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991.
992.
本研究以胰岛素样生长因子Ⅰ(insulin-like growth factors-Ⅰ, IGF-Ⅰ)基因作为候选基因,运用PCR-RFLP法检测基因变异,并分析其变异与鸡末期产蛋性能的相关性。以绿壳蛋鸡(n=113)作为试验材料,对IGF-Ⅰ基因5'调控区进行遗传多样性研究。研究结果表明,该调控区扩增产物经PstⅠ酶切后出现AA、AB、BB共3种基因型,经χ2检验绿壳蛋鸡在IGF-Ⅰ位点上符合Hardy-Weinberg平衡状态(P>0.05)。相关分析表明,IGF-Ⅰ基因5'调控区PstⅠ位点对于产蛋末期(14和15月龄)的产蛋性能没有显著影响(P>0.05)。 相似文献
993.
阐述基本实现农业机械化应坚持的基本思想;明确了基本实现农业机械化的内涵、标志和评价指标体系建立的基本原则;初步构建了评价体系的基本框架。 相似文献
994.
针对安庆市5处景观水体现状进行调查研究,并对其水域水体进行取样分析,测定COD,浊度,NH3-N,DO,BOD55项水质指标,进行分析对比。根据分析结果提出相应的可行性治理措施。 相似文献
995.
Abstract A fish‐based assessment method was developed to estimate the ecological status of boreal rivers. Electric fishing data were collected from 902 rapids, together with information on the land use, channel modification and water chemistry. Discriminant function analysis was used to select fish variables that most correctly classified the undisturbed reference sites and human impacted sites into exact classes. The relationship between the level of human alteration and fish metrics was examined. Five metrics were selected for the index: the number of fish species, proportion of sensitive species, proportion of tolerant species, density of cyprinid individuals and the density of age‐0+ salmonids. The value for each metric (between 0 and 1) was calculated according to a point estimate for classical probability. The index is used to estimate the ecological classification of rivers according to the EU Water Framework Directive. 相似文献
996.
997.
以双歧杆菌完整肽聚糖为模型药物,胆固醇和卵磷脂为脂质体的成膜材料,纳米Fe3O4为磁性材料,采用薄膜法、逆向蒸发法和高压均质法制备磁性脂质体,比较三种方法制备的磁性脂质体的优劣,并对其经口饲喂小鼠的血液生化进行分析.结果表明,采用薄膜法制备的磁性脂质体密度较高,逆向蒸发法制备的磁性脂质体密度较低,高压均质法制备的磁性脂... 相似文献
998.
Although crop residue management is known to affect near‐surface soil physical quality, little is known about the temporal variability of these indicators over short time intervals. This study evaluates the temporal changes of nine indicators of soil physical quality. These are organic carbon content, structural stability index, bulk density, macroporosity, air capacity, relative field capacity, plant available water capacity, Dexter's S‐index and saturated hydraulic conductivity. A second set of soil physical indicators, based on the distribution of soil pore volume, was also evaluated. The indicators were determined in three different times during the growing cycle of winter durum wheat cultivated within a long‐term field research carrying out in Southern Italy and comparing two types of crop residue management, that is, burning (B) and soil incorporation (I). Only the bulk density changed over time for both treatments, although the air capacity also changed for the incorporation of wheat residues. Residual effects of the autumnal soil tillage and soil compaction were a common source of variability, irrespective of which treatment was used. Based on the existing guidelines for evaluating the physical quality of these agricultural soils, optimal or near‐optimal values were detected in about half of the cases under consideration. This suggests that both B and I create sufficiently good conditions for crop growth during the crop cycle. The comparison between observed and optimal soil pore distribution function was always poor. The pore volume distributions showed lower densities of small pores and relatively higher densities of large pores than the proposed optimal distribution. This study also suggests that the considered optimal or references curves probably cannot be applied successfully to a wide range of agricultural soils. 相似文献
999.
农业网站评价方法与评价指标体系研究 总被引:2,自引:0,他引:2
互联网技术的迅速发展推动了科技的进步与信息的迅速传播,农业网站利用现代技术服务"三农"、推动产业升级,是现代农业发展的重要体现和重要标志。通过对当前农业网站建设情况的分析,结合农业行业特点,总结了开展农业网站评价的方法与原则,提出了一套适合农业网站的评价指标体系,为农业网站建设提供参考。 相似文献
1000.
《Communications in Soil Science and Plant Analysis》2012,43(12):1391-1398
Abstract A short hand notation for depicting inped soil macropores is presented. By utilizing symbols for macropore diameter, facial shape, pore length, inped shape and pore orientation; it is possible to quickly portray inped field macropores. Circles, ellipses, and triangles of differing dimensions are used to symbolize round, elliptical, and irregular facial shaped pores of different diameters. The pore length and orientation are symbolized by line length and line direction. The inped shapes (spherical, tubular, and elongated) are respectively represented by one line, two parallel lines, or three parallel lines within or intersecting the pore shape symbols. Field application of this methodology saves time and is valuable when numerous inped pores need to be depicted. 相似文献