奶牛酒精阳性乳与自由基代谢及乳腺损伤关系的研究

对酒精阳性乳患牛衄清与乳清中的抗氧化指标进行了检测，从自由基代谢与损伤的角度探讨了酒精阳性乳的发病机理；同时检测了阳性牛血清与全乳中微量元素Zn、Cu、Mn、Fe的含量，分析了微量元素含量变化与自由基代谢的关系。试验结果显示阳性牛体内发生了过度的过氧化反应，机体总抗氧化能力下降，机体的扰氧化系统已不能有效地清除活性氧及代谢产物，过多的氧自由基可能对乳腺上皮分泌细胞细胞膜造成微损伤，从而引起乳腺细胞分泌异常乳。     

基于全产业链视角的食用菌产业经济效益分析

依照食用菌产业链关系,有效反映以价值转让和食用菌产品生产为主线的企业联系,并体现企业彼此间在市场供需关系基础上建立的内在关联。发展食用菌产业具备成本低、周期短、市场潜力大以及产生经济效益高等积极效应,利用食用菌产品投入产出比值方法,计算投入产出数值,衡量经济效益水平高低,有效评价食用菌产业经济效益。依据食用菌产业发展趋势,提出增加科研及技术投入,推动产业链发展、以及加强食用菌产业规划两点策略,以促进食用菌产业经济效益提升。     

正反螺旋式土壤改良石灰播撒机设计与试验

为了提高石灰播撒的效率和精准控制播撒量,研制了正反螺旋式石灰播撒机,并与旋耕机组合成一体机,采用复合作业方式。该文论述了正反螺旋式石灰播撒机的结构和工作原理、灰量调节机构原理和调节方法,并对播撒机的出灰口尺寸和播撒辊的转速进行了试验设计,计算了播撒机的总功率;最后将石灰播撒旋耕机一体机在冬天的稻田进行石灰播撒-旋耕组合的田间试验。结果表明:当石灰播撒-旋耕一体机前进速度平均为5 km/h,播撒辊转速为80 r/min,调节机构档位处于最大播撒量的13档时,满足第1年的播撒量要求;当档位分别位于12档(或10档)和7档时,播撒量分别满足第2年和第3年的播撒量要求。该研究为改善农业作业条件、降低劳动力成本、提高石灰播撒效率提供了参考。     

Adaptive evolutionary expansion of the ribonuclease 6 in Rodentia

Ribonuclease 6 (RNase6 or RNase K6) is a protein that belongs to a superfamily thought to be the sole verte‐brate‐specific enzyme known for a wide range of physiological functions, including digestion, cytotoxicity, angiogenesis, male reproduction and host defense. In our study, 51 functional genes and 11 pseudogenes were identified from 27 Rodentia species. Intriguingly, in the 3 main lineages of rodents there were multiple RNase6s identified in all species of Ctenohystrica, whereas only a single RNase6 was observed in other Rodentia species examined except for 2 species in the mouse‐related clade. The evolutionary scenario of “birth (gene duplication) and death (gene deactivation)” and gene sorting have been demonstrated in Ctenohystrica. In addition, bursts of positive selection, diversification of isoelectric point and positive net charge have been identified in Ctenohystrica, especially at two key sites that are involved in antimicrobial function. Site Trp30 has undergone positive selection and Ile45 has changed into other residues in Group B and Group C of the Ctenohystrica. Our results demonstrated a complex and intriguing evolutionary pattern of rodent RNase6, and indicated that functional modification may have occurred, which establishes an important theoretical foundation for future functional assays in rodent RNase6.     

不同通风工艺在浅圆仓中应用的研究

在对大豆进行冬季通风作业时,采用正压上行压入式、负压下行吸出式和先负压后正压三种作业方式分阶段进行通风,充分的利用自然冷源,达到降温目的,通过对比三种作业方式的降温效果、水分损耗、降温能耗、人工投入等,并根据粮情,找出最合适的通风方式。     

二阶Neumann边值问题的正解

利用锥上的不动点指数理论研究了二阶Neumann边值问题-u″(t)+a(t)u(t)=f(t,u(t)),t∈[0,1];u′(0)=u′(1)=0正解的存在性和多重性.其中a(t):[0,1]→(0,+∞)连续;f(t,u):[0,1]×[0,+∞)→[0,+∞)连续.     

非线性四阶两点积分边值问题正解的存在性

研究非线性四阶微分方程两点积分边值问题解的存在性.利用一些分析技巧及锥上不动点定理,给出该问题存在一个及两个正解的充分条件.     

Isolation and characterization of Streptomyces species from potato common scab lesions in Norway

The present survey was conducted to isolate and characterize Streptomyces species from common scab lesions of potato in Norway. Bacteria were isolated from scab lesions on tubers sampled in two consecutive years at different locations in Norway spanning ～1400 km from south to north. In total, 957 independent isolations from individual tubers were performed, with 223 putative pathogenic isolates obtained from 29 different potato cultivars and 130 different fields. Streptomyces europaeiscabiei was the most abundant species isolated from common scab lesions (69%), while 31% of the isolates obtained were S. turgidiscabies. Streptomyces scabies was not found. Pathogenicity of selected Streptomyces isolates was tested on potato. The ability of the bacterial isolates to infect potato was consistent with the presence of the txtAB operon. The results revealed no pattern in geographical distribution of S. europaeiscabiei and S. turgidiscabies; both could be found in the same field and even the same lesion. Four different pathogenicity island (PAI) genotypes were detected amongst the txtAB positive isolates: nec1+/tomA+, nec1–/tomA+, nec1+/tomA? and nec1?/tomA?. The current findings demonstrate that there is genetic variability within species and that the species are not spread solely by clonal expansion. This is thought to be the most comprehensive survey of Streptomyces species that cause common scab of potato in a European country.     

长江中游某矿区水体和沉积物重金属来源解析及分布特征和生态风险评估

为探究长江中游沿江某矿区周边水-沉积物重金属分布特征、潜在风险及其来源,本研究以江西省北部某矿区周边水体及其沉积物中7种重金属(As、Cd、Cr、Cu、Hg、Pb和Zn)为研究对象,通过多点采样分析其在地表水-沉积物系统中的污染特征,并运用单因子评价指数和地累积指数(I_geo)分别对地表水和沉积物中所含重金属进行风险评价,最后通过正定矩阵因子分析(Positive definite matrix factorization,PMF)模型解析沉积物中重金属来源。结果表明：受酸性矿山废水直排影响,该地区地表水和沉积物酸化严重,pH最低分别为2.12和2.62。水体和沉积物中,以Cu、Zn和Cd超标较为严重,水体中分别为0.001～46.96、0.01～122.90、ND～64.97 mg·L^-1,沉积物中分别为21.30～1 840.61、54.20～1 487.55、0.04～18.73 mg·kg^-1,其中以Cd点位超标率最高(68.97%)。风险评价结果表明,超过50%的点位受到Cu和Cd的污染,属于重度风险等级,且多...