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901.
902.
Lily Maynard 《Environmental Communication: A Journal of Nature and Culture》2018,12(2):177-190
Zoos and aquaria are controversial institutions, vilified by animal rights activists and championed by those who value their entertainment and educational resources. Examining media frames of these institutions can identify public perspectives. A qualitative content analysis was conducted for print and online magazine articles that discussed zoos and aquaria in North America. Sixty-five articles were analysed, and eight different frames were identified. The diverse frames highlight the differing roles of zoos and aquaria. Most of the articles were positive and supportive of zoos; 11% were negative. Animal welfare was the most common frame, from both positive and negative perspectives. Other frames, such as conservation and education, were less prevalent in the sample than expected, since zoos and aquaria portray themselves to be leaders in these fields. The unbalanced media discourse and small publication rate over the four years sampled suggest opportunities for increased media engagement on zoos and aquaria. 相似文献
903.
21世纪以来中国产业扶贫研究脉络与主题谱系 总被引:1,自引:0,他引:1
反贫困历来是发展研究中的最重要议题之一,尤其是进入21世纪以来,产业扶贫已日趋成为具有中国特色的反贫工作重心任务,受到学界和社会的热切关注,因此有必要对其研究脉络与热点主题等内容进行深入探索,以更好地促进产业扶贫实践的发展。本研究以2000—2015年间CNKI数据库收录的1 982篇产业扶贫研究的期刊论文为样本,采用文献计量分析法和可视化知识网络分析工具Cite Space,首先对中国产业扶贫研究总体现状进行了概述,然后着重分析了产业扶贫研究历经的四个演进阶段:初创期、探索期、爆发期和深化期,并描述了研究的整体发展脉络所沿着的四条轨迹,即产业扶贫主体由政府主导逐渐演变为政府主导、市场力量和社会参与并重;扶贫对象由农村贫困地区和人口逐步转向城市贫困人口,农村和城市扶贫两者并重;扶贫渠道由财政资金扶持逐步扩散到科技扶贫、智力扶贫、旅游扶贫等多元化方式;扶贫思路由农村推进向城市扶贫过渡,再到协调区域发展的精准扶贫战略。在此基础上挖掘和探讨了当前研究的热点主题,包括产业扶贫的发展历程、内涵与理论基础、模式与机制、现实困境与对策,以及经济效应等五个方面。最后指出当前研究成果在理论深度与体系构建、实践模式提炼、研究视角和地域、实证研究方法等方面存在不足,并提出了未来重点研究方向需要从高度重视产业扶贫与精准扶贫和参与式治理之间的内在逻辑,加快推进产业扶贫的本土化特色研究,以及鼓励跨学科视角的研究、注重规范研究与实证研究的协同三大方面展开探索。 相似文献
904.
Marija M. Saric-Krsmanovic Dragana M. Bozic Ljiljana M. Radivojevic Jelena S. Gajic Umiljendic 《Journal of environmental science and health. Part. B》2017,52(11):812-816
The effects of field dodder on physiological and anatomical processes in untreated sugar beet plants and the effects of propyzamide on field dodder were examined under controlled conditions. The experiment included the following variants: N—noninfested sugar beet plants (control); I - infested sugar beet plants (untreated), and infested plants treated with propyzamide (1500 g a.i. ha?1 (T1) and 2000 g a.i. ha?1(T2)). The following parameters were checked: physiological—pigment contents (chlorophyll a, chlorophyll b, total carotenoids); anatomical -leaf parameters: thickness of epidermis, parenchyma and spongy tissue, mesophyll and underside leaf epidermis, and diameter of bundle sheath cells; petiole parameters: diameter of tracheid, petiole hydraulic conductance, xylem surface, phloem cell diameter and phloem area in sugar beet plants. A conventional paraffin wax method was used to prepare the samples for microscopy. Pigment contents were measured spectrophotometrically after methanol extraction. All parameters were measured: prior to herbicide application (0 assessment), then 7, 14, 21, 28 and 35 days after application (DAA). Field dodder was found to affect the pigment contents in untreated sugar beet plants, causing significant reductions. Conversely, reduction in the treated plants decreased 27% to 4% for chlorophyll a, from 21% to 5% for chlorophyll b, and from 28% to 5% for carotenoids (T1). Also, in treatment T2, reduction decreased in infested and treated plants from 19% to 2% for chlorophyll a, from 21% to 2% for chlorophyll b, from 23% to 3% for carotenoids and stimulation of 1% and 2% was observed 28 and 35 DAA, respectively. Plants infested (untreated) by field dodder had lower values of most anatomical parameters, compared to noninfested plants. The measured anatomical parameters of sugar beet leaves and petiole had significantly higher values in noninfested plants and plants treated with propyzamide than in untreated plants. Also, the results showed that propyzamide is an adequate herbicide for control of field dodder at the stage of early infestation. 相似文献
905.
以1992~2012年长江流域196个土壤观测站的旬土壤相对湿度资料为基础,通过线性趋势和Kriging插值等方法分析0~50 cm土层土壤相对湿度年际、年内时空分异和季节变化特征,并从气候和NDVI要素探寻其变化原因。结果表明:(1)长江流域年均土壤相对湿度自1992年以来整体上呈波动增加趋势,年际变化倾向率为0.26%/a。江源地区土壤相对湿度增幅大于其他地区。(2)土壤相对湿度表现为东南和西南部较高,东北和西北部较低的空间分布特点。(3)四季土壤相对湿度增加的强烈程度由大到小依次是秋季、冬季、夏季、春季。(4)土壤相对湿度增加的主要原因是潜在蒸发减少和NDVI增加。 相似文献
906.
907.
908.
Deepa R Senthilkumar P Sivakumar S Duraisamy P Subbhuraam CV 《Environmental monitoring and assessment》2006,116(1-3):185-195
The Cu accumulation capacity of stem cuttings of Portulaca oleracea was assessed in two different soils, alfisol and vertisol, which differ from each other mainly due to their clay content~—
several fold lower in the former than in the latter. The DTPA extractable concentration of Cu in soil and the level of its
accumulation in stem cuttings were, therefore, greater in alfisol than in vertisol. In the mixed soils, the DTPA extractable
as well as plant accumulated levels of Cu decreased with an increase in the proportion of vertisol. With an increase in the
soil available and plant accumulated Cu, a decrease has been observed in the ability of stem cuttings to regenerate leaves
and roots. As a consequence biomass reduction has been observed with an increase in the concentration of Cu in the soil and
plant body. In view of comparatively low availability of Cu in vertisol, regeneration of stem cuttings occurred up to a concentration
of 1600 $μ gofCu/gofsoil, whereasinalfisolitoccurredonlyupto200μ g of Cu/g of soil. The results of the present study showed that P. oleracea stem cutting is an accumulator of Cu and the availability of Cu in soils could be manipulated through addition of clay since
the plant available concentration of Cu is less in the soil (vertisol) with high clay content. 相似文献
909.
Sylaios GK Tsihrintzis VA Akratos C Haralambidou K 《Environmental monitoring and assessment》2006,119(1-3):275-301
Vassova lagoon is a typical Mediterranean (small, shallow, micro-tidal, well-mixed) coastal lagoon, receiving limited seasonal freshwater inflows from direct precipitation and underground seepage. An intensive study was carried out in order to quantify the mechanisms responsible for the intra-tidal and residual transport of water, salt, nutrients and chlorophyll at the mouth of this lagoon and to assess the lagoon's flushing behavior. Results indicated that although the system is micro-tidal, tidal effects appeared to be the dominant factor for the longitudinal distribution of physical and chemical parameters, while the associated residual flow is also important and serves as a baseline measure of overall circulation. However, analysis of the net longitudinal currents and fluxes of water, salt and nutrients revealed the importance of non-tidal effects (wind effect and precipitation incidents) in the mean tidal transport. It is shown that the Eulerian residual currents transported water and its properties inwards under southern winds, while a seaward transport was induced during precipitation incidents and northern winds. The Stokes drift effect was found an order of magnitude lower than the Eulerian current, directed towards the lagoon, proving the partially-progressive nature of the tide. Nutrients and chlorophyll-α loads are exported from the lagoon to the open sea during the ebb phase of the autumn and winter tidal cycles, associated with the inflow of nutrient-rich freshwater, seeped through the surrounding drainage canal. The reverse transport occurs in spring and early summer, when nutrients enter the lagoon during the flood tidal phase, from the nutrient-rich upper layer of the stratified adjacent sea. Application of a tidal prism model shows that Vassova lagoon has a mean flushing time of 7.5 days, ranging between 4 to 18 days, affected inversely by the tidal oscillation. 相似文献
910.