关键词: 生物制氢, 生物制氢, 光解水, 光发酵, 暗发酵, 两步发酵

Abstract: The paper aims to introduce suitable crop varieties and reasonably adjust planting structure and improve agricultural industry level. Based on the data of the first and last frost date (the lowest ground temperature ≤0℃) and annual temperature of 4 meteorological stations in eastern Hexi corridor during 1961- 2014, change characteristics of the first and last frost date and frost- free period were studied by climate diagnosis analysis method. The results showed that the first frost date was significantly delayed, the last frost date was significantly advanced and the frost-free period was significantly prolonged in time variation. Time series of the first and last frost date and frost-free period had 8-10 years, 9-11 years and 9-10 years quasiperiodic variation respectively. The first and last frost date and frost-free period all had a climate abrupt change. On space distribution, because of the influence of altitude, topography and vegetation cover, the first frost date appeared in an order of mountainous area, desert region and oasis plain, while the sequence of the last frost date was in contrary. The frost-free period was the shortest in mountainous area, followed by that in the desert region and was the longest in oasis plain. The first and last frost date and the frost-free period were significantly correlated with the annual temperature and latitude.