临泽北部乔灌结合固沙林的生态效益和经济效益评价

近年来,为保护绿洲,防止土地沙漠化及风沙流对绿洲农田的危害,利用农闲水灌溉丘间地,采用丘间地营造乔木林,沙丘迎风坡中部以下营造灌木林的方法,在甘肃省河西地区临泽镇北部流沙中营造乔灌结合林2000ha多,初步形成一条防风固沙护田的绿色林带。随着林木的生长发育,使生态条件发生了一系列变     

又到苁蓉花开时

四月下旬，冒着强烈的沙尘天气，我们考察了位于乌兰布和沙漠边缘磴口县（属内蒙古西部巴彦淖尔市）的苁蓉人工接种试验区，去看看多年来难得一见的苁蓉开花。     

Effects of Salt Stress on Carbohydrate Metabolism in Desert Soil Alga Microcoleus vaginatus Gom.

The effects of salt stress on carbohydrate metabolism in Microcoleus vaginatus Gom., a cyanobacterium isolated from desert algal crusts, were investigated in the present study. Extracellular total carbohydrates and exopolysaccharides （EPS） in the culture medium produced by M. vaginatus increased significantly during the growth phase and reached a maximum during the stationary phase. The production of extracellular carbohydrates also significantly increased under higher salt concentrations, which was attributed to an increase in low molecular weight carbohydrates. In the presence of NaCI, the production of cellular total carbohydrates decreased and photosynthetic activity was impaired, whereas cellular reducing sugars, water-soluble sugars and sucrose content and sucrose phosphate synthase activity increased, reaching a maximum in the presence of 200 mmol/L NaCI. These parameters were restored to original levels when the algae were transferred to a non-saline medium. Sodium and K＋ concentrations of stressed cells decreased significantly and H＋-ATPase activity increased after the addition of exogenous sucrose or EPS. The results suggest that EPS and sucrose are synthesized to maintain the cellular osmOtic equilibrium between the intra-and extracellular environment, thus protecting algal cells from osmotic damage, which was attributed to the selective exclusion of cellular Na＋ and K＋ by H＋-ATPase.     

西藏时光

行走在魂牵梦绕的西藏大地，岁月流淌，光影变换万千，把这片神秘净土装扮得分外梦幻：光影中雅鲁藏布江纵横交错，神来之笔的光线划过寂静湖面，柔光轻抚流动的沙漠……与河流山川相遇，与速度时间碰撞，自由的阳光嬉戏、穿透万物，光影交汇奏起浑厚、优美、抒情乐章。用多少语言可以慰藉勇敢的天路者疲惫的心灵，大美西藏!     

Diet,Food Intake of Phrynocephalus frontalis （Agamidae） and Its Potential Role in Desert Habitat

We examined the dietary diversity and food intake of Phrynocephalus frontalis, compared the difference of insect diversity in the natural habitats with different lizard densities, and discussed the potential role of this lizard in the desert ecosystem. The results show that： （1） arthropodans of the orders Coleoptera, Hymenoptera and Hemiptera were major dietary components of P. frontalis; （2） coleoptera larvae always formed the predominant component of lizard diets; （3） dietary diversities of P. frontalis were not significantly different between summer and autumn or between the two sexes; （4） the similarity in trophic niches between seasons was 0.756, whereas the similarity in trophic niches between sexes was 0.994; （5） stomach content weight of lizards varied significantly among different seasons, but there was no significant difference in stomach content weight between sexes; （6） insect diversity differed significantly among the groups of the habitat with different degrees of lizard density, and the habitat with moderate lizards density had the highest insect diversity. We infer that P. frontalis prey mainly on insects and change their diet and food intake with season; males and females consumed similar preys in types and weights. As an important predator, P. frontalis could affect the insect community in the arid ecosystem of Hunshandak Desert on the Mongolian Plateau.     

不怕烫的人

神话小说《西游记》里,孙悟空被太上老君关在炼丹炉里烧了几天几夜,结果,孙悟空终于死里逃生,一脚踢倒炼丹炉,反出天庭。孙悟空不怕火烧是因为他会念避火诀。那么人能不能像孙悟空那样耐受高温呢