“苛捐”砸不碎

在供应商生产过剩、同质化严重的情况下，零售商永远有机可乘。     

浅谈渠道衬砌成本控制

机械化衬砌在南水北调工程中得到广泛应用,但在衬砌机的运用过程中产生了一系列问题。通过对混凝土超量方面进行分析,提出了相关混凝土方量控制的建议,节省了工程投资。     

Experimental investigation on water quality standard of Yangtze River water source heat pump

Due to the surface water in the upper reaches of Yangtze River in China containing large amounts of silt and algae, high content of microorganisms and suspended solids, the water in Yangtze River cannot be used for cooling a heat pump directly. In this paper, the possibility of using Yangtze River, which goes through Chongqing, a city in southwest China, as a heat source-sink was investigated. Water temperature and quality of the Yangtze River in the Chongqing area were analyzed and the performance of water source heat pump units in different sediment concentrations, turbidity and algae material conditions were tested experimentally, and the water quality standards, in particular surface water conditions, in the Yangtze River region that adapt to energy-efficient heat pumps were also proposed. The experimental results show that the coefficient of performance heat pump falls by 3.73% to the greatest extent, and the fouling resistance of cooling water in the heat exchanger increases up to 25.6% in different water conditions. When the sediment concentration and the turbidity in the river water are no more than 100 g/m3 and 50 NTU respectively, the performance of the heat pump is better, which can be used as a suitable river water quality standard for river water source heat pumps.     

我国农村居民在外饮食的实证研究

一、研究背景改革 2 0年来 ,农民收入有了较大幅度的增长。按可比价计算 ,1 999年农村居民人均纯收入是 1 978年的 4倍。随着收入的增加 ,农民的饮食方式发生了较大变化 ,在外饮食有较大幅度的增长。按 1 998年可比价计算 ,农民生活消费由 1 991年的人均 1 2 2 5元增加到 1 998年的1 6 4 7元 ,增长了 34 % ;农民食品消费由 1 991年人均 6 95元增加到 1 998年的 90 7元 ,增长了31 %。然而 ,同期在外饮食却增加了 1倍多 ,在外饮食支出占食品消费的比例由 7%上升到1 1 %。尽管近几年来农村居民食品消费有下降趋势 ,但在外饮食却呈增长趋势。同…