排序方式: 共有443条查询结果,搜索用时 0 毫秒
101.
102.
103.
104.
我老家是赤峰市松山区西部的一个偏僻小山村,西部和南部与河北省围场县毗邻,北与本公社(过去的称呼)东沟大队接壤.全大队(过去的称呼)辖九个生产队,一千多口人,大的生产队约二百多人,小的生产队在百人左右.村庄大都是坐落在两山夹一沟的沟底部,水浇地极少,95%都是山坡地,纯属靠天吃饭的老天爷农业. 相似文献
105.
SI Hu BI Hai-pu 《重庆大学学报(英文版)》2008,7(1):1-7
We established a hydrodynamic model to simulate the pollutant transport and decay process in the case of a pollution incident in the sections of the Yangtze and the Jialing passing through the city area of Chongqing. The Boussinesq assumptions and the Navier-Stokes equations of incompressible fluid were applied to setting up the pollutant diffusion equations and the equations for the decay process. E. coli was taken as the example pollutant, and chloride dosage, light, temperature and ultraviolet intensity were considered in the equations for bacterial decay process. The calculated values of the fluid velocities in the two rivers agree well with corresponding measured results, indicating an ideal accuracy of the model. In simulation, the concentration of E. coli in water was assumed to be zero before the accident. The upriver boundary velocity was (1.35 m/s for the Jialing flow and 1.75 m/s for the Yangtze flow, and the downriver boundary was water depth set at 0. Simulation results show that the bacteria are transported downstream along the riverbank. A long and narrow pollutant belt develops at 12 h after the start of the accident ascribed to the quick longitudinal transfer. After the pollution sources are cut off, the pollutant concentration decreases slowly, mostly by advection and diffusion, suggesting inadequate self-purification ability of the rivers and the necessity of effective decontaminating measures in the case of a pollution incident. The model can be a useful tool for understanding the polluting situations of an improper discharge incident and evaluating the effects of decontaminating measures for the water body of the Three Gorges Reservoir. 相似文献
106.
107.
108.
109.
110.
乐不思蜀 《中学生(作文版)》2014,(17):30-33
VOL.“等一下,把这个带上。”路航转过身,看见爸爸将一把伞递了过来。他面无表情地接过伞,转身出了家门。刚出门,他就发现地上躺着一枚粉红色信封,上面有个巨大的黑鸭子邮戳,并写着“路航亲启”四个七扭八歪的大字。路航诧异地捡起信封,打开来看。上面写着:路航先生,11部队诚邀您于这周日上午带着一包面包糠去河水公园见面。如若不来,您将会遭受审判。署名是:皮丹苏尤周。 相似文献