全文获取类型
收费全文 | 24451篇 |
免费 | 177篇 |
出版年
2021年 | 46篇 |
2020年 | 66篇 |
2019年 | 63篇 |
2018年 | 3559篇 |
2017年 | 2887篇 |
2016年 | 2335篇 |
2015年 | 271篇 |
2014年 | 156篇 |
2013年 | 528篇 |
2012年 | 724篇 |
2011年 | 2525篇 |
2010年 | 2602篇 |
2009年 | 1576篇 |
2008年 | 1831篇 |
2007年 | 2303篇 |
2006年 | 158篇 |
2005年 | 338篇 |
2004年 | 284篇 |
2003年 | 240篇 |
2002年 | 187篇 |
2001年 | 112篇 |
2000年 | 149篇 |
1999年 | 76篇 |
1998年 | 94篇 |
1997年 | 72篇 |
1996年 | 62篇 |
1995年 | 45篇 |
1994年 | 52篇 |
1993年 | 57篇 |
1992年 | 57篇 |
1991年 | 65篇 |
1990年 | 60篇 |
1989年 | 62篇 |
1988年 | 50篇 |
1987年 | 43篇 |
1986年 | 37篇 |
1985年 | 49篇 |
1984年 | 45篇 |
1983年 | 38篇 |
1982年 | 50篇 |
1981年 | 54篇 |
1980年 | 48篇 |
1979年 | 35篇 |
1978年 | 48篇 |
1977年 | 27篇 |
1976年 | 33篇 |
1975年 | 48篇 |
1974年 | 38篇 |
1973年 | 37篇 |
1972年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Sarah B. Woods Angela Hiefner Patricia N. E. Roberson Nida Zahra Elizabeth Mayfield Arnold Victoria Udezi 《Family process》2023,62(1):230-253
African Americans are at significantly greater risk of hypertension and worse cardiovascular outcomes than other racialized groups, yet hypertension intervention effects remain limited. Thus, it is necessary to understand the potential mechanisms whereby interventions may be more effectively targeted to improve health. Supported by prior research evidence and guided by the Biobehavioral Family Model, this study examined associations between family relationship quality, psychological wellbeing, and self-management behaviors for African Americans with hypertension. Data were pooled from three Midlife Development in the U.S. projects, resulting in a sample of 317 African Americans (63.4% female, Mage = 53.32) with self-reported high blood pressure in the past 12 months. We tested four cross-sectional multiple mediator models, with depressed mood and environmental mastery mediating associations between family strain and exercise, smoking, problematic alcohol use, and stress-eating. Environmental mastery mediated the association between greater family strain and decreased odds of achieving recommended exercise levels; greater odds of reporting problematic alcohol use; and greater stress-eating. Though family strain was associated with depressed mood in each model, this variable did not serve as an indirect pathway to self-management behaviors. Family strain, and the potential pathway identified via environmental mastery, may be a meaningful predictor of disease self-management for African Americans with hypertension. Longitudinal studies are needed to examine directionality and to support intervention trials for improving self-management and hypertension outcomes. 相似文献
82.
Civic actions are behaviours intended to improve conditions for others or help shape a community's future. Such actions vary widely from voting to voluntary helping, from canvassing to community organizing, and attempts have been made to categorize the array of civic actions. However, the question of why young adults engage in some types of civic actions versus others is not well understood. Using data from 598 White, cisgender, heterosexual young adults in the United States, we examined the relations between individual civic efficacy, collective civic efficacy, and seven actions: writing social media posts, voting, buycotting, volunteering, participating in an organization, supporting political candidates, and protesting. We hypothesized that individual efficacy would be positively related to all seven actions, but collective efficacy would be more strongly related to collective or political actions, compared to the individual or civil ones. Logistic regression analyses showed that individual efficacy positively predicted engagement in all seven civic actions. Individual and collective efficacy had a complex curvilinear relation with buycotting and supporting political candidates. Implications for future research and applications aimed at promoting civic engagement amongst young adults are discussed. Please refer to the Supplementary Material section to find this article's Community and Social Impact Statement . 相似文献
83.
84.
Edgar M. Johnson 《Psychometrika》1972,37(1):103-106
A computational short cut suggested by Feldman and Klinger for the one-sided Fisher-Yates exact test is clarified and is extended to the calculation of probability values for certain two-sided tests when sample sizes are unequal. 相似文献
85.
Patricia M. Blough 《Attention, perception & psychophysics》1972,12(4):342-348
This three-part study describes wavelength generalization gradients around a series of training wavelengths ranging from 480 to 645 om. Luminance was controlled for the pigeon’s spectral sensitivity. The response measure was probability of keypecking during a 2-sec stimulus presentation. Both an extinction procedure, where stimulus wavelengths occurred in 15-nm steps, and a maintained discrimination procedure, where step size was 2 to 4 nm, were used to obtain gradients. During a portion of the maintained discrimination procedure, new luminances were introduced, so that the effect of luminance level on gradient slope could be examined. Comparison of the resulting functions across training wavelengths revealed: (1) consistent differences in gradient slope in different spectral regions and (2) an increase in slope with luminance increase. The findings are related to recent electroretinographic wavelength contrast data and to psychophysical measures of wavelength discriminability. 相似文献
86.
87.
88.
The effects of unavoidable shocks on a multiple schedule having an avoidance component 总被引:1,自引:1,他引:0
下载免费PDF全文
![点击此处可从《Journal of the experimental analysis of behavior》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Marcus B. Waller Patricia F. Waller 《Journal of the experimental analysis of behavior》1963,6(1):29-37
Two dogs were maintained on a multiple schedule having both a food reinforced and an avoidance component (Mult VI 1′ SΔ AvoidSS20 RS20 SΔ). The effects of superimposing an Estes-Skinner procedure for delivering unavoidable shocks on all components of the multiple schedule were observed. The buzzer-shock pairing of the Estes-Skinner procedure produced an increased rate of responding on the avoidance component of the schedule and also on the SΔ components. No persistent change in rate was observed on the food component during the pre-shock stimulus. Control performances on all components could be regained by either extinguishing or eliminating the buzzer-shock pairing. Extinction of the avoidance responding had little effect on the increased rates of responding produced by the Estes-Skinner procedure on the SΔ and avoidance extinction components and did not lead to a conditioned suppression of the food reinforced responding. Rate of responding during the pre-shock stimulus was observed to be relatively independent of changes in the maintaining schedules. Responding during the pre-shock stimulus could be conditioned and maintained after an extensive history of avoidance extinction. 相似文献
89.
F. Craig Johnson 《Journal of counseling and development : JCD》1967,45(6):589-592
Over 18,000 students at Michigan State University reported their attendance at 46 campus events. Student characteristics were analyzed in terms of student attendance patterns. The 46 events were grouped into 4 independent categories that were attended by students with different characteristics. Students who attended cultural events were mostly single upperclassmen majoring in liberal arts; musical events were attended mostly by music majors; those attending athletic events tended to be single male undergraduates from the more applied disciplines; and social events were attended mostly by undergraduate girls. 相似文献
90.