In order to reveal the characteristics and climatic controls on the stable isotopic composition of precipitation over Arid Northwestern China, eight stations have been selected from Chinese Network of Isotopes in Prec...In order to reveal the characteristics and climatic controls on the stable isotopic composition of precipitation over Arid Northwestern China, eight stations have been selected from Chinese Network of Isotopes in Precipitation(CHNIP).During the year 2005 and 2006, monthly precipitation samples have been collected and analyzed for the composition of δD and δ18O.The established local meteoric water line δD=7.42δ18O+1.38, based on the 95 obtained monthly composite samples, could be treated as isotopic input function across the region.The deviations of slope and intercept from the Global Meteoric Water Line indicated the specific regional meteorological conditions.The monthly δ18O values were characterized by a positive correlation with surface air temperature(δ18O(‰) =0.33 T(℃)-13.12).The amount effect visualized during summer period(δ18O(‰) =-0.04P(mm)-3.44) though not appeared at a whole yearly-scale.Spatial distributions of δ18O have properly portrayed the atmospheric circulation background in each month over Arid Northwestern China.The quan-titative simulation of δ18O, which involved a Rayleigh fractionation and a kinetic fractionation, demonstrated that the latter one was the dominating function of condensation of raindrops.Furthermore, the raindrop suffered a re-evaporation during falling processes, and the precipitation vapor might have been mixed with a quantity of local recycled water vapor.Multiple linear regression equations and a δ18O-T relation have been gained by using meteorological parameters and δ18O data to evaluate physical controls on the long-term data.The established δ18O-T relation, which has been based on the present-day precipitation, could be considered as a first step of quantitatively reconstructing the historical environmental climate.展开更多
重症监护病房(intensive care unit,ICU)的患者常因严重疾病或手术而处于高度应激状态,对能量和营养素的需求增加[1]。目前,鼻肠管是ICU患者早期空肠内营养的主要途径,但超声引导下鼻肠管尖端定位存在挑战。相关文献报道,经管注入水、...重症监护病房(intensive care unit,ICU)的患者常因严重疾病或手术而处于高度应激状态,对能量和营养素的需求增加[1]。目前,鼻肠管是ICU患者早期空肠内营养的主要途径,但超声引导下鼻肠管尖端定位存在挑战。相关文献报道,经管注入水、气可增强回声,提高鼻肠管的可视化效果,过量的水、气摄入将加重ICU患者的胃肠胀气、水肿,影响探查效果[2]。本次研究评估水气混合注射法在判断鼻肠管位置方面的可行性。展开更多
基金National Natural Science Foundation of China,No.40830636 No.40671034Foundation of Isotopes in Precipitation of Chinese Ecosystem Research Network
文摘In order to reveal the characteristics and climatic controls on the stable isotopic composition of precipitation over Arid Northwestern China, eight stations have been selected from Chinese Network of Isotopes in Precipitation(CHNIP).During the year 2005 and 2006, monthly precipitation samples have been collected and analyzed for the composition of δD and δ18O.The established local meteoric water line δD=7.42δ18O+1.38, based on the 95 obtained monthly composite samples, could be treated as isotopic input function across the region.The deviations of slope and intercept from the Global Meteoric Water Line indicated the specific regional meteorological conditions.The monthly δ18O values were characterized by a positive correlation with surface air temperature(δ18O(‰) =0.33 T(℃)-13.12).The amount effect visualized during summer period(δ18O(‰) =-0.04P(mm)-3.44) though not appeared at a whole yearly-scale.Spatial distributions of δ18O have properly portrayed the atmospheric circulation background in each month over Arid Northwestern China.The quan-titative simulation of δ18O, which involved a Rayleigh fractionation and a kinetic fractionation, demonstrated that the latter one was the dominating function of condensation of raindrops.Furthermore, the raindrop suffered a re-evaporation during falling processes, and the precipitation vapor might have been mixed with a quantity of local recycled water vapor.Multiple linear regression equations and a δ18O-T relation have been gained by using meteorological parameters and δ18O data to evaluate physical controls on the long-term data.The established δ18O-T relation, which has been based on the present-day precipitation, could be considered as a first step of quantitatively reconstructing the historical environmental climate.
文摘重症监护病房(intensive care unit,ICU)的患者常因严重疾病或手术而处于高度应激状态,对能量和营养素的需求增加[1]。目前,鼻肠管是ICU患者早期空肠内营养的主要途径,但超声引导下鼻肠管尖端定位存在挑战。相关文献报道,经管注入水、气可增强回声,提高鼻肠管的可视化效果,过量的水、气摄入将加重ICU患者的胃肠胀气、水肿,影响探查效果[2]。本次研究评估水气混合注射法在判断鼻肠管位置方面的可行性。
