不同油菜品种耐铝性比较研究

通过根长测量法和全株鲜重比较法鉴定了8个油菜材料的耐铝性。相关分析表明,油菜幼苗根的绝对长度和全株绝对鲜重之间呈极显正相关（R=0.4147)。方差分析表明,不同品种间、不同Al^3 浓度间油菜幼 苗根的绝对长度、相对长度、幼苗全株绝对鲜重、相对重量差异极显,不同品种和不同Al^3 浓度间交互作用不显。在8个油菜材料中,Pume平均单株绝对鲜重最低,但是平均相对重量居于第一位,平均单根绝对长度居于第二位,平均相对长度居于第三位;华杂4号平均单根绝对长度居于第五位,但是平均相对长度和平均绝对鲜重居于第一位,平均相对重量居于第二位。中油821平均单根绝对长度居于第一位,平均单株绝对鲜重居于第二位,但是平均相对长度居于倒数第二位,平均相对重量居于倒数第一位。     

用富集因子法评价我国城市土壤风沙尘元素的污染

用富集因子法分析土壤风沙尘17个元素的富集(污染)状况.结果表明,C a、C r、Co、N i、Cu、Zn、B r、Pb是广泛富集的元素;地区间元素污染级别差异显著;相对于不同参比元素(A l、F e、T i)的富集因子明显不同.     

内蒙古不同地理及生态环境下羽茅的过氧化物酶同工酶的研究

用聚丙烯酰胺凝胶电泳对内蒙古常见禾本科牧草羽茅（Achnatherum sibiricum(L.)Keng)在6个不同地理及生态环境下的种群进行了过氧化酶同工酶研究，通过对酶谱的比较分析，结果表明：羽茅的种内变异很小，各样点间的同工酶谱十分相近，酶谱不随地理、生态环境的改变而发生相应的变化，说明其体内遗传资源的相对稳定性。     

蒲公英药材总DNA的提取

采用改良的CTAB法、SDS法、高盐低pH法提取蒲公英药材基因组总DNA,通过紫外吸收、琼脂糖凝胶电泳检测其纯度与浓度.结果表明,改良的CTAB法所得DNA纯度最高,电泳条带最清晰、完整性好,可作为RAPD,ISSR等分子生物学研究.     

干旱绿洲植物叶片光合作用特性及季节变化规律

针对西北干旱区绿洲经济作物葡萄树叶片光合作用特性及季节动态差异等相关问题,在甘肃省敦煌市南湖绿洲应用便携式光合作用-荧光测量系统GFS-3000,测定了无核白葡萄叶片的光合特性指标及相关生理、生态指标的季节变化.结果表明:6-9月的净光合速率随光照强度的增加整体呈先上升后平稳的趋势,最大净光合速率与表观量子效率季节变化规律一致,光补偿点和暗呼吸速率季节变化规律一致,净光合速率随CO_2分数的升高快速上升,而后增速缓慢并逐渐趋于稳定,最后出现下降趋势.最大净光合速率和羧化速率季节变化规律一致,单位叶面积氮质量与最大净光合速率表现出正相关关系.     

导电薄板通电瞬间绝热裂尖处温度场的复变函数解

采用对通电瞬间的导电薄板中绝热裂纹尖端放置等效热源的方法。给出了温度场的复变函数解,从而确定了裂尖附近的温度分布,为进一步确定裂尖附的近的应力场奠定了基础。     

Method of Hill Tunneling via Weighted Simplex Centroid for Continuous Piecewise Linear Programming

This paper works on a heuristic algorithm with determinacy for the global optimization of Continuous PieceWise Linear(CPWL) programming. The widely applied CPWL programming can be equivalently transformed into D.C. programming and concave optimization over a polyhedron. Considering that the super-level sets of concave piecewise linear functions are polyhedra, we propose the Hill Tunneling via Weighted Simplex Centroid(HTWSC) algorithm, which can escape a local optimum to reach the other side of its contour surface by cutting across the super-level set. The searching path for hill tunneling is established via the weighted centroid of a constructed simplex. In the numerical experiments, different weighting methods are studied first, and the best is chosen for the proposed HTWSC algorithm. Then, the HTWSC algorithm is compared with the hill detouring method and the software CPLEX for the equivalent mixed integer programming, with results indicating its superior performance in terms of numerical efficiency and the global search capability.     

石墨化度对炭/炭复合材料力学性能的影响

通过三点弯曲试验,并借助SEM断口形貌分析,研究了石墨化度对炭/炭复合材料抗弯强度的影响,对其断裂机制进行了探讨．试验所用材料的基体为沥青浸渍炭+少量CVD炭,增强体炭纤维由乱短纤维和成束长纤维织成的炭布构成,长纤维沿X-Y平面分层铺开,长纤维层之间是随机分布的乱短纤维层．研究结果表明当石墨化度不同时,复合材料的断裂机制不同;在所研究的石墨化度范围28.4%～77.3%内,随着石墨化度的提高,材料的抗弯强度呈现加速下降的趋势;当石墨化度为77.3%时,材料的抗弯强度仅为石墨化度为28.4%时的60%．在石墨化度较低(如27.4%和56.8%)时,材料中的长纤维呈现以拔出机制为主,裂纹沿长纤维束层与乱短纤维层之间的界面传播;在石墨化度较高(如70.6%和77.3%)时,材料中的长纤维被横向切断,裂纹切过长纤维向前传播．这对炭/炭复合材料的研究、开发具有指导意义．     

全氟丁烷磺酸与益生菌对斑马鱼甲状腺内分泌系统的联合效应研究

全氟丁烷磺酸(Perfluorobutanesulfonate, PFBS)是一种新污染物,对鱼类甲状腺内分泌系统具有一定损害效应.益生菌能在一定程度上减轻环境污染物对生物体造成的危害,但其能否调节PFBS的甲状腺内分泌干扰效应尚不清楚.通过将成年斑马鱼暴露于不同质量浓度(0、10和100μg/L)PFBS的养殖水中28 d,投喂添加或不添加益生菌(鼠李糖乳杆菌,Lactobacillus rhamnosus)的饲料,测定亲代下丘脑-垂体-甲状腺轴关键基因,以及亲代大脑、血液和子代胚胎中甲状腺激素水平,以探究PFBS与益生菌共暴露对斑马鱼甲状腺内分泌系统的联合效应.结果显示,在激素水平上,PFBS降低了亲代血液T3水平,而添加益生菌能减轻雄鱼血液T3水平的降低.在基因水平上,100μg/L PFBS与益生菌共暴露促进雄鱼大脑tshβ基因表达以应对低水平的T3,并与相应PFBS单独暴露相比差异显著,表明添加益生菌可以减轻高质量浓度PFBS诱导的雄鱼大脑T3水平的降低;PFBS单独暴露能上调雌鱼大脑trα基因表达,而PFBS与益生菌共暴露则上调trα和trβ基因表达,表明添加益生菌能使机体...     

Super-plasticity of Zr<Subscript>64.80</Subscript>Cu<Subscript>14.85</Subscript>Ni<Subscript>10.35</Subscript>Al<Subscript>10</Subscript> bulk metallic glass at room temperature

Generally, bulk metallic glasses （BMGs） exhibit a very limited plastic deformation under a compression load at room temperature, often less than 2% before fracturing. In this letter, through an appropriate choice of BMGs＇ composition, an amorphous rod of Zr64.80Cu14.85Ni10.35Al10 with a diameter of 2 mm was prepared by using copper mold suction casting. X-ray diffraction and differential scanning calorimetry were utilized to determine its structure and thermal stability, and the uniaxial compression test was adopted to study its plastic deformation behavior at room temperature simultaneously. The results showed that the glass transition temperature and onset temperature of the exothermic reaction of the amorphous rod were 646 and 750 K, respectively, and its micro-hardness was 594.7 Hv. During compression, when the engineering strain and engineering stress arrived at 9.05% and 1732 MPa, respectively, i.e., the true strain and true stress reached 9.42% and 1560 MPa, respectively, the amorphous rod started to yield. After yielding, with the increase of load, the strain increased and the glass rod ulti- mately were compressed into flake-like form. Although the maximum engineering strain was larger than 70%, i.e., the maximum true strain exceeded by 120%, the amorphous specimen was not fractured, indicating that it has super-plasticity at room temperature. Through the appropriate choice of composition and optimization of the technological process, flexible BMG with super-plasticity at room temperature could be produced.