丛枝菌根真菌生态功能及其与共生植物互作机理

丛枝菌根真菌是陆生植物根系广泛存在的一类真菌类群,并与宿主植物形成互惠共生体,在土壤生态环境中发挥着重要的生态作用和功能。从丛枝菌根提高宿主植物非生物胁迫(水、温度、盐碱和重金属等)抗性、生物胁迫(植物病害等)抗性以及改变宿主根际微生态等方面,对丛枝菌根真菌的生态作用、互作机理和研究热点进行了综述。     

南疆棉区机采棉发展中存在的问题及对策探讨

针对南疆棉区人工植棉成本上涨,人工采收异性异色纤维多等情况,分析了南疆发展机采棉意义重大,并剖析了在南疆发展机采棉所面临的问题,提出了今后发展建议,以推进南疆机采棉的发展和促进棉花产业的发展.     

Thermal and structure properties of biobased cellulose nanowhiskers/poly (lactic acid) nanocomposites

Cellulose nanowhiskers were used to improve the performance of poly (lactic acid) (PLA). The nanocomposites mixed with three different molecular weight of poly (ethylene glycol) (PEG) were characterized by mechanical testing, thermal gravimetry and differential scanning calorimetry. The tensile test showed an increase in tensile strength and elongation at break with the addition of PEG to PLA/CNW nanocomposites, the thermal analysis results showed an increase of crystallization temperature (T _c) and crystallization compatibility (larger crystallization and melting areas), which indicated that the cellulose nanowhiskers (CNW) and PEG or CNW alone should not be considered as nucleating agents for the PLA matrix; The CNW was homo-dispersed which contributed to decreasing mobility of polymer chain segments. The compatibility between hydrophobic PLA matrix and the hydrophilic CNW was improved by the addition of different molecular weight polymeric-PEG. The thermo gravimetric analysis indicated that the thermal stability of the different composites were reflected well in the region between 25 °C and 245 oC. The structure of the PLA/CNW/PEG composites was characterized by AFM, which showed that the CNW dispersed in the PLA matrix evenly.     

Reliability Analysis of Wedge Slopes

The material parameters and geometric parameters of wedge slopes have high variability, and there are several failure modes for a wedge slope. It is necessary to carry out system reliability analysis for wedge slopes. We consider a wedge slope as a series system which is composed of four failure modes, and we consider each failure mode as a parallel sub-system with three components. Then, the reliability analysis is carried out by using the product of conditional marginal method and bound method of system reliability analysis. A new method for the linearization of nonlinear performance function is proposed for computing the coefficient of correlation between each failure modes in the parallel sub-system. Through the reliability analysis of a wedge slope, it is illustrated that a wedge slope can be considered as a series-parallel system, and the new linearization method can simulate the failure domain accurately. The failure modes computed from the reliability analysis and the deterministic method is different. Reliability analysis method is suitable for the design and management of wedge slopes.     

Experimental study on adaptability of well pattern using sandstone plate model with ultra-low permeability

Because the porous flow state is difficult to be simulated by one-dimensional cores and two-dimensional sand filled models,this paper proposes a method of making large-scale natural outcrop flat model and defines two parameters to evaluate adaptability of different well pattern on the ultra-low permeability sandstone flat model. With natural sandstone plate model,production of different well patterns in homogeneous oil reservoirs is simulated. A concept of pressure sweep efficiency and deliverability index for researches on adaptability of well patterns are put forward. Through experiments,plane pressure gradient field of different well patterns under different drawdown pressures are measured,and then seepage areas of the models are divided into immobilized seepage area,nonlinear seepage area,and quasi-linear seepage area,with the help of small core nonlinear seepage curve. Experiments show that adaptability of inverted nine-spot equilateral well pattern is better than those of inverted nine-spot rhombus well pattern and rectangular well pattern. With the increase of drawdown pressure,deliverability index of all well patterns increases,immobilized seepage area reduces,and quasi-linear seepage area expands. At the same time,nonlinear seepage area of inverted nine-spot equilateral well pattern reduces,while those of inverted nine-spot rhombus well pattern and rectangular well pattern fluctuate as expanding first and then reducing.     

不同类型食用植物油国家标准与行业标准的分析比较

食用植物油标准是衡量食用植物油品质优劣的依据,由于对食用植物油品质要求不同,使得国内现存的食用植物油标准之间存在诸多差异.通过对现行有效的各食用植物油国家标准、无公害食品标准、绿色食品标准之间的品质指标及其限量,以及安全卫生指标及其限量进行系统比较,寻找不同标准的差异,并以此来对不同标准的严格程度加以比较,从而为我国食用植物油相关标准的制定及修订提供参考.     

湖南农业产业集群集聚效应实证研究

湖南农业生产已经形成与其他各领域多产业结合互补的发展新局面,产业集群的集聚效应日益体现。文章基于湖南省2001～2010年农业产业的相关数据,对粮食、油料和棉花三种主要农产品的产业集群集聚效应进行了实证分析,结果表明只有棉花的产业集群集聚效应较为明显,体现出较高的市场集中度,虽然湖南的油料产业集群集聚效应比粮食产业集群的集聚效应略高,但行业中的集中程度仍不强,针对问题提出了依靠科技创新促进农业产业链的升级、依托龙头企业带动农业产业化经营和加强对农业产业集群的金融扶持等建议,以促进湖南农业经济的发展。     

产人参皂苷类似物工程菌提取物TLC展开系统的研究

薄层层析(TLC)是化学成分研究的重要检测手段,通过TLC法可以对多种代谢产物进行检测、分离和纯化。为了得到快速检测、高效分离能产人参皂苷类似物的酵母工程菌株Y828-15-1中组成成分,对工程菌株甲醇提取物TLC展开系统进行了研究,共使用6种展开系统对抽提物进行分离。结果表明,4种展开系统具有分离效果,其中新展开系统S4(氯仿∶甲醇∶水=130∶70∶37)具有最好的分离效果且分离得到2种未知产物。     

长江师范学院校园白颊噪鹛取食生态位的初步研究

2010年2～6月,对长江师范学院校园白颊噪鹛(Garrulax sannio)的取食生态位进行了初步研究.结果表明,在该校园内共观察到白颊噪鹛165只,取食行为365次,白颊噪鹛主要倾向分布于建筑区及其周边绿地(55.62％),其次为乔灌林(19.45％)、水域(12.33％)、农田(12.60％);白颊噪鹛的取食策略是采取拾取的取食方式(73.70％,B=1.74),以地面作为最佳的取食基质(32.88％,B=4.24)和取食高度(45.75％,B=3.00);白颊噪鹛的取食生态位很广,为杂食性鸟类,对生境表现出较强的适应性.     

美味牛肝菌菌丝体营养特性分析

研究了美味牛肝菌(Boletus edulis Bull.:Fr)菌丝体的营养特性.结果表明,美味牛肝菌生长的最适碳源是葡萄糖,最适氮源是蛋白胨,最适无机盐是KH2PO4,最适维生素是VB1,最适培养基为葡萄糖3.0％、蛋白胨0.20％、KH2PO4 0.60％、MgSO4· 7H2O 0.20％和VB1 0.000 5％,最适pH为5.0,最适温度为28℃,此时菌丝体生长速度最快,长势最好.