β-桉烯和其衍生物的合成及其抗生育活性

本文叙述了倍半萜类化合物——β-桉烯、衍生物Neointermedeol以及1,2,3,4,7,8-六氢-5,8-二甲基-3-异丙烯基萘的合成。初步药理筛选结果表明,这三个化合物均具有一定的抗生育活性。化合物还未见报道,它的化学结构在本文得到证实。     

FORTRAN下拉式菜单的设计

本文设计了FORTRAN下拉式菜单。在TurboC环境下，根据面向对象（oop）的设计思想，进行设计。从原理菜单功能给出了详细的说明。     

CTAB胶束溶液对正脂肪酸乙酯碱性水解反应的催化动力学行为研究

在20℃条件下，运用电导测定方法及非线性动力学模型进行数据处理，得到了在不同浓度十六烷基三甲基溴化胺(CTAB)胶束水溶液中正脂肪酸乙酯(甲酸乙酯，乙酸乙酯，丙酸乙酯，丁酸乙酯及正戊酸乙酯)碱性水解反应的速率常数．依据离子交换模型(PIE)理论讨论了在第一和第二临界胶束浓度(CMC)时，CTAB对正脂肪酸乙酯碱性水解反应速率的影响及规律性．     

Triazolotriazine-based thermally activated delayed fluorescence materials for highly efficient fluorescent organic light-emitting diodes (TSF-OLEDs)

Thermally activated delayed fluorescence (TADF) sensitized fluorescent organic light-emitting diodes (TSF-OLEDs) have shown great potential for the realization ...     

广义进化的定义

广义进化的基本理论,尤其是一些基本概念有待研究。要找到广义进化的准确定义,必须分析清楚四个关系：第一,有序与适应性的关系;第二,进化与复杂化的关系;第三,复杂与有序的关系;第四,复杂与适应性的关系。序参量的评价标准应该是系统功能的总价值,只有当系统的新结构导致新功能出现时,才会使有序度增大。进化就是复杂化,复杂化就是创新,就是对称性破缺程度增大的过程,广义进化是所有物质系统的复杂化过程。     

Performance analysis of Turbo-Codes in communication channels with impulsive noise

Performance of Turbo-Codes in communication channels with impulsive noise is analyzed. First, mathematical model of impulsive noise is presented because it has non-Gaussian nature and is found in many wireless channels due to impulsive phenomena of radio-frequency interference. Then, with linear Log-MAP decoding algorithm for its low complexity, Turbo-Codes are adopted and analyzed in such communication channels. To confirm the performance of the proposed method, simulations on both static and fully interleaved fiat Rayleigh fading channels with impulsive noise have been carried out. It is shown that Turbo-Codes have a better performance than the conventional methods (e.g. convolutionally coded system).     

DDFS spurious signals due to amplitude quantization in absence of phase-accumulator truncation

Spurious signals in direct digital frequency synthesizers (DDFSs) are partly caused by amplitude quantization and phase truncation, which affect their application to many wireless telecommunication systems. Thee signals are deterministic and periodic in the time domain, so they appear as line spectra in the frequency domain. Two types of spurious signals due to amplitude quantization are exactly formulated and compared in thetime and frequency domains respectively. Then the frequency spectra and power levels of the spurious signals due to amplitude quantization in the absence of phase-accumulator truncation are emphatically analyzed, and the effects of the DDFS parameter variations on the spurious signals are thoroughly studied by computer simulation. And several important conclusions are derived which can provide theoretical support for parameter choice and spurious performance evaluation in the application of DDFSs.     

Delta算子描述的离散系统鲁棒滤波

研究基于Delta算子描述的线性不确定离散时间系统在稳态估计误差方差约束下的鲁棒滤波问题。目的是设计线性滤波器 ,使得闭环系统稳定 ,且闭环系统的稳态估计误差的方差满足预先给定的约束条件。基于Riccati方程或Riccati不等式方法 ,给出Delta算子描述的系统鲁棒滤波器的存在条件和显式表达式     

Fast motion estimation algorithm for H.264/AVC based on centered prediction

H.264/AVC video coding standard can achieve roughly half of the bit-savings over MPEG2 and MPEG4 for a given quality. However, this comes at a cost in considerably increased complexity at the encoder and thus increases the difficulty in hardware implementation. The high redundancy that exists between the successive frames of a video sequence makes it possible to achieve a high data compression ratio. Motion estimation (ME) plays an important role in motion compensated video coding. A fast motion estimation algorithm for H.264/AVC is proposed based on centered prediction, called centered prediction based fast mixed search algorithm (CPFMS). It makes use of the spatial and temporal correlation in motion vector (MV) fields and feature of all-zero blocks to accelerate the searching process. With the initialized searching point prediction, adaptive search window changing and searching direction decision, CPFMS is provided to reduce computation in block-matching process. The experimental results show that the speed of CPFMS is nearly 12 times of FS with a negligible peak signal-noise ratio (PSNR) loss. Also, the efficiency of CPFMS outperforms some popular fast algorithms such as hybrid unsymmetrical cross multi-hexagongrid search and a novel multidirectional gradient descent search evidently.