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1.
基因线路是生命体对自身生命过程控制的动态调控系统。在工程化的设计原理的指导下,人工基因线路是对天然基因调控线路进行简单化处理和重新编程,以及引入自然界不存在的人造法则。人工基因线路由遗传开关、生物振荡器、逻辑门等组成,以执行诸多调控功能。多种多样的人工基因线路设计与构建,不仅极大地促进了人们对生命调控基本规律的认识,也进一步丰富了人们对天然的生物系统进行改造、再创的手段,并为医药健康、农业环境和工业发酵等领域的实际需求提供了全新解决方案。虽然在过去20年里,人们在人工基因线路领域取得了丰硕的研究成果,但是细胞体内蕴含着的众多复杂生化反应和信号传导途径,为设计和组装具有更加高级功能的基因线路带来了挑战。相应地,如何实现微小细胞内复杂基因线路的可预测设计组装,如何保障基因线路在复杂的体内外环境下发挥稳健的功能,将成为未来几年人工基因线路研究的关键核心问题和势必克服的重大挑战。 相似文献
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The reproducibility of microwave integrated circuits can be improved by employing substrates which are anisotropic. A method is presented which facilitates the computation of the characteristics of distributed integrated microwave circuits of finite conductor thickness on anisotropic and inhomogeneous substrates. The method is variational and it relies on a quasi-static approach which assumes that the charge distribution on each side of the conductor can be represented by a spatially dependent set of exponential functions. 相似文献
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从适用于ＣＭＯＳ的开关－信号理论着手,建立了具有三值四态输出功能的ＣＭＯＳ输出级电路,提出了基于开关－信号理论指导三值四态门设计的方法和过程,经过ＰＳＰＩＣＥ计算机程序对设计的电路进行了模拟,结果俞垢电路具有正确的逻辑功能,良好的ＤＣ和瞬态性能。 相似文献
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According to the mathematical classification of topological band structures, there exist a number of fascinating topological states in dimensions larger than three with exotic boundary phenomena and interesting topological responses. While these topological states are not accessible in condensed matter systems, recent works have shown that synthetic systems, such as photonic crystals or electric circuits, can realize higher-dimensional band structures. Here, we argue that, because of its symmetry properties, the 4D spinless topological insulator is particularly well suited for implementation in these synthetic systems. We explicitly construct a 2D electric circuit lattice, whose resonance frequency spectrum simulates the 4D spinless topological insulator. We perform detailed numerical calculations of the circuit lattice and show that the resonance frequency spectrum exhibits pairs of 3D Weyl boundary states, a hallmark of the nontrivial topology. These pairs of 3D Weyl states with the same chirality are protected by classical time-reversal symmetry that squares to +1, which is inherent in the proposed circuit lattice. We also discuss how the simulated 4D topological band structure can be observed in experiments. 相似文献
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A general theory is developed for extended bandwidth operation of actively compensated finite gain amplifiers. Designs for three new circuits are given which implement the theory. These circuits employ only operational amplifiers and resistors and their gains depend only on their resistor ratios. Thus they are suitable for IC fabrication. Further in IC technology, the characteristics of the operational amplifiers as well as the resistor ratios track closely with each other with reference to temperature and aging. Thus the extended bandwidth operation of the amplifiers will be available over a wide temperature range as well as under varying aging conditions. Their characteristics can be tuned easily by trimming only two resistors. Applications of the new amplifiers have been considered in RC active filters as well as in inductance simulation schemes. Experimental results are given which closely agree with theoretical predictions. The results also indicate that substantial improvement in the usable bandwidth of the circuits employing the new amplifiers may be expected over those using the conventional design of finite gain amplifiers. 相似文献
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从电流型CMOS电路的特点出发,提出了混合开关理论,并将该理论应用于三值电流型CMOS电路的设计.此外,对所设计的极性变换电路利用SPICE程序进行了计算机模拟. 相似文献
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印度模式以"不可思议的印度"作为全球市场营销品牌,并基于产品/设施目的地发展、市场发展援助、公共与私营合作战略和旅游路线全面开发四大战略政策层面。近几年该模式效果明显,印度旅游经济得到了快速发展。印度模式给中国的启示:大力开发中国旅游文化资源、打造华夏特色旅游体验路线、鼓励支持社会各界积极参与和提高旅游企业社会影响力,以促进我国从旅游大国走向旅游强国。 相似文献
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In this paper, switched circuits are modeled based on wavelet decomposition and neural network. Also describes the usage of wavelet decomposition and neural network for modeling and simulation of nonlinear systems. The switched circuits are piecewise-linear circuits. At each position of switch the circuit is linear but when considered all switching positions of the circuit it becomes nonlinear. An important problem which arises in modeling switched circuit is high structural complexity. In this study, wavelet decomposition is used for feature extracting from input signals and neural network is used as an intelligent modeling tool. Two performance measures root-mean-square (RMS) and the coefficient of multiple determinations (R2) are given to compare the predicted and computed values for model validation. The evaluated R2 value is 0.9985 and RMS value is 0.0099. All simulations showed that the proposed method is more effective and can be used for analyzing and modeling switched circuits. When we consider obtained performance, we can easily say that the proposed method can be used efficiently for modeling any other nonlinear dynamical systems. 相似文献
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探讨利用Matlab软件辅助分析交流电路的方法。以Matlab软件为辅助工具,具体分析了动态电路、正弦稳态电路及非正弦交流电路。结果表明,利用Matlab软件辅助分析交流电路问题,逻辑清晰、程序简短、结果精确。因此,Matlab软件是分析和研究电路的有效工具。 相似文献
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A general, unified and systematic approach is employed to study realization of operational amplifier (OA) based sinusoidal RC-active oscillators. Both single frequency and variable frequency operations are investigated. A set of circuits is found for each case. The sets consist of 12 and 16 circuits respectively. The circuits are canonic, that is, they require the minimum number of active and passive components. For each circuit, the single frequency set requires one OA, two capacitors and four resistors, while the variable frequency set needs one OA, two capacitors and five resistors. Both sets are shown to be complete in that generation of any additional canonic circuit is not possible. Variable frequency oscillators are all single resistor controlled. They are classified into four groups according to the nature of their dependence on the variable resistor. All the circuits are laboratory tested. Experimental results agree closely with the theoretical analysis. Representative test results are included. 相似文献
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三值TTL极性变换电路 总被引：3，自引：0，他引：3
对TTL门电路的结构进行了分析,并在此基础上提出了各种三值TTL极性变换电路的设计.设计的电路已用SPICE程序予以计算机模拟,结果表明它们具有正确的逻辑功能及与二值TTL电路相当的瞬态特性. 相似文献
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单片机系统实用抗干扰设计 总被引：1，自引：0，他引：1
介绍了单片机系统主要干扰形式、来源、特性及传播途径，同时给出若干抗干扰措施－－硬件上采用抑制电源干扰源、抑制了扰耦合通道，则利用监控程序对局部故障处理等方法来抑制软件上数据采集的干扰，提出了用电感电容零件来抑制电源高次谐波，起到了很好的效果，具有较强的实际意义。 相似文献
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对锁相环型频率综合器中的高速分频器进行了较为深入的分析。比较了同步分频器和异步分频器,表明了异步分频器在高频应用中的特点。对相位切换型异步分频器中第1级和第2级2分频电路的实现方案进行了仔细分析和对比,并针对Wang提出的2分频电路中存在的电荷分享问题提出了改进方案,仿真显示改进后的电路有效解决了电路中的电荷分享问题。采用Chartered 0.35μm 2P4M CMOS工艺,对第1级与改进后的第2级2分频电路整体仿真显示,电路的最高工作频率为3.3GHz,电流消耗为1.9mA。 相似文献
16.
刘志华 《科学．经济．社会》2006,24(2):92-96
集成电路布图设计是TRIPS协议规定的知识产权保护对象之一。集成电路产业是当今电脑网络技术的基础产业,如何对集成电路布图设计的知识产权进行法律保护是近年来知识产权法律界很关心的课题。由于集成电路布图设计具有的特殊特征,对它采取何种知识产权的保护方法也在理论界引发了分歧。本文论述了其作为特殊的知识产权客体而受到专门保护的必要性,并阐述了我国集成电路布图设计保护的理论体系,对其中的一些问题提出了自己的一些看法。 相似文献
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从三值ＧａＡｓ逻辑输出级电路的等效开关模型出发,探索了适用于指导ＧａＡｓ极性变换电路的设计。设计的电路已用ＰＳＰＩＣＥ程序予以模型,结果表明,它们具有正确的逻辑功能与理想的瞬态特性。 相似文献
18.
Reinhold Rüdenberg 《Journal of The Franklin Institute》1942,234(1):39-61
The sudden development of short-circuit currents, and of recovery voltages at interruption of currents, depends on the effects of stator and rotor leakages as well as of saturation in the generating synchronous machines.The non-linear problem of the interaction of these features with the performance of the main windings and auxiliary damper circuits is solved analytically.This leads to a simple graphical representation which is numerically determined by the well-known magnetic and electric characteristics of machine and network and by two time constants of very different magnitudes which are derived from the ordinary data of the machines. Hence the variation with time, of short-circuit currents and of recovery voltages, can easily and rigorously be computed for every given example.The deviations of actual damper circuits from the ideal form and the effects of eddy currents in solid steel parts of the rotor are discussed so far that numerical results can be derived readily.A new transient test for synchronous machines is suggested by which rotor and stator leakage voltages can be measured separately, avoiding the uncertainties of the usual steady state leakage tests. 相似文献
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本文论述了数字电路与系统在电子科学技术领域中的重要地位,并结合作者的工作介绍了国内外在数字电路与系统方面的几个主要研究方向,基于多值数字电路与系统近年来在国际上受到广泛重视,因此本文着重介绍多值数字电路与系统的研究意义,主要研究方向及在理论上的新进展。 相似文献