超声波作用下金属锂诱发的芳香醛的还原偶联反应

芳香醛和金属锂在超声波作用下于THF中室温反应2，邻二醇的收率为15%-79%。     

有序民主化:中国政治发展的路径选择

伴随着全球化浪潮的高涨,政治领域的“第三波”民主化浪潮席卷广大发展中国家,为促进民主化进程提供了发展的契机,然而许多国家无视本国历史与现实,或过快过激地推进民主化进程,或全盘照搬西方民主模式,其结果引发了政治不稳定与社会动荡,阻碍甚至破坏了经济增长,在民主化进程中,我国也充满了社会风险,有鉴于此,我国必须积极、稳妥、渐进、有序地推进民主化进程。有序民主化,是中国政治发展的路径选择。     

量子力学中德布罗意波的波长和频率的计算

通过对德布罗意关系中和的意义及其之间关系的分析。澄清德布罗意波的波长和频率计算过程中的一些问题。     

一个非局部波动方程组解的爆破增长率的估计

本文考虑如下非局部波动方程组的初值问题:这里0相似文献   

超薄CRT的S校正

为了对大偏转角下的超薄CRT图像S畸变进行校正,针对匀强磁场和六极场以及理想纯平和实际曲率荧光屏的情况,分别推导了进行S校正以实现匀速屏幕扫描所需的扫描电流理论形式.继而采用高阶正弦信号来逼近这一理论电流波形,以便于电路实现.优化计算后的扫描电流可以在90°直到140°的偏转角范围内以足够精度逼近理论值,谐波阶数随着角度增大而增加直至四阶.提出了一种梯形电路来实现这一方法,模拟和实验结果证实了该方法对校正S畸变的效果.     

新熊彼特派和马克思主义长波理论述评

本文介绍了长波理论的创始人范·盖尔德伦的理论观点。对现代两种主要的长波理论———马克思主义范式和新熊彼特派范式做了比较。长波理论的发展方向是把马克思主义范式与新熊彼特派范式相结合 ,而这要求对马克思主义传统的利润率下降理论进行改造     

电磁场与波实验教学的探索与实践

针对“电磁场与波”课程理论性强、概念抽象的特点,对该课程的实践环节进行了研究,设计了演示型和指导型等实验,并通过生动形象的实践环节的具体实施,达到了实验辅助与深化课堂教学的效果,激发了学生对理论知识的学习兴趣。     

等离子体中的波动

分析了“冷”、“热”等离子体中波动现象的普遍色散关系，比较了其异同点，给出了反映“冷”等离子体中波动分类的CMA图和反映“热”等离子体中波动的（ω，κ）色散关系图。     

Study on EEG power and coherence in patients with mild cognitive impairment during working memory task

To investigate the features of electroencephalography (EEG) power and coherence at rest and during a working memory task of patients with mild cognitive impairment (MCI). Thirty-five patients (17 males, 18 females; 52～71 years old) and 34 sex- and age-matched controls (17 males, 17 females; 51～63 years old) were recruited in the present study. Mini-Mental State Examination (MMSE) of 35 patients with MCI and 34 normal controls revealed that the scores of MCI patients did not differ significantly from those of normal controls (P＞0.05). Then, EEGs at rest and during working memory task with three levels of working memory load were recorded. The EEG power was computed over 10 channels: right and left frontal (F3, F4), central (C3,C4), parietal (P3, P4), temporal (TS, T6) and occipital (O1, O2); inter-hemispheric coherences were computed from five electrode pairs of F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 for delta (1.0～3.5 Hz), theta (4.0～7.5 Hz), alpha-1 (8.0～10.0 Hz), alpha-2 (10.5～13.0 Hz), beta-1 (13.5～18.0 Hz) and beta-2 (18.5～30.0 Hz) frequency bands. All values of the EEG power of MCI patients were found to be higher than those of normal controls at rest and during working memory tasks. Furthermore, the values of EEG power in the theta, alpha-1, alpha-2 and beta-1 bands of patients with MCI were significantly high (P＜0.05) in comparison with those of normal controls. Correlation analysis indicated a significant negative correlation between the EEG powers and MMSE scores. In addition, during working memory tasks, the EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group (P＜0.05). However, there was no significant difference in EEG coherences between two groups at rest. These findings comprise evidence that MCI patients have higher EEG power at rest, and higher EEG power and coherence during working conditions. It suggests that MCI may be associated with compensatory processes at rest and during working memory tasks. Moreover, failure of normal cortical connections may be exist in MCI patients.     

常微分方程的精确解及其应用

考虑非线性常微分方程，利用分析的方法得到其精确解，并给出了它在n维非线性Chaffe-Infante方程和非线性波动方程中的应用。