风筛式清选装置筛面气流场试验

在DFQX-3型物料清选仿真试验台上,通过空间布点测量了筛面不同位置的气流速度.根据测量值得出筛面上流速小于或等于4.81m/s,属低速气流.利用Matlab绘制了筛面不同位置的横断面、纵断面、水平面的等速线和速度变化曲线,分析了风筛式清选装置的筛面气流场速度分布规律.试验表明,筛面两侧的流速对称分布,前后两端流速较接近,中间流速变化复杂.     

Estimating chlorophyll content from hyperspectral vegetation indices: Modeling and validation

Leaf chlorophyll content, a good indicator of photosynthesis activity, mutations, stress and nutritional state, is of special significance to precision agriculture. Recent studies have demonstrated the feasibility of retrieval of chlorophyll content from hyperspectral vegetation indices composed by the reflectance of specific bands. In this paper, a set of vegetation indices belonged to three classes (normalized difference vegetation index (NDVI), modified simple ratio (MSR) index and the modified chlorophyll absorption ratio index (MCARI, TCARI) and the integrated forms (MCARI/OSAVI and TCARI/OSAVI)) were tested using the PROSPECT and SAIL models to explore their potentials in chlorophyll content estimation. Different bands combinations were also used to derive the modified vegetation indices. In the sensitivity study, four new formed indices (MSR[705,750], MCARI[705,750], TCARI/OSAVI[705,750] and MCARI/OSAVI[705,750]) were proved to have better linearity with chlorophyll content and resistant to leaf area index (LAI) variations by taking into account the effect of quick saturation at 670 nm with relatively low chlorophyll content. Validation study was also conducted at canopy scale using the ground truth data in the growth duration of winter wheat (chlorophyll content and reflectance data). The results showed that the integrated indices TCARI/OSAVI[705,750] and MCARI/OSAVI[705,750] are most appropriate for chlorophyll estimation with high correlation coefficients R² of 0.8808 and 0.9406, respectively, because more disturbances such as shadow, soil reflectance and nonphotosynthetic materials are taken into account. The high correlation between the vegetation indices obtained in the developmental stages of wheat and Hyperion data (R² of 0.6798 and 0.7618 for TCARI/OSAVI[705,750] and MCARI/OSAVI[705,750], respectively) indicated that these two integrated index can be used in practice to estimate the chlorophylls of different types of corns.     

Desiccation and cracking behaviour of clay layer from slurry state under wetting-drying cycles

Laboratory tests were conducted to investigate the effect of wetting-drying (W-D) cycles on the initiation and evolution of cracks in clay layer. Four identical slurry specimens were prepared and subjected to five subsequent W-D cycles. The water evaporation, surface cracks evolution and structure evolution during the W-D cycles were monitored. The effect of W-D cycles on the geometric characteristics of crack patterns was analyzed by image processing. The results show that the desiccation and cracking behaviour was significantly affected by the applied W-D cycles: the measured cracking water content θ_c, surface crack ratio R_sc and final thickness h_f of the specimen increased significantly in the first three W-D cycles and then tended to reach equilibrium; the formed crack patterns after the second W-D cycle were more irregular than that after the first W-D cycle; the increase of surface cracks was accompanied by the decrease of pore volume shrinkage during drying. In addition, it was found that the applied W-D cycles resulted in significant rearrangement of specimen structure: the initially homogeneous and non-aggregated structure was converted to a clear aggregated-structure with obvious inter-aggregate pores after the second W-D cycle; the specimen volume generally increased with increasing cycles due to the aggregation and increased porosity. The image analysis results show that the geometric characteristics of crack pattern were significantly influenced by the W-D cycles, but this influence was reduced after the third cycle. This is consistent with the observations over the experiment, and indicates that the image processing can be used for quantitatively analyzing the W-D cycle dependence of clay desiccation cracking behaviour.     

不同小麦品种对土壤重金属镉吸收能力初探

In order to select the low accumulation wheat varieties on the soil heavy metal contaminated plots, 14 representative wheat varieties were selected for field experiments in this study. The results showed that with the increase of cadmium concentration in the soil, the cadmium content of different varieties of wheat grains was also increasing, which had a high risk of planting wheat exceeding the standard. In this experiment, 11 varieties of wheat grain cadmium exceeded the standard, and 3 varieties met the safety standard. When the soil cadmium concentration reached 6.07mg / kg, the increasing trend of cadmium content in the stalk was obvious, indicating that the wheat reduced the transfer of cadmium to the grain, which may be related to the genetic shape of the plant. The stalk transfer coefficient of Xinwheat 26 was the largest and the grain transfer coefficient of Benong 207, indicating that high cadmium stress inhibited cadmium transfer across parts of the crop.     

山羊内毒素休克时山莨菪碱对肾脏自由基代谢的影响

３６头杂交山羊随机分成３组,每１组静脉注射生理盐水作为对照;第Ⅱ组静脉注射大肠力（Ｏ１１１Ｂ４）内毒素,１８００Ｕ／ｋｇ,注射两次,间隔２４ｈ;第Ⅲ组处理同第Ⅱ组,但于第２次注射内毒素１０ｍｉｎ静脉注射山莨菪碱２．５ｍｇ／ｋｇ。分别于试验后第５和１２ｈ各组剖杀６头,检测肾组织中丙二醛（ＭＤＡ）含量和抗氧化参数。结果表明：第Ⅱ组肾组织ＭＤＡ含量明显升高,谷胱甘肽过氧化物酶（ＧＳＨ－ＰＸ）、谷胱甘肽还     

抗伤寒杆菌Fe—SOD血清对志伤寒杆菌攻击小鼠的免疫保护作用

目的：制备兔抗伤寒杆菌Ｆｅ－ＳＯＤ血清,并研究其对鼠伤寒杆菌攻击小鼠的免疫保护作用,探讨ＳＯＤ与沙门氏菌致病性的关系。方法：用纯化的伤寒杆菌Ｆｅ－ＳＯＤ免疫家兔,制备兔抗ＳＯＤ血清,并用ＥＬＩＳ法检测抗血清效价;免疫电泳、双向琼脂扩散试验和抗血清对酶活笥抑制试验检测抗血清的特异性。将所制备的抗血清与鼠伤寒杆菌混合,放３７℃３０ｍｉｎ,经腹腔注入小鼠体内,并观察３天和７天小鼠的存活情况,以确定抗血清     

水稻根系建成对高产形成的模拟模型与调控决策研究Ⅱ.水稻根系生理参数与产量形成关系及其模拟模型研究

研究了水稻根系生理参数与产量形成之间的关系,结果表明齐穗期上位根的根表面积密度和活性表面积密度与叶片含氮量、每蔸有效穗数及水稻籽粒产量呈显著正相关;水稻产量与成熟期的根系活力也有较好的相关,与土壤生物量的关系品种间表现不一,并对水稻根系参数与产量形成的定量关系进行了讨论.     

烤烟栽培若干农艺措施的产质效应：Ⅱ.农艺措施与烟叶品质

中、上等烟叶量和烟叶化学成分是反映烤烟品质的二个主要的方面．打顶时期和单株留叶数是影响烤烟品质的主要农艺因素．现蕾和现蕾前打顶留２０叶，中、上等烟叶率稳定在８０％左右；现蕾和现蕾前打顶，增施氮肥提高中、上等烟叶量．烟叶中烟碱和糖的含量可变性较大，全氮、钾等含量可变性较小．打顶早、留叶数较少时．烟碱和全氮含量较高；留叶较多时增施氮肥，有使烟碱含量增高趋势．含糖量以现蕾打顶处理的较高，与施氮量、密度不呈相关趋势．早打顶、较少留叶可提高烟叶含钾量．本试验条件下．Ｎ（９０）水平现蕾留２０叶打顶为烤烟优质丰产优化组合．     

特征线法在燃气管道动态模拟中的应用

对燃气管道不稳定流进行了研究，推导了了计算管内燃气流动的特征线法和公式。特征线法从基于流体力学基本原理推导出来的连续性方程、动量方程和能量方程出发，将难以求解的偏微分方程组转移为便于工程数值计算的等价差分方程组，从而解决了燃气管道中快瞬交流的计算问题。特征线法物理概念明确，数学分析严谨，计算精度高。     

棉花产量与纤维品质的典型相关分析

1986～1989年,运用典型相关分析方法,研究了50个品种(系)和三个杂交组合 F_2、F_3、F_4代皮棉产量与纤维品质这两组性状的相关关系。结果表明:(1)皮棉产量与纤维品质间存在相关关系,这与前人报道相一致;(2)遗传背景不同,构成产量与纤维品质之间相关性的主要原因也不同。品种(系)群体,主要是皮棉产量与2.5%跨距长度间关联性引起的;组合Ⅰ和Ⅱ,主要是单株结铃数与比强度之间的关联性引起的:组合Ⅲ,主要是单铃籽棉重与麦克隆值之间的关联性造成的。讨论了典型相关分析结果对选择的指导意义,并提出了棉花产量与纤维品质相关性的一般规律与特殊规律的概念。