一种产氢产乙酸菌互营共培养体的筛选及其群落结构解析

厌氧消化系统中的产氢产乙酸菌在营养生态位上位于产酸发酵菌群和产甲烷菌群之间,在功能上起着承上启下的重要作用.该菌群具有与耗氢菌互营共生的特性,其分离纯化非常困难.为了深入了解其生理生态特性,为开发高效的厌氧生物处理技术提供理论基础,采用丙酸和丁酸混合培养基,以具有甲烷发酵功能的厌氧活性污泥为出发菌群,进行了产氢产乙酸菌互营共培养体的选育,并借助于PCR-DGGE技术对其菌群结构进行了解析.经过选择培养基的不断传代培养,最终筛选到2个产氢产乙酸互营共培养体7-m-2a和11-O-1.这2个共培养体不仅对丙酸和丁酸具有很强的降解和产乙酸能力,而且不产甲烷和硫化氢.在这种非产甲烷菌和非硫酸盐还原菌与产氢产乙酸菌组成的互营共培养体中.含有专性的互营产乙酸菌Desulfotomaculum sp.Iso-W2及其伴生菌,其中的伴生菌是能利用甲酸盐和H2/CO2的Uncultured bacterium 054E12_B_DI_P58和Sedimentibacter sp.JN18_A14_H.对这一新的产氢产乙酸菌互营共培养体的发现和选育成功,为更全面地研究产氢产乙酸菌的生理生态特性提供了样本.     

Research on catalysis of sodium-metallochlorophylls in Ni/MH battery

The effects of sodium-metallochlorophylls including sodium-iron chlorophyllin, sodium-copper chlorophyllin and sodium-magnesium chlorophyllin on performance of Ni/MH battery were investigated. The results show that sodium-iron chlorophyllin can effectively activate the gases produced during charge in Ni/MH battery, therefore reducing the reduction potential of oxygen and the oxidation potential of hydrogen, and the increased speed of inner pressure of battery is decreased significantly. With the aid of DMol3 software, the activation process of oxygen and hydrogen by sodiummetallochlorophylls was simulated and analyzed. It was found that the catalysis behavior is in agreement with the experimental results, and the activation process also gets a reasonable explanation from the calculated results.     

Climate change impacts on crop yield,crop water productivity and food security-A review

This paper provides a comprehensive review of literature related to the assessment of climate change impacts on crop productivity using climate,water and crop yield models.The existing studies present that climate change models with higher spatial resolution can be a way forward for future climate projections.Meanwhile,stochastic projections of more than one climate model are necessary for providing insights into model uncertainties as well as to develop risk management strategies.It is projected that water availability will increase in some parts of the world,which will have its own effect on water use efficiency and water allocation.Crop production can increase if irrigated areas are expanded or irrigation is intensified,but these may increase the rate of environmental degradation.Since climate change impacts on soil water balance will lead to changes of soil evaporation and plant transpiration,consequently,the crop growth period may shorten in the future impacting on water productivity.Crop yields affected by climate change are projected to be different in various areas,in some areas crop yields will increase,and for other areas it will decrease depending on the latitude of the area and irrigation application.Existing modelling results show that an increase in precipitation will increase crop yield,and what is more,crop yield is more sensitive to the precipitation than temperature.If water availability is reduced in the future,soils of high water holding capacity will be better to reduce the impact of drought while maintaining crop yield.With the temperature increasing and precipitation fluctuations,water availability and crop production are likely to decrease in the future.If the irrigated areas are expanded,the total crop production will increase;however,food and environmental quality may degrade.     

小议生物的种间关系在农业生产上的应用

人们为了充分利用阳光和土地,往往在一块地里种上几种作物。然而,如果忽视了它们之间的关系,可能会事与愿违。其结果不是一方受害,就是两败俱伤。因此,我们应合理搭配,充分利用植物之间的微妙关系,提高作物产量。合理调节植物种间竞争夺高产自然界对同一环境内生长的动植物所提供的生活条件（包括空间）是有限的,生长在一起的植物,特别是不同种植物,对自然条件的利用和竞争是很激烈的。凡吸收能力强,生长迅速,光合效率高,抗逆能力强的植物种,会在竞争中占优势。而那些生命力较弱的种则受到抑制,甚至死亡。     

范弘伟 为了高产玉米新品种的选育

玉米是最好的肉蛋奶能量来源和工业乙醇加工原料,随着生活水平的提高和生物燃料替代品的需求,对玉米需求不断加大,而我国耕地面积有限,单位面积产量的提高是唯一出路。因此,高产稳产的玉米新品种选育就成了范弘伟和同事们不懈的追求。     

统计不相关最佳鉴别矢量集的本质研究

Until recently the hydrogen molecule structural parameters are calculated with the methods of quantum mechanics. To achieve results close to experimental values, the wave function used is complicated and has no clear physical meaning. Because the distribution of the electron probability density is a statistical rule, the macro-time has actually been used in the concept on a electron cloud graph. Here are obtained three formulas with a classical mechanics method on the bond-length re , bond-energy De and force constant k of the ground state hydrogen molecule, which have a clear physical meaning but no artificial parameters, and compared with experimental values, the relative errors are respectively less than 1% , 2% and 4% .     

浅谈长清区花生全生育期气象条件及栽培技术

通过对长清区花生全生育期的气象条件分析,发现其生长期间的光、热、水、三个因子是花生在生长发育和产量形成过程中必不可少的,满足三方面的要求是其获得高产、稳产的主要因素,评价了有利的气象条件对花生生长和产量的影响以及花生稳产高产的栽培技术。     

二氧化碳浓度增加致农作物产量提高品质下降

德国农作物专家经过多年的试验证明,气候变暖及二氧化碳浓度的变化将对农作物生长产生一定影响,通常农作物的产量会增加,但质量会下降。进行这项试验的是位于布伦瑞克的德国联邦农、林、渔业研究所,专家在试验田里搭起多个直径20米的塑料棚,并向棚里的农作物输入二氧化碳,     

虚拟设备在煤矿监控类实训中的应用研究

在煤矿安全监控和产量监控系统应用的实训课程中,运用虚拟设备进行辅助,能够解决实际实验室硬件设备数量不足的问题。本文对上述两个系统的教学实施情况进行分析和研究,针对实际系统的特点,提出在课程中采用虚拟设备的解决方法,总结虚拟设备在节约教学成本,提高教学质量中的作用。     

低渗透气藏单井合理产量确定新方法

针对低渗透气藏稳产期较短的特点,本文提出了一种确定低渗透气藏单井合理产量的新方法。新方法首先建立每口生产井的单井稳产时间随产量的变化关系方程,根据方程确定气藏的最大稳产时间,再把气藏最大稳产时间分别代入每口井的稳产时间随产量的变化关系方程,进一步反求各单井的合理产量。实例计算证明新方法可以显著提高低渗透气藏的稳产时间,且计算方法十分简便。