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51.
Using the combined approach of questionnaire and semi-structured interview, this study aims to examine the characteristics of a small agricultural business, and benefits perceived by the participants, and challenges. The “multi-industrial system” regional initiative for creating new high-value-added businesses project encourages rural residents to commercialize their surplus agricultural and forestry products, such as pickled or dried wild and cultivated plants. Knowledgeable older people, women farmers in particular, are motivated to market their vegetables directly to the urban market, and their home-processed wild plants to local restaurants and hotels. It found that the older people involved in the business considered that their health and economic situation had been improved through participating in vegetable cultivation and sales. Some lessons from this case study can be identified: the empowerment of older people and women farmers, through active interaction with the market and learning new technologies, including internet-based information search strategies.  相似文献   
52.
棚户区改造的目的是为了改善城市面貌和居民居住环境,提高城市品位和居民生活质量.目前,我国城市开展了大规模棚户区改造工程,然而大多数改造工作重心仍以拆建房屋为主,对棚户区的系统改建不足.针对这一问题,从棚户区改造与城市再生的关系入手,结合国内外大量棚户区改造的经验与教训,强调棚户区的改造不仅是单纯意义上的物质再生,更是涵盖经济复兴、社区重构、文化重建的社会再生.以辽宁省阜新市棚户区改造作为实证案例进行分析,指出当前棚户区改造中存在的诸多问题.在棚户区改造中,需要将建筑、就业、环境、文化、社会等因素融合一起,以促进城市再生与可持续发展.  相似文献   
53.
Collections of mature medusae from Lake Rotoiti proved all to be male and provide further evidence that the origin of the species in New Zealand was from a very limited introduction.  相似文献   
54.
55.
塔里木盆地塔中地区下古生界二次生烃的类型及其特征   总被引:10,自引:0,他引:10  
塔中地区下古生界碳酸盐岩烃源岩中的干酪根、吸附有机质、包裹体有机质和晶包有机质,可以成为二次生烃的物质来源。该地区存在两类二次生烃——构造运动二次生烃和碳酸盐岩深埋二次生烃,二者所形成的包裹体在类型、数量、大小、气液比、荧光颜色及强度等方面均有明显不同。通过对塔中地区多口探井和人工井的埋藏史和生烃史研究,表明塔中北斜坡下古生界碳酸盐岩可以二次生烃,面积约9000km^2,生烃时代主要为中新生代。此外,还利用逐级升温爆破—气相色谱方法,测定了高过成熟碳酸盐岩烃源岩中吸附有机质、包裹体有机质以及晶包有机质的数量和释放过程,以评价高过成熟碳酸盐岩烃源岩的生烃能力。研究塔中地区的二次生烃,对深部油气勘探有着重要的现实意义。  相似文献   
56.
福建省永安市西洋镇2.5 a生人促阔叶林分平均胸径、树高、密度、单位面积蓄积量和平均年生长量分别为2.0 cm、1.8 m、19 533 株/hm2 、7.0 m~3/hm~2和2.80 m~3/(hm~2·a),乔木层物种丰富度R、多样性指数SW、均匀度E和生态优势度ED分别为33、2.93、0.62和0.21,林分相对直径分布范围0.25-3.00,直径分布为反J型,表现为异龄林特征.35 a生的伐前林分平均胸径、树高、密度、单位面积蓄积量和平均年生长量分别为13.6 cm、10.5 m、1 185 株/hm2 、101.3 m~3/hm~2和2.89 m~3/(hm~2·a),乔木层物种丰富度R、多样性指数SW、均匀度E和生态优势度ED分别为24、3.72、0.81和0.10,林分相对直径分布范围0.44-2.50,直径分布为反J型,表现为异龄林特征.  相似文献   
57.
A 24 hour time series survey was carried out during a spring tide (tidal range ca.2 m) of May 1995 on a tidal estuary in the Seto Inland Sea, Japan, in the context of an integrated program planned to quantify the dynamics of biophilic elements (carbon, nitrogen and phosphorus) and the roles played by the macrobenthos on the processes. Three stations were set along a transect line of about 1.4 km, which linked the river to the rear to the innermost part of the subtidal zone. Every hour, at each station, measurements were made of surface water temperature, salinity and dissolved oxygen concentration, and surface water was collected for the determination of nutrients [NH4 +−N, (NO3 +NO2 )−N, PO4 3−−P and Si (OH)4−Si]. During the ebb flow, riverine input of silicate and nitrate+nitrite significantly increased the concentrations of both the intertidal and the subtidal stations. Conversely, during the high tide, river nutrient concentrations were lowered by the mixing of fresh water with sea water. As a result, best (inverse) correlations were found at the river station for salinity against silicate (y=-2.9 Sal.+110.7,r 2=0.879) and nitrate+nitrite (y=-1.3 Sal.+48.4,r 2=0.796). In contrast, ammonium nitrogen concentrations were higher at intermediate salinities. Indeed, no significant correlation was found between salinity and ammonium. The effect of the macrobenthos, which is abundant on the intertidal flat, is discussed as a biological component that influences the processes of nutrient regeneration within the estuary. The effect of the tidal amplitude is an important one in determining the extent of the variations in nutrient concentrations at all three stations, which were stronger between the lower low tide and the higher high tide.  相似文献   
58.
研究了顶芽、节数和埋藏深度对穗花狐尾藻、黑藻、篦齿眼子菜、菹草、金鱼藻和轮藻等6种沉水植物断枝再生能力的影响.结果表明,顶芽显著抑制了菹草的断枝再生能力,但是对其它5种植物没有显著影响;随着节数增加,断枝萌生再生枝和根的能力显著增强,总体上,5节以上的断枝具有明显更强的再生能力;穗花狐尾藻和6节以下的黑藻在埋藏条件下没...  相似文献   
59.
张婧  潘炜  闫连山  罗斌 《海洋学报》2010,32(10):7002-7007
针对基于光纤自相位调制效应的多波长全光再生系统,分析了光纤平均色散对再生器品质因子改进量的影响,提出一种色散管理优化方法.由于波长间色散差异会导致再生系统性能的稳定性下降,通过选择色散补偿光纤和单模光纤的长度,使其合成的色散曲线与各波长分别达到最优再生性能时对应的色散曲线近似拟合,同时保证该色散曲线落在性能满意度高的色散区域,然后调整信号输入功率和滤波器的偏移量,可有效改善多波长再生性能的稳定性,实现再生器的色散管理优化.  相似文献   
60.
The results from four cruises(Nov.1991—Jul.1992)to examine fluxes of ammonium uptake andregeneration in the surface layer of Jiaozhou Bay are presented.Seasonal variations of the two fluxeswere in the order:summer>spring>autumn>winter.Diel patterns were characterized by higher uptake inthe daytime and higher regeneration at night.Averaged uptake and regeneration fluxes on an annual scalewere 0.073 and 0.053 μmol·L~(-1)·h~(-1)respectively.Regeneration fluxes were always less than uptakefluxes throughout the year.The longest turnover time was 16.34 d(in winter),and the shortest one was0.68 d(in summer).The major uptake flux was contributed by the smallest fraction-picoplankton.Theextents of light-dependence of ammouium uptake by different size fractions were in the order:netplankton>nanoplankton>picoplankton..  相似文献   
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