recent years, both mainland China and Taiwan have not only made great progress in information and computation technologies, but have also gradually taken a close look into the quality of medicine delivery. Thus, it becomes unavoidable for both sides to create each one's population-based genetic databases (Biobank). Theoretically speaking, the Biobank development shall benefit the study on the correlation between genes and disease and also the solution for disease treatment as well. At the same time, medical diagnostic technology has also been significantly improved. It is believable that the population-based genetic database might be utilized to promote medical quality and to reduce the cost of public health delivery. Further; in the near future, it might become the "raw materials "for medical research application. However when taking promotion of public welfare as the premises for a Biobank development, the severe and multi challenge occurred against the traditional legal rules in terms of the privacy protection, public trust development, the compliance of informed consent principle, the implementation of benefit-sharing doctrine and the possible discrimination concern about the population/participants selection and some other ELSI issues. In this paper, the major legal issues encountered by the Biobank development will first be reviewed accompanied by the background information concerning the Biobank development scenario crossing the Taiwan Strait. Also, mainly following the realm of comparative policy or legal approaches, the paper learning from the fruits of this comparative study, tries to propose some recommendations for future legislative consideration by both mainland China and Taiwan. It's been this author's wish that, when establishing a large scale population based Biobank, the promotion of public trust shall be placed as the primary goal together with the emphasis on supporting publicity and transparency on the administrative practices, so as to encourage the public participation in observing the principle of altruism and, in turn, benefit the future biomedicine development. 相似文献
944.
945.
The study examines whether self-efficacy mediates between intention and behavior, and whether appearance norms and self-efficacy are additive or synergistic predictors of sunscreen use. At two measurement points in time, 14 weeks apart, 154 individuals responded to an online questionnaire. Moderated mediation was tested by hierarchical regression analyses. Self-efficacy mediated the intention-behavior relationship, whereas appearance norms emerged as a moderator of the self-efficacy-sunscreen use relationship. The model accounted for 22% of the behavior variance at time 2. For individuals who believe that they would look more attractive with a tan, self-efficacy did not have a strong effect on behavior. Thus, for skin-protection motivation to become effective, self-efficacy is needed in conjunction with less positive appearance norms. Implications for public health promotion and mass media sunscreen use campaigns are discussed. 相似文献
946.
947.
Although growth in head circumference (HC) during infancy is known to predict later childhood outcomes, the mechanisms underlying this association with later sociocognitive abilities remain undetermined. Thus, using a sample of 241 pairs of normally developing Japanese twins, this study investigated the underpinnings of the association between HC growth (difference between HC at birth and at 10 months) and sociocognitive abilities at 19 months as measured by 10 items from the M-CHAT. Phenotypic correlations between HC at birth and sociocognitive abilities and between HC growth and sociocognitive abilities were marginal and not significant. However, multivariate genetic analyses using Cholesky decomposition revealed that genetic influences on HC growth and those on sociocognitive abilities were negatively associated. On the other hand, shared and nonshared environmental influences on HC growth were positively associated with influences on sociocognitive abilities. Genetic and environmental influences on HC at birth were not significantly associated with influences on sociocognitive abilities. These results help to clarify the role of brain growth during infancy in the subsequent development of sociocognitive abilities and highlight the importance of examining the different roles of genetic and environmental influences in studies of these areas. 相似文献
948.
Autism spectrum disorder (ASD) symptoms are present in unaffected relatives and individuals from the general population. Results are inconclusive, however, on whether unaffected relatives have higher levels of quantitative autism traits (QAT) or not. This might be due to differences in research populations, because behavioral data and molecular genetic research suggest that the genetic etiology of ASD is different in multiplex and simplex families. We compared 117 unaffected siblings and 276 parents of at least one child with ASD with 280 children and 595 adults from the general population on the presence of QAT using the Social Responsiveness Scale (SRS). Mean SRS scores for siblings, control children, parents and control adults were 25.4, 26.6, 33.7 and 32.9. Fathers of children with ASD showed significantly higher levels of QAT than controls, but siblings and mothers did not. We could not detect a statistically significant difference in SRS scores between relatives from simplex and multiplex families. These results do not support the theory of differential (genetic) etiology in multiplex and simplex families and suggest that a carried genetic risk is generally not expressed phenotypically in most relatives, except in fathers. 相似文献
949.
950.
Verhaeghen P Martin M Sędek G 《Neuropsychology, development, and cognition. Section B, Aging, neuropsychology and cognition》2012,19(1-2):1-12
The papers in this Special Issue compellingly show that older adults' everyday cognitive life is governed not by the decline in elementary cognitive processes as measured in the lab, but by a multitude of compensatory mechanisms, most of which are of the social/motivational variety. Much of this compensatory behavior can be elicited with no or only little experimental prodding, underscoring the self-organizing or self-initiated nature of this type of behavior, even in advanced old age. We suggest that the study of compensation and the orchestration of cognitive, social, and motivational compensatory mechanisms in effective and healthy aging provides a meaningful challenge to traditional ways of examining developmental changes in cognitive performance. 相似文献