DNDC模型对川中丘陵区稻田CH_4、N_2O排放的模拟对比分析

利用IKONOS高分辨率(1m)卫星遥感图,进行典型抽样和地形→土地利用→土地覆盖→综合信息提取的方法,选定了代表川中丘陵区类特征的四川省金堂县为研究区域,通过对研究区域中不同固定耕作制度下代表性田块的选取,于2005年5月—2006年5月对田块管理者进行作物田间管理、作物产出等农业生产实际情况调查和分析,进行土壤理化性状、水样的测定,并结合当地的气象资料,利用DNDC模型模拟川中丘陵区不同耕作制度下稻田温室气体的排放情况。结果表明:冬水田-水稻田(PF)水稻生长期CH4排放通量为2.24 kg.hm-2.d-1,占年排放量的80.73%;水稻生长期和冬闲期N2O通量分别为0.033和0.003 6 kg.hm-2.d-1,水稻生长期排放量为4.28 kg.hm-2,占年总排放量的83.59%。CH4和N2O排放量在水稻整个生季节存在明显的互为消长关系。油菜-小麦田(RR)水稻生长期CH4排放通量为1.16 kg.hm-2.d-1,是休闲期的20.71倍,水稻生长期CH4排放量占年排放量的90.48%;水稻生长期和非水稻生长期N2O排放通量分别为0.070和0.027 kg.hm-2.d-1,水稻生长期N2O...     

Major brain lesions by intrauterine herpes simplex virus infection: MRI contribution

The majority of neonatal Herpes Simplex Virus (HSV) infections are acquired at birth as a consequence of direct fetal contact with the infected birth canal or through an ascending infection after premature rupture of the amniotic membranes. Intrauterine transmission of HSV infection from mother to the fetus is rare; in only 5% of the cases it occurs from haematogenous transplacental dissemination. We present a case of transplacental intrauterine HSV infection after a primary maternal HSV infection in the first trimester of pregnancy. The diagnosis was assessed by viral culture and serologic tests. Ultrasound imaging revealed fetal brain damage in the third trimester. Finally, the MRI showed the devastating extensiveness of the HSV infection, which was beyond the expectation based on the ultrasound images. Copyright © 2007 John Wiley & Sons, Ltd.     

Protective effect of weak pulsed magnetic fields on early ontogeny of tugun Coregonus tugun (Pallas) under conditions of chronic oil pollution

The state of internal organs in tugun larvae was analyzed histologically in the intact (control) group, the group treated with a water-soluble oil fraction (WSOF) in fivefold excess over the maximum allowable concentration, and the group exposed in a weak pulsed magnetic field at the stage of hatching, prior to treatment with WSOF. Larvae of the second group had severe pathologies of inner organs that caused 100% mortality before the age of 15 days, but no pathomorphological changes in the organs of larvae and juvenile fish of the third group were revealed for up to 40 days. Probable causes of high resistance to the toxic agent in fish of the experimental group are discussed.     

磁处理对有机污水降解的影响

通过自行设计的强磁水处理循环系统,进行了葡萄糖和淀粉溶液这两种模拟有机污水的磁处理试验研究。结果表明:磁处理使两种溶液的COD值出现不同程度的下降,其中300mg/L葡萄糖溶液在磁场强度1150mT,流速2m/s,水温30℃,处理2h条件下,COD最大降幅达到10.1%;300mg/L淀粉溶液在磁场强度1200mT,流速2m/s,水温30℃,处理时间2.5h条件下,COD最大降幅为17.6%。由此可见,对于不同溶液,影响磁处理效果的最佳条件不同。文章最后对其作用机理进行了推断。     

10kV配电站电磁场对周边环境的影响分析

介绍了极低频电磁场对人体的影响,结合城市居民对10kV配电站电磁场的投诉情况,分析了10kV配电站电磁场对周边居民的影响,提出了对10kV配电站的电磁辐射防治对策。     

油气储罐罐壁焊缝静载拉伸检测试验研究*

为建立磁记忆信号与罐体焊接缺陷演变的对应关系,获得以非接触方式检测焊缝处的磁记忆信号来实现对罐体的早期预警和无损检测技术,开展罐壁焊缝试样静载拉伸试验,研究油气储罐在静载拉伸过程中焊缝的磁记忆信号变化规律,并结合有限元模拟仿真进行磁场分布规律的分析。结果表明:磁记忆信号梯度值会在焊缝缺陷处产生突变;随着裂纹深度的增加,磁记忆信号梯度峰峰值呈线性增加,并且峰值随着拉伸载荷的增加而线性增加。     

亚洲地区稻田N2O排放影响因子统计模拟分析

关于稻田N2O排放大样本统计分析大多只涉及水分因子和肥料因子,本研究收集历年亚洲稻田N2O排放资料和更多影响因子(水分管理、肥料类型及用量、土壤属性、气候和水稻类型等)的相关信息,从中筛选出具有统计学意义的因子,构建排放通量和上述因子的统计模型.具有统计学意义的因子包括不同水分管理措施、肥料用量、不同有机肥类型、不同p...     

磁强化Fenton处理苯酚废水的试验研究

试验对比了普通Fenton试剂和磁Fenton试剂处理模拟苯酚废水的效果,并探讨了磁Fenton的作用机理.当磁场强度为592mT,pH=3,按m(COD):m(H2O2)=1:2,n(H2O2):n(Fe2+)=15:1投加一定量的FeSO4·7H2O和H2O2,反应时间60min,挥发酚和COD去除 率分别达到99...