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921.
Sygna Linda Fuglestvedt Jan S. Aaheim H. Asbjørn 《Mitigation and Adaptation Strategies for Global Change》2002,7(1):45-62
This article looks at the ability of Global Warming Potentials (GWPs) towork as indicators of equivalence for temperature development and damagecosts. We look at two abatement scenarios that are equivalent when using100-year GWPs: one scenario reduces short-lived gases, mainly methane(CH4); the other scenario reduces carbon dioxide (CO2).Despite their equivalence in terms of CO2 equivalents, the scenariosdo not result in equal rates or levels of temperature change. The disparitiescontinue as we move further down the chain of causality toward damagecosts, measured either in terms of rate of climate change or level of climatechange. Compared to the CH4 mitigation scenario, the CO2mitigation scenario gives present value costs 1.3 and 1.5 times higher forlevel- and rate-dependent damage costs, respectively, assuming a discountrate of 3%. We also test the GWPs for other time horizons and theconclusions remain the same; using GWP as an index to reflect equivalentclimate effects and damage costs from emissions is questionable. 相似文献
922.
923.
Identification of sex pheromone components of the pea midge, Contarinia pisi (Diptera: Cecidomyiidae) 总被引:1,自引:0,他引:1
Ylva Hillbur Peter Anderson Heinrich Arn Marie Bengtsson Jan Löfqvist Anthony J. Biddle Olof Smitt Hans-Erik Högberg Ernst Plass Stephan Franke Wittko Francke 《Die Naturwissenschaften》1999,86(6):292-294
Three components in extract of pheromone glands of female pea midges, Contarinia pisi, were found to be active on male pea midge antennae by coupled gas chromatographic-electroantennographic detection. The EAD
active components were identified as 2-acetoxytridecane, (2S,11S)-diacetoxytridecane, and (2S,12S)-diacetoxytridecane. A blend of these compounds proved to be highly attractive to males in windtunnel experiments.
Received: 12 November 1998 / Accepted in revised form: 26 january 1999 相似文献
924.
The Science of Nature - 相似文献
925.
Jan H.A. Boerboom 《Agriculture, ecosystems & environment》1984,11(2):182-183
926.
Marta Heroldov Josef Bryja Jan Zejda Emil Tkadlec 《Agriculture, ecosystems & environment》2007,120(2-4):206-210
Small mammal communities were snaptrapped for six years in agricultural landscapes to establish their relationship to various crop habitats in southern Moravia, Czech Republic. The presence of 14 small mammals was documented; 77% of the community found in crops consisted of three rodents, namely Microtus arvalis, Apodemus microps and A. sylvaticus, whereas in woody habitats, 89% of the community was represented by Clethrionomys glareolus, Apodemus flavicollis and A. sylvaticus. In permanent habitats (windbreaks, small woods and fallow land), the community was more abundant and diversified. Among the crop fields, the lowest abundance was found in cereal fields whereas the lowest diversity was observed in alfalfa. Soil-cultivating practices affected abundances especially in sugar beat and maize. Seasonal variation in numbers was lowest in forest and fallow land. Species richness decreased from spring and summer to autumn and winter in annual crops (cereal, maize, sugar beet and other crops), increased in alfalfa and fallow land, and remained relatively stable in windbreaks and forests. Based on similarity indices, two groups of small mammal communities were identified: one for field crops and another for permanent habitats. The fallow land assemblages in spring and summer were more similar to field crop species assemblages and in autumn and winter to permanent habitats one. Trophic requirements of small mammals and the food supply available in the various habitats are discussed. 相似文献
927.
A case of mosaicism of trisomy 15, with two-thirds of the cells trisomic, was detected at 12 weeks of gestation in amniotic fluid cell cultures obtained with the filtration technique. Ultrasound examination at 13 weeks showed a nodule protruding into the amniotic cavity which was speculated to be remnants of a co-twin, causing the trisomic cell line. At 20 weeks of gestation, a malformation scan (level III) was normal, but supplementary fetal echocardiography revealed a severe cardiac defect (mitral atresia and a ventricular septal defect). Fetal lymphocytes obtained by cordocentesis showed trisomy 15 mosaicism, but only in 5 per cent of the mitoses. After termination, the same percentage of trisomy 15 mosaicism was found in cells from skin and tendon as in the original early amniocentesis. No sign of earlier twinning was found in the placenta or membranes. We conclude that mosaicism in early amniotic fluid obtained by the filter technique in this case reflected the true karyotype accurately and that supplementary echocardiography added significantly to the interpretation of the clinical implications. 相似文献
928.
P.Monica Lind Anders Bergman Mats Olsson Jan rberg 《Ambio-人类环境杂志》2003,32(6):385-388
本文利用非侵入计算层析X射线摄影法(pQCT)研究了雄性波罗的海灰海豹(4~23岁龄)骨组织的矿物密度(mg/cm3).资料按照收集的年份分组.A组1850~1955年,有机氯(OCs)大量引入之前的时期;B组1965~1985年,OC污染十分严重的时期;C组1986~1997年,OCs浓度逐渐减小的时期.测量结果的复现性良好,变异系数(CV)为0.1%~2.1%.1986~1997年收集的标本中桡骨小梁的矿物密度比1965~1985年收集的标本的明显要高(p<0.05).1986~1997年收集的标本中,下颌骨的皮层骨矿物密度明显地低于1850~1955年收集的标本(p<0.05).这些结果表明小梁和皮层骨在一段时间内的不同响应.在OC污染非常严重的时期(1965~1985年),小梁骨矿物密度最低,而在1985~1997年收集的标本中,皮层骨密度最低,该时段是一个OC污染程度相当低的时期.有关这些效应背后的机制目前尚不知道.但是,可以假定这里涉及到OCs.由于目前缺乏有关研究个体中OCs残留水平的资料,因此不可能评估OCs在这方面的影响. 相似文献
929.
930.
Jill Man-Ying Chiu Vengatesen Thiyagarajan Jan A. Pechenik Oi-Shing Hung Pei-Yuan Qian 《Marine Biology》2007,151(4):1417-1431
Larvae of the slipper limpet Crepidula onyx metamorphose in response to marine biofilms. In this study, we investigated how the percentage of larval metamorphosis in
this species was affected by biofilms that differed in certain attributes. To manipulate bacterial and diatom cell densities
and community composition, we developed biofilms in the laboratory (1) at different temperatures (16, 23 and 30°C) and salinities
(20, 27 and 34‰), (2) with or without addition of antibiotics, and (3) in the light or in the dark. We also allowed biofilms
to develop at three field sites with different prevailing environmental conditions so as to generate biofilms with different,
but natural, attributes. Bacterial and diatom community composition in biofilms were determined using a DNA fingerprinting
technique and microscopic examination, respectively. The effects of biofilms on metamorphosis were investigated in laboratory
assays. The percentage of larval metamorphosis correlated with bacterial and diatom cell densities in only one of the three
experiments conducted, but was substantially affected by differences in bacterial and diatom community composition in all
three experiments. It also appears that metamorphosis of C. onyx depends on the simultaneous presence of both bacterial and diatom communities in biofilms. 相似文献