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This article examines the effects of social support on the receipt of adequate prenatal care. A study was conducted to test the hypotheses that social support helps women overcome obstacles to obtaining such care, and that social support has greater effects on women facing the most obstacles. Survey data were gathered for more than 90% of the women who gave birth in Oklahoma hospitals during specific periods in the summer of 1986. The authors found only weak support for the first hypothesis, and for the second hypothesis found only support that must be qualified according to the measure of social support. Strong evidence indicates, however, that difficulty in paying for prenatal care, personal inconveniences, and unwanted pregnancies are obstacles to obtaining such care. The findings account for some of the frequently observed demographic differences associated with receipt of adequate prenatal care, although such differences persisted even after the obstacles were considered. The authors present implications for policy makers seeking to improve women's receipt of adequate prenatal care.  相似文献   
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The present study employed reinforcement-based methods to induce existing members to recruit new members to join a chamber of commerce. Three interventions took place during June and July of 3 successive years. The investigators trained chamber leaders to use reinforcement methods (e.g., contingent tokens) to reinforce recruitment and dues collections. All three interventions produced substantial increases in their targets.  相似文献   
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The efficacy of three different schedules of reinforcement for promoting and sustaining drug abstinence was compared in this study. Cigarette smoking was studied as an exemplar of stimulant drug self-administration. Sixty cigarette smokers were assigned to one of three groups (progressive rate of reinforcement, fixed rate of reinforcement, and yoked control). Participants in all three groups were asked to refrain from smoking for 1 week. Participants in the progressive and fixed groups achieved greater mean levels of abstinence than those in the control group. Participants in the progressive group were significantly less likely to resume smoking when they became abstinent than participants in the other groups.  相似文献   
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“Epidemic” models of transitions between stages of cigarette smoking describe the spread of smoking behavior through face-to-face encounters. An epidemic model was successfully fitted that allowed epidemic parameters to be conditioned on the smoking status of adolescents' parents. Model comparisons supported the conclusion that the transition from nonsmoker to trier involved social contacts, whereas the transition from trier to regular smoker was best modeled as a constant rate (i.e., did not depend on the population prevalence of smokers). The transition rate from nonsmoker to trier was more rapid in children of smoking parents than in children of nonsmoking parents. Adolescents with and without smoking parents did not differ in the rate of transition from trier to regular smoking.  相似文献   
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