立式捏合机混合釜内流场遍历性研究

流场遍历是流场混合的必要条件.根据立式捏合机混合釜内螺旋桨刃尖的运动特征,定义了穿越、遍历率和遍历时间等基本概念;提出了用遍历率和遍历时间来评价流场遍历性能;分析了螺旋桨的自转公转转速比对流场遍历率和遍历时间的影响.研究结果表明:螺旋桨的自转公转转速比对流场遍历性能具有极大影响,并可以通过比较不同转速比所对应的遍历率大小得到较优的螺旋桨的自转公转转速比;采用双螺旋桨能明显提高系统遍历率,降低遍历时间.     

Response of Cotton to Irrigation Methods and Nitrogen Fertilization: Yield Components,Water‐Use Efficiency,Nitrogen Uptake,and Recovery

Efficient crop use of nitrogen (N) fertilizer is critical from economic and environmental viewpoints, especially under irrigated conditions. Cotton yield parameters, fiber quality, water‐ and N‐use efficiency responses to N, and irrigation methods in northern Syria were evaluated. Field trials were conducted for two growing seasons on a Chromoxerertic Rhodoxeralf. Treatments consisted of drip fertigation, furrow irrigation, and five different rates of N fertilizer (50, 100, 150, 200, and 250 kg N /ha). Cotton was irrigated when soil moisture in the specified active root depth was 80% of the field capacity as indicated by the neutron probe.

Seed cotton yield was higher than the national average (3,928 kg/ha) by at least 12% as compared to all treatments. Lint properties were not negatively affected by the irrigation method or N rates. Water savings under drip fertigation ranged between 25 and 50% of irrigation water relative to furrow irrigation. Crop water‐use efficiencies of the drip‐fertigated treatments were in most cases 100% higher than those of the corresponding furrow‐irrigated treatments. The highest water demand was during the fruit‐setting growth stage. It was also concluded that under drip fertigation, 100–150 N kg/ha was adequate and comparable with the highest N rates tested under furrow irrigation regarding lint yield, N uptake, and recovery. Based on cotton seed yield and weight of stems, the overall amount of N removed from the field for the drip‐fertigated treatments ranged between 101 and 118kg and 116 and 188 N/ha for 2001 and 2002, respectively. The N removal ranged between 94 and 113 and 111 and 144 kg N/ha for the furrow‐irrigated treatments for 2001 and 2002, respectively.     

枯草芽孢杆菌替代抗生素对平养和笼养肉鸡的影响研究

 将240只1日龄罗斯308（ROSS 308）肉仔鸡，按照饲养方式（地面平养和笼养）以及添加枯草芽孢杆菌替代抗生素与否（替代和不替代）分为4个处理组（1组：抗生素地面平养组；2组：抗生素笼养组；3组：枯草芽孢杆菌地面平养组；4组：枯草芽孢杆菌笼养组），进行42 d的饲养试验。结果显示：试验全期，肉鸡末体重和饲料/增重比指标，4组显著优于（P<0.05）1组，2组和3组之间无差异（P>0.05）。21日龄和42日龄肉鸡血清生化指标分析显示：4组肉鸡血清白蛋白浓度显著大于1组；且血清尿酸浓度4组小于1组；而2组和3组之间所有血清测定指标均无差异。以上结果证明，无论是地面平养还是笼养方式，枯草芽孢杆菌替代抗生素对改善肉鸡生长性能均有良好效果，其作用机理主要是提高饲料蛋白的营养利用率.     

Development of buffer methods and evaluation of pedotransfer functions to estimate pH buffer capacity of highly weathered soils

The pH buffer capacity of a soil (pHBC) determines the amount of lime required to raise the pH of the soil layer from its initial acid condition to an optimal pH for plant growth and the time available under current net acid addition rate (NAAR) until the soil layer acidifies to a critical pH leading to likely production losses. Accurate values of pHBC can also be used to calculate NAAR from observed changes in soil pH. In spite of its importance, there is a critical shortage of pHBC data, likely due to the long period of time needed for its direct measurement. This work aimed to develop quick, simple and reliable methods of pHBC measurement and to test these methods against a slow (7‐day) titration used as benchmark. The method developed here calculates pHBC directly from the pH buffer capacity of the buffer solution and the increase in soil pH and corresponding decrease in pH of the buffer solution following mixing and equilibration. The pHBC values calculated using Adams and Evans or modified Woodruff buffers were in accord with those measured by slow titration. Buffer methods are easily deployed in commercial and research laboratories as well as in the field. The advantage of using buffer solutions to calculate pHBC instead of lime requirement is the broad application of this soil property. The pHBC of a soil is an intrinsic property that would not be expected to need remeasurement over periods of less than decades. Recurring lime requirement can be calculated from the soil's pHBC, initial and target pH values. A large proportion of the variability in pHBC was explained by the soil organic carbon content. This relationship between pHBC and soil organic carbon content allowed us to develop local pedotransfer functions to estimate pHBC for different regions of Australia.     

我国牛群中牛病毒性腹泻病毒流行的Meta分析

为全面评估我国牛群中牛病毒性腹泻病毒（bovine viral diarrhea virus,BVDV）病原流行率对该病毒感染的防控，在中国知网（CNKI）、万方、维普、PubMed和ScienceDirect 5个数据库中，检索截止到2021年9月1日发表的关于中国牛群BVDV流行情况的文献，并进行系统评价和Meta分析。共筛选出93篇关于BVDV病原学检测的研究论文纳入Meta分析中。分析结果显示：我国牛群中BVDV病原（抗原和核酸）流行率为9.8%(95%CI:7.8,11.9)，其中BVDV抗原流行率为3.1%(95%CI:2.1,4.4),BVDV核酸流行率为19.5%(95%CI:16.0,23.3)。各省间比较发现，吉林流行率最高，为26.3%(95%CI:24.3,28.4)，其次是湖北和福建省。进一步开展亚组分析和Meta回归分析的结果显示，品种（牦牛vs奶牛：比值比（odds ratio,OR）=1.37,95%CI:1.05～1.79）、饲养模式（散养vs规模化：OR=1.41,95%CI:1.08～1.85）、诊断方法（RT-PCR vs ELISA:OR=1....     

0.3%氯化血红素可湿性粉剂对马铃薯生长与品质的调节效果

摘要：为了明确0.3%氯化血红素可湿性粉剂对马铃薯生长的调节效果，确定最佳用量，以克新6号马铃薯为材料，以8%甲哌鎓可湿性粉剂和清水分别作为药剂和空白对照，采取随机区组排列开展田间应用试验，分析不同用量0.3%氯化血红素可湿性粉剂配施专用助剂（SD）对马铃薯生长、产量及品质的影响。结果表明：处理1—处理5（667 m2分别施用0.3%氯化血红素可湿性粉剂10、20、30、40、0 g，并配施SD 20 g）平均株高、全叶鲜质量、茎粗和小区平均产量均较空白对照有所增加，且均以处理4（667 m2施用0.3%氯化血红素可湿性粉剂40 g＋SD 20 g）最大，处理3（667 m2施用0.3%氯化血红素可湿性粉剂30 g＋SD 20 g）次之，2者小区平均产量较空白对照分别极显著增加13.80%、10.73%，但与药剂对照差异均不显 著；处理1—处理5马铃薯块茎干物质量、淀粉含量、还原糖含量和VC含量等也均较空白对照有所增加，其中以处理4最高，处理3次之，2者均显著高于空白对照。安全性评价表明，各处理对马铃薯均是安全的。在马铃薯生产上，推荐每667 m2使用0.3%氯化血红素可湿性粉剂30～40 g＋SD 20 g。     

干旱对不同地力水平、不同品种小麦生育性状及产量的影响

在相同的水分条件下 ,对不同地力水平、不同品种小麦的生育性状及产量进行比较。研究结果表明 ,小麦品种 9350 31在高肥力条件下表现突出 ,鲁麦 2 1适应性广 ,在中、低肥力地块上表现最佳     

东北马鹿茸重性状遗传力和重复力的估测

采用同父异母半同胞组内相关法，对乌兰坝林场７只东北马鹿种公鹿７１只后裔，１９９２～１９９７年９锯时四杈茸鲜重遗传力估测结果为０４０，属高遗传力；采用组内相关系数法，对该场７～１１锯１３只东北马鹿种公鹿锯四杈茸鲜重的重复力估测结果为０６９（Ｐ＜００１），属高重复力，为东北马鹿的纯种选育提供了主要性状的遗传参数。     

吡啶羧酸铬对肉鸭后期作用效果初探

选用21日龄樱桃谷鸭36只，采用有重复对照试验，比较饲粮中添加0．2×10－6吡啶羧酸铬对肉鸭生产性能、屠体品质和血液生化指标的影响。结果表明，吡啶羧酸铬对增重、饲料转化率无显著影响，对屠宰率、胸肌率和皮脂率亦无显著影响；但使心重、血清总甘油三酯显著降低，血清总胆固醇、高密度脂蛋白胆固醇显著增加。     

城镇居民收入分配状况及其对消费需求的影响

收入分配差距是伴随经济增长出现的一种社会经济现象,它对经济增长本身又会产生一定的影响。近年来我国城镇居民收入水平保持较快的增长速度,社会物价水平稳中有降,但消费需求不旺,市场疲软的迹象已十分明显。究其原因,除了供求存在结构性矛盾造成有效供给不足,住房、教育、医疗保险制度的改革使居民预期购买压力增大,以及落后的消费观念和消费信贷体制外,居民收入分配差距扩大,城市低收入和贫困人口的增加已成为对消费需求产生消极影响的一个重要因素。因此,政府在积极增加投资支出、调整经济结构和发展消费信贷的同时,切不可忽视改善收入分配状况,以最终实现刺激消费、促进经济增长的目标。