九种根际促生菌最适培养条件初探

测定了分离自燕麦和小麦根际九株促生菌对温度、pH值、光照及培养方式的需求,结果表明:虽然九株促生菌适应范围较广,即在5~45℃、pH4~9、3种光照条件(12h黑暗12h光照、24h光照和24h黑暗)和3种培养方式(全天振荡、间歇振荡和静止培养)下均能较好生长,但不同菌株的最适培养条件不尽相同。通过对各菌株的最适培养条件进行了测定和分析,为后续确定促生菌的最佳发酵条件和生态适应性评价提供了依据。     

Proton accumulation accelerated by heavy chemical nitrogen fertilization and its long-term impact on acidifying rate in a typical arable soil in the Huang-Huai-Hai Plain

Cropland productivity has been signiifcantly impacted by soil acidiifcation resulted from nitrogen (N) fertilization, especialy as a result of excess ammoniacal N input. With decades’ intensive agricul...     

pH对洛美沙星与BSA之间结合常数的影响

[目的]研究洛美沙星与血清白蛋白之间的作用,了解药物分子在体内的运输和分布情况。[方法]采用毛细管区带电泳法,通过测定在不同pH值、不同牛血清白蛋白浓度的缓冲溶液条件下药物迁移时间的变化,计算出洛美沙星与牛血清白蛋白相互作用的结合常数（Kb）。[结果]pH分别为6.8,7.4和8.0时,洛美沙星与BSA之间的Kb分别为10.185×1045、.319×1045、.356×104 L/mol。[结论]环境pH对洛美沙星与BSA之间的相互作用有强烈影响,当pH处在6.8～7.4之间时,Kb对pH尤为敏感。     

基于机器视觉的玉米秸秆行实时定位机器人设计

为了实现机器人玉米秸秆行的精确定位,对耕作玉米机器人的结构进行了改进,并提出了一种基于泰勒级数展开式的RSSI定位方法,提高了机器人玉米秸秆行的定位精度。定位系统使用高清晰度的摄像机采集图像,并采用PID闭环反馈的方式控制机器人的位移,利用PC主控端图像处理,实现了实时定位功能。为了验证机器人玉米秸秆行定位的可靠性,采用田间试验的方法对机器人的性能进行了测试。结果表明:RSSI定位方法的定位精度较高,且图像处理系统可以准确地标定玉米秸秆行,实现机器人在玉米田中的精确定位,避免了机器人在作业过程中对农作物造成损害。     

消费者价格指数与生产者价格指数“倒挂”之谜

消费者价格指数（Consumer Price Index,CPI）与生产者价格指数（Producer Price Index,PPI）是我国最重要的两个价格指数，一般说来，CPI与PPI应当是同步变化的.但是自2000年以来，CPI与PPI出现了多次“倒挂”现象，这无疑对当前经济通胀情况的判断带来了挑战.采用最新的X-13-ARIMA-SEATS方法对我国的CPI与PPI指数进行季节调整；在谱分析的基础上采用BK滤波方法将其趋势-循环因素进行分解得到趋势因素与循环因素.研究后发现是经济周期导致了“倒挂”现象.     

土壤pH值对极小种群毛枝五针松生理特性的影响

幼苗建成期是毛枝五针松(Pinus wangii)天然更新的关键阶段,为找出影响毛枝五针松幼苗存活的关键生态因子,采用植物生理学方法,研究在7个酸碱度土壤培育下,毛枝五针松松针超氧化物歧化酶(SOD)、过氧化物酶活性(POD)活性和脯氨酸、可溶性糖质量分数及丙二醛(MDA)摩尔质量浓度的变化。结果表明:毛枝五针松在弱碱土壤中抗逆性更强,形态观察得知其在弱碱性土壤中生长更好;生理指标测定结果表明,土壤在p H=7.69~8.42时最适宜毛枝五针松幼苗的生长发育。     

Biochar has little effect on soil dissolved organic carbon pool 5 years after biochar application under field condition

Biochar application can improve soil properties, such as increasing soil organic carbon content, soil pH and water content. These properties are important to soil dissolved organic carbon (DOC); however, the effects of biochar on DOC concentration and composition have received little research attention, especially several years after biochar application under field conditions. This study was conducted in a long‐term experimental field where the biochar was only applied once in 2009. The purpose of the study was to investigate the effect of different biochar application rates (0, 30, 60 and 90 t ha^?1) on the dynamics of soil water content, DOC concentration and DOC compositions (reducing sugar, soluble phenol and aromatics) over nine samplings during a 12‐month period in 2014. Our results showed that soil water content and DOC concentration varied from 7.1% to 14.5% and 59 to 230 mg C kg^?1 soil during the 12 months, respectively. However, the biochar application rates did not significantly (p > 0.05) affect soil water content, DOC concentration and DOC composition at the same sampling period. The DOC concentration across the biochar treatments was positively correlated to soil water content. Moreover, the DOC composition (reducing sugar, soluble phenol or aromatics) and their concentrations were positively correlated to the total DOC concentration. In addition, biochar did not affect soil bulk density, pH, saturated hydraulic conductivity and crop yields. The results indicated that some benefits of biochar to soil may not persist 5 years after the application of biochar under a field condition.     

带常利率和相依结构更新风险模型的破产概率

研究了一类具有常利率及相依结构的Sparre Andersen模型, 模型中假设理赔间隔时间决定下一次理赔额的分布情况. 对一般分布情形, 利用推广后的调节系数方程与递归更新技巧, 得到了此模型的最终破产概率上界的估计. 最后以理赔额和理赔间隔时间都服从指数分布的情况下的实例分析来说明该模型的有效性.     

Drought Stress in Grain Legumes during Reproduction and Grain Filling

Water scarcity is a major constraint limiting grain legume production particularly in the arid and semi‐arid tropics. Different climate models have predicted changes in rainfall distribution and frequent drought spells for the future. Although drought impedes the productivity of grain legumes at all growth stages, its occurrence during reproductive and grain development stages (terminal drought) is more critical and usually results in significant loss in grain yield. However, the extent of yield loss depends on the duration and intensity of the stress. A reduction in the rate of net photosynthesis, and poor grain set and grain development are the principal reasons for terminal drought‐induced loss in grain yield. Insight into the impact and resistance mechanism of terminal drought is required for effective crop improvement programmes aiming to improve resistance to terminal drought in grain legumes. In this article, the impact of terminal drought on leaf development and senescence, light harvesting and carbon fixation, and grain development and grain composition is discussed. The mechanisms of resistance, management options, and innovative breeding and functional genomics strategies to improve resistance to terminal drought in grain legumes are also discussed.