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271.
通过对芜湖赭山东路神东村上新塘市政合流污水在不同条件下进行的混凝对比试验,研究聚合氯化铝-聚丙烯酰胺混凝效果影响因子之间的交互效应。由正交试验设计安排水处理剂对原水除浊率影响试验。结果表明:在水处理剂的混凝条件中,药剂种类和比例的交互作用对浊度处理率有一定程度的协同效应。温度为20℃时,当用聚合氯化铝-聚丙烯酰胺进行水处理时,pH值为7.5~8.4,1 L原水投加药剂80 mg,组分V(PAC)∶V(PAM)=8∶2时,混凝效果最优,除浊效率达到93.18%。  相似文献   
272.
We describe activity patterns, relative abundances and pollen transport by insect floral visitors in the Skukuza Ranger District, Kruger National Park, Republic of South Africa, based on field surveys conducted during the early rainy seasons of years 2006 to 2012 (inclusive). Diagnostic notes, illustrations and natural history observations are provided for species in the families Buprestidae, Cerambycidae, Cleridae, Lycidae and Scarabaeidae (Coleoptera), Muscidae, Platystomatidae and Tabanidae (Diptera), Apidae, Halictidae, Megachilidae, Sphecidae and Vespidae (Hymenoptera), and Pieridae and Thyrididae (Lepidoptera) that transported pollen of tree or shrub species. Observations on floral phenology and pollination syndrome are presented for 27 flowering tree or shrub species. To provide a foundation for studies of the effects of drought and climate change on pollination services in the Kruger National Park, we applied methods of food web analysis to characterise this plant-pollinator assemblage. The food web analysis shows moderate levels of redundancy in plant-pollinator interactions (with connectance values averaging 0.19 for plant species and 0.20 for pollinator species), suggesting that pollination services in this system may exhibit some resilience to environmental perturbations. Possible conservation strategies for maintaining pollination services in this ecological system are discussed, including habitat management to conserve larval or nesting areas for social and solitary bees and scarab beetles, as well as further inventories and long-term monitoring of pollinator species.  相似文献   
273.
Betaine homocysteine methyltransferase (BHMT), a Zn2+-dependent thiolmethyltransferase, contributes to the regulation of homocysteine levels, increases in which are considered a risk factor for cardiovascular diseases. Most plasma homocysteine is generated through the liver methionine cycle, in which BHMT metabolizes approximately 25% of this non-protein amino acid. This process allows recovery of one of the three methylation equivalents used in phosphatidylcholine synthesis through transmethylation, a major homocysteine-producing pathway. Although BHMT has been known for over 40 years, the difficulties encountered in its isolation precluded detailed studies until very recently. Thus, the last 10 years, since the sequence became available, have yielded extensive structural and functional data. Moreover, recent findings offer clues for potential new functions for BHMT. The purpose of this review is to provide an integrated view of the knowledge available on BHMT, and to analyze its putative roles in other processes through interactions uncover to date. Received 26 May 2006; received after revision 3 July 2006; accepted 24 August 2006  相似文献   
274.
水稻钵苗对辊式拔秧机构   总被引:1,自引:0,他引:1  
针对我国水稻钵苗移栽技术对栽植机械的要求,在分析现有机型特点的基础上,提出了用于水稻钵苗拔秧的对辊式拔秧机构的设计方案,并介绍了该机构工作原理;通过拔秧机构的运动和拔秧过程分析,确定了拔秧机构工作参数的选取原则和取值范围,完成了对辊式拔秧机构的设计、试制及试验.试验结果表明,采用对辊式拔秧机构实现了水稻钵苗的自动输秧和拔秧,具有结构简单、秧苗损伤小、工作可靠等优点,为水稻钵苗有序成行栽植机械的设计奠定了基础.  相似文献   
275.
Crotalaria plants and Utetheisa ornatrix are closely linked to each other: the larvae destroy the seeds, while the moth depends on hostplants for alkaloids. To better understand the ongoing co-evolution, the present study examines how native hostplants compare to exotic ones. Leaf-feeding on Crotalaria pumila, C. rotundifolia, and C. incana, native to the moth’s range, led to faster larval development than on the exotic C. lanceolata, C. spectabilis, and C. pallida. Seed-feeding on all species of Crotalaria led to accelerated larval development and a resultant larger adult moth, and correlates with a higher nitrogen content in the plant tissues. These results add a novel dimension to the previous studies of reproductive biology of this model organism. In controlled settings, mature larvae showed preference for leaves of C. spectabilis over those of other species, perhaps due to the higher alkaloid content. Differences in morphology and phenology of Crotalaria determine the ecology of U. ornatrix populations in Florida. The introduction of novel hostplants, on which U. ornatrix can have a significant negative effect and which are of concern to humans as invasive toxic weeds, has greatly expanded the niche occupied by this moth. Possible co-evolution of Utetheisa sensu lato and plant defences in the genus Crotalaria is discussed.  相似文献   
276.
过江隧道穿越既有铁路的相互影响是一个难点.依托重庆长江隧道穿越襄渝铁路工程进行研究,研究结果表明:过江隧道施工对既有铁路两个方向地表沉降的影响都很小,最大值为2.549 mm,故受影响的既有铁路附近地层不需做特殊加固处理,但要加强监控;既有铁路对过江隧道结构安全性及洞周位移影响也较小,在列车荷载作用下结构最小安全系数为6.8,过江隧道结构仍是偏于安全的,故隧道结构可不作加固处理,只需加强监控.研究成果为保证既有铁路的正常运营及过江隧道的结构安全性提供了理论基础,并可为相似工程提供参考.  相似文献   
277.
随着互联网海量信息的快速增长,由原来单一的以文本信息为主的信息处理发展成文本、语音、图像等多模态的信息处理.同时,用户的需求也从关键词搜索为主的信息获取向着基于语义理解的自动问答、辅助决策等智能交互的方向发展.本文从互联网服务信息处理特点以及用户需求变化出发,阐述了互联网信息处理面临的挑战和发展趋势.首先介绍了基于互联网的海量信息处理特点以及基本方法,然后分别阐述了互联网文本信息处理、语音信息处理、图像信息处理、位置信息处理的挑战以及发展趋势.最后介绍了如何对互联网的用户从属性、状态、兴趣3个维度进行建模,以满足用户个性化服务和商业分析的需要.  相似文献   
278.
由天津大学软件学院发起并召集,东北大学秦皇岛分校和燕山大学承办的信息可视化战略研讨会于2012年6月9-10日在北戴河成功举行.本文总结了此次会议的讨论内容和达成的共识,对当前信息可视化和可视分析领域的挑战和国际上这方面的研究方向做了大致的分析,并对今后信息可视化和可视分析的大方向提出一些建议,以及对具体行动提出一系列倡议.  相似文献   
279.
《Journal of Natural History》2012,46(21-22):1359-1367
We present data on predatory behaviour in Deltochilum cupreicolle viridescens, which belongs to the subgenus Aganhyboma, and we contrast it with the behaviour of a species from the subgenus Deltohyboma. By this comparison we can investigate whether the predatory behaviour in Deltochilum could have appeared independently in these two subgenera, or if the behaviour is so similar that it suggests a single origin in a possible ancestor exclusive to those two groups. These laboratory studies on the behaviour of Deltochilum c. viridescens individuals on diplopods are described and divided into the following stages: (1) approach and recognition of the diplopod; (2) attack and death of the prey; (3) on-site feeding; (4) transport of the diplopod. The results found here strengthen the hypothesis of a primitive and highly specialized behaviour within a possible clade formed by the predatory species of Diplopoda.  相似文献   
280.
基于LVQ神经网络的植物种类识别   总被引:2,自引:0,他引:2  
提出一种基于学习矢量量化(LVQ)神经网络的计算机植物种类识别新方法. 使用2-D不变矩、 多尺度2-D Gabor滤波器等多种方法分别提取了叶片的几何特征和纹理特征, 应用LVQ神经网络识别植物种类. 实验结果表明, 该方法对植物种类的识别效率较高.  相似文献   
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