用单片机实现汽车远近灯光自动控制系统的设计

本文介绍了一种由STC12C2052AD型单片机控制,光敏传感器采集信号,继电器执行动作的夜间汽车前大灯远近灯光转换的自动控制系统。该系统安装在汽车上,使汽车在夜间行驶时,根据对头车驶近驶离的情况,能够自动调节前大灯远近灯光转换。该系统稳定可靠,成本低廉。有一定的推广和使用价值。     

Synthesis of novel hyperbranched poly(ester‐amide)s based on neutral α‐amino acids via “AD + CBB′” couple‐monomer approach

A series of novel hyperbranched poly(ester‐amide)s (HBPEAs) based on neutral α‐amino acids have been synthesized via the “AD + CBB′” couple‐monomer approach. The ABB′ intermediates were stoichiometrically formed through thio‐Michael addition reaction because of reactivity differences between functional groups. Without any purification, in situ self‐polycondensations of the intermediates at elevated temperature in the presence of a catalyst afforded HBPEAs with multihydroxyl end groups. The degrees of branching (DBs) of the HBPEAs were estimated to be 0.40–0.58 and 0.24–0.54 by quantitative ¹³C NMR with two different calculation methods, respectively, depending on polymerization conditions and structure of monomers. The influences of catalyst, temperature, and intermediate structure on the polymerization process and molecular weights as well as properties of the resultant polymers were investigated. FTIR, NMR, and DEPT‐135 NMR analyses revealed the branched structure of the resultant polymers. The HBPEAs possess moderately high molecular weights with broad distributions, glass transition temperatures in the range of ?25.5 to 36.5 °C, and decomposition temperatures at 10% weight loss under nitrogen and air in the regions of 243.4–289.1 °C and 231.4–265.6 °C, respectively. Among them, those derived from D ,L ‐phenylalanine display the lowest degree of branching, whereas the highest glass transition temperature and the best thermal stability. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Enantiomeric separation of citalopram base by supercritical fluid chromatography

The chiral separation of citalopram base by supercritical fluid chromatography on a semipreparative Chiralpak AD column was studied with the use of three alcohol‐type modifiers (methanol, ethanol, and 2‐propanol) with different volume percentages (5, 10, and 15%). The best separation was achieved when 10% 2‐propanol was used in the presence of 0.1% diethylamine as additive. Under these conditions, the resolution reached 2.15 and the selectivity was 1.388. In addition, other parameters that affected the retention and separation properties, i.e. temperature, pressure, and density, were studied in detail. At the same pressure, a decrease in the temperature improved the enantioselectivity as the experimental temperature range was below the isoelution temperature. However, the temperature dependence of the retention factor was complicated. As a rule, the retention factor decreased when the temperature increased at the same density. A satisfactory regression of the logarithm of the retention factor versus density and temperature was obtained using a simplified lattice‐fluid model. Surprisingly, the relationship between the Henry constant and density can be accurately correlated by using the same quadratic equation.     

接口时序对数字中频发射机边带抑制的影响

结合AD9142在GSM无线通信发射机中的应用,指出了边带信号对系统性能的影响,着重从原理上分析了接口时序错误对边带信号的贡献、成因及改善方法,并给出了时序优化前后的数据对比验证结果。为了保证DAC输出性能达到最优,需要保证接口时序满足建立时间和保持时间要求。通过调整基带处理侧的延时和DAC内部的延时可以使接口时序满足要求。     

单芯片8通道超声模拟前端

简述用于便携式超声设备的单芯片8通道模拟前端.     

AD73322L及其与DSP5416的接口设计

片AD73322L是AD公司推出的低成本．低功耗CMOS通用双通道模拟前端。可以同时进行AD和DA转换。本文介绍了芯片AD73322L的性能特点．功能、基本原理及其与DSP5416的接口设计。     

Bis-Amiridines as Acetylcholinesterase and Butyrylcholinesterase Inhibitors: N-Functionalization Determines the Multitarget Anti-Alzheimer’s Activity Profile

Using two ways of functionalizing amiridine—acylation with chloroacetic acid chloride and reaction with thiophosgene—we have synthesized new homobivalent bis-amiridines joined by two different spacers—bis-N-acyl-alkylene (3) and bis-N-thiourea-alkylene (5) —as potential multifunctional agents for the treatment of Alzheimer’s disease (AD). All compounds exhibited high inhibitory activity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with selectivity for BChE. These new agents displayed negligible carboxylesterase inhibition, suggesting a probable lack of untoward drug–drug interactions arising from hydrolytic biotransformation. Compounds 3 with bis-N-acyl-alkylene spacers were more potent inhibitors of both cholinesterases compared to compounds 5 and the parent amiridine. The lead compounds 3a–c exhibited an IC₅₀(AChE) = 2.9–1.4 µM, IC₅₀(BChE) = 0.13–0.067 µM, and 14–18% propidium displacement at 20 μM. Kinetic studies of compounds 3a and 5d indicated mixed-type reversible inhibition. Molecular docking revealed favorable poses in both catalytic and peripheral AChE sites. Propidium displacement from the peripheral site by the hybrids suggests their potential to hinder AChE-assisted Aβ₄₂ aggregation. Conjugates 3 had no effect on Aβ₄₂ self-aggregation, whereas compounds 5c–e (m = 4, 5, 6) showed mild (13–17%) inhibition. The greatest difference between conjugates 3 and 5 was their antioxidant activity. Bis-amiridines 3 with N-acylalkylene spacers were nearly inactive in ABTS and FRAP tests, whereas compounds 5 with thiourea in the spacers demonstrated high antioxidant activity, especially in the ABTS test (TEAC = 1.2–2.1), in agreement with their significantly lower HOMO-LUMO gap values. Calculated ADMET parameters for all conjugates predicted favorable blood–brain barrier permeability and intestinal absorption, as well as a low propensity for cardiac toxicity. Thus, it was possible to obtain amiridine derivatives whose potencies against AChE and BChE equaled (5) or exceeded (3) that of the parent compound, amiridine. Overall, based on their expanded and balanced pharmacological profiles, conjugates 5c–e appear promising for future optimization and development as multitarget anti-AD agents.     

一种基于分时复用的PCI AD总线再复用模型

在研究PC I AD双向总线及PC I总线读操作时序特性的基础上,提出了基于分时复用技术实现PC I AD总线再复用的模型。挂接在PC I用户端的存储器可以复用PC I AD总线完成主设备对其进行的读写操作。实际流片结果表明该模型切实可行。PC I AD总线再复用模型不仅可以保证功能正确,而且节约了32根管脚资源,进而缩小了芯片面积,降低了设计成本。     

带通∑-△调制中频子系统芯片AD6140

AD6140是AD公司生产的采用∑-△调制的ADC中频集成电路芯片,适用于需要高动态范围和多个滤波器带宽的接收机。该器件被设计在Motorola的ReFLEX 系统中,可用于FLEX Re-FLEX接收机和多模式接收机中。文中介绍了AD607的原理、特点、性能参数和典型应用电路。     

DDS芯片AD9832的原理及应用

AD9832是AD公司生产的直接数字频率合成器。它体积小、重量轻、操作方便,同时具有极高的频率分辩率。文章介绍了直接数字频率合成器（DDS）AD9832的原理,分析了AD9832的内部结构、引脚功能以及在高频测试仪中的应用。