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排序方式: 共有225条查询结果,搜索用时 46 毫秒
191.
Josef CF Adriano LR De França EJ Arantes de Carvalho GG Ferreira JR 《Environmental pollution (Barking, Essex : 1987)》2008,152(3):592-596
An analytical procedure for the determination of Hg in otter (Lontra longicaudis) feces was developed, to separate fish scales for the identification of the animal diet. Samples were washed with ultra-pure water and the suspension was sampled and transferred for digestion. The solubilization was performed with nitric-perchloric acid mixture, and detection carried out by the atomic fluorescence spectrometry (AFS). The quality of the analytical procedure was assessed by analyzing in-house standard solutions and certified reference materials. Total Hg concentrations were in the range of 7.6-156 ng g(-1) (July 2004), 25.6-277 ng g(-1) (January 2005) and 14.6-744 ng g(-1) (May 2005) that is approximately the same order of magnitude for all samples collected in two reservoirs at the Tiete River, Brazil. Although Hg concentrations varied with sampling periods and diet, high levels were correlated to the percentage of carnivorous fish scales present in the otter feces. 相似文献
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E. Meyer E. Lamla Josef Zemann H. G. Wagner F. Firbas B. Rensch R. Bachmann 《Die Naturwissenschaften》1961,48(18):607-608
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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
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Untersuchungen zum Vorkommen polycyclischer Moschus-Duftstoffe in verschiedenen Umweltkompartimenten
Hans -Dietrich Eschke Josef Traud Heinz -Jürgen Dibowski 《Environmental Sciences Europe》1994,6(4):183-189
New flavors have been detected in GC/MS chromatograms of surface and sewage waters and fish analyzed for nitro musk compounds. This article names the polycyclic musk flavors 1,3,4,6,7,8-hexahydro-4, 6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyrane (HHCB, known for instance under the trade names: Galaxolide® and Abbalide®), 7-acetyl-1,1,3,4,4,6-hexamethyltetralin (AHTN, known for instance under the trade names: Tonalide® and Fixolide®) and 4-Acetyl-1,1-dimethyl-6-tert.butylindane (ADBI, known for instance under the trade names: Celestolide® and Crysolide®). These substances, which are widely used in the cosmetics and flavor industries, here have been established for the first time in the aquatic environment. HHCB, AHTN and ADBI — as relatively non-polar lipophilic chemicals — like organochlorine pesticides and PCBs after extraction and consecutive purification by gel permeation and silicagel adsorption chromatography are accessible to analysis by gas chromatography/mass spectrometry. Mass spectra show typical mass fragments which allow an unambigous identification and quantification. First results for surface and sewage waters and fish underline the persistence and a relatively high bioconcentration potential of these substances and suggest their ubiqitious distribution in the aquatic environment. 相似文献
199.
For the last 6 years, sonographic signs for excessive fluid accumulation in the backs of 10- to 12-week-old fetuses have been looked for prior to transabdominal chorionic biopsy. In 1400 pregnancies, subsequent karyotype analyses revealed 28 cases of Down syndrome. In 15 ( = 54 per cent), a large fluid cushion over most of the back had been documented at the time of biopsy. Only a few chromosomally normal fetuses with the same peculiarity were observed. The cushion was also present in fetuses with trisomies 18 and 13 , and in Turner syndrome. Systematic first-trimester screening for nuchal fluid accumulation seems to be a recommended method for the detection of Down syndrome and other chromosome anomalies in young pregnant women at low risk. It compares favourably with current methods of maternal serum screening performed at 16–18 weeks which require a higher number of invasive procedures. 相似文献
200.
Josef Schurz 《Die Naturwissenschaften》1954,41(15):363-363