植树挖坑机钻头主轴扭转振动数学建模与求解

介绍国内外机械化植树造林机械发展状况,指出国内植树用挖坑机研究重点,利用空间运动学和机械振动理论以及弹性动力学原理着重分析建立钻头主轴扭转振动模型并用数值方法进行求解,同时系统地分析钻头主轴下端部件与土壤的相互作用力、钻头主轴重力及惯性力等因素的影响,给出动态的准随机边界条件和初始条件.为下一步的钻头动力学特性仿真及整机动态特性研究,合理预测和控制钻头的运动规律,改善钻头的动力学特性,提高钻头工作效率及改进设计方法提供新的理论依据.     

早熟、优质、耐贮运西瓜新品种‘爱耶一号’

 ‘爱耶一号’是采用自交分离、杂种优势利用, 并结合化学诱变而育成的早熟西瓜新品种, 具有成熟早、丰产、抗病、品质佳、果肉红、抗裂果、耐贮运、适应性广等优良特性。     

Impact of coleopteran targeting toxin (Cry3Bb1) of Bt corn on microbially mediated decomposition

Genetically engineered corn expressing crystalline proteins for insect control and encoded by genes derived from soil bacterium Bacillus thuringiensis (Bt) are widely adopted in the United States. Among the seven different events of Bt corn available commercially, YieldGard^® Rootworm (MON863) expresses a variant of the cry3Bb1 protein in the root tissue to control corn rootworm larvae. Although numerous laboratory and field studies show no unexpected ecological risks at the insect community-level above-ground, few studies have addressed the possible impact of cry proteins released from living or decaying roots of Bt corn on soil microbial communities. Here, we test the hypothesis that coleopteran-active Bt corn does not affect nontarget ecological processes, such as decomposition or the function of the associated saprophytic microbial community. Experimental treatments were: (1) a Bt hybrid; (2) a non-Bt, isogenic hybrid treated with a conventional soil insecticide; and (3) a non-Bt, isogenic hybrid without insecticide. Soil and root samples were collected at various times throughout 2 years from experimental plots to estimate microbial community function by quantifying activity of extracellular enzymes on 10 substrates. Decomposition was measured as mass loss by root decay in litter bags. Bt corn (MON863) exuding the cry3Bb1 toxin does not appear to have adverse effects on saprophytic microbial communities of soil and decaying roots or on decomposition. The addition of the soil insecticide had greater effects on microbial function in soil and decaying roots than Bt corn. Our results are similar to those found previously for the cry3Bb1 protein that showed no adverse effects on microbial community composition in controlled and natural environments. This field study is one of the first to report the use of extracellular enzyme assays to examine the effect of transgenic crops on the functional activity of microbes in soil and decaying roots.     

葡萄果实中糖类成分与品质特征研究进展

葡萄具有极高的经济价值,但其果实品质影响市场竞争力,所以一直为学界所关注.然而在制约葡萄果实品质构成的因素中,果实中糖类的组成与含量是决定果实品质的最重要因素.在综合有关文献的基础上,对葡萄果实中糖分与品质特征进行了评述,重点阐述了糖分影响葡萄鲜食品质和酿酒品质的重要作用,并提出了开展此项研究的重要意义.     

动物脂滴结构及功能研究进展

脂滴是脂肪组织的基本单位,是维持脂质和能量稳态的一种动态细胞器,脂滴相关蛋白参与调控胞内脂类代谢、膜运输以及信号传导等多个生理过程.脂滴在动物各个组织器官中的功能不尽相同,可通过营养及生理手段调节畜禽外周组织中的脂滴变化,进一步影响畜禽胴体性状及肉品质.本文简述了脂滴的生物学结构、脂滴蛋白分类、脂滴重塑、脂滴生物学功能...     

天津地区野生软枣猕猴桃资源开发利用现状分析与建议

为加快天津地区野生猕猴桃资源的开发和利用,从天津地区野生猕猴桃的种类特征、地理分布及营养、经济、观赏等应用价值进行阐述,对野生软枣猕猴桃的开发利用现状进行分析,并对今后软枣猕猴桃进一步健康发展提出建议。     

猪圆环病毒病原学研究进展

猪圆环病毒(porcine circovirus,PCV)有2种不同的血清型,即猪圆环病毒1型(PCV1)和猪圆环病毒2型(PCV2)。目前研究表明PCV1暂无致病性,但PCV2则被认为是引起猪圆环疾病(PCVDs)的主要病原。很多地区养猪业的经济效益因此而遭受了重大的影响。PCV现已受到全球的关注,引起了许多专家学者的高度重视。本文对PCV的病原学最新研究进展进行了综述。     

真菌RNA沉默研究进展

阻抑(Quelling)与减数分裂沉默(Meiotic silencing by unpaired DNA,MSUD)等真菌RNA沉默(RNA silencing)现象的研究拓展了我们当前对基因表达调控的认知。随着测序信息量的爆炸性增长与功能研究的不断深入,真菌RNA沉默展示出的复杂与多样为真核生物研究提供了全新的视角。本文就当前真菌RNA沉默及相关小分子RNA(Small RNA,sRNA)的研究现状做一简要概述。     

丙环唑·嘧菌酯在玉米和土壤中的残留分析

经过对样品前处理过程的研究和优化,建立了丙环唑和嘧菌酯的气相色谱分析方法。样品经乙腈水溶液提取分配后,用弗罗里硅土小柱净化,采用气相色谱(μ-ECD)测定。方法中目标物在50~2 000μg·L-1浓度范围内线性良好,相关系数分别为0.999 1和0.999 4。在5,50,200μg·kg-13个添加浓度水平下,平均加标回收率在79.2%~110.9%之间,相对标准偏差不大于15%。该方法可灵敏、简便、快速地测定玉米中丙环唑和嘧菌酯的残留。