溶剂超临界CO2雾化萃取法制备乙基纤维素微粒的研究

通过溶剂超临界CO2雾化萃取法制得了乙基纤维素微粒．研究了溶液喷口流速、溶液浓度、温度、压力对颗粒粒径及其粒径分布的影响．结果表明，改变工艺参数，可在较大范围内调控微粒大小，所得微粒平均粒径为0．64～10．83μm．随着温度和溶液浓度的增加，颗粒粒径及其粒径分布增加；随着压力和溶液喷口流速的增加，颗粒粒径及其粒径分布减小．     

Estimating functions in indirect inference

Summary.  There are models for which the evaluation of the likelihood is infeasible in practice. For these models the Metropolis–Hastings acceptance probability cannot be easily computed. This is the case, for instance, when only departure times from a G / G /1 queue are observed and inference on the arrival and service distributions are required. Indirect inference is a method to estimate a parameter θ in models whose likelihood function does not have an analytical closed form, but from which random samples can be drawn for fixed values of θ . First an auxiliary model is chosen whose parameter β can be directly estimated. Next, the parameters in the auxiliary model are estimated for the original data, leading to an estimate     . The parameter β is also estimated by using several sampled data sets, simulated from the original model for different values of the original parameter θ . Finally, the parameter θ which leads to the best match to     is chosen as the indirect inference estimate. We analyse which properties an auxiliary model should have to give satisfactory indirect inference. We look at the situation where the data are summarized in a vector statistic T , and the auxiliary model is chosen so that inference on β is drawn from T only. Under appropriate assumptions the asymptotic covariance matrix of the indirect estimators is proportional to the asymptotic covariance matrix of T and componentwise inversely proportional to the square of the derivative, with respect to θ , of the expected value of T . We discuss how these results can be used in selecting good estimating functions. We apply our findings to the queuing problem.     

诘问历史,探寻真实--从《101/2章人的历史》看后现代主义小说中真实性的隐遁

传统文学批评一向热衷于文学真实性的讨论,并将其发展成一种重要的文学观念。但在后现代主义文学中,这一观念受到挑战。英国当代小说家巴恩斯在其小说《101/2章人的历史》中以独特的实验手法,探讨了历史、艺术与真实的关系。这部形式新奇的小说告诉读者:在后现代条件下,历史不再是对真实的记录,艺术所再现的并非本真的真实,真实和虚构之间的界限已经模糊,而真实性的存在主要取决于话语权力的操作者和话语的阐释者。     

Approximations to noncentral distributions

Two methods for approximating the distribution of a noncentral random variable by a central distribution in the same family are presented. The first consists of relating a stochastic expansion of a random variable to a corresponding asymptotic expansion for its distribution function. The second approximates the cumulant generating function and is used to provide central χ² and gamma approximations to the noncentral χ² and gamma distributions.     

CeO_2还原表面水煤气变换反应机理的研究

本文采用原位红外（ＦＴ—ＩＲ）、程序升温脱附（ＴＰＤ）、脉冲反应（ＰＳＲ）等技术研究了ＣｅＯ＿２还原表面在中温变换反应气氛中表面物种的生成及脱附情况，并归纳出水煤气变换反应机理。     

Laws of large numbers for bootstrappedU-statistics

For the bootstrapped mean, a strong law of large numbers is obtained under the assumption of finiteness of the rth moment, for some r>1, and a weak law of large numbers is obtained under the finiteness of the first moment. The results are then extended to bootstrapped U-statistics under parallel conditions. Stochastic convergence of the jackknifed estimator of the variance of a bootstrapped U-statistic is proved. The asymptotic normality of the bootstrapped pivot and the bias of the bootstrapped U-statistic are indicated.     

乙酸正丁酯催化合成的探讨

本文报道了新型催化剂Ti(Al)SiW_(12)O_(40)/TiO_2的制备方法,实验考察了该催化剂催化合成乙酸正丁酯的醇酸比、催化剂用量、带水剂,反应时间等因素对酯收率的影响。实验表明:在以苯为带水剂时催化剂的用量为反应液的0.36％,醇酸摩尔比为1.10:1,酯化反应时间为1.5hour,乙酸正丁酯的收率达79.0％,超过以浓硫酸、磷钨酸催化的水平。     

论经济哲学面临的三大前沿问题

作为以社会经济变化发展规律和特征为主要研究对象的经济哲学 ,须下功夫分析社会诚信与经济发展的内在关系、生态环境与经济发展的内在关系、知识价值与经济发展的内在关系三大前沿问题 ,积极引导人们建立与社会经济良性运行和持续发展相适应的思维方式和行为方式。     

关于持续经营的不确定性的探讨

我国会计核算是以持续经营作为假设前提之一。企业间竞争日益激烈 ,研究持续经营的不确定性成为必然。针对“企业普遍来说是持续经营的”潜意识观念 ,提出对持续经营不确定性的评估方法。     

快速电合成法制备K2 FeO4新工艺研究

于 1 4mol LNaOH溶液中 ,以铁网为阳极 ,采用阳极两面同时电解的方式 ,通电 6h ,可产生 0 .2 3～ 0 .30mol L的Na2 FeO4阳极液。测定了在上述阳极液中结晶K2 FeO4时的溶解 -沉淀平衡曲线。由Na2 FeO4阳极液经 1次性结晶、洗涤和干燥 ,可制得纯度大于 94%的固态K2 FeO4。