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971.
José A. Donázar Alejandro Travaini Olga Ceballos Alejandro Rodríguez Miguel Delibes Fernando Hiraldo 《Behavioral ecology and sociobiology》1999,45(1):55-65
Phenotype-limited interference models assume competitive asymmetries among conspecifics and unequal sharing of resources.
Their main prediction is a correlation between dominance status and patch quality: dominant individuals should preferentially
exploit better-quality habitats. We tested assumptions and predictions of the phenotype-limited interference model in Andean
condors (Vultur gryphus), a New World vulture with strong sexual size dimorphism (males are 30–40% heavier than females). We recorded searching birds
in habitats differing in quality: mountains and plains. We also observed scavenging behaviour at 20 sheep carcasses, and videotaped
5 of them. Intraspecific hierarchy at carcasses was based on size: males dominated females and, within each sex, older birds
dominated younger ones. Adult males and juvenile females occupied extreme positions in the feeding hierarchy. Aggression was
directed at those individuals belonging to lower hierarchical levels. In high-quality areas (mountains), more condors arrived
at carcasses. Juvenile females were more often observed searching in low-quality areas (plains), far from breeding areas and
main roost sites. GLM analyses of individual behaviour showed that the hierarchy did not influence time of arrival, but low-ranking
individuals spent more time at carcasses, especially if the number of condors at arrival was high. Additionally, low-ranking
condors spent less time feeding at carcasses when individuals of higher hierarchical levels were present. On the other hand,
the number of condors present had a positive effect on feeding rates of dominant individuals, probably because of a reduction
in individual vigilance. These results support most of the assumptions and predictions of the phenotype-limited distribution
model, although a spatial truncated distribution between phenotypes was not observed. Asymmetric feeding pay-off, unequal
parental roles and sexual selection constraints could favour sexual divergence in body size in Andean condors.
Received: 6 April 1998 / Accepted after revision: 11 July 1998 相似文献
972.
973.
絮凝剂PAN-DCD的结构和性质研究 总被引:3,自引:0,他引:3
以聚丙烯腈(PAN)和双腈双胺(DCD)为原料,合成了有机絮凝剂PAN-DCD。用IR、1HNMR和13CNMR等方法对其结构进行了表征,探讨了PAN-DCD溶解度随pH值变化的规律,研究了PAN-DCD对活性染料的絮凝脱色和去除CODCr的性能。结果表明,PAN-DCD是侧链带有多种极性基团的聚合物;在酸性条件下溶解度较小,碱性条件下溶解度较大;在加入量较少的情况下使活性染料的脱色率接近100%,并对CODCr的去除有较大贡献。 相似文献
974.
街谷地区CO污染现状分析 总被引:1,自引:0,他引:1
本文分析了典型街谷地区CO污染的现状及其浓度的垂直分布和水平分布的变化情景。由监测结果可知,街谷地区CO浓度是较高的,而且峰值出现在采暖期。 相似文献
975.
小麦-玉米轮作制度下潮土硝态氮的分布及合理施氮肥研究 总被引:1,自引:0,他引:1
利用田间小区试验研究了小麦-玉米轮作中在不同施氮量和不同时期潮土1m土层中硝态氮的计中状况结果表明:3年不施氮肥的土壤仍有6~16kg/hm2的硝态氮,其中0~20cm土层占20%~34%.80%~100cm上层占10%~18%;每季施氨量小于225kg/hm2时.1m上层中各时期硝态氮含量变化不大,在11.4~41.3kg/hm2之间;当施氮量增加到375kg/hm2时,1m土层的硝态氮含量增加1.5~7.4倍,有7.4%~29.9%分布在0~20cm上层中,10%~16%分布在80~100cm上层中225kg/hm2对作物斋求及对土壤环境来说是一个合理的施只量。 相似文献
976.
Ozone measurements along vertical transects in the Alps 总被引:1,自引:1,他引:0
Herbert Werner Manfred Kirchner Gerhard Welzl Markus Hangartner 《Environmental science and pollution research international》1999,6(2):83-87
To investigate the vertical profiles of air pollutants in the boundary layer, aircraft and balloon-born measurements and measurements
using a cable car as an instrument platform have been performed in different parts of the Alps. This on-line monitoring of
atmospheric pollutants requires expensive and sophisticated techniques. In order to control ambient air quality in remote
regions, where no infrastructure like power supply is available, simple instruments are required. The objective of this study,
which was coordinated and evaluated by the GSF-Forschungszentrum für Umwelt und Gesundheit was first, to investigate the vertical
distribution of ozone in different parts of the Alps and secondly, in addition to continuous analyser measurements, to test
monitoring by means of two types of passive samplers. The selection of these samplers — one for one week use and another one
for two week application — was based on a passive sampler intercomparison done in a preliminary study one year earlier. 相似文献
977.
978.
979.
滇池水体和沉积物中营养盐的分布特征 总被引:16,自引:4,他引:12
在滇池外海不同方位选取6个采样点,研究了水质现状,沉积物Eh,pH,总氮,总磷以及间隙水重金属的剖面分布特征。结果表明,滇池水体仍属富营养化状态。在氧化表层下,Eh随沉积深度的增加迅速降低,沉积物深层为还原状态。pH在沉积物剖面变化不大,为7 0~8 5。滇池沉积物含有丰富的营养物质,总氮和总磷最高质量分数分别为8 67和3 46g kg。剖面分布表明,沉积物表层总氮和总磷含量远高于底层,在表层0~10cm含量随深度增加而迅速降低。重金属元素在水-土界面的浓度梯度为沉积物向水体的扩散提供了条件。不同采样点相比,位于昆明市附近的S6点沉积物内负荷较大。在外源减少的情况下,沉积物内负荷可能在一定时间内成为控制滇池水质的主导因子。 相似文献
980.