电控柴油机泵喷嘴技术

为了提高柴油机的动力性、燃油经济性,降低排放(浮游颗粒PM和NOx)和噪声,优良的混合气准备是解决以上问题的关键因素。这要求高效喷射系统产生高喷射压力,确保燃油雾化良好,并且还必须精确控制喷油始点和喷油量。研究结果表明,本文介绍的泵喷嘴技术可以满足这一严格要求。泵喷嘴技术的关键是把喷油泵和喷嘴合成一体,以省去高压油管并获得高喷射压力。     

拖拉机悬挂机组动态性能的计算机模拟

从力调节犁耕机组的实际外载出发,对机组的动态工况进行计算机模拟,并提出了评价机组性能的几项主要指标。经过试验对比,考核方法的可行性,并通过算例,对拖拉机牵引性能的预测进行初步尝试。     

提高春玉米主产区玉米单产的技术途径

针对制约春玉米单产进一步提高的主要因素,研究了发展耐密型玉米单交种,推行"夏季深松、春季不翻动土壤直接播种"的保护性耕作技术,坚持基肥、种肥与追肥相结合施肥原则,增加钾肥用量,将追肥期后移,增加追肥深度,改善与提高耕地质量等提高春玉米主产区玉米单产的主要技术途径。     

论基层农业科技单位的科技创新与成果转化

通过对科技创新和成果转化状况的分析,认为基层农业科技单位是中国农业科技创新和科技成果转化的重要力量;但基层农业科技单位面临规模小负担重,资金不足人才匮乏,竞争能力不强等诸多问题。面对这一现状,基层农业科技单位唯有积极探索机制改革,强化科技创新,加速成果转化才能得以生存、发展和壮大。     

Future land utilization and management for sustainable crop production

Soil cultivation caused a great change in the ecological state, from a situation with the soil surface protected by vegetation to a situation with bare soil exposed to climatic forces during part of the year. Annual crops require annual soil cultivation, and the increased mineralization of organic matter and the loss of soil productivity by erosion, leaching and other degradation processes remain a problem for sustainable food production. The challenge for the future is to manage the agricultural landscape in units which are catchments. These units would contain intensively drained and cultivated areas, permanent vegetation zones, as well as natural and constructed wetlands working as condensors and self-purifying units. The management would be differentiated according to a land suitability approach with intensity of use based on productivity and requirements for maintenance of environmental quality.     

在粮食单产预测中应用马尔柯夫链——以吉林省为例

以1981~2006年共26年的统计资料为实例,用加权的马尔柯夫链模型预测和分析了吉林省未来粮食生产的丰欠年景。     

绵农6号小麦分蘖成穗特性研究

经过品种×密度2因素3水平田间试验,对绵农6号等3个小麦品种分蘖成穗特性进行了初步观察。结果表明,绵农6号单株分蘖数为2.08~4.76个,分蘖成穗率为54.3%~59.3%,均低于对照品种绵阳20号。与对照单株分蘖力的差异主要表现在有效分蘖期(12月20日前)。绵农6号主茎与分蘖穗重差异较小,茎蘖cv为14.0%~15.7%。穗粒数、千粒重及单穗重明显较高,分别为:42.1~58.2粒、43.0~50.3g、1.84~2.93g,突出地表现了大穗大粒、穗重型品种的特性。在大面积生产上要获得高产,其种植密度应低于绵阳20号等品种。     

有机无机肥配施改土增产效果定位研究

本研究根据8年试验资料,综合分析了在中上肥力双季稻田,两季采取早稻亩施2000公斤紫云英晚稻2000公斤鲜猪粪(M),各季与有机肥等量的氮磷钾化肥(F),及半量(M+F),M+F,三分之一的(M+F)等方式单施或配施,对水稻产量、养分平衡和有机质含量、土壤腐殖质组成、土壤结构、土壤生物性质等的影响。     

柴河流域典型景观类型土壤氮磷含量的空间变异特征

为了从流域尺度了解柴河流域土壤氮、磷含量的空间变异特征,在柴河流域选择6个景观类型,并根据每个景观类型内不同土地利用方式及景观位置,共进行了72个样点的表层土壤采集,并对土壤有机质、氮、磷含量进行了测定。结果表明,磷素主要以磷矿区及富磷区林地区域含量较高,其中磷矿区土壤全磷含量平均高达20 g/kg,富磷区林地有效磷含量平均为3 687.7 mg/kg;而氮素则表现为沟渠和柴河河道底泥的含量较高,柴河底泥中全氮及碱解氮含量高达2.99 g/kg和631.8 mg/kg。相同景观类型下不同土地利用方式土壤氮磷含量在富磷区、坡耕地及坝平地均表现出较高的差异。嵌套方差分析表明景观类型及土地利用方式或所处的景观位置对土壤有机质及氮磷含量均具有显著的影响。以上结果表明柴河流域内土壤养分含量空间变异程度较高,不同景观类型和土地利用方式共同决定了土壤氮磷含量的变异。因此,在面源污染输移风险评估及防控时应同时结合景观类型及土地利用类型进行分析,并在此基础上探讨主要影响因素。     

The origin of the A genome donor of wheats (Triticum: Poaceae) – a perspective based on the sequence variation of the 5S DNA gene units

In a prior study on the haplomes of wheat using the 5S rRNA gene we assigned the long A1 and short A1 unit classes to the A haplome in the diploid T. monococcum. The short A1 unit class is absent in the tetraploids T. turgidum and T. timopheevii and in the hexaploid T. aestivum, although present in the hexaploid T. zhukovskyi. Both T. turgidum and T. aestivum contained a different 5S DNA unit class labeled the short A2.The purpose of this paper was to study the short A2 units in the two diploid species to shed light on the theory that the A haplome donor of T. turgidum and T. aestivum was T. urartu. Fifty eight clones were obtained from 12 accessions, sequenced and analyzed. As expected T. baeoticum, which is often classified as a subspecies of T. monococcum, contained the long A1 and the short A1 5S DNA units. Unexpectedly, T. urartu had the long A1 and the short G1 unit classes instead and other units not found so far in Triticum. These findings support the hypothesis that the donor of the A genome in T. zhukovskyi was T. monococcum, as identified by the short A1 units. However, the short A1 units are absent in T. timopheevii, also a carrier of the A genome. The short G1 units found in T. urartu also identify it as a possible donor of the G genome to T. timopheevii. The short G1 units were also found in T. aestivum in our prior study. The long G1 unit class was not found in T. urartu but reported from T. timopheevii and T. zhukovskyi. The implications of these and related findings on the evolution of wheats are discussed.