By assuming the weak lens focal length expression to be the first term in a power series a simple and accurate formula can be derived for the objective focal length of a magnetic electron lens.

用假设弱透镜焦距表达式是一个幂级数中的第一项的方法，可以导出相当准确且便于实用的电磁电子透镜物镜焦距公式。

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The fissure lens group, in en echelon arrangement, is ease to be developed and conserved in the weak strain domain of tectonic lens.

透镜状裂隙群之间呈雁列式排布，易发育和保存于构造透镜体弱应变域中。

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Results indicate: (1) At stage 19 the lens plate separated from the presumptive corneal epithelium and weak fluorescence appeared in its basal cells.

结果表明：角膜上皮与内角膜细胞均可合成、分泌胶原蛋白。

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