Co掺杂SnO_2纳米粉的微结构和磁学性质

采用湿化学方法制备了Co掺杂的二氧化锡纳米粉(Sn1-xCoxO2),经研究发现,Co以离子形式存在,而不是以单质形式存在,样品中除了金红石型的SnO2相之外,没有发现其他杂质的相,随着Co掺杂含量的增加,晶粒尺寸减小,光吸收谱红移,禁带宽度线性下降。钴离子磁矩随掺杂含量的增加而减小,这可能是由于占据晶格上近邻阳离子位置的磁性离子数目增加使磁性离子成反铁磁性排列的结果。     

国有商业银行不良贷款问题的因素分析

与金融领域的其他改革相比,我国国有商业银行的改革显得有些滞后,此间严峻的不良贷款问题明显成为其改革进程的巨大障碍。十几年来,各方为扫清这一障碍采取了诸多措施,但效果并不显著。解决国有商业银行不良贷款问题须做通盘考虑,既要有全方位的宏观视角,又要有行之有效的微观思路,综合分析解决这一问题的内外因素,才能有效克服此障碍。     

Nonparametric estimation of the lower tail dependence λL in bivariate copulas

The lower tail dependence λ_L is a measure that characterizes the tendency of extreme co-movements in the lower tails of a bivariate distribution. It is invariant with respect to strictly increasing transformations of the marginal distribution and is therefore a function of the copula of the bivariate distribution. λ_L plays an important role in modelling aggregate financial risk with copulas. This paper introduces three non-parametric estimators for λ_L. They are weakly consistent under mild regularity conditions on the copula and under the assumption that the number k = k(n) of observations in the lower tail, used for estimation, is asymptotically k ≈ √n. The finite sample properties of the estimators are investigated using a Monte Carlo simulation in special cases. It turns out that these estimators are biased, where amount and sign of the bias depend on the underlying copula, on the sample size n, on k, and on the true value of λ_L.     

高校过度扩招的十大弊端

大学教育的发展超过一定限度,即在一定时期规模过大,发展速度过快,其负效果可能比正效果更多,会给社会、学校和群众带来严重的消极影响。从经济角度分析,其弊端主要有十个方面。     

从资产评估的角度解读中国银行业的不良资产问题

帮助中国银行业走出困境的方法之一就是剥离不良资产.以企业价值为参照,考查了银行不良资产的价值评估特征,提出了为银行不良资产处理专门立法,明确赋予金融资产管理公司重组企业资产的权利;由于银行的不良资产主要集中于大企业、大项目,可考虑先剥离这类单位的不良资产进行评估重组;协调财务审计与资产评估的关系等对银行不良资产价值评估工作的若干建议.     

完整PbWO4晶体偏振性质的模拟计算

利用完全势缀加平面波局域密度泛函近似，计算了完整的PbWO4(PWO)晶体的电子结构，模拟计算了复数折射率、介电函数及吸收光谱的偏振特性．分析了各个吸收光谱的峰值所对应的可能的电子跃迁以及PWO晶体的偏振特性．     

Asymptotic properties of the maximum-likelihood estimator for a class of birth-and-death processes admitting a unique stationary distribution

The asymptotic properties of the maximum-likelihood estimator of the parameter vector for a class of birth-and-death processes admitting a unique stationary distribution are studied. Also, it is shown that identifiability of the parameter vector with respect to the likelihood implies that the Fisher information matrix is of full rank. Two special cases of biological interest are presented. One of these, the exponential birth-and-death process, is proposed as a more appropriate model of density dependence than the logistic process.     

中国期货市场价格波动非对称性效应的实证研究

采用EGARCH模型,以铜、大豆及小麦三个主要的连续期货合约收益序列为样本的实证研究表明:利空消息对我国期货价格波动的影响,要大于利多消息对期货价格波动的影响.对300个期货交易者的问卷调查结果也表明:我国期货投资者普遍存在的"过度恐惧"心理,是造成利空消息对期货价格波动的影响大于利多消息对期货价格波动的影响的最为重要的原因.     

Evaluating technical efficiency of human capital formation in the Italian university: Evidence from Florence

This paper models the human capital formation in the Italian university and utilizes a measure of technical efficiency to estimate the output-efficiency of human capital formation in the University of Florence, by using Data Envelopment Analysis (DEA) on a selected set of inputs and outputs. It uses the Program Evaluation (PE) procedure as well, in an attempt to attribute shares of the variation in efficiency to factors that are beyond the control and factors that are under the control of the graduates and faculties. The authors thank two anonymous referees for their valuable comments.     

试论国家利益的内涵与特征

国家利益是一国制定外交政策的重要依据,亦是一国对外交往与合作的重要参考。国家利益并不是随着国家的产生而产生的,而是在独立的民族国家出现后,在对外交往中逐渐形成了国家利益的雏形。国家利益和国家一样,具有阶级性和民族性。除此之外,国家利益还具有动态性的特点,会随着时代的发展而发展变化。从国家及其本质入手,阐述国家利益的起源、内涵及其特点,对国家利益的研究进行了一个基本的概述。