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排序方式: 共有167条查询结果,搜索用时 281 毫秒
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Jane Mendle K. Paige Harden Eric Turkheimer Carol A. Van Hulle Brian M. D'Onofrio Jeanne Brooks-Gunn Joseph L. Rodgers Robert E. Emery Benjamin B. Lahey 《Child development》2009,80(5):1463-1480
Children raised without a biological father in the household have earlier average ages of first sexual intercourse than children raised in father-present households. Competing theoretical perspectives have attributed this either to effects of father absence on socialization and physical maturation or to nonrandom selection of children predisposed for early sexual intercourse into father-absent households. Genetically informative analyses of the children of sister dyads ( N = 1,382, aged 14–21 years) support the selection hypothesis: This association seems attributable to confounded risks, most likely genetic in origin, which correlated both with likelihood of father absence and early sexual behavior. This holds implications for environmental theories of maturation and suggests that previous research may have inadvertently overestimated the role of family structure in reproductive maturation. 相似文献
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Quality of education and student earnings 总被引:2,自引:2,他引:0
When a university increases expenditures in an attempt to improve quality, a natural question for social policy is raised: is the improvement worth the cost? One partial measure of “worth” in this context is given by earnings of graduates: will those earnings rise by enough to pay a reasonable return on the investment in higher quality? The question is hard to answer by statistical means: universities of higher quality have better reputations which allow them to select students who are themselves of higher quality; so in trying to measure the relation between earnings and university quality, quality of the school may be confounded with quality of the students. Recently, however, several large data sets have been made available which give sufficient information on the students' own backgrounds, and on their later earning, that we can hope to disentangle the effect on earnings of the school from that of the student himself. This article summarizes the results of several such studies, including our own work. The verdict to date is that the relation between “quality”, however measured, and earnings is significant, and that expenditures to improve quality are worth the cost, even when “worth” is measured narrowly as higher earnings for graduates. 相似文献
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Nonmaternal care of infant children is increasingly common, but there is disagreement as to whether it is harmful for children. Using data from 9,185 children (5 years and older) who participated in the Children of the National Longitudinal Survey of Youth, the current study compared 2 groups: those for whom nonmaternal care was initiated in the first 3 years and those for whom it was not. Between-family comparisons showed that early nonmaternal care was associated with higher achievement and lower behavior problem scores in childhood and adolescence. However, within-family comparisons failed to detect differences between siblings who had different early nonmaternal care experiences. The study concludes that the timing of entry to nonmaternal care in the first 3 years has neither positive nor negative effects on children's outcomes. 相似文献
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Looi Mee Lee Wong Alwyn Khai Howe Gnapragasan Shelly Anne Japri Anis Zafirah Rajedadram Aiysvariyah Pin Kar Yong 《Journal of Zhejiang University. Science. B》2020,21(9):745-748
Journal of Zhejiang University-SCIENCE B - 本文研究了槟榔 (Piper betle, PB)... 相似文献
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