磁性纳米颗粒系统的铁磁共振和共振线宽分析

 对非相互作用磁性纳米颗粒系统的FMR线型模型进行了研究,以铁磁体从应用场中获得自由能F为例,导出磁性颗粒在较小各向异性时,共振场H_r与有效各向异性场H_A^eff的关系,这个结果与Raikher和Stepanou的结果一致.继而还对共振场线宽进行了分析,并与Smit和Beljers模型进行了比较,其结论说明:在超顺磁区域有效各向异性场H_A^eff对塞曼(Zeeman)相互作用和附加应用场H是不确定的.尤其是这种情况在H_A^eff较小、高温(高温区域),且H_A^eff≈H时,变得更显著.为此提出了随机颗粒阵列及参数特征对这个结果的影响机制.     

环上的最大流通量问题

 研究一个新颖的最大流通量问题,集中考察在SONET环上的情形,即令R为SONET上的一个环,其顶点集{0,1,2,…,n-1},每条边e_i=(i,i+1)和边上的整数容量限制d_i及m个所要求通过的点对{s_i,t_i}(1≤i≤m且s_i≠t_i).要求一个方案,选择所要求的m个点对中的某些点对(也许是所有的),此时每个点对就由一条道路相连,在通过环上每条边的总条数不超过其边整数容量限制的条件下,最大化所用到的道路条数.通过引入单方向概念并应用LP-rounding技巧,证明了环上的单方向最大流通量问题属于P类,即可有多项式时间算法求解,并因此获得了环上最大流通量问题的一个2-近似多项式算法.     

Insights into the subunit interactions of the chloroplast ATP synthase

Subunit interactions of the chloroplast F0F1- ATP synthase were studied using the yeast two-hybrid system. The coding sequences of all the nine subunits of spinach chloroplast ATP synthase were cloned in two-hybrid vectors. The vectors were transformed into the yeast strains HF7c and SFY526 by various pairwise combinations, and the protein interactions were analyzed by measuring the yeast growth on minimal SD medium without serine, lucine and histidine. Interactions of γ Subunit with wild type or two truncated mutants of γ sununit, △εN21 and △εC45, which lose their abilities to inhibit the ATP hydrolysis, were also detected by in vitro and in vivo binding assay. The present results are largely accordant to the common structure model of F0F1-ATP synthase. Different from that in the E. Coli F0F1-ATP synthase, the δ subunit of chloroplast ATP syn- thase could interact with β,γ,ε and all the CF0 subunits in the two-hybrid system. These results suggested that though the chloroplast ATP synthase shares the similar structure and composition of subunits with the enzyme from E. Coli, it may be different in the subunit interactions and con- formational change during catalysis between these two sources of ATP synthase. Based on the present results and our knowledge of structure model of E. Coli ATP synthase, a deduced structure model of chloroplast ATP synthase was proposed.     

农业自然灾害系统灰色分析方法的探讨

对灰色关联方法在农业自然灾害系统分析中的应用进行了探讨。认为，农业自然灾害对干农业生产的影响完全有别于生产资料投入的作用。当系统特征行为序列（Ｘｏ）为增长序列，相关因素序列（Ｘｉ）亦为增长序列时，不能就此判定Ｘｏ与Ｘｏ为正相关关系而直接进行建模。当促进因素的作用大于抑制因素的作用时，即使灾害的危害有所增加，农业生产仍可表现为一个增长序列。提出判定关联性的命题应为：设系统特征行为序列为Ｘｏ，相关因素序列为Ｘｉ，则，１°当影响因素的性质一致时（如均为促进或抑制），设Ｘｏ为增长序列，若Ｘ１为增长序列，则Ｘ１与Ｘｏ呈正相关关系；若Ｘ１为衰减序列，则Ｘｉ与Ｘｏ呈负相关关系。２°当系统主行为受性质不一致的因索（包含促进和抑制因素）影响时，若Ｘｉ的增长促使Ｘｏ增长或衰减趋势减弱，Ｘｉ的衰减使Ｘｏ衰减或增长趋势减弱，则Ｘｉ与Ｘｏ呈正相关关系；若Ｘｉ增长促使Ｘｉ衰减或增长趋势减弱、Ｘｉ衰减使Ｘｏ增长或衰减趋势减弱，则Ｘｉ与Ｘｏ为负相关关系。     

A Note on the Multifractal Decomposition of Directed Graph Self Similar Sets

We investigated the directed graph self similar sets under some weak overlapping condition. We get the multifractal decomposition formulas for these sets, i. e.,dim Ku^a DimKu^a =f(a), where fis the multifractal spectral function of the directed graph self similar measure. Especially, the results improve that of Edgar and Mauldin to the case which allows certain overlapping.     

Cu2+对两种海洋微藻生长和叶绿素荧光特性的影响

运用水样叶绿素荧光仪(WATER-PAM)研究Cu2+胁迫下,湛江叉鞭金藻(Dicrateria zhanjiangensis)和球等鞭金藻3011(Isochrysis galbana MACC/H59)叶绿素荧光特性的变化,同时监测微藻的生长情况.结果就叶绿素荧光参数而言,湛江叉鞭金藻和球等鞭金藻3011的叶绿素荧光参数Fv/Fm,Fv/F0,Yield和ETR均随着Cu2+浓度的增大而明显降低;就生长情况而言,随着Cu2+浓度的增大,两种海洋微藻细胞密度的增长明显变缓.在24 h时Cu2+对湛江叉鞭金藻的毒性大于球等鞭金藻3011,48～96 h时Cu2+对球等鞭金藻3011的毒性大于湛江叉鞭金藻,Cu2+的毒性随着胁迫时间的延长而逐步增大.     

RAgSb2金属间化合物的第一性原理研究

本文从理论计算的角度研究RAgSb_2(R=La-Sm,Gd-Er)合金的部分物理性质,为解释这些化合物的奇特物理性质提供理论依据。采用第一性原理计算方法研究RAgSb_2化合物的结构、机械性能、声子以及热力学性质。根据Birch-Murnagha方程拟合结果,发现LaAgSb_2无磁性,其余合金均表现磁有序,其中除了CeAgSb_2和GdAgSb_2外,其余的RAgSb_2合金的反铁磁态能量低于铁磁态。这些化合物的结合能计算数值均为负值,说明它们具有稳定的结构。而弹性模量的计算结果表明这些化合物具有稳定的机械性能。根据泊松比和B/G值,可以证实GdAgSb_2合金和TbAgSb_2合金具有韧性,而其余的合金表现为脆性。声子谱的计算结果显示这些合金具有稳定的热力学性质,其热容CV随着温度的升高,在低温下急剧增加并与T~3成正比,在较高温度下缓慢增加并趋向于Dulong-Petit极限,高温下的热容接近47.5cal·cell~(-1)·K~(-1)。     

Study on the DME-cytochrome<Emphasis Type="Italic">b</Emphasis><Subscript>5</Subscript> and its mutants at site of F58

Phenylalanine-58 is one of the conservative residues in the hydrophobic pocket of Cyt bs, which forms aromatic stacking with the heme b. Previous study showed that both the stacking and the property of the aromatic residue affect hydrophobicity of the heme pocket, leading to change of protein‘s property. In order to further reveal the essence we esterify the heme propionate of Cyt bs, F58Y and F58W, and eliminate the hydrogen bond between heme propionate and Ser64 in examining the effect of hydrogen net on the π-π interaction. In this paper thermal denaturation of DME-Cyt b5 and its F58Y and F58W mutants has been studied by UV-visible and CD spectra. The heme transfer reactions between these proteins and apo-myoglobin have been studied as well. The results demonstrate that esterification did not destroy the aromatic stacking; however, it affects the stability of the proteins due to different volumes, hydropho-bicities and hydrogen bonds forming ability of these substituents.     

平均弱局部一致凸及强端点在置换空间的提升

主要研究平均弱局部一致凸性及强端点从Banach空间Xn到置换空间PxXn上的提升问题,证明了这两种性质都可以在置换空间PxXn上得到提升。     

Secular variations in geomagnetic Field caused by the fluctuations in the fluid flow in the outer-core

The theoretical spatial power spectrum of a dipole located at ( r0, θ60, φ0) can be fitted by a straight line in logarithmic scale when n is larger than 2. Based on the spherical harmonic coefficients of geomagnetic field during 1900-1995, the depth( r0) of source-layer of every 5a is calculated. The results show that r0 decreased from 1900 to 1960; abruptly changed from 1945 to 1950 related to some kind of disturbance; decreased again from 1960 to 1975; increased from 1975 to 1985; and kept stable after 1985. Then the mean energy density (MED) of each year is induced to its corresponding r0. We find that MED of dipole field kept nearly unchanged from 1900 to 1960. While, MED of non-dipole field increased. The change of r0 coinciding with the geomagnetic secular variation, impulse and length-of-day happened around 1970, suggesting that the change of r0 may be related to the impulse. The variation in the fluid flow in the outer-core caused by the core-mantle coupling is a plausible candidate in explaining the changes in geomagnetic Jerk, length-of-day, and r0.     

Effects of soil stoichiometry of the CaCO<Subscript>3</Subscript>/available phosphorus ratio on plant density in <Emphasis Type="Italic">Artemisia ordosica</Emphasis> communities

In soil, CaCO3 can reduce the availability of phosphorus in arid and semi-arid regions, thereby influencing plant growth. However, the effects of soil stoichiometry of the CaCO3/available phosphorus ratio (CaCO3/AP ratio) on plant density are unknown. In this study, we examined 4 Artemisia ordosica communities located in arid and semi-arid regions, and performed a pot experiment with an orthogonal design to examine the relationships between the soil CaCO3/AP ratio and plant density. The results showed that the soil stoichiometry of the CaCO3/AP ratio had a greater effect on growth of A. ordosica than either CaCO3 or AP as single factor. The influence of the soil CaCO3/AP ratio on density of A. ordosica was related to the climatic zone and the types and/or amplitudes of increases in the soil CaCO3/AP ratio. When the soil CaCO3/AP ratio was within the same amplitude and was less than 2.5, the A. ordosica density increased in the semi-arid region, whereas the density decreased with increasing soil CaCO3/AP ratios in the arid region. In the semi-arid region, when the soil CaCO3/AP ratio was within the same amplitude and the increase in the soil CaCO3 content was greater than the increase in soil AP, the A. ordosica density increased with increasing soil CaCO3/AP ratios. This means that the relationship between the soil CaCO3/AP ratio and the A. ordosica density remained the same. In the arid region, an increase in the soil CaCO3/AP ratio as a result of increased soil CaCO3 content and decreased soil AP resulted in increased density of A. ordosica. Therefore, the relationship between soil CaCO3/AP ratios and density of A. ordosica was altered by these changes in soil chemistry. Thus, the soil stoichiometry of the CaCO3/AP ratio is an important factor affecting the density of A. ordosica in arid and semi-arid regions.     

应用正交试验法的RHT模型参数敏感性研究

基于RHT模型的理论分析,选出A、N、B、M、B_Q、f_s/f_c、T_ten、D₁和E_f,min 9个参数作为正交试验分析参数,研究RHT模型中参数的敏感性.运用Autodyn程序对弹丸侵彻混凝土过程进行数值分析,确定了不同参数、不同水平值下弹丸的侵彻深度.采用极差分析法对参数的敏感程度进行量化分析,得出9个参数的敏感性排序为B > E_f,min > T_ten > f_s/f_c > N > M > D₁ > B_Q > A.结合3组典型数值试验损伤云图和侵彻深度的对比分析,认为参数B、E_f,min和T_ten对数值模拟试验结果的影响极大,应采取可靠的技术手段准确确定其取值.      

Photosynthesis characteristics of three species of forages in the arid-hot valleys

By using TPS-1 portable photosynthesis measuring system, the photosynthesis characteristics of three kinds of high quality forages used in the arid-hot valley eco-agricultural models in Yuanmou were measured. The paper shows that Pennisetum purpureum Schumach is the heliophilous shade tolerance C4 plant and Styiosanthes guianensis is the heliophilous shade tolerance plant, both of them could make full use of the light energy under the weak light environment and have relatively strong CO2 assimilation capacity. Cajanus cajan（L.） Millspaugh is the strong heliophilous plant with high requirement for light and has a relatively weak CO2 assimilation capacity. Generally, these three kinds of high quality forages are drought resistant and show a relatively good adaptability to the arid-hot valley environment. To improve cultivation administration level and to interplant timely in the forest can be helpful to the ecological niche and to improve the productivity force.     

医疗信息化效用影响研究

通过对医院信息化投入、医院运营管理对医疗效益的影响规律进行分析,根据重庆市某三级甲等医院在2009-2015年间的信息化投入、医院运营管理2个方面与医疗毛收入的数据资料,通过Pearson相关分析得到医疗毛收入与11个影响指标均相关(P0.05),通过熵值法,选择指标权重值大于0.08的指标有医院全年财务信息化投入x_1、医院全年门诊量x_4、医院全年入院患者人数x_6、医院全年手术量x_7以及医院初级职称人数x_10,其权重分别为0.190、0.086、0.085、0.084、0.084。建立多因素回归分析的数学模型,得到了指标x_1、x_4、x_6、x_7、x_10与医疗毛收入拟合函数,可决系数分别为0.948 8、0.927 1、0.994 1、0.993 0、0.948 1,医疗毛收入的回归方程的可决系数为0.996 3,因此,本研究通过熵值法得到的影响医疗毛收入的5个指标,并建立得到的回归方程可应用于医院信息化投入决策的制定,为医疗卫生管理提供新的依据。     

The influence of the nonmagnetic metal spacer Bi, Ag and Cu on the properties of the multilayer films

When a ferromagnetic (FM)/antiferromagnetic (AFM) bilayer is field-cooled below the Neel temperature (TN) of the AF layer, a unidirectional anisotropy is induced in the FM. Exchange bias is one of the phenomena as- sociated with the exchange anisotorpy cr…     

Correlation between the standard formation enthalpy and the path index of pyridine-derivatives

A formulated as △fH _m ^◯ (PPDs,g)=a+Σb_iP_i + c_if_i is put forward for estimating standard formation enthalpies of pyridine-derivatives (PDDs), in which,P _i is path index andc _i f _i is an amended term of interaction between substituent and N atom on pyridine ring. The Calculations based on the model were carried out for some pyridine-derivatives. The values of standard formation enthalpy calculated are consistent with those in literature. Foundation item: Supported by the National Natural Science Foundation of China (29971024) Biography: LI Liang-chao (1958-), male, Associate professor, Research direction: calculating chemistry.     

Effect of Ni addition on the glass-forming ability and soft-magnetic properties of FeNiBPNb metallic glasses

The effect of Ni addition on the glass-forming ability (GFA) and soft-magnetic properties of an (Fe1-xNix)75.5B14.5P7Nb3 (x=0-0.6) alloy system were investigated. We found that the addition of Ni was effective in allowing the alloy to approach a eutectic point as well as increasing the thermal stability of the supercooled liquid. By increasing the amount of Ni,the supercooled liquid region (ΔTx),the reduced glass transition temperature Trg (Tg/Tl) and the Y parameter [Tx/(Tg+Tl)] increased from 49 to 75 K,0...     

Effects of nitrogen sources and glucose on the consumption of ethylene and methane by temperate volcanic forest surface soils

There is limited knowledge with regard to the consumption of ethylene (C2H4) and methane (CH4) in volcanic forest soils containing low microbial carbon-to-organic carbon ratio, and to the responses of both consumptions to nitrogen and carbon additions. Temperate volcanic forest surface soils under three forest stands (e.g. Pinus sylvestris L., Cryptomeria japonica and Quercus serrata) were used to compare CH4 and C2H4 consumption by forest soils, and to study the effects of nitrogen sources and glucose on both consumptions. There was a good parallel between CH4 and C2H4 consumption by for- est soils, but mineralization reduced CH4 consumption rather than C2H4 consumption in forest soils, particularly in a Pinus forest soil. The stimulatory effect of glucose addition on both CH4 and C2H4 consumption by forest soils was increased by increasing the pre-incubation period after glucose addi- tion, and a largest stimulation occurred in the Pinus forest soil. The addition of KNO3-N at the rate of 100 μg·g1 significantly reduced the consumptions of both C2H4 and CH4 by forest soils (P≤0.05). In the presence of urea plus dicyandiamide, the consumption rates of C2H4 and CH4 by forest soils were higher than those in the KNO3-N and urea-N treated soils at the same N rate (P≤0.05), but were similar to those of the control. Hence, under experimental conditions, there was a strong inhibitory effect of NO3 rather than NH4 addition on the CH4 and C2H4 consumption in these forest soils. When amount of the added NO3-N increased up to more than 2―3 times the soil initial NO3-N concentrations, both C2H4 and CH4 consumption rates were reduced to 10%―20% of the rates in soils without nitrate addition. By comparing the three forest stands, it was shown that there was a smallest effective concentration of the added nitrate that could inhibit C2H4 and CH4 consumption in the Pinus forest soil, which indicated that C2H4 and CH4 consumption of the soil was more sensitive to NO3-N addition.     

无机-有机杂化材料催化合成乙酸异戊酯及动力学研究

以甘氨酸(Gly)和磷钨酸为原料合成的一系列无机有机杂化材料为催化剂,考察各因素对其催化合成乙酸异戊酯的影响,并利用响应面分析法优化乙酸异戊酯合成工艺。研究表明,[GlyH]_(1.0)-H_(2.0)PW_(12)O_(40)催化剂具有最高的催化酯化反应活性和重复使用性能。响应面分析法优化乙酸异戊酯合成的最佳条件为:醇酸摩尔数比为1.05∶1,催化剂用量为酸质量的4.5%,反应时间2.0h,带水剂量10mL,该条件下,乙酸异戊酯产率为98.5%,结果与模型预测值基本相符。优化条件下[GlyH]_(1.0)-H_(2.0)PW_(12)O_(40)催化酯化反应表观活化能为79.73kJ/mol。     

Research on effects of hydrostatic pressure on the dielectric property of Pb(Zn<Subscript>1/3</Subscript>Nb<Subscript>2/3</Subscript>)O<Subscript>3−</Subscript>BaTiO<Subscript>3−</Subscript> PbTiO<Subscript>3</Subscript> relaxor ferroelectric ceramics

The dielectric properties of Pb(Zn1_1/3Nb_2/3)O₃₋ BaTiO₃₋PbTiO₃ relaxor ferroelectric ceramics near the rhombohedral and tetragonal phase boundary were investigated under hydrostatic pressure. It was found that hydrostatic pressure made their phase transition temperature T _c and the peak temperature T _m decreased, and the frequency dispersion and relaxor behavior enhanced. In these disorder systems of composite pervoskite structures, there appeared polar clusters or nanodomains. The unique physical characteristics, which made the relaxor behavior enhanced, is that the correlation length among these nanodomains decreases greatly with the pressure increasing.