三项式xn-x-a的二次不可约因式

设n是正整数,f(x)=xn-x-a,其中a是非零整数. 证明了当n>5时,如果f(x)有首项系数为1的二次整系数不可约因式g(x),则必有n≡2(mod6),a=-1,g(x)=x2-x+1或者n=7,a=±280,g(x)=x2t(±)x+5.     

三元TBZ/HPB-铜(Ⅱ)-L-蛋氨酸配合物的合成、表征、抑菌活性及与DNA的作用

本文合成了2个新的三元铜(Ⅱ)配合物:[Cu(TBZ)(L-Met)(H2O)]ClO4.H2O(1)和[Cu(HPB)(L-Met)]ClO4(2)[TBZ=2-(4′-噻唑基)苯并咪唑,HPB=2-(2-吡啶)苯并咪唑,L-Met=L-蛋氨酸]。通过元素分析、摩尔电导率、IR、UV-Vis及电喷雾质谱对这些配合物进行了表征。用二倍稀释法研究了配合物的抗菌活性,发现配合物对金黄色葡萄球菌(Staphylococcus aureus,G+),枯草杆菌(Bacillussubtilis,G+),沙门氏杆菌(Salmonella,G-)和大肠杆菌(Escherichia coil,G-)具有良好的抑制作用。采用电子吸收光谱、荧光光谱、粘度测定及琼脂凝胶电泳方法研究了配合物与DNA的相互作用,结果表明,配合物以插入方式与DNA作用,在维生素C存在下通过羟自由基.OH,单线态氧1O2或者1O2类似物如Cu-O2,切割pBR322 DNA双螺旋结构。     

Modified lattice Boltzmann solution for non-isothermal rarefied gas flow through microchannel utilizing BSR and second-order implicit schemes

Journal of Thermal Analysis and Calorimetry - Thermal microscale gas flow was simulated into a coplanar microchannel was simulated at a broad range of Knudsen numbers. Attempts were made to improve...     

Synthesis, molecular structure and intramolecular aromatic-ring stacking interaction of a novel binuclear Cu(Ⅱ) complex with 1, 10-phenanthroline and phenylacetate

The complex [Cu(phen)2(POAc)3]ClO·4H2O has been synthesized and investigated by elemental analysis, IR spec-troscopy and X-ray diffraction methods, where phen = 1,10-phenanthroline, POAc = phenylacetate group). The complex crystallizes in the triclinic space group PI with two molecules in a unit cell of dimensions a = 1.0579(2) nm, b = 1.2423(3) nm, c = 1.9190(4) nm, α = 71.84(1)°, β = 80.50(2)°, γ = 88.60(1)°, V = 2.3625(9) nm3, R = 0.0407 and Rw = 0.0656. The complex results from bridging of two Cu(phen)2 units by three carboxylate groups, and each Cu2 ion is in a distorted square pyramidal geometry with two nitrogen atoms of phen and three carboxylate oxygen atoms of POAc. It has been showed that intramolecular stacking interactions occur between the phenyl moieties of POAc and aromatic rings of phen, leading to a novel molecule structure with two coordinating modes of carboxylate ligands, of which two phenylacetates are μ2-carboxylate-O-bridging ligands, and the other is a μ2-carboxylate-     

On Problems in the Calculus of Variations in Increasingly Elongated Domains

This paper deals with minimization problems in the calculus of variations set in a sequence of domains, the size of which tends to infinity in certain directions and such that the data only depend on the coordinates in the directions that remain constant. The authors study the asymptotic behavior of minimizers in various situations and show that they converge in an appropriate sense toward minimizers of a related energy functional in the constant directions.     

CONSERVATION OF ENDANGERED ENDEMIC SEABIRDS WITHIN A MULTI‐PREDATOR CONTEXT: THE BARAU'S PETREL IN RÉUNION ISLAND

Abstract Seabirds breeding on islands are vulnerable to introduced predators, such as rats and cats, and the removal of such predators is generally viewed as a priority for seabird conservation and restoration. However, multiple invasive mammal species interacting may generate unexpected outcomes following the removal (eradication) of one species. Generally these indirect interactions are not well understood or demonstrated. We propose and study a prey (seabird)‐mesopredator (rat)‐superpredator (cat) model, taking into account the juvenile stages in the prey population, in order to direct conservation management for seabird conservation. We give a more biologically realistic differential system than those studied before (Courchamp et al. [1999] ; Fan et al. [2005] ), in particular for long‐lived seabird species. We present a theoretical study and show existence and uniqueness of a positive solution as well as a qualitative study of the equilibria that may appear. Because standard numerical methods, usually implemented in scientific softwares, can fail to give the right biological approximations ( Anguelov et al. [2009] ), we propose a reliable algorithm that preserves most of the qualitative properties of the continuous system, using the theory of nonstandard finite difference methods. Finally, we use biologically realistic parameters available for the representative Barau's petrel (Pinet et al. [2008] ), an endemic species from Réunion island, to present numerical simulations that support the theoretical study. Cats play the major role in seabird prey population dynamics. Seasonality in seabird breeding delays but does not prevent extinction. In all scenarios, cat control (or preferably eradication) is imperative to prevent extinction of vulnerable long‐lived seabirds, like the Barau's petrel.     

我国证券市场风险计量模型的构建

证券风险的计量准确与否,是证券组合理论能否有效运用的前提,在现有研究成果的基础上,结合我国证券市场的特点,选取“流通市值”作为影响我国证券风险的第二个因素,建立了证券风险计量模型,并使用统计软件对模型的适用性进行了检验．     

Calculation of α decay half-lives for superheavy elements using the double folding model＊

α decay half-lives of some new synthesized superheavy elements, possibly synthesized superheavy elements and decay products are calculated theoretically within the WKB approximation by using microscopic α-nucleus interaction potentials. These nuclear potentials between the α particle and daughter nuclei are obtained by using the double folding integral of the matter density distribution of the α particle and daughter nuclei with a density-dependent effective nucleon-nucleon interaction, in which the zero-range exchange term is supplemented. The calculated α decay half-lives are compared with those of the different models and experimental data. It is shown that the present calculation successfully provides the half-lives of the observed decays for some new superheavy elements and therefore gives reliable predictions for α decay of possibly synthesized superheavy elements in future experiments.     

Synthesis, Characterization, Crystal Structure and Stability of a Ternary Cu(Ⅱ) complex with 1,10-Phenanthroline and L-Valinate

Introduction It is important to research the mixed-ligand copper complexes containing bioligands,such as amino acids, nucleic acids and proteins,in exploring the functional mechanism of microelement copper in organism because the reaction of any micronutrient with two or more bioligands in the concentrated bioligands background gives mixed-ligand ternary complexes, which are more stable[1]and related with storage of substance and transportation of metal ions in the life process.     

GC-MS分析氧化亚铁硫杆菌培养液的挥发性成分

GC- MS联用技术对耐强辐射微生物氧化亚铁硫杆菌 [Thiobacillus ferroxidans(T.f) ]的挥发性代谢产物进行了研究 ,发现 4 3种代谢物 ,由标准谱图鉴定了其中 2 3种化合物。