罗曼蛋种鸡种蛋受精率孵化率和健雏率的相关性分析

通过对山东大蔡牧业集团有限公司种鸡场(2008年5月—2009年4月)孵化生产记录数据进行整理、归纳和汇总,对种蛋受精率、受精蛋孵化率和健雏率3个指标进行相关统计分析,计算两两之间的相关系数,并建立回归方程。结果发现:种蛋受精率和受精蛋孵化率的相关系数r=0.9223(P<0.01);种蛋受精率和健雏率的相关系数r=0.4097(P<0.05);受精蛋孵化率和健雏率的相关系数为r=0.3980(P<0.05)。     

Detection of transgenic DNA in tilapias (Oreochromis niloticus, GIFT strain) fed genetically modified soybeans (Roundup Ready)

We used nested-polymerase chain reaction (PCR) to detect Roundup Ready soybean in aquatic feeds and feeding tilapias. A template concentration of 10⁻¹⁰ g μL⁻¹ DNA solution could be detected with a dilute degree of 0.01%. Most (90.6%) of the aquatic feeds containing soybean byproduct included exogenous DNA segments. We also compared genetically modified (GM) soybean with non-GM soybean diets in feeding tilapias ( Oreochromis niloticus , GIFT strain) and examined the residual fragments (254 bp) of GM soybeans. Tilapias receiving GM soybean diets had DNA fragments in different tissues and organs, indicating that exogenous GM genes were absorbed systemically and not completely degraded by the tilapia's alimentary canal.     

Using plant community uniqueness and floristic quality assessment in management decision-making in an urban park setting

With the densification of cities, it is imperative to identify urban ecosystems that should be protected or restored. We aimed to determine the conservation and restoration needs in a large urban park (1,35 km²) in Quebec City (Canada), based on site history, current species richness, floristic uniqueness, and floristic quality assessment of its diverse ecosystems: forest, swamp, wooded peatland, open peatland, and marsh. We evaluated the cover of all vascular species in 70 plots (400 m²) and assessed 18 environmental variables. We found that forest and swamp plots were the richest while peatland plots were the poorest, with marsh plots showing intermediate values. Ecological uniqueness (LCBD) was not correlated with richness (ρ = 0.17; p > 0.05), with marsh and peatland plots showing the highest and lowest uniqueness, respectively. With a regression tree, we identified canopy openness as the most influential variable explaining plot uniqueness across all ecosystems, especially in the peatland, indicating that future recreational development should be avoided in open ecosystems. By plotting ecological uniqueness (LCBD) with tolerance to disturbance (Mean C) values, we identified areas that could benefit from conservation or restoration, and areas that could sustain future development for recreational use. For each area, floristic composition, site characteristics, and past land-use history were investigated further to identify appropriate actions. The open peatland was identified as the main conservation priority, but actions will be needed to limit rapid tree encroachment. Three marshes were identified as areas that would floristically benefit from restoration actions. Still, since they also act as natural retention basins hosting species adapted to the soil conditions, we suggested monitoring the expansion of exotic and invasive species. Approaches developed and lessons learned from this project will serve as guidelines for municipalities aiming to implement a restoration and management plan in urban parks.     

Co‐solvent effects on the adsorption of carbofuran by two Indian soils

The adsorption of carbofuran on soils from water‐methanol mixtures has been evaluated by batch shake testing. Two uncontaminated soils having different physicochemical properties were used in these experiments. The volume fraction of methanol in the liquid phase (f_s) was varied from 0.25 to 1.0. Higher adsorption of carbofuran was observed in medium black (silt loam) soil than in alluvial (sandy loam) soil; calculated values of the Freundlich constant (K^m) and distribution coefficient (K_d) showed that adsorption of carbofuran in both soils decreased with increase in f_S values. The decreased carbofuran adsorption in methanol–water mixtures meant a greater potential of ground‐water contamination through leaching from potential sites. The data have been used to evaluate the co‐solvent theory for describing adsorption of carbofuran in methanol–water mixtures. The aqueous phase partition coefficient K_dw (mol g⁻¹) normalized with respect to f_oc and the aqueous phase adsorption constant K_w for carbofuran were evaluated by extrapolating to f_S = 0. © 2000 Society of Chemical Industry     

容积率对地价的影响及修正系数的确定--以南京市六合区为例

容积率是评价地价的重要指标,它对地区的经济发展有很大的影响。为此,通过对容积率内涵的挖掘,分析了容积率影响地价的几个主要方面;结合南京市六合区本次基准地价更新的调查资料,从样点地价的容积率修正和基准地价的容积率修正两个方面对容积率修正系数进行了分析。     

Impacts of an inter‐basin water transfer: distribution and abundance of Micronecta poweri (Insecta: Corixidae) in the River Wear,north‐east England

1. Micronecta poweri (Insecta: Corixidae) is potentially sensitive to changes in river flow. A field experiment was designed to assess the impact of an inter‐basin water transfer on the distribution and abundance of M. poweri in the receiving River Wear, north‐east England. 2. The transfer increased river discharge threefold for a period of 1 h; the transfer discharge was then reduced to a rate equivalent to double the receiving flow. Velocity changes were variable: some parts of the river channel were subjected to order of magnitude increases in near‐bed velocity, others suffered no perceptible change. Losses of fine particulate organic material were associated with the areas of greatest velocity increase. 3. Downstream of the transfer outlet, average total M. poweri abundance in replicate samples was reduced by approximately 50% during the transfer. Losses were variable within the 250 m reach monitored, with some areas gaining and some losing animals. Differences could not be explained simply as a function of proximity to the transfer outlet. 4. Results suggest that transfer impacts are location specific, varying greatly even over short (250 m) distances. For flow sensitive taxa, even relatively minor flow changes (increasing discharge to the 50 percentile flow value) may be considered as disturbance events when viewed at the patch or reach scales. 5. Despite the impacts identified for M. poweri, transfers are generally viewed as having a beneficial effect on the conservation of aquatic habitat in the River Wear. They ensure that water abstractions for potable and industrial supply can continue during the summer months without reducing the availability of suitable salmonid habitat. However, there remains a need to assess the possible transfer of biological material from the donor River Tyne to the receiving River Wear. Copyright © 2000 John Wiley & Sons, Ltd.     

覆膜滴灌棉田蒸散量的模拟研究

通过综合考虑影响作物蒸散量的土壤、作物、大气3方面因子,结合新疆滴灌棉田覆膜栽培的生产实际,设计了不同覆盖度和品种试验,以Penman－Montieth方程估算参考作物蒸散量,确定了不同覆盖度及品种条件下的作物系数,并在此基础上实现了覆膜滴灌棉田蒸散量较为准确地估计。试验结果认为覆膜滴灌棉田全生育期蒸散量在540～620 mm之间,全生育期蒸散量和作物系数都随着覆盖度的增加而减小,叶面积指数与日蒸散量及作物系数关系密切,品种间由于品种特性的差异而引起的叶面积指数变化,最终导致了品种间作物系数K_c的不同。     

喷灌施肥灌溉均匀性对土壤硝态氮空间分布影响的田间试验研究

在2002～2003年冬小麦生育期内进行了喷灌施肥条件下均匀系数对土壤水氮时空分布及淋失影响的田间试验。试验中,喷灌均匀系数设置低、中、高三个处理,灌溉季节内的平均喷灌均匀系数分别为72%、79%和84%,施肥灌溉均匀系数分别为71%、78%和85%。对70和90 cm深度处的土壤水势进行了监测以评估均匀系数对水氮淋失的影响,结果表明,在所研究的喷灌均匀系数范围内深层渗漏量很小。试验结果还指出,土壤硝态氮随时间和空间表现出很强的变化特征,均匀系数变化范围为23%～97%,变差系数的变化范围为0.04～1.00;灌溉季节内土壤硝态氮分布的均匀性主要取决于初始硝态氮分布的均匀程度,而喷灌均匀系数对土壤氮素的空间分布无明显影响。     

基于称重式蒸渗仪的喷灌条件下冬小麦和糯玉米作物系数估算方法

利用位于北京的称重式蒸渗仪,对喷灌条件下的冬小麦和糯玉米需水规律进行了测定,进而计算了两种作物的作物系数。结果表明,冬小麦和糯玉米的作物系数与播种后天数之间的关系均可以用四次多项式来表征。根据FAO-56推荐的作物系数计算方法,计算了两种作物的分段单值作物系数和双作物系数,发现华北平原喷灌条件下冬小麦和糯玉米的作物系数在生育期内的变化可以用FAO-56推荐的模式来描述,但实测值一般大于FAO-56的建议值。为了能利用FAO-56推荐的模式较好地描述喷灌作物系数变化规律,依据实测资料对FAO-56建议的单值作物系数和基础作物系数进行调整后,模拟了两种作物需水量的变化,模拟的作物阶段需水量与实测值吻合良好。     

Relative solubilities of bifenox and 1-naphthylacetic acid (NAA) in plant cuticles and in selected pure or aqueous glycol additives

The driving force for foliar penetration is the product of the partition coefficient (K) between the cuticle and the formulation residue, and the concentration of the active ingredient in the spray residue. Ethylene glycols and polyethylene glycols (PEGs) are often contained in commercial formulations, because they are good solvents and not toxic. Since they are humectants, the water content of the formulation residue varies with humidity of the air. At 25°C and 65% relative humidity PEG 400 contains about 50% water. The partition coefficients for the lipophilic herbicide, bifenox, increased with increasing water content of the ethylene glycols and PEGs, such that log K was a linear function of the mass fraction of water or PEG. The K value was about 0·5 for the system cuticle/pure PEG and 27500 for the system cuticle/water. When PEG contained 50% water, K was only 110. Partition coefficients of bifenox between cuticle and ‘Tween’ 80 depended also on humidity, having values of 0·75 in cuticle/pure ‘Tween’ 80 and 29·1 when ‘Tween’ 80 contained 50% water. With 1-naphthylacetic acid (NAA), which is a weak acid, partition coefficients also depended on water content of PEG 400, but a maximum curve was obtained. The maximum partition coefficient (211) was observed with a mixture of 30% PEG 400 and 70% water, which corresponded to a humidity of 88%. We suggest that this is due to an effect of PEG 400 on the ionisation of NAA. Our data demonstrate that partition coefficients are affected by humidity, because solubilities of lipophilic compounds and weak acids in PEG/water mixtures vary greatly with the water content. This in turn affects driving forces, mainly by the effect of humidity on partition coefficient. With non-ionisable lipophilic compounds, partition coefficients, driving forces and rates of foliar uptake therefore increase with increasing humidity. © 1998 SCI