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耳源性眩晕占所有眩晕病例的半数以上，其致病机制复杂，涉及多个感觉系统和中枢信息整合，临床诊断与疗效分析普遍缺乏客观指标。前庭相关中枢网络是形成眩晕感知的最终部位，其功能改变可能是眩晕的后果及其症状慢性持续的潜在原因。脑功能评估技术从高级中枢角度探索了耳源性眩晕的特征，证实了患者的皮层多感觉前庭皮质网络发生了活动性及功能连通性改变，为临床认识提供了新的视角。本文阐述了耳源性眩晕脑功能改变的研究进展，并着重探讨脑电图在此领域的应用现状与前景。.

Factor analysis was applied to the phenotypic correlation matrix of 15 linear type traits (scored linearly 1 to 50 points) for 2035 Holstein cows of 38 sires computed from data collected between 1988 and 1992 in Beijing Shuangqiao Farm and Beijing Xijiao Farm. The 15 linear type traits were stature, body strength, body depth, dairy form, rump angle, rump length, rump width, rear leg side view, foot angle, fore udder attachment, rear udder height, rear udder width, udder cleft, udder depth and teat placement rear view. The first four components accounted for 49.1% of the total variance in type scores. Factor 1 reflected strong cows, with deep bodies, with long and wide rumps, and tall in stature. Factor 2 reflected cows with well attached fore udders, wide rear udders and whose udders were supported by strong suspensory ligaments with close teat placement. Factor 3 reflected cows with good dairyness, sickled in the hocks, high rear udders and udder floors above the hocks. Factor 4 reflected cows with sloping rumps from hooks to pins and with steep foot angle. Principal component and factor analyses are useful to clarify the relationships among type traits.

The genetic structure and genetic variation of eight beef cattle cross parents populations were analyzed by six microsatellite loci, and heterosis of beef cattle was predicted. On the basis of microsatellite analysis, the effect of 18 cross combinations was estimated by the method of individual animal model BLUP. A new method of molecular quantitative genetics that select best of all cross combination was submitted. The results showed that the combinations with Hereford Limousine and Charolais as paternal parent are better than others in Fengning and Longhua regions; the combinations with Limousine Angus and Hereford as paternal parent are better than others in Zanhuang regions; the combinations with Hereford Limousine and Piemontese as paternal parent are better than others in Funing regions. Effect of three breeds cross is better than two breeds.

The dissociative chemisorption of N2O and O2 on carbon‐covered Ru(001) surfaces has been studied by Auger electron spectroscopy. Small amounts of carbon sharply lower the dissociative probability for N2O as compared to O2. Carbon blocks sites for atomic oxygen adsorption and one monolayer of carbon removes the dissociation activity for O2 and N2O. The results are interpreted in terms of a significant effect of carbon on the N2O molecular precursor state and in terms of more restrictive surface site requirements for N2O as compared to O2.

Experiments showed that the extent of molecular oxygen adsorption at 160/sup 0/K was sensitive to the amount and structure of preadsorbed oxygen, and that the structure of atomically absorbed oxygen changed in the 160/sup 0/-900/sup 0/K temperature range.

The interaction of O 2 and N 2 O are compared on the basal plane of Ru as a function of the coverage of copper. Dissociative N 2 O uptake (N 2 O(g) → O(a) + N 2 (g)) on clean Ru was measured using AES and transient partial pressures. The initial dissociative reaction probability is a steadily declining function of temperature while the saturation uptake of oxygen remains constant from 300–900 K. The saturation oxygen AES signal for N 2 O chemisorption was one half that observed for O 2 chemisorption. The presence of 0.02 monolayers of Cu retards the initial dissociative adsorption of N 2 O by 40% but has little effect on the total uptake of oxygen. The initial dissociative sticking coefficient for O 2 is not retarded significantly by small amounts of copper. Deposition of larger amounts of Cu leads to the completion of a 2D overlayer before growth in 3D begins. Surfaces covered with less than 3 monolayers of Cu exhibit larger O 2 sticking coefficients and greater oxygen stability than pure Cu.

The titration of oxygen chemisorbed on Ru(001) by H 2 at low pressures is reported. For near-saturation doses of O 2 , the subsequent H 2 titration is characterized by three distinct features: first, a long induction time, then a rapid reaction and, finally, a slow reaction. Electron spectroscopies, AES and XPS, were used to follow the decay of the oxygen signal. The first two features are accounted for by a model which involves dissociative adsorption of hydrogen and blockage of dissociation sites. The third feature is accounted for in terms of an inactive form of chemisorbed oxygen. All three regions are approximately first order in hydrogen pressure. The rate in the second region, at a fixed oxygen signal, is sensitive to the initial amount of oxygen present. This is ascribed to variations in the size and degree of perfection of (1 × 2) domains. With increasing temperature, the break between the second and third regions becomes less pronounced. This is accounted for in terms of an activated (6.5 ± 1.0 kcal mole −1 ) conversion of inactive to active oxygen. The induction times are very sensitive to small changes in surface oxygen concentration caused by electron stimulated desorption of oxygen.