全文获取类型
收费全文 | 5728篇 |
免费 | 284篇 |
国内免费 | 4篇 |
专业分类
6016篇 |
出版年
2023年 | 63篇 |
2022年 | 89篇 |
2021年 | 108篇 |
2020年 | 157篇 |
2019年 | 140篇 |
2018年 | 279篇 |
2017年 | 261篇 |
2016年 | 238篇 |
2015年 | 162篇 |
2014年 | 178篇 |
2013年 | 743篇 |
2012年 | 435篇 |
2011年 | 434篇 |
2010年 | 265篇 |
2009年 | 192篇 |
2008年 | 336篇 |
2007年 | 281篇 |
2006年 | 246篇 |
2005年 | 223篇 |
2004年 | 135篇 |
2003年 | 150篇 |
2002年 | 138篇 |
2001年 | 61篇 |
2000年 | 82篇 |
1999年 | 54篇 |
1998年 | 31篇 |
1997年 | 24篇 |
1996年 | 23篇 |
1995年 | 21篇 |
1994年 | 16篇 |
1993年 | 21篇 |
1992年 | 30篇 |
1991年 | 23篇 |
1990年 | 26篇 |
1989年 | 25篇 |
1988年 | 28篇 |
1987年 | 19篇 |
1986年 | 12篇 |
1985年 | 13篇 |
1984年 | 17篇 |
1983年 | 14篇 |
1980年 | 11篇 |
1979年 | 19篇 |
1978年 | 13篇 |
1976年 | 13篇 |
1974年 | 11篇 |
1973年 | 11篇 |
1971年 | 13篇 |
1968年 | 11篇 |
1965年 | 10篇 |
排序方式: 共有6016条查询结果,搜索用时 8 毫秒
51.
Use of the World-Wide Web among academics has grown explosively during the last few years. To date, most applications of the Web have focused on the storage and dissemination of relatively static information, in part because of the cost associated with manual collating and updating of data. This paper presents an example of a dynamic worldwide database devoted to maintaining inherently transient information: The database accepts international travel itineraries submitted by individual academic psychologists, and makes them publicly available to potential hosts on the basis of various search keys. The objective of the database (http://www.psy.uwa.edu.au/wave/) is to facilitate international exchange among academics. 相似文献
52.
53.
54.
55.
Michael von Grunau Stéphane Dubé Cesar Galera 《Attention, perception & psychophysics》1994,55(5):575-592
Effects of the similarity between target and distractors in a visual search task were investigated in several experiments. Both familiar (numerals and letters) and unfamiliar (connected figures in a 5 × 5 matrix) stimuli were used. The observer had to report on the presence or absence of a target among a variable number of homogeneous distractors as fast and as accurately as possible. It was found that physical difference had the same clear effect on processing time far familiar and for unfamiliar stimuli: processing time decreased monotonically with increasing physical difference. Distractors unrelated to the target and those related to the target by a simple transformation (180° rotation, horizontal or vertical reflection) were also compared, while the physical difference was kept constant. For familiar stimuli, transformational relatedness increased processing time in comparison with that fort unrelated stimulus pairs. It was further shown in a scaling experiment that this effect could be accounted for by the amount of perceived similarity of the target-distractor pairs. For unfamiliar stimuli, transformational relatedness did have a smaller and less pronounced effect. Various comparable unrelated distractors resulted in a full range of processing times. Results from a similarity scaling experiment correlated well with the outcome of the experiments with unfamiliar stimuli. These results are interpreted in terms of an underlying continuum of perceived similarity as the basis of the speed of visual search, rather than a dichotomy of parallel versus serial processing. 相似文献
56.
This paper makes use of a unique data set fordoctoral-level biochemists, earth scientists,physicists, and physiologists to examine the question ofwhether the rewards to publishing in science are gender blind. The longitudinal nature of the data, andthe inclusion of different research outcome variables,permit the estimation of a wage-change model thatcontrols for fixed effects and productivity differences. We find little evidence that the reward processin academe during the 1970s was affected by gender. Wedo, however, find evidence that catch-up was occurring,implying that all was not well in the past for the women scientists in the study. [The1975 Survey of Doctorate Recipients indicates thatracial minority groups (Blacks, American Indians, andAsians) comprised, respectively, 5.9%, 6.3%, 2.8%, and 6.3% of the doctoral populations in physics,chemistry, earth science, and thebiosciences.] 相似文献
57.
Maritza Rubio-Stipec Patrick E. Shrout Glorisa Canino Héctor R. Bird Peter Jensen Mina Dulcan Mary Schwab-Stone 《Journal of abnormal child psychology》1996,24(1):67-83
Empirically defined scales of depressive, attention deficit hyperactivity disorder, oppositional-defiant disorder, and conduct symptoms from the lay-administered National Institute of Mental Health (NIMH) Diagnostic Interview Schedule for Children (DISC), version 2.3, and evidence of their reliability and validity, are presented. The scales were developed using factor analyses of data obtained from an epidemiologic survey of over 1,200 children drawn from four sites across the U.S. and Puerto Rico (the NIMH Methods for the Epidemiology of Child and Adolescent Mental Disorders, or MECA Study). Their psychometric properties were tested in a subsample of children reinterviewed by clinicians. The findings support the use of these continuous measures. The scales are strongly related to the diagnostic categories and show good test-retest reliability. The scales can be used to characterize severity in children with diagnoses and to describe problems and symptoms in children without diagnoses. Because these scales can measure gradations in symptomatology, they may be more useful than categorical measures. Like categorical measures, the scales based on the DISC are greatly influenced by the informant, whether child or parent.This research was supported by grant MH-46732 from the National Institute of Mental Health, Bethesda, Maryland.The MECA Program is an epidemiologic methodology study performed by four independent research teams in collaboration with staff of the Division of Clinical Research, which was reorganized in 1992 with components now in the Division of Epidemiology and Services Research and the Division of Clinical and Treatment Research, of the NIMH, Rockville, Maryland. The NIMH Principal Collaborators are Darrel A. Regier, MD, MPH, Ben Z. Locke, MSPH, Peter S. Jensen, MD, William E. Narrow, MD, MPH, and Donald S. Rae, MA; the NIMH Project Officer was William J. Huber. The Principal Investigators and Coinvestigators from the four sites are as follows: Emory University, Atlanta, Georgia, UO1 MH46725: Mina K. Dulcan, MD, Benjamin B. Lahey, PhD, Donna J. Brogan, PhD, Sherryl Goodman, PhD, and Elaine Flagg, PhD; Research Foundation for Mental Hygiene at New York State Psychiatric Institute (Columbia University), New York, New York, UO1 MH46718: Hector R. Bird, MD, David Shaffer, MD, Myrna Weissman, PhD, Patricia Cohen, PhD, Denise Kandel, PhD, Christina Hoven, PhD, Mark Davies, MPH, Madelyn S. Gould, PhD, and Agnes Whitaker, MD; Yale University, New Haven, Connecticut, UO1MH46717: Mary Schwab-Stone, MD, Philip J. Leaf, PhD, Sarah Horwitz, PhD, and Judith H. Lichtman, MPH; University of Puerto Rico, San Juan, Puerto Rico, UO1 MH46732: Glorisa Canino, PhD, Maritza Rubio-Stipec, MA, Milagros Bravo, PhD, Margarita Alegría, PhD, Julio Ribera, PhD, Sarah Huertas, MD, and Michael Woodbury, MD.The authors gratefully acknowledge Zenaida González and José Martínez who performed the data nalayses, as well as Elizabeth Pastrana, and Felícita Laboy, secretaries, for their valuable contributions to this work. 相似文献
58.
Marc Berthiaume Hélène David Jean-François Saucier François Borgeat 《Sex roles》1996,35(11-12):781-800
This study was designed to examine the relationship between gender role orientation and psychological adjustment during pregnancy and the postpartum period in a large sample of French-speaking Caucasian mothers. Gender role was assessed with the Bem Sex Role Inventory, which classifies subjects into four categories: androgynous, masculine, feminine, and undifferentiated. A discriminant analysis showed a relationship between androgyny and the following measures of psychological adaptation: self-esteem, satisfaction with social support, and level of apprehension toward perinatal stressors. The masculine gender role was linked with self-esteem, work involvement, age, and severity of perinatal stress. No relationship was found between gender role and the level of antenatal or postnatal depressive symptomatology. Stress, marital support, and social support were among the predictors of postpartum depression, which underlined the importance of taking these variables into account when studying the well-being of mothers during the postnatal period. Results are discussed in light of previous literature on the association between gender role and motherhood. The limitations of Bem's model and inventory are also considered. 相似文献
59.
This article presents an approach we have developed for the assessment of public research institutions in the natural sciences
and engineering. The method consists in the exploitation of available S&T databases and indicators, including bibliometrics
(databases of scientific as well as technical literature), patents, and internal data. Results are therefore derived through
multiple databases. The objective is to profile a specific national R&D community in order to assess the positioning of a
public institution or program within the community to which it belongs. It involves obtaining the profile of the evolution
of an R&D area, the R&D performers, the financing and support institutions, the users of R&D results, and the interactions
between all these actors. A case-study of Canadian research in polymers is presented.
Part of this research was financed by the National Research Council of Canada, and by a strategic grant from the Social Sciences
and Humanities Research Council. The research benefited from the expertise of Robert Letellier, Robert H. Marchessault, Jacques
Martel, and Marielle Piché, and from the technical assistance of Maryse Prud’homme, Marcel Parent, and Benoit Longpré. 相似文献
60.