我国农业机械化与城镇化关系的协整分析

在讨论我国农业机械化发展的内在机制以及与城镇化关系的基础上,运用协整分析方法建立时间序列数据模型,经过格兰杰因果关系检验,验证农业机械化与城镇化之间的长期稳定关系,进一步建立误差修正模型探讨这种稳定关系在长期内与短期内的动态变化特征,并预测我国2020年农业机械化发展水平。结果表明,在长期内,城镇化率增加一个单位农业机械化水平将提高1.09个单位。但是,农业机械化对当期城镇化的推进反应是滞后的,而是反映在长期趋势上。预测显示,2020年我国农业机械化水平将达到67.45%。     

基于AHP法的4U-1400马铃薯收获机机械结构的设计

通过对机械设计方法学知识的理解与运用,给出了4U-1400马铃薯联合收获机的黑箱模型和形态学矩阵及功能原理的设计方法,提出其潜在可能的设计方案;利用层次分析法(AHP法),建立了马铃薯收获机的评价指标体系,对不同方案进行定性和定量的综合性评价和优劣排序;最后得出4U-1400马铃薯收获机机械结构的最优设计方案。     

Sources of Resistance to Anthracnose (Colletotrichum truncatum) in Wild Lens Species

Lentil anthracnose (Colletotrichum truncatum (Schwein.) Andrus et W.D. Moore is a potential threat in many lentil (Lens culinaris Medik.) production regions of North America. In the lentil germplasm maintained in Germany and North America, 16 lines were reported to have resistance to race Ct1, but none has resistance reported to race Ct0. The objective of this study was to examine accessions of wild Lens species for their resistance to races Ct1 and Ct0 of lentil anthracnose. Five hundred and seventy-four wild accessions of six species and control lines were screened in two replications under both field and greenhouse conditions using a 1–9 scoring scale (1, highly resistant; 2–3, resistant; 4–5, moderately resistant; 6–7, susceptible; and 8–9, highly susceptible). Indianhead and PI 320937 were resistant while Eston and Pardina were susceptible to race Ct1 as expected. However, none of the check lines were resistant to race Ct0. Among the six Lens wild species tested, accessions of Lens ervoides (Brign.) Grande had the highest level of resistance, 3–5 to race Ct1 and Ct0 followed by L. lamottei Czefr. in the field and greenhouse. Lens orientalis (Boiss.), L. odemensis L., L. nigricans (M. Bieb.) Godron and L. tomentosus L. were highly susceptible, 8–9 to race Ct0 in the greenhouse. The highest frequency of resistance, especially in L. ervoides (Brign.) Grande, was found in accessions originating from Syria and Turkey. The usefulness of these L. ervoides (Brign.) Grande accessions as sources of resistance to the more virulent race of anthracnose in a lentil breeding program is discussed.     

嘉陵江上游低山暴雨区不同水土保持林结构模式水源涵养效益研究

水土保持林的水源涵养效益是研究森林防止水土流失的一个热点问题。以20世纪80年代末期营造和自然恢复的湿地松林、桤柏混交林、刺槐(灌木)林 、刺槐林 和桤木林为研究对象,选择林冠截留、土壤容重、土壤孔隙度、土壤贮水能力、土壤渗透性和枯落物持水性,作为研究不同水土保持林结构模式水源涵养效益的指标,对不同水土保持林的水源涵养机理和水源涵养效益进行了较深入的研究。结果表明,各水土保持林的水源涵养能力均明显高于农耕地;不同水土保持林结构模式的水源涵养效益也有较大差异。最后提出了桤柏混交林、湿地松林、桤木林等优良水土保持林结构模式,为当地的生态环境建设,特别是当前正在进行的退耕还林工程的模式选择提供了依据。     

不同比例尺DEM提取地面坡度的精度研究——以在黄土丘陵沟壑区的试验为例

以陕北绥德县韭园沟流域为试验样区 ,采用高精度 1∶ 1万 DEM所提取的坡度为准值 ,应用多层面复合分析和比较分析的方法 ,研究该地区 1∶ 5万 DEM提取地面坡度的误差特征与纠正方法。试验结果显示 ,所获得的不同空间尺度下 DEM所提取坡度值的转换图谱 ,可对 1∶ 5万 DEM计算的地面坡度统计值进行有效修正。该成果对于 DEM数据在水土保持领域若干应用标准的制定 ,提供了重要的理论依据与技术路线     

The sensitivity of water extractable soil organic carbon fractions to land use in three soil types

Soil organic carbon (SOC) has a high impact on the sustainability of ecosystems, global environmental processes, soil quality and agriculture. Long-term tillage usually leads to SOC depletion. The purpose of this study was to determine the impact of different land uses on water extractable organic carbon (WEOC) fractions and to evaluate the interaction between the WEOC fractions and other soil properties. Using an extraction procedure at 20°C and 80°C, two fractions were obtained: a cold water extractable organic carbon (CWEOC) and a hot water extractable organic carbon (HWEOC). The results suggest that there is a significant impact from different land uses on WEOC. A lower relative contribution of WEOC in SOC and a lower concentration of labile WEOC fractions are contained in arable soil compared to forestlands. Chernozem soil was characterized by a lower relative contribution of WEOC to the SOC and thus higher SOC stability in contrast to Solonetz and Vertisol soils. Both CWEOC and HWEOC are highly associated with SOC in the silt and clay fraction (<53 µm) and were slightly associated with SOC in the macroaggregate classes. The WEOC fractions were highly and positively correlated with the SOC and mean weight diameter.     

不同地貌类型区1∶25万比例尺DEM的建立方法

以在 3个不同地貌类型区的试验为例证 ,研究探讨建立栅格化 DEM的技术要点和技术方法 ,并对所建立 DEM的精度进行评价。研究结果表明 ,在平原区可以直接利用 Terlk层及水系要素建立 DEM;在山区 ,则首先需要进行构造地形结构线的预处理 ,而在黄土丘陵沟壑区 ,不仅需要构造地形结构线 ,而且需借用大比例尺的高程数据进行高程加密处理 ,以最大限度地减少地貌特征信息的损失 ,为区域水土流失的动态监测基础地理数据库的建立提供重要的技术方法     

CASE REPORT: Corneal papilloma associated with papillomavirus in a one‐humped camel (Camelus dromedarius)

A 15‐year‐old male dromedary camel with a history of chronic severe keratoconjunctivitis and corneal mass in the left eye of 6 months’ duration was referred to the Veterinary Medical Teaching Hospital at Adnan Menderes University. A superficial keratectomy was performed and biopsy material submitted for histopathology. The diagnosis was corneal papilloma. There has been no recurrence of the neoplasm to date (6 months, 1 year). Corneal papilloma has not been reported previously in camels and seems to be associated with papillomavirus.     

饲料蛋白质和脂肪水平对亚东鲑亲鱼生长性能、消化酶活性和血清指标的影响

本试验旨在研究饲料蛋白质和脂肪水平对亚东鲑亲鱼生长性能、性腺指数、消化酶活性和血清指标的影响。试验采用5×2两因素随机设计,设5个蛋白质水平(36%、39%、42%、45%、48%)和2个脂肪水平(9%、18%),共配制10种实用试验饲料。每种试验饲料投喂3个重复,每个重复19尾鱼。初重为(462.53±45.40)g亚东鲑在室内水族箱中流水饲养,饲养周期为77 d。结果表明:同一脂肪水平下,随饲料蛋白质水平的升高,增重率有所升高,而饲料系数逐渐降低,至蛋白质水平为48%时又有所升高。饲料蛋白质和脂肪水平对雌性亲鱼性腺指数无显著影响(P0.05),雄性亲鱼性腺指数随蛋白质水平的升高而降低,但至蛋白质水平为48%时又有所回升。同一脂肪水平下,随着饲料蛋白质水平的升高,胃、肠道和幽门盲囊的脂肪酶活性逐渐增加,蛋白质水平为48%时显著高于蛋白质水平为36%时(P0.05);而胃、肠道和幽门盲囊的蛋白酶活性虽有所增加,但各组间无显著差异(P0.05)。同一蛋白质水平下,18%脂肪水平组胃、肠道和幽门盲囊的蛋白酶和脂肪酶活性均略高于9%脂肪水平组。同一脂肪水平下,血清氨含量随饲料蛋白质水平的升高而逐渐增加。饲料蛋白质和脂肪水平对血清超氧化物歧化酶、溶菌酶活性以及葡萄糖、甘油三酯、总蛋白、白蛋白和丙二醛含量均未产生显著影响(P0.05)。由此得出,亚东鲑亲鱼对饲料蛋白质(36%~48%)和脂肪(9%~18%)水平有一定的适应性反应;以增重率为指标进行折线模型分析,得出饲料脂肪水平为9%和18%时,亚东鲑亲鱼对蛋白质需要量分别为43.11%和45.69%。