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黄河三角洲及渤海莱州湾滨海区土壤资源及其合理开发利用 总被引：6，自引：0，他引：6
郭洪海赵树慧史立本林守宗刘兆辉 《资源科学》1994,16(3):12-19
黄河三角洲及渤海莱州湾滨海区土壤含盐量高和肥力低为其突出特点。干旱的气候、黄河尾闾河道的摆动、咸水的侵染、风暴潮的侵袭等自然条件和人类活动决定着土壤发生与发展的总趋势。生物与工种措施相结合综合治理旱、涝、盐、咸、瘦、农、林、牧、渔、盐综合发展，是合理开发4黄河三角洲、土壤资源、土壤盐 相似文献
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Lynn S. Liben 《Child development》2008,79(6):1600-1605
This article introduces a collection of essays on continuity and discontinuity in cognitive development. In his lead essay, J. Kagan (2008) argues that limitations in past research (e.g., on number concepts, physical solidarity, and object permanence) render conclusions about continuity premature. Commentaries respectively (1) argue that longitudinal contexts are essential for interpreting developmental data, (2) illustrate the value of converging measures, (3) identify qualitative change via dynamical systems theory, (4) redirect the focus from states to process, and (5) review epistemological premises of alternative research traditions. Following an overview of the essays, this introductory article discusses how the search for developmental structures, continuity, and process differs between mechanistic‐contextualist and organismic‐contextualist metatheoretical frameworks, and closes by highlighting continuities in Kagan’s scholarship over the past half century. 相似文献
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Jacqueline Schwab Howard E. Kulin Elizabeth J. Susman Jordan W. Finkelstein Vernon M. Chinchilli Susan J. Kunselman Lynn S. Liben M. Rose DÂ⊃Arcangelo & Laurence M. Demers 《Child development》2001,72(5):1439-1450
The objective of the present study was to determine the role of sex steroids in the development of self-perceived competence during adolescence. The Harter Self-Perception Scale was administered to 56 adolescents with delayed puberty who were receiving depo-testosterone (males) or conjugated estrogens (females) administered in 3-month blocks alternating with placebo. Treatment was given at three dose levels approximating early, middle, and late pubertal replacement levels. Hormone treatments had a significant positive effect for both males and females in one subscale domain--perceived job competence. Significant positive hormone effects were also obtained for perceptions of romantic appeal and close friendship in females and perception of athletic abilities in males. It can be inferred from the results of this study that the hormonal changes associated with sexual maturation have targeted influences on specific domains of self-perceived competence and that there are clear gender differences. 相似文献