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31.
蓝花野茼蒿Crassocephdum rubens(Juss.ex Jacq.)S.Moore是一种原产非洲的常见菊科杂草,近年在我国云南发现有逸生,为我国新记录的归化种.  相似文献   
32.
Question: How to refine simulations based on a global vegetation model in order to apply it to regional scale? Location: Europe from 35° N to 71° N and 25° W to 70° E. Methods: Geographical ranges of European plants were georeferenced and used with monthly mean climatic data (diurnal temperature ranges, ground frost frequencies, precipitation, relative humidity, rain frequencies, amount of sunshine hours and temperature) and growing degree days to infer climatic boundaries for 320 taxa. We performed a discriminant analysis to define their potential geographic ranges. Hierarchical clustering was computed on potential ranges. Results: Clustering provided 25 Bioclimatic Affinity Groups (BAG) of plants consisting of 13 tree, seven shrub and five herb groups. These B AGs are characterized by different geographical ranges and climatic tolerances and requirements. Conclusion: The use of monthly data instead of annual values improved the prediction of potential distribution ranges and highlighted the importance of climate seasonality for defining the plant groups with accuracy. The B AGs are detailed enough to provide finer reconstructions and simulations of the vegetation at the regional scale.  相似文献   
33.
Over the past two decades there has been increasing interest in the development of an objective, or formalized “medical logic”, and many authors have employed classical symbolic logic as a part of their approach. On the other hand, it has become clear that certain patterns of reasoning which are commonplace in evaluating patients clinicopathologically are awkward to handle in classical symbolic logic. The present paper proposes an extension of classical symbolic logic which addresses three problems in medical reasoning: (i) the problem of provisional diagnosis, (ii) the problem of inaccessible data, and (iii) the problem of the adequate discharge summary. It is proved mathematically that with a suitably constructed logic, the system “complains” until all questions involving threats to the patient's health are either answered or shown to be unanswerable because of inaccessibility of data. To illustrate this method, the cause of death was studied in 108 patients who had been autopsied at The Johns Hopkins Hospital after coronary artery bypass surgery. The analysis disclosed that 46% of patients suffered a fatal complication which could be attributed to events in the perioperative period; in 15% of patients the cause of death was unexplained by the analysis. Computerized symbolic logic analysis is a useful supplement to intuitive reasoning in assigning cause of death to patients with complex medical histories.  相似文献   
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35.
This protocol describes rapid colorimetric detection of Escherichia coli, Salmonella spp., and Listeria monocytogenes from large volumes (10 L) of agricultural waters. Here, water is filtered through sterile Modified Moore Swabs (MMS), which consist of a simple gauze filter enclosed in a plastic cartridge, to concentrate bacteria. Following filtration, non-selective or selective enrichments for the target bacteria are performed in the MMS. For colorimetric detection of the target bacteria, the enrichments are then assayed using paper-based analytical devices (µPADs) embedded with bacteria-indicative substrates. Each substrate reacts with target-indicative bacterial enzymes, generating colored products that can be detected visually (qualitative detection) on the µPAD. Alternatively, digital images of the reacted µPADs can be generated with common scanning or photographic devices and analyzed using ImageJ software, allowing for more objective and standardized interpretation of results. Although the biochemical screening procedures are designed to identify the aforementioned bacterial pathogens, in some cases enzymes produced by background microbiota or the degradation of the colorimetric substrates may produce a false positive. Therefore, confirmation using a more discriminatory diagnostic is needed. Nonetheless, this bacterial concentration and detection platform is inexpensive, sensitive (0.1 CFU/ml detection limit), easy to perform, and rapid (concentration, enrichment, and detection are performed within approximately 24 hr), justifying its use as an initial screening method for the microbiological quality of agricultural water.  相似文献   
36.
Abstract. The effects of grazing upon the establishment, survival, growth and reproduction of a grassland annual Geranium dissectum growing in a sward dominated by grasses were examined in a replicated grazing experiment with sheep. Seeds were sown in both summer and autumn, and grazing was controlled to produce two levels of grazing in winter, two levels in spring, and two in summer, combined in a 2 x 2 x 2 factorial experimental design. Higher intensities of grazing in the period immediately before emergence benefitted plant establishment, but subsequent survival showed many interactions between factors, demonstrating that under certain conditions and at certain times grazing was detrimental. It is suggested that the frequency of G. dissectum in the grassland was low because the heavy grazing conditions that foster seedling emergence also jeopardize subsequent survival. This may also be why productive grassland communities in general contain few palatable dicots.  相似文献   
37.
The frequency of long-calling in untreated and hormone-treated juvenile laughing gulls was compared. While both estrogen and testosterone increased the calling rate, testosterone was more effective for both sexes. Both estrogen- and testosterone-treated males called more often than similarly treated females. As both sexes normally call in laughing gulls, these results were compared to the more usual situation where only males of the species sing. Possible control mechanisms were discussed.  相似文献   
38.
Recently discovered correspondence between Charles Darwin and David Moore shows the latter's role in providing fresh material of importance to Darwin's studies on insectivorous plants. One letter relates to Moore's experimental work on potatoes. This research, probably concerned with resistance of selected varieties of potato to blight, is apparently not supported by Glasnevin Botanic Garden (Dublin) records or contemporary literature.  相似文献   
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