铜石并用时代的

Results show that Pb enrichment factors varied from 1.0～1.8 in the cultural layers, and were not quite high. However, with the history going on from the Dawenkou Culture to the Longshan Culture, the Pb enrichment factor displayed an obvious rising trend, which indicated that the Pb in the cultural layers was probably associated with the development of metallurgic activities in the middle stage of the primitive society. From 5 050 cal a BP to 4 000 cal a BP, China underwent Stone Age, Chalcolithic Age and Bronze Age in sequence. Pb dust in the atmosphere increased with intensifying utilization of copper resources, which was probably the main cause of the rising enrichment factor in the cultural layers.

但是随着时间的推移，从大汶口文化到龙山文化，Pb的富集系数有明显逐步上升的趋势，表明遗址剖面中的Pb很可能与原始社会中期发展起来的冶金活动有关。5 050～4 000 cal a BP间，中国先后经历了石器时代、铜石并用时代，到最后进入青铜时代，这个过程中铜资源利用越来越多导致产生的大气粉尘铅越来越多，很可能是YC1剖面中Pb富集系数逐步增长的主要原因。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。