野生与人工饲养条件下花尾榛鸡卵孵化率的比较

20 0 3年5月～2 0 0 4年6月,在黑龙江省带岭林业局采用人工孵化技术,对野生花尾榛鸡卵和人工饲养花尾榛鸡卵的孵化率及其影响因素进行比较研究,野生花尾榛鸡卵的孵化率为74 4 0 % ,人工饲养条件下花尾榛鸡卵的孵化率为4 1 4 1%。对孵化率进行T检验,其T =7 830 ,df=10 ,T >t10 ,0 0 1=2 76 4 ,差异极其显著。分析认为,产生花尾榛鸡卵孵化率差异主要是因所食食物和栖息生境的不同所致。     

桩西联合站能量平衡分析及节能措施

针对桩西联合站生产环节中的某些运行温度不合理、生产工艺不完善、能量利用率较低等现状,建立了能量平衡分析模型,给出了相应的评价指标和计算方法.根据计算结果,对该站在能耗方面存在的问题及节能潜力进行了分析,提出了相应的节能措施.     

黄河三角洲地区鲈鱼越冬技术研究

根据海水盐度不同，其结冰点就不同的原理，进行了自然环境下鲈鱼大面积越冬试验，发现盐度越低，鲈鱼越冬成活率越高，最好将池水盐度控制在10以下，并指出越冬鱼种规格100－200g／尾为宜。     

莲潜根线虫回收率的影响因素初步研究

不同温度，PH值和分离时间对莲潜根线虫回收率的影响表明，以30℃，PH=7时分离回收率最高，温度在15℃时，分离7天，回收率达100％。     

Family Outcrossing Rates of Pinus caribaea Morelet var. caribaea in Seed Orchard and Natural Populations

Family outcrossing rates of Pinus caribaea var. caribaea populations that differed in origin and management were estimated by using isozyme markers. The family outcrossing rates were estimated by (1)fixing the probability of pollen gene frequency (p); (2) allowing pollen gene frequency to vary among families. The estimates of family outcrossing rates for all the populations varied widely among families (clones of the seed orchard), ranging from 0.39 to 2.0. The average family outcrossing rates of both methods were greater than the     

微贮对秸秆在瘤胃NDF降解率的影响

试验采用3个重复对比设计，将玉米，小麦和稻草秸秆的微贮样与原样放置在永久瘘管牛体内，分别在6．12、24．36、48和72小时时间点取出样本进行NDF降解率试验测定分析，结果：秸秆处理样NDF在各个时间点的NDF瞬间降解率和有效降解率均极显著优于原样（P＞0．01）而玉米秸秆处理样与小麦和稻草处理样相比差异不显著（P＞0．05）。     

平遥县农机年度检审的现状和对策

本文通过对当地农机监理现状分析，找出了农机度检审率下滑的原因，提出了提高农机年度检审率的对策。     

钢筋混凝土结构中钢筋锈蚀后力学性能变化的试验研究

本文通过工程实例调查分析的方法,研究了钢筋混凝土结构中钢筋在锈蚀、腐蚀后的力学性能的变化,有助于评估服役钢筋混凝土结构承载力的降低程度和耐久性。     

Study on Large Power Tractor Driver’s Heart Rate and Fatigue in Sowing Work

In order to reduce the driving fatigue in sowing work, this paper based on heart rate (HR) as the main indicator to survey, tested and analyzed the fatigue condition of the drivers of three imported tractors and one domestic tractor in sowing work. The results showed that when driving the imported tractors in sowing work, the HR increasing rate was 10.4%-14.3%, labor intensity belonged to the light level;when driving domestic tractor in sowing work, the HR increasing rate was 23.4%-33.0%, it was remarkably bigger than that of driving imported tractors (P＜0.05), labor intensity belonged to the middle level. The main effects on driving fatigue included the control methods, tractors' cab environment, processing time, operating content, and so on. Finally, we proposed the concrete measures and suggestions to reduce driving fatigue and improve drivers' work condition.     

微分及其在理论力学中的应用

微分有两个含义:1.对于与时间有关的函数(称之为动态函数)f而言,微分df表示在无限小的时间dt内函数f的增加量,即df=f(t dt)-f(t);2.对于与时间无关的函数(称之为静态函数)g而言,微分dg表示g的微小部分,所有dg之和等于g。时间的微分即时间的增加量dt总是恒大于0的正实数。函数f的增加量df与时间的增加量dt之比称为函数f的增加率,而非变化率。函数f的减小量-df与时间的增加量dt之比称为函数f的减小率。变化率包括增加率与减小率两种情况。质点所受到的合外力等于它的动量的增加率。作用力与反作用力互为对偶力。保守力与势能梯度互为对偶矢量。势能定理即势能的减小量等于保守力所作的功。