中国藏猪ESR基因PvuⅡ位点多态性分析

采用PCR-RFLPs方法,对中国藏猪ESR基因多态性进行了研究,并与太湖猪、金华猪、成华猪、内江猪、长白猪、大白猪等中外猪种的ESR基因频率、基因型频率作了对比分析。结果表明藏猪有3种ESR基因型,ESR等位基因之间的频率较其它猪种均衡,从而证明西藏猪选择压力较小,ESR基因的分布处于原始的自然状态。     

梁子湖表层水氮的季节变化与沉积物氮释放初步研究

采用室内模拟的方法研究梁子湖沉积物N在pH值和温度控制下释放的特征。研究表明,梁子湖的入水口和出水口由于沉积环境影响到N的形态,其N的释放明显较湖心高,在试验初期由于搅动的影响使得N的释放在第1天较第2、3天高,其后则迅速增加释放量。温度对N释放影响明显,30℃条件下N释放曲线的峰值较4℃条件下高近1倍,20℃条件下N释放曲线的峰值较4℃条件下高30％。pH值对沉积物N释放同样有明显的影响。在偏酸（pH5．5）和偏碱（pH11．5）条件N的释放量较湖水正常pH值（pH8．5）增大。湖水全N含量在0。180-1．362mg／L之间,平均0.713mg／L;NH4^＋-N含量在0．023-0.130mg／L之间,平均含量为0．065mg／L;硝态N在0．005-0．72mg／L之间,平均含量为0．257mg／L。梁子湖表层水中氮含量呈明显的季节性变化,全N和NO3^--N是春季高,冬季低;NH4^＋-N是春季含量最高,而夏季含量最低。     

犬市繁荣,是投资需求还是消费需求?

国外有专家认为,犬展犬赛是犬业繁荣与否的晴雨表。     

犬究竟有没有"思维活动"?

在词典解释中,思维是指人脑对现实事物间接和概括的加工形式：它以内隐的或外显的动作或言语形式表现出来。因此,“思维”是特指人的“思维”。     

谈搜爆犬兴奋性仔细性和搜索耐力的培养

当前,以爆炸方式进行的各种犯罪活动呈逐年上升趋势,造成的社会危害性极大、后果严重。     

非圆齿轮行星轮系传动的栽植机构参数优化与试验

为了进一步优化栽植嘴的轨迹、姿态及其挖出的穴口形状,提高钵苗移栽的立苗率,提出了基于两级非圆齿轮行星轮系传动的栽植机构组合设计思路,运用变性椭圆-共轭非圆齿轮、变性偏心圆-共轭非圆齿轮、变性巴斯噶蜗线非圆齿轮、变性傅里叶非圆齿轮和变性正弦非圆齿轮5类非圆齿轮副,组合设计了25种不同的栽植机构。建立了基于非圆齿轮行星轮系传动的栽植机构通用数学模型,并将通用数学模型代入旋转式钵苗栽植机构多目标优化模型,根据给定的栽植农艺条件,优化得到了满足理想栽植要求的栽植机构类型及其对应的机构参数。选取其中的偏心-椭圆齿轮行星轮系栽植机构与变性椭圆齿轮行星轮系栽植机构进行对比分析,结果表明运用多种非圆齿轮副进行组合设计的栽植机构具有优越性。根据优化得到的栽植机构类型及其对应的参数进行结构设计和样机研制,并进行了运动学高速摄像试验和模拟田间栽植试验。由高速摄像试验得到的轨迹、姿态、速度等指标和理论计算的对比分析,验证了通用数学模型的正确性;由模拟田间栽植试验可得本栽植机构立苗率较高,约为95%。     

新疆农田水利工程灌溉

通过分析当前新疆地区水利工程中存在的问题,总结出新疆实施水利工程灌溉的主要技术点。     

春伐桑树不同技术处理的试验初报(Ⅱ)——不同技术处理对夏秋季桑叶产质量的影响

在栽植密度一定且其它桑园管理措施一致的前提下,对春伐桑树不同技术处理与夏秋季桑叶产质量的关系进行了调查。结果是栽植密度每667 m2桑地面积1000~1200株、N∶P2O5∶K2O=10∶5∶5的施肥比例,每667 m2桑地面积留条7500~8000根,低干无拳式树形的组合,可适当提高幼虫生命力、茧层率和良卵率及实用孵化率,显著提高桑叶产量和全茧量、茧层量及产卵量。     

The Ecological Effects of Young Elm Trees Belt-Pumpkin Strip Intercropping System at the Agro-Pastoral Ecotone in Northern China

Young elm trees belt-pumpkin strip intercropping was studied to solve the actual problem of resource losses in the large barren area resulted from reconverting cultivated land into forest in the agro-pastoral ecotone in northern China. The final objective was to realize effective utilization of the barren land with both ecological improvement and economic development. Field experiments were conducted together with laboratory analysis. The results indicated that the soil moisture level was remarkably increased in young elm trees belt-pumpkin strip intereropping because the pumpkin vines covered the gap between pumpkin planting-furrow and elm trees belt. The water use efficiency of the intercropping system was increased by 23.7-163.3% as compared with the single cropping. Elm trees belt-pumpkin strip intercropping changed the sequential succession trend of the grasses growing in the gap of the pumpkin planting-furrow. The annual grasses become the dominant vegetation. The nutritive value as fodder and yield of the annual grasses were also increased remarkably. The biomass of pumpkin, elm trees and grasses under intercropping increased by 24.4, 28.4 and 144.4%, respectively, as compared with those under single cropping. The land use efficiency was increased by 132%. It was also indicated that the soil erosion from the intercropping land was not increased due to pumpkin plantation. The differences in the soil erosion among intercropped area, elm trees belt and pumpkin strip with single cropping were not remarkable. Therefore, it was concluded that young elm trees belt-pumpkin strip intercropping is an effective way to utilize the barren land between the young elm trees belt and realize synergistic enhancement of ecological benefit and economic profit.