Soil spiders were pitfall-trapped once every month in three forest vegetation types of Ziwuling natural secondary forest region, Gansu Province from April to October, 2004. A total of 2 164 spiders were collected, bel...Soil spiders were pitfall-trapped once every month in three forest vegetation types of Ziwuling natural secondary forest region, Gansu Province from April to October, 2004. A total of 2 164 spiders were collected, belonging to 43 species in 19 families, captured in 630 pitfall trap collections. Linyphiidae, Gnaphosidae and Lycosodae were found to be the dominant families in all habitat types, and the composition of soil spider assemblages was different between the three habitats. Ecological indices of diversity, richness and evenness were significantly different between the three habitats （ P 〈 0.05）. The relative abundance of guilds （based on numbers of individuals） varied greatly （P 〈 0.01）, which may releet resource availability within habitat types. The existence of different patterns within the assemblages reflects the importance of maintaining habitat heterogeneity and vegetation types in order to preserve soil spider biodiversity.展开更多
A study of the gate current variation is presented for various thickness ultrathin gate oxides ranging from 1.9 to 3.0nm under the constant voltage stress.The experimental results show the stress induced leakage curre...A study of the gate current variation is presented for various thickness ultrathin gate oxides ranging from 1.9 to 3.0nm under the constant voltage stress.The experimental results show the stress induced leakage current(SILC) includes two parts.One is due to the interface trap-assisted tunneling.The other is owing to the oxide trap-assisted tunneling.展开更多
The effect of neutral trap on tunneling currentin ultrathin MOSFETs is investigated by num erical analy- sis.The barrier variation arisen by neutral trap in oxide layer is described as a rectangular potential well in...The effect of neutral trap on tunneling currentin ultrathin MOSFETs is investigated by num erical analy- sis.The barrier variation arisen by neutral trap in oxide layer is described as a rectangular potential well in the con- duction band of Si O2 .The different barrier variation of an ultrathin metal- oxide- sem iconductor(MOS) structure with oxide thickness of4nm is numerically calculated.It is shown that the effect of neutral trap on tunneling cur- rent can not be neglected.The tunneling current is increased when the neutral trap exists in the oxide layer.This simple m odel can be used to understand the occurring mechanism of stress induced leakage current.展开更多
Infection by the human immunodeficiency virus （HIV） is characterized by a progressive depletion of CD4 T lymphocytes, which leads to dysfunction of the immune system. Although a variety of mechanisms may contribute ...Infection by the human immunodeficiency virus （HIV） is characterized by a progressive depletion of CD4 T lymphocytes, which leads to dysfunction of the immune system. Although a variety of mechanisms may contribute to the gradual T cell decline that occurs in H/V-infected patients, abnormal apoptosis of infected or bystander T lymphocytes is an important event leading to immunodeficiency. The HIV envelope glycoprotein plays a crucial role in HIV associated apoptosis through both death receptor-mediated and mitochondria-dependent pathways. This review summarizes current knowledge of Env-mediated T lymphocyte apoptosis.展开更多
文摘Soil spiders were pitfall-trapped once every month in three forest vegetation types of Ziwuling natural secondary forest region, Gansu Province from April to October, 2004. A total of 2 164 spiders were collected, belonging to 43 species in 19 families, captured in 630 pitfall trap collections. Linyphiidae, Gnaphosidae and Lycosodae were found to be the dominant families in all habitat types, and the composition of soil spider assemblages was different between the three habitats. Ecological indices of diversity, richness and evenness were significantly different between the three habitats （ P 〈 0.05）. The relative abundance of guilds （based on numbers of individuals） varied greatly （P 〈 0.01）, which may releet resource availability within habitat types. The existence of different patterns within the assemblages reflects the importance of maintaining habitat heterogeneity and vegetation types in order to preserve soil spider biodiversity.
文摘A study of the gate current variation is presented for various thickness ultrathin gate oxides ranging from 1.9 to 3.0nm under the constant voltage stress.The experimental results show the stress induced leakage current(SILC) includes two parts.One is due to the interface trap-assisted tunneling.The other is owing to the oxide trap-assisted tunneling.
文摘The effect of neutral trap on tunneling currentin ultrathin MOSFETs is investigated by num erical analy- sis.The barrier variation arisen by neutral trap in oxide layer is described as a rectangular potential well in the con- duction band of Si O2 .The different barrier variation of an ultrathin metal- oxide- sem iconductor(MOS) structure with oxide thickness of4nm is numerically calculated.It is shown that the effect of neutral trap on tunneling cur- rent can not be neglected.The tunneling current is increased when the neutral trap exists in the oxide layer.This simple m odel can be used to understand the occurring mechanism of stress induced leakage current.
文摘Infection by the human immunodeficiency virus （HIV） is characterized by a progressive depletion of CD4 T lymphocytes, which leads to dysfunction of the immune system. Although a variety of mechanisms may contribute to the gradual T cell decline that occurs in H/V-infected patients, abnormal apoptosis of infected or bystander T lymphocytes is an important event leading to immunodeficiency. The HIV envelope glycoprotein plays a crucial role in HIV associated apoptosis through both death receptor-mediated and mitochondria-dependent pathways. This review summarizes current knowledge of Env-mediated T lymphocyte apoptosis.
