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761.
边镜贸易作为我国作为开放的重要组成部分,进展显著。本文在概述我国边境贸易发展所产生的环境问题的基础上,以我国最大的陆边口岸--满州里市为例,运用灰色预测,动态规划等方法探讨边境贸易与环境保护协调发展的途径。 相似文献
762.
汽车尾气净化非贵金属催化剂SO2中毒机理研究 总被引:9,自引:0,他引:9
用TPD,IR,XPS等方法研究了汽车尾气净化的复合氧化物催化剂SO_2中毒机理。结果表明,催化剂SO_2中毒失(?),首先是SO_2在催化剂活性中心上进行化学吸附,然后部分SO_2与活性组分生成相应的亚硫酸盐和硫盐酸,从而使催化剂失活。SO_2的化学吸附及部分生成相应的亚硫酸盐,与生成硫酸盐相比,对催化剂失活的影响,前者更为明显。 相似文献
763.
Scenarios of major terrestrial ecosystems in China 总被引:2,自引:0,他引:2
The spatial pattern and mean-center shift of major terrestrial ecosystems, termed Holdridge Life Zones (HLZ), during the periods from 1961 to 1990 (T1), from 2010 to 2039 (T2), from 2040 to 2069 (T3) and from 2070 to 2099 (T4) were analyzed by combining the zonal patterns of climatic change in China and the climatic change scenarios of HadCM2 and HadCM3. The results showed that nival area would decrease rapidly with temperature increase in the future. HadCM2 and HadCM3 predicted that the nival areas might disappear in 552 years and 204 years, respectively. Using both HadCM2 and HadCM3, the five HLZ types with the largest areal extent are nival zone, cool temperate moist forest, warm temperate moist forest, subtropical moist forest and boreal wet forest, which collectively account for more than 50% of China's land mass. Among these five HLZ types, nival zone, warm temperate moist forest and boreal wet forest would decrease continuously, whereas subtropical moist forest and cool temperate forest would increase continuously during the four periods. HLZ diversity and patch connectivity would increase continuously in the 21st century. The shift distances of mean centers of HLZ types simulated using HadCM3 were markedly greater than those simulated using HadCM2, in general. The results from both HadCM2 and HadCM3 showed that boreal wet forest, subtropical moist forest, tropical dry forest, warm temperate moist forest and subtropical wet forest had bigger shift ranges, indicating that these HLZ types are more sensitive to the climatic change scenarios of HadCM2 and HadCM3. 相似文献
764.
765.
Single and joint effects of acetochlor and urea on earthworm Esisenia foelide populations in phaiozem 总被引:5,自引:0,他引:5
Much attention is paid to soil health and environmental safety. Earthworms are an important indicator of soil ecosystem health and safety. Ecological toxicity of acetochlor and excessive urea, in both their single and joint effects, on earthworm Esisenia foelide was thus studied using the soil-culture method. Acetochlor had an enhanced toxicity from low concentration to high concentration. The mortality of earthworms after a 6-day exposure was changed from 0 to 86.7%, and the weight change rate ranged from 7.86 to -30.43%, when the concentration of acetochlor was increased from 164 to 730 mg kg(-1). Urea expressed its positive and beneficial effects on earthworms when its concentration was lower than 500 mg kg(-1). Strongly toxic effects took place when the concentration of urea was higher than 1000 mg kg(-1). The mortality of earthworms exposed to urea reached 100% when its concentration was more than 1500 mg kg(-1). When the concentration of urea was lower than 500 mg kg(-1), there were antagonistic effects between the two agrochemicals on earthworms; when the concentration of urea was higher than 500 mg kg(-1), joint toxic effects of acetochlor and excessive urea on earthworms were synergic. In any case, excessive urea application is very harmful to the health of soil ecosystems. 相似文献
766.
X.J. Xie W. Ran Q.R. Shen C.Y. Yang J.J. Yang Z.H. Cao 《Environmental geochemistry and health》2004,26(2):237-243
Field experiments were done in two sites, Yixing and Changshu, Jiangsu province, China, to study P movement and leaching in flooded paddy soils. P movement in soil was investigated by using the KH2
32PO4 tracker method, and the amount of P leached from the soil layer in different depths was estimated by measuring P concentrations in the soil solution and saturated hydraulic conductivities in field. Determination was done about one month after P application. There was 46% and 42% of total 32P retained in the 0–5cm layer of soil in the Yixing site and in the Changshu site respectively. The 32P retained in the 25–30 cm layer was only about 1–2% of the total 32P added. Furthermore, 8.01% of 32P in the soil of Yixing site and 16.8% of 32P in the soil of Changshu site was lost from the layer 0–30cm soil. The seasonal amounts of P leached from the top soil layer and from bottom layer are about 4.5–5.8% and 1.6–2.1% of the total P application, respectively. Changes of total P concentrations in soil solutions during rice growth showed that the fertilizer P applied before flooding of the paddy fields suffered a flash leaching loss and a slow leaching loss. We concluded that the fertilizer P could quickly move in the flooded paddy rice field and parts of it can enter into surface water and ground water. Unless the P application is well managed the risk of P loss and consequently environmental pollution exist. 相似文献
767.
周继娥 《湖南环境生物职业技术学院学报》2006,12(2):232-234
会计档案管理电算化是重要的会计基础工作,需要我院各部门相互协调、共同完成、规范管理、科学使用并及时维护计算机管理系统.做好会计档案管理电算化工作,有机地将会计核算、系统安全有效长期运行结合起来,充分发挥电算化会计档案快捷、方便的特点,才能确保我院内部信息资源的共享,使财会人员真正摆脱繁琐、单调、机械的手工操作,达到会计工作电算化、效率化、制度化、规范化. 相似文献
768.
苯磺酰基环烷烃甲酸酯结构对发光菌的毒性影响 总被引:1,自引:0,他引:1
测定了一批具有大小不同碳环的的苯磺酰基环烷烃甲酸酯对发光菌的毒性数据,值得注意的是碳环大小的改变会影响化合物的毒性,碳环对毒性的影响按三元环〉四元环〉五元环〉六元环的顺序减小。 相似文献
769.
双波长标准加入法同时测定水中硝酸盐和亚硝酸盐 总被引:2,自引:0,他引:2
本文应用双波长标准加入法同时测定了硝酸盐和亚硝酸盐,在研究硝酸盐和亚硝酸盐紫外光谱的基础上,精确选择亚硝酸盐等吸收点波长202.5nm,216.5nm为测定波长。亚硝酸盐含量回归方程经推导得C=-3.841+156.6A,相关系R=1.000。将该法用于合成样品及实际水样分析,所得结果较满意。 相似文献
770.
城市生态系统的预测与综合评价的思想体系 总被引:2,自引:0,他引:2
本方针对国内外城市生态系统的研究,提出了一套预测一评价一对策的思想体系,并对其预测、评价方法作了初步理论探讨. 相似文献