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| 1 | Relationships between Artemisia ordosica communities and environmental factors following sand-dune stabilization in the Mu Us desert,northwest China显示文摘Artemisia ordosica is an excellent sand-fixing shrub for sand stabilization in northwestern China. Sand dune stabilization, a critically important process, leads changes in abiotic factors, such as soil structure and nutrient contents. However, the effects of factors on an A.ordosica community following sand stabilization remain unclear. In this study, we used canonical correspondence analysis(CCA) to examine the relationships between A.ordosica communities and environmental factors at three habitats: semi-fixed dune(SF), fixed dune with low-coverage biological soil crust(F), and fixed dune with highcoverage biological soil crust(FC) in Mu Us desert. The mean height and coverage of plants increased with sand stabilization, while species diversity and richness increased initially and then reduced significantly. Correlation analysis and CCA revealed that slope, soil organic carbon, and nutrient contents, proportion of fine soil particles, soil moisture, and thickness of biological soil crust were allhighly correlated with vegetation characteristics. These environmental factors could explain 40.42 % of the vegetation–environment relationships at the three habitats. The distribution of plant species was positively related to soil moisture in the SF dune. Soil moisture, soil nutrient, and fine-particle contents mainly affected plants distribution in the F dune. In the FC dune, distribution of plant species was positively and negatively correlated with the thickness of biological soil crust and soil moisture at a depth0–20 cm, respectively. The dominance value of typical steppe species increased significantly following sand-dune stabilization and relations between species and samples in CCA ordination bi-plots showed that perennial grasses could invade the A. ordosica community on FC, indicating A. ordosica communities had a tendency to change into typical steppe vegetation with the further fixation. We conclude that the significant differentiation not only occurred in community characteristics, but also in the relationships between vegetation and environmental factors among the three stages of dune fixation. So, restoration of degraded dune ecosystems should be based on habitat conditions and ecological needs. | Dongqing Fan Yuqing Zhang Shugao Qin Bin Wu | 2017 | Journal of Forestry Research2017，28，1： | 3 |
| 2 | DEGRADATION DUE TO ENERGY PULSE IN HIGH-ENERGY ZnO VARISTORS显示文摘The degradation phenomena due to the energy pulse in the high-energy ZnO varistors used for deexitation and overvoltage protection of hydroelectric generator are investigated. The energy pulse, obtained by releasing the energy stored in an inductor, can be equivalent to the combination of the DC field components and the energy component. The variations of the characterized voltages, nonlinear coefficients and pre-breakdown V-A characteristics, increase with the number of the applied energy pulse. The asymmetrical variations of the electric properties of the high-energy ZnO varistors after the energy pulse arise from the deformation of the double Schottky barriers due to the ion migration occuring in the depletion layer and in the grain boundary. | Zhang Shugao Huang Baiyun Fang Xunhua (Powder Metallurgy Research Institute, Central South University of Technology, Changsha 410083, China)Ji Youzhang (Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China) | 1997 | Journal of Central South University1997，9，2： | 0 |
| 3 | Association of cardiac disease with the risk of post-lung transplantation mortality in Chinese recipients aged over 65 years显示文摘The current organ allocation rules prioritize elderly and urgent patients on the lung transplantation(LT)waiting list.A steady increase in the threshold at which age is taken into consideration for LT has been observed.This retrospective cohort study recruited 166 lung transplant recipients aged≥65 years between January 2016 and October 2020 in the largest LT center in China.In the cohort,subgroups of patients aged 65–70 years(111 recipients,group 65–70)and≥70 years(55 recipients,group≥70)were included.Group D restrictive lung disease was the main indication of a lung transplant in recipients over 65 years.A significantly higher percentage of coronary artery stenosis was observed in the group≥70(30.9%vs.14.4%in group 65–70,P=0.014).ECMO bridging to LT was performed in 5.4%(group 65–70)and 7.3%(group≥70)of patients.Kaplan–Meier estimates showed that recipients with cardiac abnormalities had a significantly increased risk of mortality.After adjusting for potential confounders,cardiac abnormality was shown to be independently associated with the increased risk of post-LT mortality(HR 6.37,P=0.0060).Our result showed that LT can be performed in candidates with an advanced age and can provide life-extending benefits. | Guohui Jiao Shugao Ye Ji Zhang Bo Wu Dong Wei Dong Liu Feng Liu Chunxiao Hu Jingyu Chen | 2023 | Frontiers of Medicine2023，17，1： | 0 |
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