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排序方式: 共有116条查询结果,搜索用时 15 毫秒
1.
Remotely sensed (RS) data is a major source to obtain spatialdata required for hydrological models. The challenge for thefuture is to obtain besides the more direct observable data(landcover, leaf area index, digital elevation model andevapotranspiration), non-visible data such as soilcharacteristics, groundwater depth and irrigation practices.In this study we have explore the option of using inversemodeling to obtain these non-RS-visible data. For a commandarea in Haryana, India, we applied for the 2000–2001 rabiseason a RS-GIS-combined inverse modeling approach to derivenon-RS-visible data required in the regional application ofhydrological models. A Genetic Algorithm loaded stochasticphysically based soil-water-atmosphere-plant model (SWAP) wasdeveloped for the inverse problem and used in the study. Theresults showed good agreement with the inventoried data suchas soil hydraulic properties, sowing dates, groundwaterdepths, irrigation practices and water quality. The deriveddata could be used to predict the state of the system at anytime in the cropping season, which can be used to evaluateoperational management strategies. 相似文献
2.
由于霉菌毒素是一类无色无臭无味的物质,所以测定饲料原料和饲料成品以监测霉菌毒素的污染是非常重要的. 霉菌毒素这一术语源自希腊语单词"mycos"和"toxikon",是指在各种各样环境条件下由真菌产生的次生有毒代谢产物. 相似文献
3.
Beatriz Gutiérrez‐Crespo Patrick R. Kircher Ines Carrera 《Veterinary radiology & ultrasound》2014,55(3):278-285
The aim of this study was to describe the appearance of the ligamentous structures of the occipitoatlantoaxial (OAA) region in the normal horse by 3 tesla (3T) magnetic resonance imaging (MRI). The MRI images of the longitudinal odontoid ligament, tectorial membrane, dorsal and ventral atlantoaxial ligaments, dorsal atlantooccipital membrane with its reinforcing ligaments, and the lateral atlantooccipital ligaments of 10 horse cadavers were evaluated. All ligaments and membranes were identified in all planes, except for the lateral atlantooccipital ligament in the sagittal plane due to its cranioventrolateral course. All were iso to mildly hypointense to musculature of the neck in T1W with the exception of the tectorial membrane that was moderately hypointense; moderately hypointense in PD‐SPIR, and markedly hypointense (isointense to cortical bone) in T2W. The PD‐SPIR was the best sequence to identify all ligaments and membranes from their cranial and caudal attachments. The longitudinal odontoid ligament, ventral atlantoaxial ligament, and reinforcing bands of the dorsal atlantooccipital membrane presented a characteristic striped heterogeneous signal behavior thought to be due to fibrocartilaginous content. The remaining ligaments and membranes showed homogeneous signal intensity. Special anatomical features in this species such as the fan‐shaped longitudinal odontoid ligament, absence of the transverse ligament and presence of the ventral atlantoaxial ligament were documented. Ligamentous structures that stabilize the equine OAA region were described with MRI in this study and these findings could serve as an anatomic reference for those cases where instability of this region is suspected. 相似文献
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5.
S. Anton A. Gasser Kerstin Nielsen Bettina Eichler-Löbermann Martin Armbruster Ines Merbach Uwe Franko 《Soil Use and Management》2023,39(2):867-880
Phosphorus is a nonrenewable resource, which is required for crop growth and to maintain high yields. The soil P cycle is very complex, and new model approaches can lead to a better understanding of those processes and further guide to research gaps. The objective of this study was to present a P-submodel, which has been integrated in the existing Carbon Candy Balance (CCB) model that already comprises a C and N module. The P-module is linked to the C mineralization and the associated C-pools via the C/P ratio of fresh organic material. Besides the organic P cycling, the module implies a plant-available P-pool (Pav), which is in a dynamic equilibrium with the nonavailable P-pool (Pna) that comprises the strongly sorbed and occluded P fraction. The model performance was tested and evaluated on four long-term field experiments with mineral P fertilization, farmyard manure as organic fertilizer and control plots without fertilization. The C dynamics and the Pav dynamics were modelled with overall good results. The relative RMSE for the C was below 10% for all treatments, while the relative RMSE for Pav was below 15% for most treatments. To accommodate for the rather small variety of available P-models, the presented CNP-model is designed for agricultural field sites with a relatively low data input, namely air temperature, precipitation, soil properties, yields and management practices. The CNP-model offers a low entry threshold model approach to predict the C-N and now the P dynamics of agricultural soils. 相似文献
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Khaitovich P Hellmann I Enard W Nowick K Leinweber M Franz H Weiss G Lachmann M Pääbo S 《Science (New York, N.Y.)》2005,309(5742):1850-1854
The determination of the chimpanzee genome sequence provides a means to study both structural and functional aspects of the evolution of the human genome. Here we compare humans and chimpanzees with respect to differences in expression levels and protein-coding sequences for genes active in brain, heart, liver, kidney, and testis. We find that the patterns of differences in gene expression and gene sequences are markedly similar. In particular, there is a gradation of selective constraints among the tissues so that the brain shows the least differences between the species whereas liver shows the most. Furthermore, expression levels as well as amino acid sequences of genes active in more tissues have diverged less between the species than have genes active in fewer tissues. In general, these patterns are consistent with a model of neutral evolution with negative selection. However, for X-chromosomal genes expressed in testis, patterns suggestive of positive selection on sequence changes as well as expression changes are seen. Furthermore, although genes expressed in the brain have changed less than have genes expressed in other tissues, in agreement with previous work we find that genes active in brain have accumulated more changes on the human than on the chimpanzee lineage. 相似文献
8.
Laccases of fungal origin have been intensively studied due to their importance in various biotechnological applications. There is a constant demand for new laccases with improved properties such as stability at higher temperatures or at an alkaline pH. Growing molecular evidence suggests that laccases may also be widespread in bacteria. While only a handful of bacterial laccases have been purified and characterized, several novel traits have already been discovered (e.g. pH-stability and 2-domain organization of the enzyme as opposed to the usual 3-domain structure of fungal laccases). The aim of this study was to examine the diversity of bacterial laccase-like genes in two types of high-organic peat soil using a cloning and sequencing approach. Gene libraries prepared of small fragments (150 base pairs) revealed an amazing diversity of bacterial laccases. The fragments clustered in 11 major lineages, and one third of the 241 sequences resembled laccase-like genes of Acidobacteria. Additionally, a new primer was used to retrieve several larger fragments of the putative bacterial laccase genes that spanned all four copper-binding sites. Both “conventional” 3-domain laccases and the recently described 2-domain small laccases have been obtained using this approach, demonstrating the potential of the primer. The present study thus contributes to the understanding of the diversity of bacterial laccases and provides a new tool for finding laccase-like sequences in bacterial strains and soil samples. 相似文献
9.
Five different methods were compared to elucidate the total activity of the acidic phytate-degrading enzymes present in the seeds of rye, wheat, and barley. Phytate-degrading activity was studied at pH 5.0 by quantifying the liberated phosphate. Rye showed the highest acid phytate-degrading activity among the cereals studied. Using an aqueous extract, only 30-50% of the activity was found (rye, 3443 mU g(-1) of grain; wheat, 1026 mU g(-1) of grain; barley, 1032 mU g(-1) of grain) compared to that found by the direct incubation of the dry-milled cereal grains in a buffered phytate-containing solution (rye, 6752 mU g(-1) of grain; wheat, 2931 mU g(-1) of grain; barley, 2093 mU g(-1) of grain). Extending the extraction time resulted in an increase in extractable phytate-degrading activity by, at maximum, 10-15%. Extraction of phytate-degrading activity is strongly enhanced in the presence of Triton X-100 and the protease inhibitor phenylmethylsulfonyl fluoride (rye, 6536 mU g(-1) of grain; wheat, 2873 mU g(-1) of grain; barley, 2023 mU g(-1) of grain), suggesting at least a partial association with membrane structures and a degradation by proteolytic activity during extraction. In addition, it was shown that determining phytate-degrading activity by quantification of the liberated inorganic phosphate is more robust and precise than determining phytate-degrading activity by quantification of the residual phytate. 相似文献
10.
Barbara Kraigher Janez Hacin Ivan Mahne Ines Mandic-Mulec 《Soil biology & biochemistry》2006,38(9):2762-2771
Fen peatlands are specific wetland ecosystems containing high soil organic carbon (SOC). There is a general lack of knowledge about the microbial communities that abound in these systems. We examined the microbial activity and community structure in two fen soils differing in SOC content sampled from the Ljubljana Marsh under different seasonal conditions. Substrate-induced respiration and dehydrogenase activity were used as indicators of total microbial activity. Both methods indicated higher microbial activities in the fen soil with the higher SOC content on all dates of sampling. To determine whether the differences in microbial activity were associated with differences in the microbial community structures, terminal restriction fragment length polymorphism (T-RFLP) of bacterial 16S rRNA genes was performed. Comparison of the T-RFLP profiles revealed very similar community structures in both fens and in the two seasonal extremes investigated. This suggested a stable community structure in the two fens, which is not affected by the SOC content or seasonal variation. In addition, a bacterial 16S ribosomal RNA gene based clone library was prepared from the fen soil with the higher SOC content. Out of 114 clones analysed, approximately 53% belonged to the Proteobacteria, 23% to the Acidobacteria, 21% to a variety of other taxa, and less than 3% were affiliated with the Firmicutes. 相似文献