China is the country with most widely distributed loess area in the world, and its loess area accounts of 6.63% of total nation land area. The landslide disaster occurs frequently for complex natural condition and bec...China is the country with most widely distributed loess area in the world, and its loess area accounts of 6.63% of total nation land area. The landslide disaster occurs frequently for complex natural condition and becomes major factors hindering the social and economic development of loess regions. Through different indexes, the authors divided the landslides into 9 principal types and analyzed the distribution characteristics of loess landslide in time and space, the affecting factors and mechanism of landslides. It is pointed out that time and spatial distributions of landslides are closely correlative to topographic and geomorphic conditions, earthquake and rainfall, and the key influencing factors include topography, geomorphology, new tectonic movements, earthquake activity, surface water, ground water and human activities. The authors emphasized that the natural condition of loess areas was favorable to landslides, human activities impelled its occurrence and that controlling the loess landslide was an urgent task for sustainable development in the loess zone.展开更多
Objective. To explore the relationship between human parvovirus B19 (HPV B19) infection and aplastic anemia (AA) and to investigate the role of HPV B19 in the occurrence of AA. Methods. The presence of HPV B19 DNA was...Objective. To explore the relationship between human parvovirus B19 (HPV B19) infection and aplastic anemia (AA) and to investigate the role of HPV B19 in the occurrence of AA. Methods. The presence of HPV B19 DNA was detected in the peripheral blood samples of 60 patients with AA (children 38 and adults 22) by nested polymerase chain reaction (PCR) assay, and 30 healthy persons were selected as control. Results. Sixteen (26.7％ ) of 60 AA cases were HPV B19 DNA positive, while all the samples in the control group were negative for HPV B19 (P = 0.000914). Among the case group, the positive rates of HPV B19 DNA were 21.4％ (6 / 28), 30.0％ (3 / 10), 20.0％ (1 / 5) and 35.3％ (6 / 17) in children acute AA (AAA), children chronic AA (CAA), adults AAA and adults CAA patients respectively, which were significantly higher than that in the control group. Furthermore, there was no remarkable difference between children AA and adults AA in the 16 HPV B19 DNA positive patients; neither was there between AAA and CAA. Conclusions. HPV B19 infection is not only correlated with the occurrence of children AAA and CAA, but also with adults AAA and CAA, and might be an important viral cause for AA in humans.展开更多
基金This article was supported by the Science and Technology Ministry of China (Grant No. 2002BA516A16-02) the Science Foundation of Chinese Academy of Forestry (Grant No.200114).
文摘China is the country with most widely distributed loess area in the world, and its loess area accounts of 6.63% of total nation land area. The landslide disaster occurs frequently for complex natural condition and becomes major factors hindering the social and economic development of loess regions. Through different indexes, the authors divided the landslides into 9 principal types and analyzed the distribution characteristics of loess landslide in time and space, the affecting factors and mechanism of landslides. It is pointed out that time and spatial distributions of landslides are closely correlative to topographic and geomorphic conditions, earthquake and rainfall, and the key influencing factors include topography, geomorphology, new tectonic movements, earthquake activity, surface water, ground water and human activities. The authors emphasized that the natural condition of loess areas was favorable to landslides, human activities impelled its occurrence and that controlling the loess landslide was an urgent task for sustainable development in the loess zone.
基金This study was supported by the Starting Fund for Returned Scholars of PLA (No. 947008).
文摘Objective. To explore the relationship between human parvovirus B19 (HPV B19) infection and aplastic anemia (AA) and to investigate the role of HPV B19 in the occurrence of AA. Methods. The presence of HPV B19 DNA was detected in the peripheral blood samples of 60 patients with AA (children 38 and adults 22) by nested polymerase chain reaction (PCR) assay, and 30 healthy persons were selected as control. Results. Sixteen (26.7％ ) of 60 AA cases were HPV B19 DNA positive, while all the samples in the control group were negative for HPV B19 (P = 0.000914). Among the case group, the positive rates of HPV B19 DNA were 21.4％ (6 / 28), 30.0％ (3 / 10), 20.0％ (1 / 5) and 35.3％ (6 / 17) in children acute AA (AAA), children chronic AA (CAA), adults AAA and adults CAA patients respectively, which were significantly higher than that in the control group. Furthermore, there was no remarkable difference between children AA and adults AA in the 16 HPV B19 DNA positive patients; neither was there between AAA and CAA. Conclusions. HPV B19 infection is not only correlated with the occurrence of children AAA and CAA, but also with adults AAA and CAA, and might be an important viral cause for AA in humans.
