功能性便秘(functional constipation,FC)是临床常见病、多发病,治疗困难,容易反复。FC的发病机制尚未十分明确,可能与胃肠道卡哈尔间质细胞(interstitial cell of Cajal,ICC)分布异常、肠神经递质紊乱、氧化应激指标不平衡、离子水平...功能性便秘(functional constipation,FC)是临床常见病、多发病,治疗困难,容易反复。FC的发病机制尚未十分明确,可能与胃肠道卡哈尔间质细胞(interstitial cell of Cajal,ICC)分布异常、肠神经递质紊乱、氧化应激指标不平衡、离子水平异常改变、肠道菌群紊乱、结直肠感觉及运动功能异常、精神心理因素影响等机制相关。本文对FC的发病机制进行总结,以期为FC的治疗提供参考。展开更多
The influence of pH on the partitioning behavior of REE at the water/particulate interface has been studied experimentally. At the beginning of colloid formation the adsorption of REE on iron hydroxide colloids is dom...The influence of pH on the partitioning behavior of REE at the water/particulate interface has been studied experimentally. At the beginning of colloid formation the adsorption of REE on iron hydroxide colloids is dominant, followed by REE desorption. Finally adsorption and desorption tend to reach equilibration. The capability of iron hydroxide colloids to adsorb the HREE is greater than that to adsorb the LREE. With increasing pH, LREE/HREE fractionations will take place between iron hydroxide colloids and water, leading to the reduction of their partition coefficient ratio (DLREE/DHREE). The DREE distribution patterns show Y anomalies (DY/DHo <1), with obvious REE tetrad effects appearing under low pH conditions. Experimental results have shown that there do exist REE tetrad effects in nature. In addition to pH, the chemical type of surface water and ion intensity are also the important factors controlling REE tetrad effects and leading to fractionations between particulate-adsorbed REE and dissolved REE.展开更多
文摘功能性便秘(functional constipation,FC)是临床常见病、多发病,治疗困难,容易反复。FC的发病机制尚未十分明确,可能与胃肠道卡哈尔间质细胞(interstitial cell of Cajal,ICC)分布异常、肠神经递质紊乱、氧化应激指标不平衡、离子水平异常改变、肠道菌群紊乱、结直肠感觉及运动功能异常、精神心理因素影响等机制相关。本文对FC的发病机制进行总结,以期为FC的治疗提供参考。
基金This work was supported by the State Outsanding Young Scientists Foundation (Grant No. 49625304) the Pre-selected Project under the State Climbing Program of China (Grant No. 95-39).
文摘The influence of pH on the partitioning behavior of REE at the water/particulate interface has been studied experimentally. At the beginning of colloid formation the adsorption of REE on iron hydroxide colloids is dominant, followed by REE desorption. Finally adsorption and desorption tend to reach equilibration. The capability of iron hydroxide colloids to adsorb the HREE is greater than that to adsorb the LREE. With increasing pH, LREE/HREE fractionations will take place between iron hydroxide colloids and water, leading to the reduction of their partition coefficient ratio (DLREE/DHREE). The DREE distribution patterns show Y anomalies (DY/DHo <1), with obvious REE tetrad effects appearing under low pH conditions. Experimental results have shown that there do exist REE tetrad effects in nature. In addition to pH, the chemical type of surface water and ion intensity are also the important factors controlling REE tetrad effects and leading to fractionations between particulate-adsorbed REE and dissolved REE.
