期刊文献+
共找到2篇文章
< 1 >
每页显示 20 50 100
Habitat selection by nestbox-breeding birds and Roe Deer are incongruent within a heterogeneous woodland landscape
1
作者 Kevin B.Briggs Mark C.Mainwaring 《Avian Research》 SCIE CSCD 2022年第1期43-48,共6页
Conserving species relies upon acquiring an understanding of their use of habitat,yet our understanding of the use of habitat by co-existing species of different guilds at microgeographic scales remains poor.In partic... Conserving species relies upon acquiring an understanding of their use of habitat,yet our understanding of the use of habitat by co-existing species of different guilds at microgeographic scales remains poor.In particular,the use of habitat by woodland species is of conservation concern because of widespread declines in woodland biodiversity.Woodland bird declines have been ascribed,in part,to high deer densities because their browsing reduces the availability of nesting sites and food.We quantify the microgeographic use of habitat by Roe Deer(Capreolus capreolus)and of Great Tits(Parus major),Blue Tits(Cyanistes caeruleus)and Pied Flycatchers(Ficedula hypoleuca)in a heterogenous woodland landscape.We examined the use of habitat at microgeographic scales by the deer and the three bird species in relation to whether the local habitat was flat or wet or had a path,fence or wall within a 25-m radius of 206 randomly selected locations.We first examined if the occupancy rates of nestboxes in those locations were correlated with the number of Roe Deer lays and second,examined if the use of habitat by the Roe Deer and the bird species were associated with each of the habitat features that we quantified.We begin by showing that the use of habitat by Roe Deer is incongruent with the use of habitat by Great Tits,Blue Tits and Pied Flycatchers during the breeding season.Also,whilst all three bird species showed no,or weak,habitat preferences,the Roe Deer preferred daytime lay sites that were in flat areas of wet woodland close to paths,whilst there were no significant effects of the presence of fences and walls.These findings show that the Roe Deer and the three bird species differ in the use of habitat within a heterogenous woodland landscape,meaning that their use of habitat did not overlap at microgeographic scales.Meanwhile,the deer showed preferences for flat areas of wet woodland,whilst none of the bird species exhibited such preferences,and we discuss the implications of our findings for the management of woodlands. 展开更多
关键词 Capreolus capreolus Cyanistes caeruleus Ficedula hypoleuca Habitat use Nestboxes Nest site selection Parus major WOODLANDS
在线阅读 下载PDF
交变负荷对自润滑干摩擦轴承性能的影响
2
作者 J.K.Lancaster D.J.Wade 何志明 《固体润滑》 CSCD 北大核心 1990年第1期61-70,共10页
实验室评价干摩擦轴承的性能通常采用的是单向负荷,而在实际应用中出现的却经常是交变负荷。本实验就交变负荷对轴承性能的主要影响进行了评价。用含聚四氟乙烯(PTFE)的几种衬里对球面轴承进行了摆动试验,并在试验过程中采用了不同的负... 实验室评价干摩擦轴承的性能通常采用的是单向负荷,而在实际应用中出现的却经常是交变负荷。本实验就交变负荷对轴承性能的主要影响进行了评价。用含聚四氟乙烯(PTFE)的几种衬里对球面轴承进行了摆动试验,并在试验过程中采用了不同的负荷波形。与单向负荷相比,在方波条件下,交变负荷的轴承衬里磨损增加,有的甚至出现了剥层现象。我们对产生剥层的原因进行了讨论。在高温(150℃),低温(-50℃)、高压(344×10~6pa)及轴承被水或其它液压液污染的条件下,方波形交变负荷对轴承性能的损害更为严重。对轴承进行密封似乎能够在某种程度上缓解上述问题。 展开更多
关键词 交变负荷 摩擦轴承 润滑 性能
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部