焊趾表面裂纹的形态发展曲线与疲劳寿命预测

以作者建立的焊地椭圆表面裂纹应力强度因子数据库以及复杂应力场中焊践半随圆表面裂纹前缘应力强度因子分布计算的基本模式法为基础上,给出了复杂应力场中焊践表面表纹在疲劳扩展过程中形态变化规律及寿命的工程分析方法。     

Growth Curve Model with Hierarchical Within-Individuals Design Matrices

This paper deals with some inferential problems under an extended growth curve model with several hierarchical within-individuals design matrices. The model includes the one whose mean structure consists of polynomial growth curves with different degrees. First we consider the case when the covariance matrix is unknown positive definite. We derive a LR test for examining the hierarchical structure for within individuals design matrices and a model selection criterion. Next we consider the case when a random coefficients covariance structure is assumed, under certain assumption of between-individual design matrices. Similar inferential problems are also considered. The dental measurement data (see, e.g., Potthoff and Roy (1964, Biometrika, 51, 313-326)) is reexamined, based on extended growth curve models.     

亚硝酸根在磷钼镍杂多酸-聚吡咯膜修饰电极上的伏安行为及其含量测定

研究了亚硝酸根(NO     

改性活性炭脱除有机硫化物的研究(英文)

考察了在使用改性活性炭脱除有机硫化物的过程中水和温度的影响。研究结果表明,水汽的存在不利于有机胺改性活性炭脱除二硫化碳;Ｋ２ＣＯ３改性活性炭用于脱除碳基硫的实验显示,在３０－６０℃的温度范围内,４０℃最适宜于脱除反应。     

DNA-modified electrodes (Ⅶ)——Preparation and characterization of DNA-bonded and DNA-adsorbed SAM/Au electrodes

Two kinds of DNA-modified electrodes were prepared by covalent and adsorptive immobilization of DNA onto self-assembled monolayers of 2, 2'-dithiodiethanol on gold electrodes and characterized by cyclic voltammetry, Xray photoelectron spectroscopy and scanning tunneling microscopy. The results suggest that the methods are satisfactory for the immobilization of DNA on electrodes.     

Effect of the nature of zeolite and modifying additives on the activity of zeolite-containing catalysts inn-butane isomerization

Isomerization ofn-butane on various types of zeolites (ZVM, ZVK, mordenite, and Y) modified with transition metals and cationic and anionic additives was investigated. Under the conditions studied, H-forms of zeolites are inactive. Pt-containing systems based on the H-form of ZVM (HZVM) are the most efficient catalysts forn-butane isomerization, and the yield of isobutane reaches 20–26 wt.% at a selectivity of 40–45%. Modification of this catalyst with Ga and Fe compounds or with an aqueous solution of HCl increases the selectivity with respect to isobutane up to 70–90%. Introduction of Zn²⁺ cations or F⁻ and SO₄ ²⁻ anions into the Pt-containing HZVM system decreases the selectivity and yield of isobutane due to the formation of very strong acidic centers on which disproportionation and hydrocracking ofn-butane mainly occur. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1281–1285, July, 1999.     

分子筛修饰电极中内电子传输机理的研究

用电化学方法聚合方法筛孔道内的苯胺,以聚苯胺分子筛修饰电极为模型研究了分子筛修饰电极的内电子传输机理,ＮａＹ分子筛的离子交换点位被苯胺修饰后,通过电聚合制得聚苯胺分子筛修饰电极（Ｐａｎ＾＋Ｙ－ＺＭＥ）,该电极通过聚苯胺链自身的电子跳跃来实现电子传输,且只有通过阴极富集后对溶液中Ｃｄ＾２＋才有响应,并能用于测定抗坏血酸。     

有理曲线和曲面的分片多项式逼近

本文利用摄动的思想,以摄动有理曲线（曲面）的系数的无穷模作为优化目标,给出了用多项式曲线（曲面）逼近有理曲线（曲面）的一种新方法．同以前的各种方法相比,该方法不仅收敛而且具有更快的收敛速度,并且可以与细分技术相结合,得到有理曲线与曲面的整体光滑、分片多项式的逼近．     

Imaging of chemical reactivity and buckled dimers on Si(100)2×1 reconstructed surface with noncontact AFM

We have investigated the force interactions between the Si tip and the Si(100)2×1 reconstructed surface in the noncontact atomic-force microscopy (AFM) measurement. We observed two types of frequency shift curves without and with discontinuity, similar to the Si(111)7×7 surface. The image contrast changes drastically whether the frequency shift curve shows discontinuity or not. In the case of the frequency shift curves without discontinuity, the noncontact AFM images almost reflect the surface topography including dimers and adsorbates. In the case of the frequency shift curves with discontinuity, they reflect strongly the chemical reactivity of surface. Furthermore, in the case of the frequency shift curves without discontinuity, for the first time, the stabilize-buckling of dimers induced by a defect can be observed. This suggests that the force interactions during the noncontact AFM measurement hardly influence the surface dynamics.     

Wei Hua’s four-parameter potential: Comments and computation of molecular constants αe and εeXe

The value of adjustable parameterC in the four-parameter potentialU(r) =D _e [(1 - exp[-b(r -r _e)])/(1 -C exp[-b(r -r _e)])]² has been expressed in terms of molecular parameters and its significance has been brought out. The potential so constructed, withC derived from the molecular parameters, has been applied to ten electronic states in addition to the states studied by Wei Hua. Average mean deviation for these 25 states has been found to be 3.47 as compared to 6.93, 6.95 and 9.72 obtained from Levine, Varshni and Morse potentials, respectively. Also Dunham’s method has been used to express rotation-vibration interaction constant (α_e) and anharmonicity constant (ω_ex_e) in terms ofC and other molecular constants. These relations have been employed to determine these quantities for 37 electronic states. For α_e, the average mean deviation is 7.2% compared to 19.7% for Lippincott’s potential which is known to be the best to predict these values. Average mean deviation for (ω_ex_e) turns out to be 17.4% which is almost the same as found from Lippincott’s potential function.