冬小麦叶片水势、气孔阻力、蒸腾速率与环境因素的关系   总被引：1，自引：0，他引：1  

康绍忠  刘晓明  王振镒 《灌溉排水学报》1991,(3)

本文依据田间试验资料,分析了冬小麦叶片水势、气孔阻力和蒸腾速率在不同土壤基质势条件下的日变化规律,探讨了其与土壤基质势和天气条件(光照强度、净辐射、饱和差、气温)之间的关系,建立了叶片水势、气孔阻力、蒸腾速率与环境因素间的定量关系式。  相似文献   

〗Effects of PPAR-α silence on ET-1 induced myocardial hypertrophy and PI3K/Akt/GSK3β-NFATc4 signal pathway     

LI Rui-fang  LE Kang  GAO Jie  YANG Guo-qing  BAO Ying-xia  LIU Pei-qing 《园艺学报》2009,25(12):2289-2294

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Variability in energy partitioning and resistance parameters for a vineyard in northwest China     

Sien Li  Fusheng Li  Shaozhong Kang 《Agricultural Water Management》2009,96(6):955-962

Grapevines are extensively grown in the semiarid and arid regions, but little information is available on the variability of energy partitioning and resistance parameters for the vineyard. To address this question, an eddy covariance system was applied to measure energy balance over a vineyard in northwest China during 2005-2006. Result indicated that 2-year average Bowen ratio (β) of vineyard was 1.0, canopy resistance (r_c) 289.3 s m⁻¹, aerodynamic resistance (r_a) 9.7 s m⁻¹ and climatological resistance (r_i) 117 s m⁻¹. This implied that the annual energy was split almost equally between sensible heat and latent heat. Compared to the corresponding values in other ecosystems reported by Wilson et al. [Wilson, K.B., Baldocchi, D.D., Aubinet, M., Berbigier, P., Bernhofer, C., Dolman, H., Falge, E., Field, C., Goldstein, A., Granier, A., Grelle, A., Halldor, T., Hollinger, D., Katul, G., Law, B.E., Lindroth, A., Meyers, T., Moncrieff, J., Monson, R., Oechel, W., Tenhunen, J., Valentini, R., Verma, S., Vesala, T., Wofsy, S., 2002. Energy partitioning between latent and sensible heat flux during the warm season at FLUXNET sites. Water Resource Research 38, 1294-1305.], the vineyard had a higher β, r_c and r_i than deciduous forests, corn and soybean, and grassland. Such difference was mainly attributed to (1) serious water stress in 2005, which resulted in a greater r_c up to 364.4 s m⁻¹; (2) sparse canopy with row spacing of 2.9 m and plant spacing of 1.8 m; (3) warm-dry climate and high attitude (1581 m) along with higher r_i and lower psychrometer (54 Pa K⁻¹) in the arid region of northwest China. These characters of vineyard revealed varying process of energy partitioning and surface resistance, and provided a scientific basis in understanding and modeling water and energy balance for the vineyard in the semiarid and arid regions.  相似文献   

Relationship between stable carbon isotope discrimination and water use efficiency under regulated deficit irrigation of pear-jujube tree   总被引：2，自引：0，他引：2  

Ningbo Cui  Taisheng Du  Shaozhong Kang  Fusheng Li  Xiaotao Hu  Mixia Wang  Zhijun Li 《Agricultural Water Management》2009,96(11):1615-1622

To investigate the relationship between stable carbon isotope discrimination (Δ) of different organs and water use efficiency (WUE) under different water deficit levels, severe, moderate and low water deficit levels were treated at bud burst to leafing, flowering to fruit set, fruit growth and fruit maturation stages of field grown pear-jujube tree, and leaf stable carbon isotope discrimination (Δ_L) at different growth stages and fruit stable carbon isotope discrimination (Δ_F) at fruit maturation stage were measured. The results indicated that water deficit had significant effect on Δ_L at different growth stages and Δ_F at fruit maturation stage. As compared with full irrigation, the average Δ_L at different growth stages and Δ_F at fruit maturation stage were decreased by 1.23% and 2.67% for different water deficit levels, respectively. Δ_L and Δ_F among different water deficit treatments had significant difference at the same growth stage (P < 0.05). Under different water deficit conditions, significant relationships between the Δ_L and WUE_i (photosynthesis rate/transpiration rate, P_n/T_r), WUE_n (photosynthesis rate/stomatal conductance of CO_2, P_n/g_s), WUE_y (yield/crop water consumption, Y/ET_c) and yield, or between the Δ_F and WUE_y and yield were found, respectively. There were significantly negative correlations of Δ_L with WUE_i, WUE_n, WUE_y and yield (P < 0.01) at the fruit maturation stage, or Δ_L with WUE_i and WUE_n (P < 0.01) over whole growth stage, respectively. Δ_F was negatively correlated with WUE_y, WUE_n and yield (P < 0.05), but positively correlated with ET_c (P < 0.01) over the whole growth stage. Thus Δ_L or Δ_F can compare WUE_n and WUE_y, so the stable carbon isotope discrimination method can be applied to evaluate the water use efficiency of pear-jujube tree under the regulated deficit irrigation.  相似文献   

金属板材数控渐进成形螺旋线轨迹生成   总被引：2，自引：1，他引：1  

朱虎  扶建辉  姜在宽 《农业机械学报》2009,40(10):223-226

在分析金属板材数控渐进成形特点的基础上,指出现行等高线运动成形方式存在的问题,提出了一种基于螺旋运动的数控渐进成形方式和基于STL数据模型的螺旋线成形加工轨迹的生成算法。利用顶点偏置方法生成STL模型的等距模型,采用一系列水平面和与Z轴平行的平面分别切割该等距模型,求出其交线的交点,并将其连接成螺旋线成形加工轨迹。算法应用实例表明,该算法能够生成无干涉的螺旋线成形加工轨迹。  相似文献   

提辊式拔棉秆阻力分析   总被引：1，自引：0，他引：1  

郭振华  史建新  康秀生 《农机化研究》2009,31(2)

机械化拔棉秆对提高农业生产效率有重要意义.以提辊式拔棉秆机械的工作部件为研究对象,并对提辊建立数学模型,分析其受力和各项功耗,得出各项阻力在总阻力中所占的比例关系;根据各参数与总阻力之间的数学关系建立函数图像,分析得出影响牵引阻力的主要参数与阻力之间的关系;结合试验,进一步得到提辊参数间的优化组合,为提辊式拔棉秆机械的进一步优化设计提供参考.  相似文献   

直线共轭内啮合齿轮泵齿轮接触强度的有限元分析     

袁丹青  康仕彬  丛小青  刘梦仙 《排灌机械》2009,27(2):111-114

针对采用传统经验公式分析计算齿轮泵齿轮接触强度存在计算过程相当复杂、繁琐,误差较大的问题.在分析齿轮受力情况基础上,采用有限元法对直线共轭内啮合齿轮泵齿轮接触强度进行计算,并与经验公式计算的接触强度进行比较分析.结果表明,两种方法计算结果基本吻合,证实了采用有限元法分析计算的可行性与优越性,为直线共轭内啮合齿轮泵齿轮的设计、选材提供了一种新的方法,具有一定的工程应用价值.  相似文献   

The activation effect of maize pollen polysaccharides on human thoracic cavity macrophages     

JIN Li-qin  LU Jian-xin  YU Kang  YUAN Qian  XIE Ke-jian  WANG Kai-fa  ZHANG Yu-lan 《园艺学报》2000,16(8):726-729

AIM: To study the activation effects of maize pollen polysaccharides(PPM) on human thoracic cavity macrophage (hTMΦ). METHODS: Activities of lactate dehydrogenase(LDH) and acid phosphatase (ACP) in the hTMΦ were detected by automatic biochemical analyzer, and the level of tumor necrosis factor alpha(TNF-α) and interleukin-6(IL-6) in the hTMΦ was analyzed by radioimmunoassay, after hTMΦ were cultured with 0.312, 0.625, 1.250, 2.500, 5.000 mg/mL PPM-RPMI 1640 for 24 and 48 hours in vitro. RESULTS: The activities of LDH and ACP increased in the hTMΦ induced by PPM, and the levels of TNF-α and IL-6 in the hTMΦ induced by PPM increased markedly too. And the induced expression effect of TNF-α and IL-6 is associated with the concentration of PPM, and time for PPM inducing. CONCLUSION: PPM can induce cytokines secretion in hTMΦ, and activate hTMΦ in vitro.  相似文献   

Isolation and characterization of nanocrystalline cellulose from different precursor materials     

Byoung-Min Lee  Joon-Pyo Jeun  Phil-Hyun Kang  Jae-Hak Choi  Sung-Kwon Hong 《Fibers and Polymers》2017,18(2):272-277

Nanocrytalline cellulose (NCC) was isolated using cellulose extracted from two different precursor materials: Eucalyptus globulus and rice straw. The two ground precursor materials were autoclaved with a 10 % NaOH solution at 120 °C for 3 h. The alkali-treated precursor materials were bleached using sodium chlorite/acetic acid and sodium hypochlorite. The bleached precursor materials were acid-hydrolyzed in 65 % (w/w) sulfuric acid at 45 °C for 30-120 min. The changes in the chemical composition of the two precursor materials were studied before and after bleaching by Fourier transform infrared spectroscopy according to the NREL report and TAPPI standards. Hydrolyzates were characterized by X-ray diffractometry, thermogravimetric analysis, Zeta-potential analysis, and transmission electron microscopy. The results revealed that the physical properties of NCC were strongly dependent on the acid-hydrolysis time.  相似文献   

陕西关中地区小麦田禾谷缢管蚜对7种杀虫剂的抗性监测     

黄彦娜  王雅丽  魏静  郭鑫  李兰  王康  陈茂华 《植物保护》2019,45(3):211-214

为明确陕西关中地区麦蚜田间种群对杀虫剂的抗药性现状,采用浸叶法测定了兴平、礼泉、凤翔、岐山、扶风地区麦田禾谷缢管蚜种群对高效氯氰菊酯、溴氰菊酯、吡虫啉、异丙威、毒死蜱、阿维菌素、氟啶虫胺腈等7种杀虫剂的抗性水平。结果表明,禾谷缢管蚜对高效氯氰菊酯的抗性水平最高,其中凤翔种群对高效氯氰菊酯达到高水平抗性(抗性倍数为72.5),岐山和扶风种群对该药产生中等水平抗性(抗性倍数分别为31.4、29.9);5个地区的禾谷缢管蚜对溴氰菊酯、吡虫啉、毒死蜱、异丙威和阿维菌素的抗性水平较低,表现为敏感、敏感性下降或者低抗性;5个地区的试虫对氟啶虫胺腈均表现为敏感。分析认为,高效氯氰菊酯不适合用于关中地区禾谷缢管蚜防治,氟啶虫胺腈作为一种新型杀虫剂,可以在该虫防治中推广使用,吡虫啉、阿维菌素等其他几种杀虫剂可以在禾谷缢管蚜的防治中交替使用。  相似文献