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Schickore J 《Endeavour》2003,27(3):134-138
In the 1820s, certain minute objects began to be used regularly as tests for microscopes. Scales of insects, animal hairs and tiny leaves served as convenient means to assess their optical performance. It was a peculiar conjunction of optics, astronomy and natural history that formed the intellectual background for the emergence of the tests; and their establishment was greatly facilitated by the culture of conversation and competition in which microscopical practice was embedded. The introduction of the tests soon gave rise to a peculiar and highly productive interaction: the application of test objects incited instrument makers to aspire after technical improvements. These pursuits led, in turn, to a differentiation and refinement of the tests themselves, which then again suggested specific kinds of improvements. Historians have paid only scant attention to these issues. But the early history of test objects deserves thorough investigation. In fact, it provides a key to the understanding of the intellectual and social contexts and the dynamics of microscopy in early 19th-century Britain. 相似文献
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Vocational decisions are important decisions for adolescents. This article takes television effects into account. A literature review for the occupational world in TV programs reveals a strong focus on some occupations as well as small cultivation effects plus learning effects from mediated role models. A secondary analysis of 2 panel waves was undertaken to study the effect of media role models on occupational aspiration. Television usage in a program segment correlated with corresponding aspirations. A process models showed a strong effect of career aspiration in 1 panel wave on related television usage and career aspirations in the following panel wave. 相似文献