不同施肥条件下农田硝态氮迁移的试验研究

NO^-₃-N的淋失是旱地农田氮素损失的重要途径之一，也是引起地下水污染的一个主要原因。在黄土高原地区，夏玉米生长正逢雨季，是NO^-₃-N淋失的主要时期。该研究基于阻水层理论和黄土高原地区传统的垄作习惯，在手工模拟机具成垄压实施肥的基础上研究了该施肥法与传统的平地施肥、垄沟施肥(成垄不压实)条件下土壤NO^-₃-N的迁移动态，结果表明，在供水量相同条件下，由于平地和垄沟条件下水分分布的差异，导致平地土壤中的NO^-₃-N较垄沟耕作易于迁移。在生育前期，由于作物根系对NO^-₃-N的吸收和拦截，成垄压实与成垄不压实施肥对阻止NO^-₃-N随水下移差异不大；生育后期，当作物需肥量减小时，成垄压实施肥能够阻止NO^-₃-N向深层土壤迁移累积。玉米收获后，3种施肥方式下土壤NO^-₃-N迁移深度为平地(>60 cm)>垄沟施肥(>45 cm)>成垄压实施肥(＜35 cm)。     

榆树市玉米宽窄行倒茬平作耕作模式的研究分析及其关键配套机具的探讨

榆树是全省农业机械化重点县(市).文章通过阐述榆树市玉米宽窄行倒茬平作耕作模式、播种方式及深松追肥、对土壤生态属性的影响,分析并探讨榆树市玉米宽窄行倒茬平作耕作模式及关有玉米收割机配套选型的注意事项.     

极晚熟蟠桃新品种‘瑞蟠20号’

 ‘瑞蟠20号’蟠桃是‘幻想’（Fantasia）ב瑞蟠4号’杂交育成的晚熟新品种。花蔷薇型,有花粉。果实扁平形,平均单果质量254.7 g,最大350 g;果肉黄白色,硬溶质,风味甜,可溶性固形物含量13.1%。离核。丰产。果实发育期160 d。     

Larval recruitment of the manila clam Ruditapes philippinarum in Ariake Sound, southern Japan

ABSTRACT: The mechanisms by which catch yields of the manila clam Ruditapes philippinarum have decreased drastically in Kumamoto Prefecture, southern Japan, and the larval recruitment by which benthic populations of the clam are maintained were studied. Samples at different growth stages (planktonic larvae, new settlers, and small to large bivalves of the species) were collected from February 1997 to December 1998 on two tidal flats (Kawaguchi and Nameishi, 20 km distance from each other) along the eastern coast of Ariake Sound. Densities of planktonic larvae, new settlers and small bivalves were generally higher at Kawaguchi than Nameishi. The higher density of large bivalves at Kawaguchi depends on a high larval density. Larval retention mechanisms coupled with water movement at Kawaguchi, such as tidal residual currents, may be related intimately with the higher larval density at Kawaguchi. Predation by shore birds at and after recruitment may be related to the lower density of large bivalves recorded at Kawaguchi in 1998, despite larval densities being higher there.     

Preparation and characterization of melt-spun PVC filament yarns

Polyvinyl chloride (PVC) fibers were melt-spun to prepare mono and multifilament yarns. To find optimum spinning and drawing conditions, various parameters such as spinning temperature, spinneret diameter, drawing temperature, and drawing ratio were examined. From the observation of the spinnability under various conditions, we found that the optimum conditions were as following: the extrusion temperature and die temperature were 175–180°C and 185–190°C, and the drawing temperature and drawing ratio were 85–95°C and 3.4, respectively. Under these conditions, the spinneret diameter could be reduced to the minimum value, 0.5 mm. Spun PVC filament yarns were subjected to the different yarn texturing process of stuffing box and pin false-twist method. The PVC yarn fabric was prepared by the knitting of textured yarns. Finally, the anion-emission and antibiotic properties of the knitted PVC fabrics were precisely evaluated.     

Nutrient and nutritional evaluation of sinasin prepared in two ways

Two types of sinasin, a rice-based fermented kanuri flat bread, were prepared and evaluated for their nutrient content and nutritional qualities. The preparation of the sinasin entailed using traditional and developed methods. The nutritional qualities of the products were evaluated in Wistar-strain albino rats using the Food Efficiency Ratio (FER), and Protein Efficiency Ratio (PER) methods. There was a higher protein content (11.11 percent) in the traditional sinasin than in the developed sinasin (9.93 percent). However, a one-way analysis of variance indicated no significant difference in FER, but a significantly different mean PER (p<0.01) of 1.3 and 1.5 for the traditional and developed sinasin respectively. The two methods of preparation of the sinasin, their nutrient composition and nutritional qualities are described in this paper.     

2BZJ-12型大豆窄行平作精密播种机设计与性能试验研究

文章针对窄行密植平作栽培模式农艺技术特点,结合我国北方大豆主产区自然条件与生产实际,研制适合该农艺要求的大型气吸式窄行密植平作高速精密播种机.该播种机设计播种施肥一体化结构形式单元组,攻克单元组机构整体仿形与防堵、高速精密播种、精量分层侧深施肥等关键技术.通过田间性能试验,各部件研制和整机机构设计合理,各项指标达到《中耕作物精密播种机产品质量分等》标准中一等品要求,施肥位置满足农艺要求.促进大豆窄行密植平作高产栽培技术规范化应用,为我国大豆产业的发展提供装备技术支撑.     

施用生活污泥改良滩涂土壤理化性状的探讨

采用符合土地改良用标准的生活污泥为材料,通过田间小区随机区组试验,研究了生活污泥的不同施用量（0、75、150、300、600 t/hm2）对滩涂土壤部分理化性质的影响。结果表明,施用生活污泥可显著改善滩涂土壤的理化性状。随着污泥施用量的提高,滩涂土壤的容重、密度、pH值逐渐下降,有机质、全氮、全磷、速效氮、速效磷、CEC均呈上升趋势,全钾、速效钾无显著变化。滩涂土壤的细菌、放线菌数量随污泥施用量的提高呈上升趋势。     

电动滚筒全滚动平面钢球减速装置的研究

以电动滚筒减速装置为研究对象,设计了全滚动平面钢球减速装置。该减速装置的结构形式采用的是活齿传动的一种,是由K-H-V型少齿差行星齿轮传动变化而形成的一种新型传动,它利用一组中间活动件——活齿(钢球)来实现两同轴之间的转速和转向变换,突破了长期以来齿轮传动的传统结构特征,将行星齿轮的轮齿与轮体的刚性联接改为运动副活动联接,使行星齿轮的全部轮齿成为一组可作循环运动的独立运动体。整机可在要求工作性能稳定可靠、传动比大、传动效率高、体积小和重量轻的场合使用。     

沿海平原河网地区纳污能力分析——以海门市为例

水体纳污能力是科学合理地制定水污染控制规划的基础。沿海河网地区水系复杂,水体具有水深较浅、流速缓慢、顺逆不定和水体自净能力不强等问题。以沿海平原河网地区的海门市水环境为研究对象,根据其水系特点和实际需要建立一维河网水量水质模型,在此基础上计算了该市主要河道的纳污能力,为当地的水环境管理提供科学依据。