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991.
目前,国内外测定乳酸和挥发性脂肪酸(VFA)的方法主要是气相色谱法,一般情况下是对乳酸和挥发性脂肪酸分别进行测定,青贮饲料中乳酸和挥发性脂肪酸的同时测定未见报道。采用简便的甲酯衍生化方法,利用气相色谱填充柱.探索出一种能同时快速测定青贮饲料中乳酸和挥发性脂肪酸的方法,以期为青贮饲料的研究提供可靠的分析技术。 相似文献
992.
993.
K. Yan P. Chen H. Shao S. Zhao L. Zhang L. Zhang G. Xu J. Sun 《Journal of Agronomy and Crop Science》2012,198(3):218-225
Gas exchange and chlorophyll a fluorescence transient were examined in leaves of sorghum under salt stress and high temperature. During salt treatment with 50 and 150 mm NaCl, photosynthetic rate (Pn) decreased, which could be ascribed to stomatal limitation. Salt stress had no effect on photosystem II (PSII) activity. At high temperatures, PSII function was inhibited in leaves of sorghum, indicated by the decrease in PSII performance index on absorption base and PSII maximal photochemistry efficiency (Fv/Fm); however, the decrease was lower in salt‐treated sorghum, suggesting that salt adaption enhanced heat tolerance of PSII. The enhanced heat resistance can be expressed on all the components of PSII including reaction centre, donor side and acceptor side. Consistently, a slight decrease in Pn was found in salt‐treated sorghum at high temperatures, indicating that salt adaption also enhanced heat tolerance of photosynthesis. Proline plays an important protective role in plant response to environmental stress, and its large accumulation in salt‐treated sorghum might be the underlying reason leading to the enhanced heat tolerance. As for this pattern of photosynthetic response, sorghum seems to be a reliable crop species for human beings in the face of global warming and increasing salinity of agricultural land. 相似文献
994.
During the vegetative phase of growth of two field bean and two field pea cultivars of different drought tolerance, the effect of short and prolonged soil drought on gas exchange (CO2 i H2O), leaf water potential (ψ), stomatal diffusive resistance (rS), uptake of CO2, and the distribution and accumulation of 14C was studied. Differences in the response to drought conditions between resistant and susceptible cultivars were marked. After 5 days of soil drought, the decrease in net photosynthesis and transpiration rate and the increase of stomatal resistance were greater in the drought-resistant cultivars than in the drought-susceptible ones. In contrast, after 10 days of drought the decrease of leaf PN (CO2 assimilation rate), E (rate of transpiration) and ψ (water potential) was greater in the susceptible cultivars than in the resistant ones. Significant differences between the resistant and the susceptible cultivars were also observed in the assimilation and translocation of 14C by the green parts of the plant. The amount of carbon accumulation in roots in drought-susceptible cultivars increased less than in the drought-resistant cultivars. For treatments in which optimal soil watering was resumed after 5 or 10 days of drought there was no evidence of effects of drought on the majority of measurements, but the drought-resistant cultivars showed a general tendency for a more rapid recovery. Our results confirm the existence of genetic variability in drought tolerance among the cultivars of field bean and field pea. The recorded differences in the response to drought of experimental cultivars may indicate that, under water deficit in the soil and in plant tissues, they may use different strategies to avoid the damaging effects of temporary limitation of water supply; for example, the drought-resistant cultivars may more effectively conserve tissue hydration through effective stomatal closure. Also, the observed changes in carbon assimilation and accumulation might be the reason for their different responses to drought. The change in radioactivity losses in the control and stressed plants may result from the differences in demand for energy to maintain cell structure and function. Similarly, the less intense carbon accumulation in the roots of the sensitive cultivars could be caused by more harmful effects of drought on root growth. 相似文献
995.
996.
E. Ivarsen A. Kjær M. Jensen K. Grevsen L. P. Christensen X. Fretté 《Journal of Agronomy and Crop Science》2013,199(6):395-404
Full‐grown Artemisia annua plants were subjected to chemical and physical stress conditions, and the effect of these on the concentration and chemical composition of essential oil components (EOC) in the leaves was studied. The chemical stress treatments were performed by foliar application of NaCl, H2O2, salicylic acid and chitosan oligosaccharide (COS). The EOC of the leaves were extracted with n‐hexane and identified and quantified by GC–MS and GC–FID, respectively. Approximately 96 % of EOC in the extracts were identified and quantified of which β‐pinene, camphene, germacrene D, camphor, coumarin and dihydro‐epi‐deoxyarteannuin B were the major EOC accounting for about 75 % of the total content of EOC in the extracts. The physical stress treatment, sandblasting of the plants resulted in a significant enhancement in the content of α‐pinene, camphene, coumarin and dihydro‐epi‐deoxyarteannuin B. The total yield of identified EOC in non‐treated plants (control) was 86.2 ± 13.8 μg g?1 fresh weight (FW) compared with 104.0 ± 9.1 μg g?1 FW in sandblasted plants. The chemical stress treatments did not affect the composition of EOC significantly. The results indicate that chemical stress treatments do not affect the concentration and composition of EOC in full‐grown A. annua plants to the same extent as physical stress treatment by sandblasting. 相似文献
997.
随着废弃管道处置工作的深入开展,对于特殊地段不能拆除的废弃管道,在管道清洗后需要通过填充注浆材料防止地面沉降。废弃管道的注浆技术,主要是利用水泥、煤粉灰等注浆材料填充废弃管段,增加管体强度,防止管段受到外力压迫而发生变形或破裂,避免引起地上物的位置移动或地面塌陷。以兰郑长管道改线段为试验对象,根据管道注浆的基本原理,自主调配了注浆材料,基于填充要求进行了注浆现场试验。结果表明:注浆技术能够实现废弃管道填充处置的要求,对特殊地段的防塌陷起到关键作用,是废弃管道处置过程中的重要保障技术。注浆技术在兰郑长管道改线段废弃管道处置工程中的实际效果,为该技术推广应用奠定了基础。 相似文献
998.
指出了蓄热式氧化焚烧技术是目前治理挥发性有机废气较为有效的一项措施。以医药化工有机废气为研究对象,采用气相色谱法分析了特征污染物废气种类及进气浓度,研究了RTO氧化焚烧技术治理有机废气实际运行效果,结果表明:RTO对甲醇削减率达94.8%,四氢呋喃削减率达94.6%,二氯甲烷削减率达95.3%,甲苯和乙醚削减率分别达88.0%和96.8%,且排放浓度满足《大气污染物综合排放标准》(GB16297-2012)。最后结合医药化工行业RTO运行所存实际问题及对应解决方案进行了归纳总结,并对该技术的发展提出了展望。 相似文献
999.
1000.
建立了简单、快速的鲜烟叶中苦参碱的测定方法。样品用0.01 mol/L的乙酸水溶液(pH 3.5)提取,强阳离子交换柱(SCX-SPE)净化,气相色谱-氮化学发光检测器(GC-NCD)测定。通过净化方法比较发现,SCX-SPE法比常规溶剂萃取法具有更好的净化效果。在选定的色谱条件下,苦参碱在0.15~15.0μg/mL范围内,其质量浓度与峰面积之间呈良好的线性关系,决定系数 R2=0.9997。对烟草空白样品进行添加回收试验,在0.05~0.4 mg/kg范围内其回收率在89.5%~91.6%之间,相对标准偏差(RSD)在2.7% ~3.6%之间,检测限(LOD)为0.03 mg/kg,能满足苦参碱在烟草样品中的残留检测。田间试验结果表明:苦参碱的消解动态曲线符合一级动力学方程,其在烟草中的半衰期为7.64 d,属易降解农药。 相似文献