Safety status of different types of rural drinking water in Lanzhou City is analyzed by measuring the major sensory characteristics and physical indicators(pH,electrical conductivity(EC) and turbidity),inorganic non-metallic indicators(NO3-N,NO2-N,NH4-N) and metal indicators(Cu,Zn,Pb and Cd) of 63 drinking water samples in rural areas of Lanzhou City,comparing with the background of Sanitary Standards for Drinking Water(GB5749-2006) and using analysis of variance and multiple comparison statistical analysis.The results show:turbidity of cellar water in Lvjiaxian Village,Yuzhong County,spring water in Lvjiazui Village,cellar water in Sanzhuang Village,Yongdeng County and river water in Yinwayao Village and Gaolan County is seriously overweight,and precipitation is recommended before drinking.Contents of NO2-N and NH4-N in river water,deep well water and low well water in Agan Town,Qilihe District are seriously overweight,and it is recommended to deal with before drinking or not drinking.Contents of Cu in river water in Yinwayao Village,Gaolan County are seriously overweight;contents of Cd in cellar water in Lianda Village,Yuzhong County,and low well water in Agan Town,Qilihe District and Dapingshan Village,Xigu District are seriously overweight,and it is recommended to not drinking.The measured indicators of other types of drinking water in the study areas complied with the background of Sanitary Standards for Drinking Water.

The effects of sodium nitropprusside(SNP) as an exogenous nitric oxide donor at the different concentrations on the maize seed germination, growth and physiological reaction of maize seedlings under low temperature stress were studied. The results showed that the low temperature stress inhibited the maize seed germination and growth of seedlings, and increased the malondialdehyde(MDA) content and cell membrane permeability, while decreased the relative water content, the proline content and the chlorophyll content in leaves of maize seedlings. The treatments with SNP at different concentrations could promote the germination rate, germination energy, index of germination and index of vigor of maize seeds, increased growth, relative water content, the proline content and the chlorophyll content, inhibited significantly the MDA content and cell membrane permeability of maize seedlings under low temperature stress. It was shown that exogenous nitric oxide had abating effect on depressed seed germination and growth of maize seedlings, could improve the antioxygen ability of maize seedlings, debasing lipid peroxidation and protect plasma membrane from being destroyed to enhance the resistance of plants under low temperature stress. The best abating effect occurred with the SNP concentration set at 100 μmol·L-1, while higher or lower SNP content had no such satisfactory effect.

Basing on the summary of the present situation and practice development,major problems in current rural drinking water safety were pointed out.Facing existent problems,it demonstrated that efforts should be made for study in the aspects of connation of rural drinking water safety,evaluation and emergency system,and ecological compensation mechanism for water source area.This had good instructional meaning to solving drinking water safety matter in rural.

The heavy metals(As,Pb,Cu and Zn) contaminations were evaluated in farmland soil of Lanzhou City according to background values and national standard(GB15618-1995),applying the single factor pollution index and Nemerow integrated index.Based on the national standard.The results showed that,the general integrated pollution index was 0.81,which demonstrated a warning level of contamination,and the single factor index was taking the order of AsPbCuZn in the whole study area;the single factor index was in order of AsPbCuZn in Xigu and Honggu District,and Gaolan County;while the single factor index was in order of AsCuPbZn in urban district,Yongdeng and Yuzhong County;there was a light pollution of As in urban and Xigu District;the integrated pollution index was Xigu Districturban districtGaolan CountyYongdeng CountyHonggu DistrictYuzhong County,and the pollution ranking was light in Xigu District and urban district,warning in Gaolan County,and safety in others.Referred to the Lanzhou background values,the results showed that the general integrated pollution index was 2.20 with a moderate level of contamination,and the single factor index was CuPbAsZn in the whole study area;the order of the single factor index in different counties or districts was the same with the results evaluated by national standard;the integrated pollution index in different counties or districts was Xigu Districturban districtGaolan CountyYongdeng CountyHonggu DistrictYuzhong County.Heavy level of contamination was found in Xigu District,the urban district and Gaolan County were moderate pollution,while others light pollution;in general,the ranking of contamination was safety in farming area,whereas light in non-farming area.

Seasonal changes of δ~(13)C values were examined in the needles of Sabina przewalskii and Sabina chinensis, aimed to probe into their relationships with freezing tolerance. The results showed that the δ~(13)C values in needles of the two species declined with monthly average temperature decreasing and maintained a relatively lower value during the whole winter. It indicated that the two species consumed more self substances in order to adapt to low temperature. As a result, the δ~(13)C values decreased. The δ~(13)C values of S. przewalskii were significantly higher than those of S. chinensis, it suggested that S. chinensis must consume more self substances than S. przewalskii under low-temperature stress. S. przewalskii showed a more prevailing strategy than S. chinensis in order to develop the tolerance to freezing. Furthermore, strong significant linear relationships were observed between δ~(13)C value and monthly average temperature, between δ~(13)C value and Pro content, and between δ~(13)C value and RWC in needles of S. przewalskii and S. chinensis. These results suggested that the δ13C values in the needles can be used as another index to evaluate freezing tolerance of Sabina.

在新课标的指引下,感悟式教学法应运而生。它受到格式塔心理学的影响,提倡学生对课程内容进行整体的感知与把握,以及学生心理结构的建构与完善。要实现这种"感悟",必须要具备敏锐的语感,丰富的记忆表象以及观察与体验的能力。使学生具备丰厚的知识与情感底蕴的心灵世界。

Study on expansion of high performance concrete (HPC) with strength grade C60 by using expansive agent (UEA) and natural an-hydrous gypsum respectively.Both the two types of concrete specimens are cured in water and natural conditions.The specimens with UEA cured in water are expansion in the early age, but when the expansion get to maximum and than down fall; the specimens cured in natural conditions are expansive a little at origin and than get to shrink.The specimens with natural anhydrous gypsum both cured in water or in natural conditions, which expansion or shrinkage is a little or no.

结合盐通高速公路工程沿线填土高度和软土分布情况,文章介绍了其中几种典型软基处理方法。根据实测沉降资料及一维固结理论的解析解编制了沉降反分析程序,利用前期沉降观测信息反演确定计算参数,从而可对后期任一时刻的沉降、沉降速率以及最终沉降量进行预测。