At present artemisinin is expensive and in short supply because its only source is sweet wormwood, a Chinese medicinal plant.

目前，由于青蒿素的唯一来源是一种叫艾蒿的中草药，因此其价格昂贵且供不应求。

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For example, if a plant needs protection against a leaf-feeding pest, the protective agent need not also be present in the grain (that's harvested for food).

例如，如果一种作物需要保护免于遭受一种以叶子为食物的害虫的侵害，保护剂不需要在（作为粮食而收割的）作物中出现。

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By combining the wires with electrolytes naturally present in the plant, the researchers were able to create a transistor that converts electrochemical signals into electrical output.

通过比较电线和植物中天然存在的电解质，研究者们能够发明一种晶体管，将电化学信号转化为电力输出。

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"Thanks to the clearance the plant is now present over a large area of the cliff above Tremadog Square, " said Doug Oliver, NRW national nature reserve warden in the area.

BBC: St John's Wort boosted by Gwynedd cliff scrub clearance

The problem at present, he says, is that North Korean farmers plant too many poor-quality seeds in a desperate attempt to boost crops, and do so in soil that is becoming increasingly less fertile.

ECONOMIST: North Korea��s dreadful spring