溢多酶对产蛋鸡日粮潜在营养价值的研究

对60只270日龄罗曼褐蛋鸡进行两期代谢试验.每期将所有参试鸡随机等分为4个处理,每处理5重复,每重复3只.试验日粮为在相同的豆粕型或杂粕型基础日粮中分别添加0、120、150和180 g/t溢多利浓缩微丸酶,分别形成A、B、C、D 4组.结果表明:纯豆粕型日粮中,蛋白质和能量表观代谢率各组间差异不显著,但处理组比对照组都有改善的趋势(P＞0.05),但在统计意义上,不能计算其潜在营养价值.杂粕型日粮中,添加酶150和180 g/t两组的蛋白质和能量表观代谢率都显著高于对照组(P＜0.05),其它各组间差异不显著(P＞0.05).杂粕型日粮中添加150 g/t酶制剂的潜在营养价值:1kg溢多利浓缩微丸酶相当于39.58 kg表观可消化粗蛋白和2.22 Mj/kg表观可代谢能.     

浅论我国农村公共危机管理

我国农村危机管理存在着诸多问题。应对农村危机,必须因地制宜。在预警工作中,完善村民自治组织,各村之间加强横向联系,形成预警网络,同时提高乡镇政府危机处理能力,施行预见管理;展开模拟灾情急救演练,提高村民自救能力;在善后工作中,完善农村社会保障制度。     

中国潜在产出测算实证研究

在对中国潜在产出测算研究状况进行评介的基础上,分别使用H-P滤波法和生产函数法估算了中国1978—2004年间的潜在产出、产出缺口和潜在产出增长率。结果表明:(1)1978—2004年间,中国的产出缺口出现了波动水平正负交替的周期情形;(2)1995年以前产出缺口的波动幅度比较剧烈且较为频繁,1996年特别是1999年以后产出缺口的变化较为平缓;(3)1997年以后,虽然经济的增长率保持较高的水平,但是生产要素的实际利用水平却逐渐降低;(4)生产函数法得到的结果基本客观的反映了改革开放后,中国开始从计划经济向市场经济过渡到市场经济初步建立这一时期的生产要素使用情况。(5)根据H-P滤波法和生产函数法估算的潜在产出,得到1978—2004年间的平均潜在产出增长率分别为9.54%和9.67%。根据估计结果,在今后几年,通过适当的宏观调控,把中国的经济增长率稳定在8%～9%可能是一个较好的选择。     

力学原理在线性规划中的一点应用

线性规化是运筹学和系统工程中常用的数学方法，将物理学直接应用于后两门学科中去解决问题并不很普遍。本文就一个属于线规划的问题，为什么能用一个简单的力学模型来求解进行了探讨。结果表明物理学的规律有可能在求解数学问题中发挥作用。     

梨火疫病菌在中国的潜在分布及入侵风险分析

 【目的】细菌性梨火疫病最早发生在北美洲，随着水果贸易等人为因素向世界其它地区传播。对当地的生物多样性和经济带来了极其严重的威胁，亟需对其在中国的适生区进行预测。【方法】苹果开花期的温度和降水量是影响梨火疫病菌适生分布的关键气候因子，本研究根据这一生物学特性及生态环境因子，应用地理信息系统分析得出了梨火疫病在中国两个苹果优势产区的潜在定殖区域。【结果】用该方法对梨火疫病在欧洲的发生情况的预测结果与其历史分布记录相符，使用相同的空间建模方法对梨火疫病在渤海湾和黄土高原两个苹果优势栽培产区的潜在定殖区域进行风险评估，结果表明这两大苹果产区中优先扶持的县大多处于梨火疫病发生的高风险范围。【结论】梨火疫病在中国的大部分地区适生，在有适宜寄主分布的地区，就可能严重发生。     

Linking plant identity and interspecific competition to soil nitrogen cycling through ammonia oxidizer communities

Both plants and microbes influence soil nutrient cycling. However, the links between plants, microbes and nutrient cycling are poorly understood. In this study, we investigated how plant identity and interspecific competition influence soil nitrogen cycling and attempted to link plant identity and interspecific competition to community structures of bacterial and archaeal ammonia oxidizers based on terminal restriction fragment length polymorphism analysis (T-RFLP) of bacterial and archaeal ammonia monooxygenase (amoA) genes. Faba bean and maize monocultures and a faba bean/maize mixture were planted with two nitrogen levels (0 and 100 mg N kg⁻¹ soil as urea). Soil mineral nitrogen, ammonia oxidizer function (potential nitrification activity, PNA) and community structures were measured 28 and 54 days after plant emergence. Faba bean and maize substantially differed in their influences on mineral nitrogen concentrations and PNA in rhizosphere soils. Soil mineral nitrogen and PNA in the rhizosphere soils of the faba bean/maize mixture were closer to those of the maize monoculture than to those of the faba bean monoculture. T-RFLP with restriction enzymes BsaJI and Hpy8I distinguished variations in bacterial and archaeal ammonia oxidizers community structure, respectively, and detected both between-cluster and within-cluster variations in bacterial ammonia oxidizers. T-RFLP data showed that nitrogen addition favored part of a Nitrosospira cluster 3b sequence type and suppressed part of a cluster Nitrosospira 3a sequence type of bacterial ammonia oxidizers, while it had no influence on the archaeal ammonia oxidizer community structure. Although multivariate analysis showed that the function and community structure of bacterial ammonia oxidizers were significantly correlated, plant species and interspecific competition did not significantly change the community structure of bacterial and archaeal ammonia oxidizers. These results indicate that plant species and interspecific competition regulate soil nitrogen cycling via a mechanism of other than alteration in the community structure of ammonia oxidizers as investigated by DNA based methods.     

宣城市“十二五”林业经济发展研究

本文从宣城市林业经济现状及特点出发,具体分析了全市林业发展面临的深层次矛盾和问题、发展的潜力及十二五的发展方向和重点,提出如下解决措施:一是科学制定指标体系;二是构建大林业格局;三是加快推进林权流转;四是实施林业产业化经营等等。     

Growth characteristic and sink strength of fruit at different CO2 concentrations in a Japanese and a Dutch tomato cultivar

The aim of the present study was to elucidate how fruit growth was limited by the source and sink capacities in a Japanese (‘Momotaro York’) and a Dutch (‘Dundee’) tomato cultivar. The two cultivars were grown hydroponically with a high-wire system in greenhouses for 25 weeks, and the growth characteristics and sink strength of fruit were determined. Fruits were pruned to four (4F) or one (1F) per truss. The latter were used to determine potential fruit growth, an indicator of fruit sink strength. Growth was also determined under normal (LC) and enriched (HC, 700 μmol mol⁻¹) CO₂ concentrations to examine the effect of source enhancement on fruit production. In both cultivars under normal CO₂, the growth rate of fruit pruned to 4F per truss was lower than that in 1F, indicating that maximum potential fruit growth was not achieved. Under HC conditions, fruit growth rate of ‘Dundee’ achieved in 4F trusses was lower than that in 1F. In ‘Momotaro York’ in HC, fruit growth in 4F trusses was close to potential. This implies that fruit growth was source-limited irrespective of CO₂ concentrations in ‘Dundee’ cultivar while fruit growth in ‘Momotaro York’ under normal and enriched CO₂ conditions was limited by source and sink strengths, respectively. Adjustments of cultural practices including increasing fruit number per truss and/or genetic approaches to enhancing fruit sink strength by breeding may improve fruit yields of Japanese cultivars under high source/sink conditions.     

作物产量潜力极限研究

应用模型模拟方法研究近5 0年来主要作物产量演变趋势结果表明,作物长期进化过程中产量演变遵循S曲线增长规律,目前主要作物产量处于S曲线驻点(最快增长值点)左右,种植效益已开始下降,进一步提高产量日益困难,作物产量将不断接近其极限,多数作物未来产量潜力极限约为目前产量的2～3倍。提高作物产量潜力途径主要包括加强农田水利建设、提高作物育种手段、强化作物栽培措施、优化投入和改善作物生长的大环境等     

南阳市小麦生产潜力研究

南阳市小麦单位面积产量自1950年来翻了三番多,形成了3个台阶,经历了低水平徘徊、缓慢上升、快速增长、平台振荡、持续提升等5个发展阶段,横向分析县(区)之间发展差距明显、不同类型之间差别巨大、同省内先进地区比较显著落后。文章指出当前南阳市小麦单产处于探索上升阶段,第4个台阶预测可能在7 500~8 250 kg/hm2区间出现。南阳市小麦生产上存在的主要问题是灾害频繁、低产田面积大、水浇地面积小、生产规模小、生产者技术方面功能性文盲、播种偏早、播量偏大、盲目施肥、病虫草害防控不力、不浇增产水等。南阳市小麦生产潜力发掘的方向是灌溉区小麦单产达到9 750 kg/hm2、非灌区小麦平均单产达到6 750 kg/hm2以上。重点任务是加强农田基础设施建设,建设旱涝保收高标准粮田;加强科技创新,提高农业资源利用率;建立长效机制,促进小麦生产可持续发展。