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<正> 三、CR-39镜片的聚合成型1.聚合反应机理CR-39塑料制品采用本体聚合的方法。单体在引发剂的作用下,双键打开,聚合成交叉 相似文献
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<正> 二、CR-39眼镜片主要原材料的生产及物化性能以前眼镜的材料几乎都是无机玻璃,随着科学的发展,对眼镜的安全性、重量提出了更高的要求。因此,眼镜的塑料化进一步兴盛起来。现在塑料透镜用的树酯材料几乎都是美国PPG 公司发明的丙烯基二甘醇聚碳酸酯。用 相似文献
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本文介绍了我国近年研制成功的CR-39塑料镜片染色技术,比较详细地叙述了染色镜片消除有害光线的理论研究和各种染色镜片的应用范围。同时也从设备、仪器、染液和操作程序等方面介绍了CR-39塑料镜片的染色工艺。 相似文献
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当今世界上流行的一种眼镜片——CR-39,优点很多,质量较好,是今后眼镜工业发展的方向。为了全面向读者介绍CR-39眼镜片的制造工艺,我们组织了几篇有关CR-39眼镜片的材料加工、聚合工艺、测试方法和表面处理等文章,将相继连载于本刊,供读者选读。 相似文献
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本文介绍了光学树脂镜片的抗冲击性、巴科尔硬度、雾度、EV 值、北极光、黄色指数等特殊性能和测试方法。 相似文献
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The fission cross section and fission probability of 197Au, induced by (1665 MeV) π-, have been studied using CR-39 track detectors. A 4π-geometry was used to count track statistics. A beam of negative pions of 1665 MeV was produced at AGS of Brookhaven National Laboratory, USA, and allowed to fall normally on the stack. Two detectors from the stack were scanned for fission fragment tracks after etching in 6N NaOH at 70℃. The statistics of fission fragment tracks in both detectors were obtained. It was found that there was a marked asymmetry of registered tracks with respect to the forward and backward hemispheres. This asymmetry could be partly accounted for on the basis of momentum transfer to the struck nucleus. On the basis of counting statistics fission cross section was measured, and fission probability was determined by dividing the fission cross section with the reaction cross section. The fission cross-section and fission probability were compared with the computed values using the cascade-exciton model code CEM95. 相似文献
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<正> 问:什么是CR39光学树脂镜片? 答:CR39是美国PPG公司哥伦比亚化学分公司研制出来的一种新型眼镜片材料,CR是Columbia Resin的缩写。它的化学名称是烯丙基二甘醇碳酸酯,是一种光学热固性塑料。CR39光学树脂镜片就是以CR39单体为主料,配加其它几种药物,在特制的玻璃模具中通过加热、控温直接浇铸出来的无需研磨、抛光的一种质轻但不易打碎的新型眼镜片。 相似文献
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The fission cross section and fission probability of 197Au, induced by (1665 MeV) π-, have been studied using CR-39 track detectors. A 4π-geometry was used to count track statistics. A beam of negative pions of 1665 MeV was produced at AGS of Brookhaven National Laboratory, USA, and allowed to fall normally on the stack. Two detectors from the stack were scanned for fission fragment tracks after etching in 6N NaOH at 70℃. The statistics of fission fragment tracks in both detectors were obtained. It was found that there was a marked asymmetry of registered tracks with respect to the forward and backward hemispheres. This asymmetry could be partly accounted for on the basis of momentum transfer to the struck nucleus. On the basis of counting statistics fission cross section was measured, and fission probability was determined by dividing the fission cross section with the reaction cross section. The fission cross-section and fission probability were compared with the computed values using the cascade-exciton model code CEM95. 相似文献
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研究了微型激光扩束镜准超光滑表面的加工工艺。分析了机床速度、压力、抛光粉、工作温度、抛光模等对高质量表面的影响。选定了一系列的工艺参数,大幅度地提高了产品的合格率。 相似文献
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8 时间测量的基础--"约定光速"
相对论诞生之后,人们逐渐认识到不仅时间的测量有问题,空间的测量也存在问题.一根尺在不同的地方,长度是否一样,尺子在移动过程中长度会不会改变,都成了需要深思的问题. 相似文献
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广义相对论研究触及了关于时间的许多问题.然而,"时间是什么?"这个看似人人皆知的问题,回答起来却万分困难.
公元4世纪,早期基督教思想家圣奥古斯丁在他的<忏悔录>中写下了一句至理名言:"时间是什么?无人问我,我很清楚,一旦问起,我便茫然."[1]现代自然科学认为,时间和空间都是物质延展性的表现. 相似文献
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2.白矮星、中子星和超新星爆发 在没有外部核能源的情况下,恒星要达到某种平衡位形,必须找到足以抗衡引力的支撑力.抵挡引力坍缩的下一道防线是电子的简并压. 我们在第三章§5中曾估算过电子简并压.若不考虑某个数量级与1相差不远的数值系数,估算的步骤大体如下:其中能量E= NEk,这里N是电子总数,Ek是每个电子的平均动能.在第三章里计算地球上物质内的电子简并压时,电子气是非相对论性的,在白矮星上物质的密度要大得多,从而费米动量可能达到相对论性的数量级,故而我们要区分开这两种情况下动能 Ek与动量 P之间的关系在两情形里动量P皆可… 相似文献