Human appropriation of net primary production as determinant of avifauna diversity in Austria

The relationship between land-use induced changes in production ecology and avifauna diversity was analysed using a GIS land cover dataset on a 0.25 km × 0.25 km grid covering Austria's national territory. Considering only aboveground processes, the “human appropriation of net primary production” (HANPP = potential NPP − NPP_t), actual NPP (NPP_act), harvest (NPP_h) and NPP_t (= NPP_act − harvest) were recalculated based on existing datasets. Elevation as well as indicators of land cover heterogeneity and landscape heterogeneity were also considered. Correlation analyses were performed between these potential determinants of avifauna diversity and breeding bird species richness data as well as the percentage of endangered breeding birds included in the Austrian red list. Four spatial scales—0.25 km × 0.25 km, 1 km × 1 km, 4 km × 4 km and 16 × 16 km, were analysed. It was shown that breeding bird species richness was more strongly correlated with production ecological indicators and elevation than with heterogeneity indicators. A residual analysis in which the effect of elevation (a proxy for climate) on species richness and its potential determinants was removed confirmed the importance of the availability of trophic energy (NPP) for bird diversity patterns. The results support the species-energy hypothesis, thus confirming the notion that HANPP could be a useful pressure indicator for biodiversity loss.     

摩托车后挡泥板冲孔模

分析了摩托车后挡泥板的冲孔工艺,着重介绍了摩托车后挡泥板冲孔模的结构。该模具布局合理,结构紧凑,提高了生产效率,降低了生产成本,从而降低了摩托车的造价,提高了摩托车的市场竞争力。     

小边距冲孔模的凹模设计

在五金、家电、办公用品等行业中,常存在一些零件需要先弯曲成形,再进行冲孔。由于结构设计要求,有些孔到弯曲边的距离尺寸较小,尺寸精度要求较高,因此在这类模具设计中,凹模的强度问题较为突出。从结构设计和工艺设计两方面给出了设计这种模具的一些心得体会。     

高等职业教育教学管理基本特征初探

教学管理和教学过程一样,也是一个复杂的过程。不同的社会背景、不同的教育类型和不同的教育层次,教育管理的目标、方法、手段等是有区别的。本文是作者在多年高职高专教育教学管理实践的基础上,形成的关于高职高专教育教学管理基本特征的一些初步认识,发表于此,以期得到同行们的指正。     

虎克定律在高精度翻孔模设计中的应用与实践

以汽车摇摆臂为应用对象 ,通过对材料在翻孔过程中变形的理论分析和实际运用 ,探讨了虎克定律在高精度翻孔模设计中的应用与实践     

湿式喷播技术在水土流失治理中的运用

介绍了湿式喷播技术的原理和植被建植方法,对示范效果进行了评估。     

浅谈粉煤灰综合治理及建议

介绍了大庆石油化工总厂热电厂自投产以来，粉煤灰综合治理的经过，所采取的措施，存在的问题和收到的成效。这对于我国高寒平原地区的燃煤电厂有一定的借鉴参考作用。     

水质综合评价灰色理论模型及其应用

根据灰色关联度的定义，运用广义加权距离构造目标函数，建立了一种水质综合评价的灰色理论模型。综合实例说明了该模型的应用，得到与用其它方法评价完全一致的结果，该模型数学推导严谨，科学合理，分辨率高，可靠性强 。     

Recurrence risk of neural tube defects following a miscarriage

Data from 280 sibships in three published series were used to see if the increased risk of neural tube defect (NTD) associated with having had a miscarriage in the immediately preceding pregnancy was also found in women with a previous affected pregnancy. A statistically significant relative risk of 4.0 (2-tail P=0.0111, Fisher exact test) was found among such women, and this could not be accounted for by the effect of parity or of a history of miscarriage in general. The finding may be useful when counselling patients.     

超细煤矸石矿粉作天然橡胶补强填充剂的性能研究

以煤矸石为原料，通过超细粉碎、表面改性等深度加工，制取了一种新的橡胶补强剂，并对煤矸石作补强剂影响因素进行初步的研究，实验表明它能够取代或部分取代炭黑用作天然橡胶的补强剂。