Fuel cells produce electricity by utilizing the power generated from electrochemical reactions. They use external sources of chemical energy such as hydrogen and oxygen to produce energy. Electrochemical reactions in the fuel cells oxidize hydrogen, which reacts with oxygen to form water and release electrons. The electrons then flow through the external circuit producing an electric current. All fuel cells are based on a standard design wherein two electrodes are separated by an electrolyte. The electrolyte carries electrically charged particles. A catalyst is used to speed up or accelerate the electrochemical reaction within the fuel cells. Fuel cells can be used in small devices that are powered by a few watts of electricity and also in large power plants that produce megawatts (MW) of electrical energy. Fuel cells are categorized by the nature of the electrolyte used in them.

上涨先后排序：旅行社板块，行业指数，大盘，酒店版块，餐饮板块，景区板块。波动性大小排序：旅行社板块，行业指数，大盘，景区板块，餐饮板块，酒店板块。

4月-6月，航母下水利好兑现带来船舶类股票调整、监管趋严带来市场情绪转弱、军工分级B基金下折加剧军工下折行情；8月中印边境冲突、10月武器装备定价机制改革带来军工行情阶段性小幅反弹。

生态文明再升级，绿色中国新时代。“十九大”报告将生态文明建设升级为千年大计，绿色中国将迎来崭新时代，这对我国环境治理相应提出更高要求。为改善环境质量，政府未来将在末端治理和前端能源结构并行发力。

1、17 年全年仍维持《机会与陷阱》一文的框架性观点保持不变，预期不能过高。16 年初至今中证军工指数经过近2 年的长期下跌，跌幅高达33.39%，跑输同期上证综指29.01 个百分点，部分资金欲为明年提前布局，寻找前期跌幅较大板块进行配置

9 月30 日，中信国防军工指数收报7241.59 点，2017 前三季度跌幅为7.20%，在29 个一级行业排名第25位。中信军工指数自2016 年起下跌幅度已达43.86%，今年以来回调幅度有明显收窄趋势。国防军工行业收入确认有明显的季节特征，主要集中在第四季度，板块1-9 月份EPS 为0.10 元，在一级行业中位列最后一名。