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本文选取51家农业上市公司为研究样本,运用EVA指标评价农业上市公司资本经营绩效。1995,2006年的EVA价值评估结果表明,农业上市公司资本创值水平和经营绩效低下。进一步的因子分析表明,农业上市公司资本创值水平与农业上市公司的盈利能力、资本成本、资产管理效率、企业成长能力以及偿债能力等因子密切相关。因此,改善上述影响因子是提升农业上市公司资本创值能力的合理选择。 相似文献
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文章在阐明我国渔业产业结构现状的基础上,运用灰色动态关联分析方法,对渔业产业重要构成要素与渔业整体的关系进行了分析。最后从捕捞业、养殖业、远洋渔业、水产品加工业、休闲渔业等方面提出了我国渔业产业结构进一步优化的对策。 相似文献
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在畜牧业与养殖业发展过程中存在科技贡献率低、污染严重、收入不高、供给与需求不匹配等问题,结合这些问题的出现,畜牧业和养殖业的融合将有利于解决现代化发展,有利于提高资源利用率,提高肉产品竞争力,实现结构优化,创建出人与自然和谐共生,要青山也要银山的发展策略。从畜牧业与养殖业发展的现状,二者融合的现状,在融合中出现的问题及在未来如何更好地发展畜牧业与养殖业的策略方面进行阐述,为相关人员提供参考。 相似文献
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优化养殖结构池塘增产增收我场第十四分场以池塘养鱼为主,面积247.8亩,其中成鱼池227.8亩,鱼种池20亩。1994年产量和效益实现三个增长。一是产量增,养殖总产142639公斤,比1993年123163公斤增加19476公斤,成鱼单产602.5公... 相似文献
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我国上市公司现金股利分配问题研究 总被引:2,自引:0,他引:2
上市公司股利政策作为一项重要的财务决策,体现了企业各类投资者、管理者等主体之间的利益分配关系,而现金股利政策则是其中非常重要的一种。对这一问题进行探讨,具有深刻的理论和现实意义。面对我国上市公司现金股利分配中存在的问题,文章对其原因进行了深刻的分析并提出了相关的政策建议。 相似文献
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传统张纲张网等渔具网口结构简单,在作业过程中易造成网口网衣皱褶、受力不均并引起网衣破损,网具网目较小引起渔获性能不佳。针对上述问题,提出并试验了对传统张网网口网衣进行剪裁、形成"有翼"结构、并适当放大网目尺寸的技术措施。使用模型试验和海上实测的方法,对试验网和对照网的作业工况、扩张性能及渔获性能进行比较,结果显示试验网的网口网衣扩张、网具总体工况较对照网得到改善,网口垂直扩张增大,网具阻力有所降低;海上生产试验同时也证实了网口的结构优化措施可有效降低张网的破网率,放大网目尺寸可减少小型鱼类和幼鱼渔获。网口结构优化措施在生产实践中得到肯定,为今后开展张网渔业的管理提供了新的思路。 相似文献
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针对规格为40.3 m×(20.8~16.2)m的我国过洋性虾拖渔业四片式虾拖网,基于L_9(3~4)正交表,设计了网身长度(L_b)、下网袖长度(L_w)、侧网宽度(W_S)3种因素各3个水平的正交试验,并利用方差分析检测3种试验因素对网具阻力、能耗系数、L/R(袖端间距与阻力之比)系数影响的显著性,旨在对此种网具的网身长度与网口周长之比(L_b/C)、下网袖长度与网口周长之比(L_w/C)、侧网宽度与上网片宽度之比(W_S/W_U)这3种结构参数进行优化。结果表明,对网具阻力的影响因素由主到次依次是下网袖长度、网身长度、侧网宽度。对能耗系数的影响因素在水平扩张L/S(袖端间距/下纲长度)=0.45时由主到次依次是侧网宽度、网身长度、下网袖长度;但在水平扩张L(袖端间距)=10 m时,下网袖长度为主影响因素。对L/R系数的主影响因素为下网袖长度。此类型网具的L_b/C应比小网目底层拖网略小,但在较大的范围内(0.26~0.38)变化亦不会对网具水动力性能有显著影响。L_w/C=0.31为试验的最佳水平,下网袖长度为3种因素中对网具性能影响最显著的因素。W_S/W_U=0.19为试验的最佳水平,侧网宽度应优先满足虾拖网作业对网口高度的要求,在此基础上,尽量缩小W_S/W_U值,不必拘泥于W_S/W_U结构参数值。 相似文献
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论述了渔业调理结构,优化资源配置是当务之急。当前应抓好渔为产业结构,浅海养殖品种结构,海洋捕捞结构,淡水渔业结构,水产品加工流通领域结构的调整。 相似文献
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Fisheries Science - A part of fishery waste, such as scallop or oyster shells, are utilized for fertilizer, feed, soil conditioner, or fishing ground preparations, and most of the shells from... 相似文献
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海水养殖业自身污染不仅制约了我国海水养殖业的发展,也对养殖区及其毗邻海域的生态环境产生了影响。本文在综述海水养殖自身污染现状的基础上,提出控制海水养殖自身污染的相应对策。 相似文献
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强调认清吉林省池塘环境危害形势并立即采取应对措施,积极主动保护资源环境。分析了吉林省池塘环境危害的主要表现及其对渔业的主要影响。指出首先应提高劳动者素质和自觉性;利用物理、生物、生态等多种方法改善精养塘环境;同时要提高品种档次,增强配套手段,发展设施渔业、扩大出口;提高渔业附加值、向多领域发展;阐述完善有关渔业法规做保障,规范渔业行为。 相似文献
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文章以中国渔业统计年鉴2004~ 2013的统计数据为依据,对河北省渔业经济产业结构的现状进行分析,发现河北省渔业经济三次产业结构不合理,渔业经济过度依赖第一产业,整体上处于发展的低级阶段.提出:缺乏资金和技术;三次产业投资结构不合理;第二、三产业专业化水平低是河北省渔业经济产业结构的主要问题.最后提出要优化渔业经济产业结构应该从科技兴渔、加大对第二、三产业的投资力度、培育产业龙头企业、完善渔业社会化服务体系、大力发展休闲渔业等方面着手. 相似文献
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One strategy for protecting the federally listed fountain darter, Etheostoma fonticola (Jordan & Gilbert), during low flow conditions is the removal of piscine carnivores [in this case, largemouth bass, Micropterus salmoides (Lacepède)]. However, headwater spring communities of the Comal and San Marcos rivers include another potential predator [red swamp crayfish, Procambarus clarkii (Girard)]. Removal of piscine carnivores could produce cascading effects by increasing crayfish consumption of benthic fish. The purpose of this study was to evaluate if piscine carnivore removal will lessen predatory pressure or induce a trophic cascade with crayfish increasing and causing declines in fountain darter. The numbers of fountain darter consumed were quantified among three predator treatments (red swamp crayfish only, largemouth bass only and red swamp crayfish and largemouth bass combined) and vegetation treatments (vegetated and non‐vegetated) at three temperature regimes (18, 22, 27°C). Vegetation had no effect on fountain darter predation. Among temperature trials, largemouth bass only and red swamp crayfish and largemouth bass combined consumed similar numbers of fountain darter, and red swamp crayfish only consumed the least numbers of fountain darter, except at 22°C. Largemouth bass did not consume more red swamp crayfish than fountain darter. Therefore, largemouth bass removal appears to be a viable option for reducing fountain darter predation during periods of low flow. 相似文献
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Francisco Encina‐Montoya Rolando Vega‐Aguayo Alfonso Mardones‐Lazcano Teresa Rueda Alfredo Tello 《Aquaculture Research》2011,42(6):835-843
Galaxias maculatus is an osmeriform native fish of the Southern Hemisphere, in which the crystalline larvae is considered as a luxury delicacy, for this reason, it has been commercially exploited in Chile, Argentina and New Zealand. However, the fisheries have been rapidly decreasing due to the overexploitation and the predation of introduced species. Because of these events, there is a need to determine a carrying capacity for an intensive fish culture. In order to optimize stocking densities for fish culture, this paper proposes objectives to determine oxygen consumption (OC) rates, dissolved oxygen concentrations that produce signs of hypoxia and the average time elapsed between food intake and peak OC in G. maculatus. In the oxygen experiments under routine metabolism conditions, we found that G. maculatus adults and whitebait showed signs of asphyxia at dissolved oxygen concentrations between 1.3 and 2.2 mg L?1 and that adults tolerated dissolved oxygen levels as low as 1.3 mg L?1. The results showed that G. maculatus individuals with an average weight of 0.04 g consumed 0.048 mg O2 h?1, whereas individuals with an average weight of 1.4 g consumed 0.345 mg O2 h?1. Galaxias maculatus increased the OC rate by 31%, from 0.39 to 0.51 mg O2 h?1 g?1, occurring 14 min after food intake. The carrying capacities for industrial cultures of G. maculatus, were estimated using an allometric equation (OC=0.2363 ×W 0.612 ), a water flow rate of 1 m3 h?1 and an input oxygen concentration of 10 mg L?1 at 12 °C. The density culture of whitebait (4 g) can be allowed to reach 8–11 kg m?3; therefore, these stocking densities reduce the risk of hypoxia and mortality, ensuring the appropriate growth and feed conversion rates. 相似文献
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渔民常常会碰到这样的情况:夏季遇到连续的高温天气,正摄食旺盛的鱼类摄食量逐渐减少,且生长缓慢。这到底是什么原因呢?让我们从以下几方面进行分析: 相似文献
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Marcos Antnio da Silva rika Ramos de Alvarenga Franklin Fernando Batista da Costa Eduardo Maldonado Turra Gabriel Francisco de Oliveira Alves Ludson Guimares Manduca Suellen Cristina Moreira de Sales Namíbia Rizzari Leite Vinícius Monteiro Bezerra Stefani Grace da Silva Moraes Edgar de Alencar Teixeira 《Aquaculture Research》2020,51(2):605-615
Feeding strategies of tilapia (initial average weight: 32 g) cultivated with Biofloc technology (BFT) (carbon source: sugarcane, C:N ratio: 6:1) for 56 days were studied. A 4 × 3 factorial experimental design was used with four feeding frequencies (one, two, three and four times a day) and three feeding rates (50%, 75% and 100% consumption in relation to apparent satiety), with four replicates. Lower levels of dissolved oxygen, protein retention rate and body protein content were found in fish fed once a day. The reduction in feeding rate resulted in lower average final weight and reduced growth but promoted a decrease in the concentration of total ammonia nitrogen, solids, hepatosomatic index and body lipids. We found better efficiency of protein utilization at 75% feed. The nutritional value of the floc was not affected by the feeding frequency, and the feeding rate reduction from 100% to 75% did not alter the protein content of the floc. Thus, twice‐daily feeding frequency is sufficient for Nile tilapia fingerlings reared in BFT. Although the feeding rate of 100% satiety has led to better performance, it may not be the best option in BFT due to higher feed conversion and reduction of water quality. 相似文献