Measure of the effective optical path of QN-1total flow extinction type smoke meter developed recently is described in detail.

对近期所研制的QN - 1型全流消光式烟度计有效光路的测定进行了较为详细的叙述。

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The exploitation history of wildlife in China is long, but the tradition utilization is the depredation type, and causes the economic species rare, or get close to extinction.

我国利用野生动物资源的历史悠久，但传统的野生动物利用方式多采取掠夺式地利用，导致许多经济价值很高的物种变得珍稀，或濒临灭绝。

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