The taxonomic status of long-tailed field mouse (Apodemus orestes) is still uncertain up to now.Some scholars regarded it as a subspecies or a synonym of dragon field mouse (A.draco),while other scholars considered it...The taxonomic status of long-tailed field mouse (Apodemus orestes) is still uncertain up to now.Some scholars regarded it as a subspecies or a synonym of dragon field mouse (A.draco),while other scholars considered it a valid species.In the study,five specimens of adult long-tailed field mouse,dragon field mouse and Chevrier's field mouse (A.chevrieri) (as a contrast) were chosen respectively.After treated,with the eyepiece micrometer in the inverted microscope,we made measurements of the widths of hairs and medullas and then calculated the medullary indexes of straight guard hairs from around the mouth,head,back,abdomen and forelimb of each species.The results indicate that,viewing at each of the five parts and the mixture of the five parts,there are no significant differences between A.orestes and A.draco,Significant differences can be found between A.orestes & A.chevrieri and A.draco & A.chevrieri though.The standpoint that A.orestes was listed as a valid species is not supported by this study.展开更多
Although the analysis of the microcosmic mechanism for low-resistivity oil zones has received much attention in China, the intrinsic relationship between low-resistivity oil zones and geological background is still un...Although the analysis of the microcosmic mechanism for low-resistivity oil zones has received much attention in China, the intrinsic relationship between low-resistivity oil zones and geological background is still under-developed. Based on the geology and logging analysis, we redefine low-resistivity oil zones. According to their genesis, low-resis- tivity oil zones can be distinguished as five different classes: low-resistivity oil zones formed by tectonic settings, by depositional settings, by diagenetic settings, by invaded settings and those which are formed by the compounding geneses respectively. We make the following observations from this study on the definition and classification of low-resistivity oil zones: 1) A low-resistivity oil reservoir has macroscopic and microscopic unity. 2) The genesis of low-resistivity oil zones varies with the type of petroliferous basin. 3) Some low-resistivity oil zones can be forecasted based on the geological study results. 4) The results in this paper suggest that well logging information is generated from two cause mechanisms, the geophysical factors and the geological setting. Future studies on the geological background cause mechanism and the theory of well logging information will enrich the theory of logging geology and improve the ability to forecast oil zones.展开更多
This study was conducted to investigate the population characteristics of small rodents in different habitats with the artificial presence and absence of dead wood, and understory vegetation after forest cutting at na...This study was conducted to investigate the population characteristics of small rodents in different habitats with the artificial presence and absence of dead wood, and understory vegetation after forest cutting at natural deciduous forest in north-eastern South Korea from April to December in 1997 and 1998. Two forests, one hectare each (100 100 m), were se-lected and designated as the control and the treatment area. Forest structure of mid and high canopy layers in both study areas was similar. But number and volume of fallen trees, and coverage of understory vegetation were higher in the control area than in the treatment area. Total captures of small rodents in two areas combined comprised Eothenomys regulus (55.5%, n = 211) and Apodemus peninsulae (44.5%, n = 169). Total abundance of E. regulus and A. peninsulae, and population stability were sig-nificantly greater in the control area than in the treatment area. The difference in the captured number of two small rodents be-tween the two sites was caused by the difference in reproduction and residency. The structure of forest floor appears to be im-portant to small rodents. The presence of dead wood and understory vegetation after the forest cutting would be necessary for the maintenance of small rodent population in the forest cutting areas.展开更多
文摘The taxonomic status of long-tailed field mouse (Apodemus orestes) is still uncertain up to now.Some scholars regarded it as a subspecies or a synonym of dragon field mouse (A.draco),while other scholars considered it a valid species.In the study,five specimens of adult long-tailed field mouse,dragon field mouse and Chevrier's field mouse (A.chevrieri) (as a contrast) were chosen respectively.After treated,with the eyepiece micrometer in the inverted microscope,we made measurements of the widths of hairs and medullas and then calculated the medullary indexes of straight guard hairs from around the mouth,head,back,abdomen and forelimb of each species.The results indicate that,viewing at each of the five parts and the mixture of the five parts,there are no significant differences between A.orestes and A.draco,Significant differences can be found between A.orestes & A.chevrieri and A.draco & A.chevrieri though.The standpoint that A.orestes was listed as a valid species is not supported by this study.
文摘Although the analysis of the microcosmic mechanism for low-resistivity oil zones has received much attention in China, the intrinsic relationship between low-resistivity oil zones and geological background is still under-developed. Based on the geology and logging analysis, we redefine low-resistivity oil zones. According to their genesis, low-resis- tivity oil zones can be distinguished as five different classes: low-resistivity oil zones formed by tectonic settings, by depositional settings, by diagenetic settings, by invaded settings and those which are formed by the compounding geneses respectively. We make the following observations from this study on the definition and classification of low-resistivity oil zones: 1) A low-resistivity oil reservoir has macroscopic and microscopic unity. 2) The genesis of low-resistivity oil zones varies with the type of petroliferous basin. 3) Some low-resistivity oil zones can be forecasted based on the geological study results. 4) The results in this paper suggest that well logging information is generated from two cause mechanisms, the geophysical factors and the geological setting. Future studies on the geological background cause mechanism and the theory of well logging information will enrich the theory of logging geology and improve the ability to forecast oil zones.
文摘This study was conducted to investigate the population characteristics of small rodents in different habitats with the artificial presence and absence of dead wood, and understory vegetation after forest cutting at natural deciduous forest in north-eastern South Korea from April to December in 1997 and 1998. Two forests, one hectare each (100 100 m), were se-lected and designated as the control and the treatment area. Forest structure of mid and high canopy layers in both study areas was similar. But number and volume of fallen trees, and coverage of understory vegetation were higher in the control area than in the treatment area. Total captures of small rodents in two areas combined comprised Eothenomys regulus (55.5%, n = 211) and Apodemus peninsulae (44.5%, n = 169). Total abundance of E. regulus and A. peninsulae, and population stability were sig-nificantly greater in the control area than in the treatment area. The difference in the captured number of two small rodents be-tween the two sites was caused by the difference in reproduction and residency. The structure of forest floor appears to be im-portant to small rodents. The presence of dead wood and understory vegetation after the forest cutting would be necessary for the maintenance of small rodent population in the forest cutting areas.
