甲型流感病毒(Influenza A viruses,IAVs)是危害人类和动物健康的主要病原之一,可通过基因重组和基因突变两种方式在自然界中不断进化,进而突破宿主屏障,扩大宿主范围,感染各种家禽、哺乳动物甚至人类,造成跨宿主传播.文章就影响IAVs跨...甲型流感病毒(Influenza A viruses,IAVs)是危害人类和动物健康的主要病原之一,可通过基因重组和基因突变两种方式在自然界中不断进化,进而突破宿主屏障,扩大宿主范围,感染各种家禽、哺乳动物甚至人类,造成跨宿主传播.文章就影响IAVs跨宿主传播因素的相关研究进行了综述,为IAVs的防控提供理论基础.展开更多
By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instr...By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instrumented five pairs of symmetrical strain gauges. The experimental results show that the fully grouted bolt suffers tensile, compressive, bending and shear stress at the same time. The bolt stress evolution is closely related to the deformation stages of the rock mass which are very gradually varying stage, gradually varying stage at the pre-peak and suddenly varying stage at the post peak stage.The axial compressive stress in the bolt is mainly induced by the moment. Thus, in most cases the axial compressive stress is distributed on one side of the bolt. For axial stresses, induced by the axial force and the bending moment at the post-peak stage, three types of changing are observed, viz. increasingincreasing type, decreasing-increasing type and increasing-decreasing type. The stress characteristics of the bolt section in the weak interlayer are significantly different from those in the hard rock. The failure models of the anchored bolt are tensile failure and shear failure, respectively. The bolt not only provides constraints on the free surface of the rock mass, but also resists the axial and lateral loading by the bending moment. This study provides valuable guidelines for bolting support design and its safety assessment.展开更多
文摘甲型流感病毒(Influenza A viruses,IAVs)是危害人类和动物健康的主要病原之一,可通过基因重组和基因突变两种方式在自然界中不断进化,进而突破宿主屏障,扩大宿主范围,感染各种家禽、哺乳动物甚至人类,造成跨宿主传播.文章就影响IAVs跨宿主传播因素的相关研究进行了综述,为IAVs的防控提供理论基础.
基金support of the National Basic Research 973 Program of China (No.2013CB036003)the National Natural Science Foundation of China (No.51374198)the National Natural Science Foundation young investigator grant program of China (Nos.51204163,51504247,and 51404255)
文摘By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instrumented five pairs of symmetrical strain gauges. The experimental results show that the fully grouted bolt suffers tensile, compressive, bending and shear stress at the same time. The bolt stress evolution is closely related to the deformation stages of the rock mass which are very gradually varying stage, gradually varying stage at the pre-peak and suddenly varying stage at the post peak stage.The axial compressive stress in the bolt is mainly induced by the moment. Thus, in most cases the axial compressive stress is distributed on one side of the bolt. For axial stresses, induced by the axial force and the bending moment at the post-peak stage, three types of changing are observed, viz. increasingincreasing type, decreasing-increasing type and increasing-decreasing type. The stress characteristics of the bolt section in the weak interlayer are significantly different from those in the hard rock. The failure models of the anchored bolt are tensile failure and shear failure, respectively. The bolt not only provides constraints on the free surface of the rock mass, but also resists the axial and lateral loading by the bending moment. This study provides valuable guidelines for bolting support design and its safety assessment.
