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排序方式: 共有249条查询结果,搜索用时 31 毫秒
81.
Ban X Huang B He J Chen Y Zeng H Han L Wang Y 《Plant foods for human nutrition (Dordrecht, Netherlands)》2011,66(2):175-180
The inflorescence of cultivated Coptis chinensis has been valued for tea production for many years in China. The antioxidant activities of C. chinensis inflorescence extracts prepared by various solvents were investigated by using several established in vitro systems: 2,2′-azinobis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS), α,α-diphenyl-β-picrylhydrazyl (DPPH) and superoxide
radical scavenging assays, reducing power assay, and ferrothiocyanate (FTC) and thiobarbituric acid (TBA) assays. The results
showed that the 70% ethanol extract (EE) had the strongest antioxidant activity in vitro among the various extracts. Based on the in vitro results, EE was used to evaluate the antioxidant activity of C. chinensis inflorescence in vivo. The liver and kidney of intoxicated animals showed a significant decrease in superoxide dismutase (SOD), catalase (CAT)
and glutathione (GSH) levels, while the malondialdehyde (MDA) level showed a significant increase. These changes were significantly
reversed after treatment with EE and the standard vitamin E. Thus, the C. chinensis inflorescence may be a valuable natural source that can be applicable to food industries. 相似文献
82.
1983-2009年西安市郊区耕地土壤有机质空间特征与变化 总被引:12,自引:3,他引:9
为充分了解关中农业区土壤肥力状况,该文以西安市郊区的长安区、户县和周至县为例,综合运用地统计学和GIS技术,分析西安市郊区耕层土壤有机质空间特征与变化。结果表明,当前研究区土壤有机质质量分数介于5.80~34.90g/kg,平均15.95g/kg,空间上呈西北低东南高格局。在约450m的采样尺度下,具有中等强度的空间相关性,空间变异性是由地形地貌、土壤质地等结构性因素和施肥、种植制度等人为因素共同作用的。2009年耕地中有机质质量分数6.42%适宜,93.46%偏低,0.12%缺乏,整体水平偏低。按西安市第二次土壤普查有机质分级标准,1983-2009年,81.75%的耕地有机质含量明显提升,2.20%出现不同程度的下降。农户老龄化、土壤性质、农艺措施等是影响当前耕层土壤有机质积累的主要因素。该文可为保养耕地和区域农业生产提供科学依据和实践指导。 相似文献
83.
摘 要:本文针对在玉溪市烤烟生产上常发生的烤烟气候性斑点病问题,从发生原因的内部因素(烟株营养)方面,采用田间调查、采集配对样品与室内检测分析相结合的方法,并以根际土壤及植株各部位叶片等为探索对象,从病害在田间分布及叶片养分变化等方面开展了研究。结果表明,在烤烟初花期气候性斑点病发生叶位以第4-7叶位(由下至上)的叶片发生较多(占83.5%)。发生气候性斑点病的烟株,内因是由于植株N、Ca、Mg含量过高,而K含量不足,从而提高了 N/K、Mg/K及Ca/K比值,导致N、K、Ca、Mg营养不平衡,其根本原因是由于土壤有效N(特别是速效的NO3-N与NH4-N)及交换性Ca、Mg含量过高,有效K含量过低所致。关键词:烤烟;气候性斑点病;土壤养分;烟叶营养 相似文献
84.
2008年以来,我国人造板产品在外贸方面与2007年相比发生了很大变化,其中体现了这样几个重要的特点:一是进、出口数量明显减少;二是价值金额升降摇摆幅度不大;三是价格行情普遍上行。仅就2008年前11个月份我国人造板进口情况的统计数据,来与2007年同期做比较,上述特点及走势完全可以说是大局已定,不会出现根本性的改变了。 相似文献
85.
Igor Pasković Marija Pecina Josip Bronić Slavko Perica Dean Ban Smiljana Goreta Ban 《Communications in Soil Science and Plant Analysis》2018,49(9):1072-1082
The Leccino olive cultivar was grown in pots contained calcareous rendzina soil amended with NPK fertilizer (control treatment) or with further addition of Zeolite A (ZA) containing either zinc (Zn2+) or manganese (Mn2+) (Zn-ZA and Mn-ZA). After one year, vegetative growth and root morphological parameters were measured and elemental analysis was performed on the root, stem, and leaves. Compared to other treatments, the Zn-ZA fertilizer enhanced Zn concentration and total quantity in the root, stem, and leaves, as well as the root diameter. The root volume was greater using Zn-ZA treatment than control treatment. The total quantity of Mn in root and the root length were enhanced when using Mn-ZA compared to control or Zn-ZA treatment. According to the results of this study, it appears that zeolites containing Zn provide favorable conditions for Zn uptake in calcareous soils, while both Zn and Mn zeolites have a positive impact on olive root morphology. 相似文献
86.
Levi Gardner Troy Munro Ezekiel Villarreal Kurt Harris Thomas Fronk Heng Ban 《Fibers and Polymers》2018,19(2):393-402
Chemical treatment of natural fibers is a well-defined means of mechanical property improvement in natural fiberreinforced composites. An understanding of mechanical and thermal properties in these media is essential for evaluating heat transfer, thermal degradation, and overall performance of these composites over their product lifetime. However, very little information is available illustrating the effect of such treatment on the thermal properties of kenaf composites. Also, no study to date has reported the thermal conductivity of individual kenaf fibers. This study reports the effects of fiber treatment (in 6 % NaOH) on thermal transport in unidirectionally oriented kenaf-epoxy composites and individual kenaf fibers. The effective thermal conductivities and thermal diffusivities of chemically treated fiber composites show a general increase over untreated fiber composites (0.210 to 0.232 W/m/K at 28 °C, 0.206 to 0.234 W/m/K at 200 °C). This improvement may be attributed to improved interfacial contact between the fibers and epoxy matrix shown in microstructural images after chemical treatment. The thermal conductivity of individual fibers was evaluated at room temperature using two techniques. Results from both techniques showed slight increases after chemical treatment (0.58±0.53 to 1.0±0.13 W/m/K and 1.2±0.54 to 1.6±0.28 W/m/K) but lacked statistical significance. Any improvement in surface crystallinity after chemical treatment does not appear to affect overall fiber thermal conductivity. A better understanding of thermal transport in kenaf fibers and composites enables better estimation of the performance of these composites in different applications. Moreover, the thermal conductivities of individual fibers are useful in understanding the fiber’s contribution to conduction in different fiber reinforcement configurations. 相似文献
87.
Branimir Urlić Maja Jukić Špika Christine Becker Hans-Peter Kläring Angelika Krumbein Smiljana Goreta Ban 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2017,67(8):748-757
The effect of suboptimal supply of nitrogen (N) and of replacing nitrate in the nutrient solution with ammonia on growth, yield, and nitrate concentration in green and red leaf lettuce was evaluated over two seasons (autumn and spring) using multiple regression analysis. The plants were grown in a greenhouse on a Nutrient Film Technique (NFT) system. Nitrogen concentrations in the nutrient solution were either 3?mM or 12?mM, and the form of N was varied as follows: 100% NO3, 50% NO3?+?50% NH4, and 100% NH4. In both seasons, the biomass (fresh weight) of lettuce heads increased with increasing NO3 concentrations and in autumn, NO3 even at 1.5?mM was sufficient for high yield. However, head dry weight was affected neither by the season nor by changes in the composition of the nutrient solution. The concentration of NO3 had no effect on root dry weight, but it decreased at higher concentrations of NH4. The number of leaves increased as the ratio of NO3 to NH4 in the nutrient solution increased and was higher in autumn because of the longer growth period. Increasing the concentration of NO3 in nutrient solution increased both total N and nitrate concentration in lettuce heads (dry weight) but decreased the concentration of total C. Also, leaf nitrate concentration was lower in spring than in autumn and decreased with increasing NH4 concentration. Nitrogen utilization efficiency was maximum when NH4 levels in the nutrient solution were either 0% or 50% irrespective of the season. Our results thus show that suboptimal N supply in autumn will not affect lettuce yield, and that nitrate concentration in leaves is lower when NH4 concentrations in nutrient solution are higher and also much lower in red lettuce than in green lettuce. 相似文献
88.
89.
90.
通过设置不同pH梯度,研究土壤pH对根肿菌侵染及病害发生的影响。结果表明:土壤酸性时病菌侵染速度快,碱性时慢,而强酸性和碱性土壤条件则抑制孢子萌发;pH为6.0时最有利于根肿菌休眠孢子萌发,萌发率最高,为53.96%;碱性条件可使初级原生质团变形凝结成球状,不能正常分裂或延迟形成游动孢子囊,从而不利于根肿菌侵染。白菜发病率与病情指数随pH升高,呈先上升后下降趋势。其中,pH为5.0时,发病率和病情指数最高,pH 7.0~8.0时发病轻。因此,适宜的偏酸性环境条件下,通过作用于病菌休眠孢子萌发和侵染,提高病害危害程度,而中性或碱性条件干扰该过程并降低病害发生。 相似文献