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261.
Climate change is increasing water scarcity in Sri Lanka. Whether these changes will undermine national-level food security depends upon the ability of the small-scale farmers that dominate rice production and the institutions that support them to overcome the challenges presented by changing water availability. Analyzing household survey data, this research identifies household, institutional, and agroecological factors that influence how water-stressed farmers are working to adapt to changing conditions and how the strategies they employ impact rice yields. Paralleling studies conducted elsewhere, we identified institutional factors as particularly relevant in farmer adaptation decisions. Notably, our research identified farmers’ use of hybrid seed varietals as the only local climate adaptation strategy to positively correlate with farmers’ rice yields. These findings provide insight into additional factors pertinent to successful agricultural adaptation and offer encouraging evidence for policies that promote plant breeding and distribution in Sri Lanka as a means to buffer the food system to climate change-exacerbated drought. 相似文献
262.
263.
可见光/H2 O2/海藻酸铁非均相催化降解吖啶橙的研究 总被引:6,自引:0,他引:6
由海藻酸钠和氯化铁反应制备了海藻酸铁凝胶小球催化剂,考察了该催化剂的吸附和可见光下催化降解吖啶橙的性能.结果表明催化剂的吸附能力随pH升高而提高,且催化剂用量为40个凝胶小球时,可见光下吖啶橙能够在较宽pH值范围内脱色,脱色速率随H2O2的用量增加而增加,该反应符合Arrhenius规律,其表观活化能为49.6 kJ/mol.自由基清除剂的加入不会降低脱色速率,表明催化反应不是羟基自由基的机理,而与高活性的类{ Fe(Ⅳ)=O}高价铁中间产物有关. 相似文献
264.
对ABR反应器的水力流态进行了示踪剂试验,分析了特征截面面积对ABR水力特性的影响,采用停留时间分布(RTD)法研究了不同进水COD浓度和HRT条件下ABR反应器的水力特性,结果表明不同进水COD浓度时ABR反应器的RTD曲线相似,表明进水COD浓度不是影响ABR水力特性的主要因素;不同HRT条件下RTD曲线差异很大,表明HRT对ABR的水力特性影响较大,随着水力停留时间的延长,N值增大,1/Pe减小,ABR的流态趋于推流流态,随着HRT的缩短,N值减小,1/Pe数增大,ABR反应器趋于完全混合流态. 相似文献
265.
Skoulikidis T Vassiliou P Tsakona K 《Environmental science and pollution research international》2005,12(1):28-33
Goal and Scope In order to realize surface consolidation of Pentelic marble on the Acropolis monuments, we have collected the criteria that have to be fulfilled by the methods and materials without side effects on the marbles (and other stones). When the existing methods and materials did not satisfy the requirements (criteria), we invented new ones.Methods The criteria were collected from the literature, by thermodynamic and kinetic viewpoints, by laboratory experiments and in situ observations on monuments, both in Greece and in several countries in which the various methods and materials were applied. Concerning our method of ‘Inversion of sulfation’, performed by spraying a K2CO3 solution, its concentration and its temperature were controlled in order to have a total inversion (certified by liquid crystals) of gypsum back to CaCO3. For the new material of ours, ‘Reinforced Lime’, in order to eliminate the disadvantages of plain lime (low carbonation rate, low mechanical properties of CaCO3 formed, lack of carbonation in the bulk of lime), measurements of the rate of carbonation were performed in plain lime and in lime with a different CaCO3 concentration beforehand as well as in a different CO2 environments, using DTG and XRD to measure the rate of carbonation. The detachment (kg/cm2) of marble specimens stuck by lime in each case was also measured. A microscope was also used to measure the dimensions of the grain in each case as well as ammonium citrate and thymolphthalein to certify the depth of carbonation in each case. Part of the work was communicated in an international congress.Results A table with the criteria of the selection of the methods and materials for the consolidation of Pentelic marble surfaces (and other stones) was established. None of the employed methods and materials fulfilled the criteria. Only the ‘Inversion of gypsum ‘ and the ‘Reinforced Lime’ were adopted and applied to the Acropolis monuments and to other monuments in Greece and in several other countries.Recommendation and Outlook All criteria must be used for the selection of methods and materials for the consolidation of the monument surfaces. This is why we have already studied with the same procedures, methods and materials for restoration, surface cleaning and protection. 相似文献
266.
A pot experiment was conducted to appraise the hazards of bound residues of metsulfuron-methyl in soil at six levels (0, 0.050, 0.089, 0.158, 0.281, and 0.500 mg kg(-1)) to the growth of four rice varieties (Xiushui 63, Eryou 810, Liangyoupeijiu, and Zhenong 952). The morphological characteristics of rice roots like root number, total length, surface area of rice roots, and rice biomass were determined. The results showed that the bound residues of metsulfuron-methyl in soil impacted the growth of rice. Root number, total length of roots, surface area of roots, and biomass were restrained by bound residues of metsulfuron-methyl in soil. The inhibition rate of root growth increased from 69.46-81.32% to 85.18-95.97% with the increasing of levels of bound residues of metsulfuron-methyl from 0.05 mg kg(-1) to 0.50 mg kg(-1). The number of rice roots could be taken as a sensitive index to screen the rice varieties endurable to bound residues of metsulfuron-methyl in soil and to predict the potential hazards of bound residues of metsulfuron-methyl in soil to rice. The level of bound residues of metsulfuron-methyl in soil causing the root numbers decreased by 50% (IC50) followed the order of Xiushui 63 < Eryou 810 < Liangyoupeijiu < Zhenong 952. 相似文献
267.
268.
活性炭吸附室内空气中挥发性有机化合物 总被引:13,自引:0,他引:13
活性炭吸附室内空气中挥发性有机化合物的10%穿透时间与气相浓度及挥发性有机化合物的种类有关,通过对苯、甲苯和丙酮的实验研究,得出了由高浓度估算室内低浓度时炭床10%穿透时间的经验公式tb,1=tb,h(C0,1/C0,h)^a,其中a值是与炭床性能及挥发性有机化合物种类有关的参数,可通过实验确定。 相似文献
269.
本文介绍了各类防毒服和防毒面具的发展历史、各国的研究情况,对装备的穿戴情况和时机作了简要的概括.最后对未来个人防护装备发展趋势进行展望,阐明了未来装备发展的重点和方向. 相似文献
270.
徐安 《中国安全科学学报》1996,6(3):35-39
对汽车防抱制动系统中制动力矩Tb与车轮滑移率S的收敛特性和收敛区域进行探讨,指出该收敛区域恰与制动稳定区重合,从而可使车辆的制动性能得到极大的改善。同时,还进行了防抱制动系统对道路交通事故影响的分析与研究。 相似文献