中国中东部农田作物水分利用效率时空分布及影响因子分析

为研究中国中东部地区农田生态系统水分利用效率时空分布特征,该文利用遥感数据、气象数据以及国家分省区农业统计数据,基于农作物种植结构所划分的地区,通过趋势分析方法,分析了2003-2012年10 a间农田水分利用效率的时空分布特征。结果发现:华北地区农田多年平均水分利用效率(water use efficiency,WUE)高于南方水田区,山东半岛、辽东半岛以及江苏沿海地区农田WUE最高,多年农田WUE均值高达2.0 g/kg,而东北平原及东南丘陵地区农田WUE多年均值则较低,平均在1.5 g/kg以下。中国中东部农田WUE总体上呈上升趋势。其中,华北平原以及松嫩平原农田WUE增加趋势明显,最大年均增幅达0.02 g/(kg·a),而东南丘陵、江淮以及三江平原等地,农田WUE则呈减小趋势,最大年均降幅达-0.007 g/(kg·a)。整体上看,北方地区农田WUE的涨幅高于南方。考虑气候变化后,灌溉和施肥对中国中东部农田WUE的影响较小。气候变化则是影响中东部农田WUE的主要因素。在北方地区,对农田WUE变化有显著影响的因子为年降水量,而在南方地区,年均温的影响则更显著。相比于在中东部北方地区农田WUE年际变化主要受到年降水量对农田蒸散发(evapotranspiration,ET)的影响,在南方地区,农田WUE年际变化则主要受到年均温对农作物总初级生产力(gross primary productivity,GPP)的影响。该研究可为农田区水资源合理利用以及中东部农田生态环境持续发展提供参考。     

纳米TiO_2对土壤中Al、Fe和Mn释放及形态的影响

为了研究纳米TiO2对土壤中Al、Fe和Mn形态转化的影响,以三峡水库消落区土壤为研究对象,采用室外模拟淹水试验,分析不同浓度的2种纳米TiO2对土壤中Al、Fe和Mn释放及形态的影响。结果表明,淹水2个月后,纳米TiO2颗粒处理引起上覆水Al和Fe浓度显著升高;促进土壤残渣态和可氧化态Al的释放,且锐钛矿颗粒的作用大于金红石颗粒,高浓度锐钛矿颗粒处理导致12.31%的Al释放到水中;纳米TiO2颗粒对土壤Fe和Mn总量影响较小,但对Fe形态转化影响较大,主要表现为可还原态和可氧化态Fe转化为酸可交换态Fe,促进Fe的活化,其中低浓度金红石颗粒与高浓度锐钛矿颗粒影响相对较大;纳米TiO2颗粒对Mn形态转化影响较小,仅低浓度金红石颗粒与高浓度锐钛矿颗粒处理组促进少量可还原态Mn的转化,其他均无明显变化。因此,不同结构纳米TiO2对土壤中Al、Fe和Mn形态转化的影响存在较大差异,在进行纳米TiO2的环境风险评估时需要区别对待。     

玉米种子加工线的计算机仿真分析

本文用计算机仿真手段对吉林省2000t的玉米种子加工线再现了其两种工艺流程,根据现场反映的配套问题和仿真结果对第一工艺流程提出了改进方案,认为现有系统的精选机生产率应增加一倍,能提高经济性,并且对具有不同仓数的系统进行了分析。     

上海土壤磷的吸附特性及缓冲性能的研究

本文以上海土壤为对象,研究选定了土壤磷等温吸附试验条件为:水土比10,平衡时间6天,控温25℃,磷加入量为100,200,400,600μgP/g土,溶液基质为0.01M CaCl₂。磷缓冲能力试验条件为:平衡时间2天,磷加入量为20,40,100,200μgP/g土。根据Freundlich, Tempkin和Langmuir方程计算的土壤吸附指标与土壤类型及土壤性质有密切关系,是土壤磷素肥力的重要指标。反映土壤缓冲能力的“磷肥指标”与土壤有机质、粘粒、活性铝及pH值相关较好。上海几种主要土壤中以青紫泥的最大吸附量(X_m),0.2ppm P吸附量和“磷肥指标”为最高,其次为青黄土,沟干泥和黄泥头,最小为夹沙泥。应用磷吸附指标与“磷肥指标”来预测土壤需磷量,初步试验是可行的,但实际应用还需进一步试验研究。     

Antitermitic activity of leaf essential oils and components from Cinnamomum osmophleum

The antitermitic activities of the essential oils from the leaves of two Cinnamomum osmophloeumclones (A and B) and their chemical ingredients against Coptotermes formosanus Shiraki were investigated according to direct contact application. Results from this experiment have demonstrated that the indigenous cinnamon B leaf essential oil has a more effective antitermitic activity than indigenous cinnamon A leaf essential oil. Furthermore, when cinnamaldehyde, eugenol, and alpha-terpineol are extracted from indigenous cinnamon leaf essential oil and used at the strength of 1 mg/g, their antitermitic effectiveness is much higher than that using indigenous cinnamon leaf essential oil. Among the congeners of cinnamaldehyde examined, cinnamaldehyde has exhibited the strongest termiticidal property.     

轮式车辆动力传动系自激振动研究（Ⅰ）——自激振动的机理分析

研究了轮式车辆动力传动系自激振动的机理。建立了动力传动系力学模型，对振动进行了相平面分析，得出地面附着系数随滑转率的增加而减小的特性是造成车辆传动系自激振动主要原因的结论     

用边际分析法确定黄河中游粗泥沙集中来源区

 为进一步寻找并治理对黄河下游主槽淤积危害最严重的粗泥沙集中来源区,根据1960年未建三门峡水库前自然水沙条件下下游河槽淤积物粒径组成,确定出黄河中游粗泥沙集中来源区界定中的粗泥沙界限为0.1mm。利用边际分析法在黄河中游多沙粗沙区确定粗泥沙集中来源区面积为1.88万km2。该面积仅占黄河中游多沙粗沙区面积的23.9%,可产生的全沙、粒径大于0.05mm和0.1 mm的泥沙分别占同期多沙粗沙区相应沙量的34.5%、47.6%和68.5%。由此看出,该区是名副其实的粗泥沙集中来源区。     

Bayesian Semiparametric Model for Pathway-Based Analysis with Zero-Inflated Clinical Outcomes

In this paper, we propose a semiparametric regression approach for identifying pathways related to zero-inflated clinical outcomes, where a pathway is a gene set derived from prior biological knowledge. Our approach is developed by using a Bayesian hierarchical framework. We model the pathway effect nonparametrically into a zero-inflated Poisson hierarchical regression model with an unknown link function. Nonparametric pathway effect was estimated via a kernel machine, and the unknown link function was estimated by transforming a mixture of the beta cumulative density function. Our approach provides flexible nonparametric settings to describe the complicated association between gene expressions and zero-inflated clinical outcomes. The Metropolis-within-Gibbs sampling algorithm and Bayes factor were adopted to make statistical inferences. Our simulation results support that our semiparametric approach is more accurate and flexible than zero-inflated Poisson regression with the canonical link function, which is especially true when the number of genes is large. The usefulness of our approach is demonstrated through its applications to the Canine data set from Enerson et al. (Toxicol Pathol 34:27–32, 2006). Our approach can also be applied to other settings where a large number of highly correlated predictors are present.Supplementary materials accompanying this paper appear on-line.     

机械式空气整根钵苗移栽器的研究

空气整根钵苗全自动移栽机的核心部件是移栽器。采用机械方式完成全自动移栽机的送秧和投苗，简化了现有全自动钵苗移栽机的电动或气动送秧和投苗装置，降低了成本。移栽器的性能试验表明，所研制的移栽器性能良好，适应国内市场需要。     

Spatial and seasonal distribution of organic amendments affecting methane emission from Chinese rice fields

The effect of fertilizers on methane emission rates was investigated using an automated closed chamber system in Chinese rice fields (Human Province). Each of three experiments compared two fields treated with a first uniform fertilizer dose and a second fertilizer dose which was different for each of the two fields. The uniform fertilizer doses for both fields in each experiment comprised mineral (experiment 1), organic (experiment 2) and combined mineral plus organic components (experiment 3). In all three experiments the second fertilizer dose comprised organic amendments for field 1 and no organic amendments for field 2. The rate of increase in methane emission with a given amount of organic manure was found to depend on the total amount of organic manure applied. A single dose of organic manure increased the emission rates by factors of 2.7 to 4.1 as compared to fields without organic manure (experiment 1). In rice fields that had already been treated with organic manure, the application of a second dose of organic manure only slightly enhanced the emission rates in experiment 2 by factors of 1.1 to 1.5 and showed no detectable increase in experiment 3. The net reduction achieved by separation of organic and mineral fertilizers was maximized by concentrating the organic amendments in the season with low emission rates, i.e. early rice, and using exclusively mineral fertilizers on late rice when emission rates were generally higher. This distribution pattern, which was not associated with significant yield losses, resulted in an annual methane emission corresponding to only 56% of the methane emitted from fields treated with blended fertilizers.