本试验以国产草本泥炭为材料,设置5个润湿剂喷施浓度处理:以不喷施处理为对照(CK),分别喷施50(T_(50))、100(T_(100))、200(T_(200))和300 ml m^(-3)(T_(300)),研究不同处理对国产草本泥炭物理性状的影响。结果表明,润湿剂喷施浓度100~3...本试验以国产草本泥炭为材料,设置5个润湿剂喷施浓度处理:以不喷施处理为对照(CK),分别喷施50(T_(50))、100(T_(100))、200(T_(200))和300 ml m^(-3)(T_(300)),研究不同处理对国产草本泥炭物理性状的影响。结果表明,润湿剂喷施浓度100~300 ml m^(-3)处理的泥炭总孔隙度较对照显著增大,其中喷施100 ml m^(-3)处理的总孔隙度和持水孔隙度分别提高了7.23%和16.79%,通气孔隙度降低了17.33%。泥炭大小孔隙比随喷施浓度增加呈先降低后升高的趋势,以喷施100 ml m^(-3)的处理最低,为27.54%;以喷施300 ml m^(-3)时最高,为43.48%。喷施润湿剂对泥炭pH值无显著影响,其饱和含水量显著升高,以喷施100 ml m^(-3)时最高,达222.38%,该处理在24 h和144 h的泥炭水分散失速率均显著低于对照。泥炭连续3次充分湿润时间均表现为T_(300)<T_(200)<T_(100)<T_(50)<CK。综上所述,润湿剂喷施浓度为100 ml m^(-3)的处理有效提升了国产草本泥炭的孔隙特性和保水性能,可为国产优质泥炭的生产提供理论参考。展开更多
Background Intravenous urography （IVU） combined with add-on CT （IVU-CT） can help to provide more diagnostic information for determining the localization and nature of ureteral abnormalities with less irradiation d...Background Intravenous urography （IVU） combined with add-on CT （IVU-CT） can help to provide more diagnostic information for determining the localization and nature of ureteral abnormalities with less irradiation dose. This study aimed to determine the value of IVU-CT for diagnosis of ureteral diseases, where IVU is insufficient to determine the diagnosis. Methods Two hundred and eighty patients underwent IVU for suspected ureteral disorders, which identified a definite diagnosis in 184 cases and was insufficient for definite diagnosis in 96 cases designated as indeterminate diagnosis. Subsequently 90 patients （six patients declined CT） with indeterminate diagnosis consented to undergo immediate or delayed helical CT scan. The CT data were transferred to the workstation for post-processing, and the cost and mean effective dose for each imaging method were calculated and compared indirectly. Results Of the 90 indeterminate diagnosis cases, diagnosis was determined in 86 cases by IVU-CT with a diagnostic accordance rate of 95.6%, while 184/280 （65.7%） had diagnosis determined by IVU alone. There was a significant difference between IVU and IVU-CT in the determination of the diagnosis of ureteral diseases （X2=36.4, P 〈0.05）. The cost of IVU equals to 1/8-1/9 of that for CT urography （CTU）, and the cost of IVU-CT is as much as 1/3 of CTU. CTU results in the highest mean effective dose, approximately nine times that for IVU and three times that for IVU-CT. Conclusion IVU-CT provides valuable information for the localization and diagnosis of ureteral abnormalities and may be considered as an efficient, cost-effective and low-dose diagnostic technique in this setting.展开更多
This study investigates the stratification of soil thermal properties induced by soil organic carbon (SOC) and its impacts on the parameterization of the thermal properties. Soil parameters were measured for alpine gr...This study investigates the stratification of soil thermal properties induced by soil organic carbon (SOC) and its impacts on the parameterization of the thermal properties. Soil parameters were measured for alpine grassland stations and North China flux stations, with a total of 34 stations and 77 soil profiles. Measured data indicate that the topsoils of alpine grasslands contain high SOC contents than underlying soil layers, which leads to higher soil porosity values and lower thermal conductivity and bulk density values in the topsoils. However, this stratification is not evident at the lowland stations due to low SOC contents. Evaluations against measured data show that three thermal conductivity schemes used in land surface models severely overestimate the values for soils with high SOC content (i.e. topsoils of alpine grassland), but they are better for soils with low SOC content. A new parameterization is then developed to take the impacts of SOC into account. The new one can well estimate the soil thermal conductivity values in both low and high SOC content cases, and therefore, it is a potential candidate of thermal conductivity scheme to be used in land surface models.展开更多
文摘本试验以国产草本泥炭为材料,设置5个润湿剂喷施浓度处理:以不喷施处理为对照(CK),分别喷施50(T_(50))、100(T_(100))、200(T_(200))和300 ml m^(-3)(T_(300)),研究不同处理对国产草本泥炭物理性状的影响。结果表明,润湿剂喷施浓度100~300 ml m^(-3)处理的泥炭总孔隙度较对照显著增大,其中喷施100 ml m^(-3)处理的总孔隙度和持水孔隙度分别提高了7.23%和16.79%,通气孔隙度降低了17.33%。泥炭大小孔隙比随喷施浓度增加呈先降低后升高的趋势,以喷施100 ml m^(-3)的处理最低,为27.54%;以喷施300 ml m^(-3)时最高,为43.48%。喷施润湿剂对泥炭pH值无显著影响,其饱和含水量显著升高,以喷施100 ml m^(-3)时最高,达222.38%,该处理在24 h和144 h的泥炭水分散失速率均显著低于对照。泥炭连续3次充分湿润时间均表现为T_(300)<T_(200)<T_(100)<T_(50)<CK。综上所述,润湿剂喷施浓度为100 ml m^(-3)的处理有效提升了国产草本泥炭的孔隙特性和保水性能,可为国产优质泥炭的生产提供理论参考。
文摘Background Intravenous urography （IVU） combined with add-on CT （IVU-CT） can help to provide more diagnostic information for determining the localization and nature of ureteral abnormalities with less irradiation dose. This study aimed to determine the value of IVU-CT for diagnosis of ureteral diseases, where IVU is insufficient to determine the diagnosis. Methods Two hundred and eighty patients underwent IVU for suspected ureteral disorders, which identified a definite diagnosis in 184 cases and was insufficient for definite diagnosis in 96 cases designated as indeterminate diagnosis. Subsequently 90 patients （six patients declined CT） with indeterminate diagnosis consented to undergo immediate or delayed helical CT scan. The CT data were transferred to the workstation for post-processing, and the cost and mean effective dose for each imaging method were calculated and compared indirectly. Results Of the 90 indeterminate diagnosis cases, diagnosis was determined in 86 cases by IVU-CT with a diagnostic accordance rate of 95.6%, while 184/280 （65.7%） had diagnosis determined by IVU alone. There was a significant difference between IVU and IVU-CT in the determination of the diagnosis of ureteral diseases （X2=36.4, P 〈0.05）. The cost of IVU equals to 1/8-1/9 of that for CT urography （CTU）, and the cost of IVU-CT is as much as 1/3 of CTU. CTU results in the highest mean effective dose, approximately nine times that for IVU and three times that for IVU-CT. Conclusion IVU-CT provides valuable information for the localization and diagnosis of ureteral abnormalities and may be considered as an efficient, cost-effective and low-dose diagnostic technique in this setting.
基金supported by National Natural Science Foundation of China (Grant No. 41105003)Key Project of Chinese Academy of Sciences (Grant No.KZCX2-YW-Q10-2)+1 种基金National Natural Science Foundation of China (Grant No. 91025004)Open Fund from the State Key Laboratory of Remote Sensing Science (Grant No. OFSLRSS201108) that is cosponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University
文摘This study investigates the stratification of soil thermal properties induced by soil organic carbon (SOC) and its impacts on the parameterization of the thermal properties. Soil parameters were measured for alpine grassland stations and North China flux stations, with a total of 34 stations and 77 soil profiles. Measured data indicate that the topsoils of alpine grasslands contain high SOC contents than underlying soil layers, which leads to higher soil porosity values and lower thermal conductivity and bulk density values in the topsoils. However, this stratification is not evident at the lowland stations due to low SOC contents. Evaluations against measured data show that three thermal conductivity schemes used in land surface models severely overestimate the values for soils with high SOC content (i.e. topsoils of alpine grassland), but they are better for soils with low SOC content. A new parameterization is then developed to take the impacts of SOC into account. The new one can well estimate the soil thermal conductivity values in both low and high SOC content cases, and therefore, it is a potential candidate of thermal conductivity scheme to be used in land surface models.
