先张法预应力空心板纵向开裂的防治

多年来先张法预应力空心板在中、小桥结构物中一直被广泛应用.但在设计回访中发现,部分空心板板底多存在有纵向裂缝的问题,为有效杜绝此弊病的发生,本文对其产生的原因进行了分析并提出了预防措施.     

Field evaluation of insect-resistant transgenic Populus nigra trees

The performance of insect-resistant transgenic poplar trees (Populusnigra) expressing a Cry1Ac gene from Bacillus thuringiensis subsp. Kurstaki HD-1 against poplar defoliators was evaluated in the field at the Manas Forest Station in Xinjiang Uygur Autonomous Region during1994–1997. The results showed that the average percentage of highly damaged leaves on the transgenic trees was 10% while that on the control trees in nearby plantations reached 80–90%. The average number of pupae per m² of soil at 20cm depth in transgenic poplar plantation was 18 which was only 20% of that found in the non-transgenic control field. The number of pupae and the leaf-damage on transgenic trees described above are all far below the threshold set for chemical protection measures. The non-transformed poplar trees grown in the same plantation with the transgenic trees were also protected indicating that cross protection occurred between these two kinds of trees. Insect-resistant transgenic poplar trees have a potential application value in afforestation. This revised version was published online in August 2006 with corrections to the Cover Date.     

水土流失区建立新的生态环境途径的探讨——以鲁山县楼子河试验区为例

本文以鲁山县楼子河试验区为例,剖析了该试验区生态环境遭受严重破坏的原因,主要是由于人为不合理的社会经济活动的影响,加陡坡开荒、毁林毁草,掠夺式的获取薪材等。为了实现农业生态系统的良性循环,促进农林牧副诸业的发展,笔者根据楼子河试验区因地制宜综合治理的经验,提出了水土流失区建立新的生态环境的途径和措施。     

Relationship between stable carbon isotope discrimination and water use efficiency under regulated deficit irrigation of pear-jujube tree

To investigate the relationship between stable carbon isotope discrimination (Δ) of different organs and water use efficiency (WUE) under different water deficit levels, severe, moderate and low water deficit levels were treated at bud burst to leafing, flowering to fruit set, fruit growth and fruit maturation stages of field grown pear-jujube tree, and leaf stable carbon isotope discrimination (Δ_L) at different growth stages and fruit stable carbon isotope discrimination (Δ_F) at fruit maturation stage were measured. The results indicated that water deficit had significant effect on Δ_L at different growth stages and Δ_F at fruit maturation stage. As compared with full irrigation, the average Δ_L at different growth stages and Δ_F at fruit maturation stage were decreased by 1.23% and 2.67% for different water deficit levels, respectively. Δ_L and Δ_F among different water deficit treatments had significant difference at the same growth stage (P < 0.05). Under different water deficit conditions, significant relationships between the Δ_L and WUE_i (photosynthesis rate/transpiration rate, P_n/T_r), WUE_n (photosynthesis rate/stomatal conductance of CO_2, P_n/g_s), WUE_y (yield/crop water consumption, Y/ET_c) and yield, or between the Δ_F and WUE_y and yield were found, respectively. There were significantly negative correlations of Δ_L with WUE_i, WUE_n, WUE_y and yield (P < 0.01) at the fruit maturation stage, or Δ_L with WUE_i and WUE_n (P < 0.01) over whole growth stage, respectively. Δ_F was negatively correlated with WUE_y, WUE_n and yield (P < 0.05), but positively correlated with ET_c (P < 0.01) over the whole growth stage. Thus Δ_L or Δ_F can compare WUE_n and WUE_y, so the stable carbon isotope discrimination method can be applied to evaluate the water use efficiency of pear-jujube tree under the regulated deficit irrigation.     

基于Ansys的泥浆泵连杆的有限元分析

运用刚体平面运动学理论对泥浆泵动力端进行受力分析,结合PROE、ANSYS建立了连杆的几何模型和有限元模型,重点讨论了连杆大、小头载荷和惯性力的处理方法,给出了加载方程及其计算过程,并使用APDL语言实现了复杂载荷的程序化加载。在此基础上,运用有限元理论对连杆进行了静力学分析,得到了连杆在在典型工况下的应力状态及其危险部位,为进一步对曲轴连杆的设计和改进提供了可靠依据。     

2008年全球农产品市场价格易涨难跌

2007年通胀成为多数人茶余饭后的谈资。引起这轮通胀的主要原因就是食品价格的大幅上涨,据统计局最新数据显示。食品类价格同比上涨18．2％。其中,粮食价格上涨6．6％,油脂价格上涨35．0％,肉禽及其制品价格上涨38．8％,猪肉上涨56．0％,鲜蛋价格上涨10．0％。水产品价格上涨6．8％。     

草原综合顺序分类法的新改进：Ⅰ类的划分指标及其分类检索图

根据全国２３５２个气象站３０年以上的气候资料以及其他资料，对草原的综合顺序分类法第一级分类的热量级，湿润度级指标进行了修正，设计了新的分类检索图，将地带性和非地带性的天然草地，以及人工草地的类，纳入到统一的检索图的中，并可进行计算机检索。     

Pharmacokinetics of sanguinarine,chelerythrine, and their metabolites in broiler chickens following oral and intravenous administration

Sanguinarine (SA) and chelerythrine (CHE) are the main active components of the phytogenic livestock feed additive, Sangrovit®. However, little information is available on the pharmacokinetics of Sangrovit® in poultry. The goal of this work was to study the pharmacokinetics of SA, CHE, and their metabolites, dihydrosanguinarine (DHSA) and dihydrochelerythrine (DHCHE), in 10 healthy female broiler chickens following oral (p.o.) administration of Sangrovit® and intravenous (i.v.) administration of a mixture of SA and CHE. The plasma samples were processed using two different simple protein precipitation methods because the parent drugs and metabolites are stable under different pH conditions. The absorption and metabolism of SA following p.o. administration were fast, with half‐life (t_1/2) values of 1.05 ± 0.18 hr and 0.83 ± 0.10 hr for SA and DHSA, respectively. The maximum concentration (C_max) of DHSA (2.49 ± 1.4 μg/L) was higher that of SA (1.89 ± 0.8 μg/L). The area under the concentration vs. time curve (AUC) values for SA and DHSA were 9.92 ± 5.4 and 6.08 ± 3.49 ng/ml hr, respectively. Following i.v. administration, the clearance (CL) of SA was 6.79 ± 0.63 (L·h^?1·kg^?1) with a t_1/2 of 0.34 ± 0.13 hr. The AUC values for DHSA and DHCHE were 7.48 ± 1.05 and 0.52 ± 0.09 (ng/ml hr), respectively. These data suggested that Sangrovit® had low absorption and bioavailability in broiler chickens. The work reported here provides useful information on the pharmacokinetic behavior of Sangrovit® after p.o. and i.v. administration in broiler chickens, which is important for the evaluation of its use in poultry.     

蓝海战略与饲料营销(1)

<正>第一章饲料蓝海1正大饲料20世纪70年代前,中国几乎没有工业饲料及饲料工业的概念。畜禽养殖还处于一家几头猪、几只鸡的农户散养的初始阶段,没有养殖成本、利润意识,养猪为过年,养鸡为换盐,只为     

方向对了路才可能对--对搞好饲料企业质量管理工作的一些探讨

饲料企业要搞好质量管理工作,首先要重视工作方法的研究。通过这样的研究,选出适合企业的方案,然后贯彻下去,这样,不但能解决企业的质量管理问题,还能推动效率问题的解决,可谓事半功倍。目前,业内的质量管理工作还处于初级阶段,现状与发展的需求不符,加强对饲料企业质量管理工作方法的研究也就很有必要。方向对了路才可能对有效的质量管理工作方法,取决于饲料企业的质量理念。宗旨———增加顾客价值为什么要研究饲料企业质量管理工作方法?有人说是为了“搞好质量管理工作”,也有人说是为了“增加顾客价值”。后者更具高度,若想做百年饲料企…