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21.
观赏竹的园林应用、分类及评价分析   总被引:17,自引:1,他引:17  
分析了观赏竹园林绿化上的应用 ,根据观赏竹的外形特征进行了特色分类以及特色评价与分析 ,为今后进一步开发利用观赏竹提供理论与实践的资料 .  相似文献   
22.
稻田水分管理方式对水稻光合速率和水分利用效率的影响   总被引:30,自引:2,他引:30  
以超级杂交稻两优培九和中优6号为材料, 设3个不同水分管理措施,在穗分化期、开花期和花后20 d分别测定叶片光合速率和水分利用率。结果表明:不同水分管理方式影响水稻地上部干物重、叶面积指数、光合速率、蒸腾速率和水分利用效率。水分好气灌溉管理地上部干物重和水分利用效率明显增加;水分低水位管理蒸腾速率、地上部干物重和叶片水分利用效率下降。淹水灌溉地上部干物重、叶面积指数、叶片光合速率和水分利用率较低。因此,水稻好气灌溉有利于光合物质积累,显著增产和提高水分利用效率。试验还表明这3种水分管理对稻米蛋白质含量的影响不显著。  相似文献   
23.
These guidelines have been prepared to assist in the planning, conduct and interpretation of studies for the assessment of the efficacy of ectoparasiticides (excluding repellents) against the biting and nuisance dipteran flies of ruminants. Information is provided on the selection of animals, dose determination and dose confirmation studies, field studies, record keeping and result interpretation. These guidelines advocate the use of pen facilities for dose determination and dose confirmation studies. These guidelines also are intended to assist investigators on how to conduct specific studies, to provide specific information for registration authorities involved in the decision-making process, to assist in the approval and registration of new ectoparasiticides, and to facilitate the worldwide adoption of standard procedures.  相似文献   
24.
Mast cell tumors are found in most organs and tissues with variable biologic behavior in dogs. This case illustrates the clinical and magnetic resonance imaging (MRI) findings in a dog with disseminated mast cell tumor infiltrating the sphenoid bones. A 6‐year‐old male neutered Greyhound presented with a 3‐day history of acute onset of blindness. General physical examination was normal. Neurological examination revealed mildly disorientated mental status, absent menace response in both eyes, bilaterally decreased vestibulo–oculocephalic reflexes and absent direct and consensual pupillary light reflex in both eyes. An electroretinogram indicated normal retinal function in both eyes. A lesion involving the middle and rostral cranial fossa was suspected. Hematology and serum biochemistry were normal except decreased urea (1.2 mmol/L). MRI of the head revealed heterogeneous signal intensity of the sphenoid bones on T2‐weighted images and loss of their normal internal architecture. Cerebrospinal fluid analysis was normal. Abdominal ultrasound revealed hepatosplenomegaly and mesenteric lymphadenopathy. Fine needle aspirates were taken from the jejunal lymph nodes and the spleen. Results were consistent with disseminated mast cell tumor. The owner declined any treatment and the dog was euthanatized. Postmortem examination confirmed disseminated mast cell tumor affecting multiple organs, including the sphenoid bones. To our knowledge, this is the first case describing MRI features of disseminated mast cell tumor affecting the sphenoid bones and causing acute onset of blindness in a dog.  相似文献   
25.
When quinoa, Chenopodium quinoa Willd., is cultivated in South America outside of its Andean origin, the heteropterans Liorhyssus hyalinus (Fabricius) and Nysius simulans Stål may emerge as important pests. Here we studied the development and reproduction of both species at different constant temperatures in the laboratory. Egg and nymphal development were investigated at 18, 22, 26, 30, 34, and 36°C. For both species, egg incubation time significantly decreased as the temperature increased. Nymphs did not successfully develop at 18°C and the total nymphal time significantly decreased as the temperature increased from 22 to 36°C. Based on a linear day-degree (DD) model, the lower developmental threshold (LDT) temperatures for eggs and nymphs were estimated to be 16.0 and 17.9°C for L. hyalinus, and 16.1 and 19.7°C for N. simulans, respectively. Thermal requirements for egg and nymphal development were 68.6 and 114.8 DD for L. hyalinus, and 77.7 and 190.3 DD for N. simulans, respectively. Reproduction and adult longevity were studied at 22, 26, 30, and 34°C. For both species preoviposition time decreased as temperature increased, and the oviposition period was longest at 26°C. The highest fecundity and egg viability were observed at 30°C, whereas longevities were higher at 22–26°C than at 30–34°C. As the lowest tested temperatures were not suitable to both heteropterans and 30°C was found to be the optimal temperature for development and reproduction, peak densities are expected in warm areas and seasons.  相似文献   
26.
The modelling framework already introduced by Doglioli, Magaldi, Vezzulli and Tucci to predict the potential impact of a marine fish farm is improved following different directions, namely (1) real historic current-metre data are used to force the simulations, (2) settling velocity values specifically targeting Mediterranean fish species are used, and (3) a new benthic degradative module, the Finite Organic Accumulation Module, is added to the modelling framework. The Finite Organic Accumulation Module uses the output of the other functional units of the modelling framework to calculate the organic load on the seabed. The Finite Organic Accumulation Module considers the natural capability of the seafloor in absorbing part of the organic load. Different remineralization rates reflect the sediment stress level according to the work of Findlay and Watling. Organic degradation for both uneaten feed and faeces is evaluated by changing the release modality (continuous and periodical) and by varying the settling velocities. It is found that the maximum impact on the benthic community is observed either for quickly sinking uneaten feed released twice a day, or for less intense near-bottom current conditions. If both the above-mentioned scenarios coexist, a high stress level is established in the sediment. The model also suggests that the use of self-feeders in cages can reduce farm impacts significantly. These results show how the new and more complete modelling framework presented here is able to improve the objectivity in the decision-making processes and how it may be successfully used for planning and monitoring purposes.  相似文献   
27.
浓缩风能装置是浓缩风能型风力发电机组的主要部件之一,其结构直接影响机组输出功率的大小。为了提高浓缩风能装置的浓缩效率,以浓缩风能装置为研究对象,应用三维建模软件与CFD(computational fluid dynamics)软件建立了几何模型与网格模型。基于上述模型,提出应用数值模拟方法对浓缩风能装置内部流场进行仿真分析,并通过比较分析不同湍流模型下的内部流场特性,得知标准κ-ω湍流模型更加适用于浓缩风能装置内部流场仿真。基于上述浓缩风能装置模型和湍流模型,分别对不同尺寸参数的浓缩风能装置内部流场特性进行仿真分析,得到了扩散角对浓缩风能装置内部流场特性的影响比收缩角、中央圆筒长度的影响大的规律,此规律为浓缩风能装置结构优化与设计提供了依据,优化后的结构能明显提高风能品质和风电机组输出功率。  相似文献   
28.
In recent years the consumption of tea and herbal infusions has increased. These hot drinks are consumed as daily drinks as well as for medicinal purposes. All tea varieties (white, yellow, green, oolong, black and puerh) originate from the leaves of the tea plant, Camellia sinensis. All extracts made of plant or herbal materials which do not contain Camellia sinensis are referred as herbal infusions or tisanes. During processing and manufacturing fungal contamination of the plant materials is possible, enabling contamination of these products with mycotoxins. In this study a multimycotoxin UPLC-MS/MS method was developed and validated for the analysis of the raw tea and herbal infusion materials as well as for their drinkable products. The samples were analyzed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), with a mobile phase consisting of variable mixtures of water and methanol with 0.3% formic acid. The limits of detection for the different mycotoxins varied between 2.1 μg/kg and 121 μg/kg for raw materials and between 0.4 μg/L and 46 μg/L for drinkable products. Afterward 91 different tea and herbal infusion samples were analyzed. Only in one sample, Ceylon melange, 76 μg/kg fumonisin B(1) was detected. No mycotoxins were detected in the drinkable products.  相似文献   
29.
三峡库区资源丰富,但库区农村存在资源利用不合理、能源紧缺的情况.库区的气候及资源是发展沼气的有利条件.沼气是一项投资少,见效快,一次投资长期受益的好项目;是能够解决库区农村燃料短缺,提高用能品质,促进农民增收节支的有效途径,并且是保护生态改善农村生活环境,促进库区农村生态经济可持续发展的有效举措.  相似文献   
30.
The pupal morphology of the pest species Cameraria ohridella is described and compared with that of the genus Phyllonorycter. The most striking differences are the longer antennal appendages, the absence of a cremaster, the presence of strong lateral thorns on abdominal segments 1–5 and an area without small spines on the same abdominal segments in Cameraria.  相似文献   
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