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Fast-Lock Low-Jitter PLL with a Simple Phase-Frequency Detector 被引量:3
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作者 陈莹梅 王志功 章丽 《Journal of Semiconductors》 EI CAS CSCD 北大核心 2008年第1期88-92,共5页
A fast-locking, low-jitter, phase-locked loop (PLL) with a simple phase-frequency detector is proposed. The phase-frequency detector is composed of only two XOR gates. It simultaneously achieves low jitter and short... A fast-locking, low-jitter, phase-locked loop (PLL) with a simple phase-frequency detector is proposed. The phase-frequency detector is composed of only two XOR gates. It simultaneously achieves low jitter and short locking time. The voltage-controlled oscillator within the PLL consists of four-stage ring oscillators which are coupled to each other and oscillate with the same frequency and a phase shift of 45. The PLL is fabricated in 0. 1Stem CMOS technology. The measured phase noise of the PLL output at 500kHz offset from the 5GHz center frequency is - 102.6dBc/Hz. The circuit exhibits a capture range of 280MHz and a low RMS jitter of 2.06ps. The power dissipation excluding the output buffers is only 21.6roW at a 1.8V supply. 展开更多
关键词 phase locked loop phase-frequency detector voltage-controlled oscillator JITTER locking time
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Robust CMOS phase frequency detector for high speed and low jitter charge pump PLL
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作者 周建政 王志功 《Journal of Southeast University(English Edition)》 EI CAS 2008年第1期15-19,共5页
In order to improve the performance of the existing phase frequency detectors (PFDs), a systematical analysis of the existing PFDs is presented. Based on the circuit architecture, both classifications and comparison... In order to improve the performance of the existing phase frequency detectors (PFDs), a systematical analysis of the existing PFDs is presented. Based on the circuit architecture, both classifications and comparisons are made. A new robust CMOS phase frequency detector for a high speed and low jitter charge pump phrase-locked loop (PLL) is designed. The proposed PFD consists of two rising-edge triggered dynamic D flip-flops, two positive-edge detectors and delaying units and two OR gates. It adopts two reset mechanisms to avoid the LIP and DN signals to be logic-1 simultaneously. Thus, any current mismatch of the charge pump circuit will not worsen the performance of the PLL. Furthermore, it has hardly any dead-zone phenomenon in phase characteristic. Simulations with ADS are performed based on a TSMC 0. 18-μm CMOS process with a 1.8-V supply voltage. According to the theoretical analyses and simulation results, the proposed PFD shows a satisfactory performance with a high operation frequency (≈ 1 GHz), a wide phase-detection range [ ± 2π], a near zero dead-zone ( 〈 0. 1 ps), high reliability, low phase jitter, low power consumption ( ≈100 μW) and small circuit complexity. 展开更多
关键词 phase frequency detectors DEAD-ZONE blind-zone phase characteristic frequency characteristic
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Pt-Pd-Ni体系相图与热力学研究进展
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作者 胡洁琼 张巧 +3 位作者 方继恒 谢明 王宝玲 聂陟枫 《贵金属》 CAS 北大核心 2024年第S01期7-13,共7页
铂基催化剂具有活性高、选择性好、电化学稳定性佳等优点,在工业催化和燃料电池领域具有非常重要的地位。然而,由于成本较高、可用性较低限制了其实际发展。因此,有必要优化铂基催化剂的利用率,设计低成本和高稳定性的铂基催化剂。本研... 铂基催化剂具有活性高、选择性好、电化学稳定性佳等优点,在工业催化和燃料电池领域具有非常重要的地位。然而,由于成本较高、可用性较低限制了其实际发展。因此,有必要优化铂基催化剂的利用率,设计低成本和高稳定性的铂基催化剂。本研究首先介绍了在燃料电池催化剂领域具有应用前景的Pt-Pd-Ni系合金电催化剂的发展和研究现状,然后详细介绍了Pt-Pd-Ni体系的三个二元系相图与热力学评估数据和研究进展,并对Pt-Pd-Ni三元系的一些实验研究进展和今后的研究工作提出展望,对不同相结构对催化性能的影响进行了分析和讨论。通过Pt-Pd-Ni系相图和相结构等的研究将为燃料电池用新型贵金属合金催化材料的设计及工业应用奠定理论和实验基础。 展开更多
关键词 燃料电池催化剂 Pt-pd-Ni体系 合金相图 热力学 有序-无序转变
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Design of 0.5V low-voltage phase and frequency detector for frequency synthesizer in wireless sensor networks
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作者 王利丹 李智群 李伟 《Journal of Southeast University(English Edition)》 EI CAS 2011年第1期8-12,共5页
Based on 0.13μm complementary metal-oxide-semiconductor(CMOS) technology,a phase and frequency detector(PFD) is designed with a low supply voltage of 0.5V for frequency synthesizers used in wireless sensor netwo... Based on 0.13μm complementary metal-oxide-semiconductor(CMOS) technology,a phase and frequency detector(PFD) is designed with a low supply voltage of 0.5V for frequency synthesizers used in wireless sensor networks(WSNs).The PFD can compare the frequency and phase differences of input signals and deliver a signal voltage proportional to the difference.Low threshold transistors are used in the circuits since a power supply of 0.5V is adopted.A pulse latched structure is also used in the circuits in order to increase both the detection range of phase errors and the maximum operation frequency.In experiments,a phase error with a range from-358° to 358° is measured when the input signal frequency is 2MHz.The PFD has a faster acquisition speed compared with conventional digital PFDs.When the input signals are at a frequency of 2MHz with zero phase error,the circuits have a power consumption of 1.8[KG*8]μW,and the maximum operation frequency is 1.25GHz. 展开更多
关键词 phase and frequency detector(PFD) low threshold transistor pulse latch
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An all-optical phase detector by amplitude modulation of the local field in a Rydberg atom-based mixer 被引量:3
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作者 Xiu-Bin Liu Feng-Dong Jia +8 位作者 Huai-Yu Zhang Jiong Mei Wei-Chen Liang Fei Zhou Yong-Hong Yu Ya Liu Jian Zhang Feng Xie Zhi-Ping Zhong 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第9期254-259,共6页
Recently,a Rydberg atom-based mixer was developed to measure the phase of a radio frequency(RF)field.The phase of the signal RF(SIG RF)field is down-converted directly to the phase of a beat signal created by the pres... Recently,a Rydberg atom-based mixer was developed to measure the phase of a radio frequency(RF)field.The phase of the signal RF(SIG RF)field is down-converted directly to the phase of a beat signal created by the presence of a local RF(LO RF)field.In this study,we propose that the Rydberg atom-based mixer can be converted to an all-optical phase detector by amplitude modulation(AM)of the LO RF field;that is,the phase of the SIG RF field is related to both the amplitude and phase of the beat signal.When the AM frequency of the LO RF field is the same as the frequency of the beat signal,the beat signal will further interfere with the AM of the LO RF field inside the atom,and then the amplitude of the beat signal is related to the phase of the SIG RF field.The amplitude of the beat signal and the phase of the SIG RF field show a linear relationship within the range of 0 toπ/2 when the phase of the AM is set with a differenceπ/4 from the phase of the LO RF field.The minimum phase resolution can be as small as 0.6°by optimizing the experimental conditions according to a simple theoretical model.This study will expand and contribute to the development of RF measurement devices based on Rydberg atoms. 展开更多
关键词 quantum sensor phase detector Rydberg atoms micorwave electromagnetically induced transparency amplitude modulation
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ROOM TEMPERATURE AND 750℃ ISOTHERMAL SECTION OF Ag-Pd-Gd(Gd≤25 AT.-%)PHASE DIAGRAM 被引量:1
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作者 ZHANG Kanghou CHEN Lili Kunming Institute of Precious Metals,Kunming,China ZHANG Kanghou,Kunming Institute of Precious Metals,Kunming 650221,China 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1990年第8期131-133,共3页
The room temperature section and the 750℃ isothermal section of the Ag-Pd-Gd ternary phase diagram containing 0—25 at.-% Gd are constructed by X—ray diffraction analysis and optical microscopy.Each section consists... The room temperature section and the 750℃ isothermal section of the Ag-Pd-Gd ternary phase diagram containing 0—25 at.-% Gd are constructed by X—ray diffraction analysis and optical microscopy.Each section consists of 3 single phase regions,3 bi-phase regions and I tri-phase region respectively. 展开更多
关键词 Ag-pd-Gd ternary system phase diagram
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Design of Digital Multi-Radian Phase Detector on J-TEXT
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作者 李俊 杨州军 +2 位作者 高丽 刘明海 庄革 《Plasma Science and Technology》 SCIE EI CAS CSCD 2014年第10期974-977,共4页
A real time system used to detect phase difference between two sinusoidal signals is proposed in this paper. The system is designed to process the phase signal of the far-infrared (FIR) hydrogen cyanide (HCN) inte... A real time system used to detect phase difference between two sinusoidal signals is proposed in this paper. The system is designed to process the phase signal of the far-infrared (FIR) hydrogen cyanide (HCN) interferometer on J-TEXT. It is based on zero-crossing detection and makes use of the digital circuit. Compared with a traditional zero-crossing phase detector, it doesn't need to sacrifice the time resolution to expand the phase range. The phase difference is divided into two parts, the integer part and the fraction part. In each detecting cycle, they are detected separately. It outputs digital signals that are more stable for transmission. A prototype was built on J-TEXT using discrete components. A practical method is proposed to deal with the counting error caused by the deviation of electronic components in manufacture. Reasonable results were obtained on the prototype. The phase resolution reaches 2π/64 in test, and can still be improved by raising the clock frequency. 展开更多
关键词 phase detector multi-radian DIGITAL HCN interferometer
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Design of IREDM System with a DSP Phase Detector
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作者 LIUJianguo WEIQingnong 《Semiconductor Photonics and Technology》 CAS 1997年第2期154-157,共4页
The design and realization of a new generation of infra-red electronic distance measurement (IR EDM) system are presented.A DSP(Digital Signal Process) phase detector based on high speed analog-to-digital converter an... The design and realization of a new generation of infra-red electronic distance measurement (IR EDM) system are presented.A DSP(Digital Signal Process) phase detector based on high speed analog-to-digital converter and DSP technique has been designed,in order to improve the precision and reliability of IR EDM system.As a result,the EDM system developed with a DSP phase detector has a precision of 3 mm in the measuring range of 2 km. 展开更多
关键词 Analogue-digital Conversion Distance Measurement DSP phase detector
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700℃ ISOTHERMAL SECTION OF THE Pd-Ru-Gd PARTIAL PHASE DIAGRAM
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作者 K.H Zhang and L.L. Chen (Institute of Precious Metals, Kunming 650221, China) 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1996年第5期329-332,共4页
The 700℃ isothermal section of the Pd-Ru-Gd partial ternary phase diagram containing more palladium than ruthenium was determined by X-rag diffraction analysis and optical microscopy. The section consists of seven si... The 700℃ isothermal section of the Pd-Ru-Gd partial ternary phase diagram containing more palladium than ruthenium was determined by X-rag diffraction analysis and optical microscopy. The section consists of seven single-phase regions,eleven two-phase regions and five three-phase regions. A new ternary compound Pd2RuGd2,which exhibits a tetragonal structure with a=0.7492 nm and c=0.7445 nm, has been found. 展开更多
关键词 PALLADIUM RUTHENIUM GADOLINIUM phase diagram pd-Ru-Gd ternary sgstem
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Passive round-robin differential-quadrature-phase-shift quantum key distribution scheme with untrusted detectors
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作者 Hongwei Liu Wenxiu Qu +3 位作者 Tianqi Dou Jipeng Wang Yong Zhang Haiqiang Ma 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第10期208-215,共8页
In this paper, we proposed the scheme for a passive round-robin differential-phase-shift quantum key distribution(RRDPS-QKD) set-up based on the principle of Hong–Ou–Mandel interference. Our scheme requires two le... In this paper, we proposed the scheme for a passive round-robin differential-phase-shift quantum key distribution(RRDPS-QKD) set-up based on the principle of Hong–Ou–Mandel interference. Our scheme requires two legitimate parties to prepare their signal state with two different non-orthogonal bases instead of single in original protocol. Incorporating this characteristic, we establish the level of security of our protocol under the intercept-resend attack and demonstrate its detector-flaw-immune feature. Furthermore, we show that our scheme not only inherits the merit of better tolerance of bit errors and finite-sized-key effects but can be implemented using hardware similar to the measurement device independent QKD(MDI-QKD). This ensures good compatibility with the current commonly used quantum system. 展开更多
关键词 quantum key distribution round-robin-differential-phase-shift untrusted detector
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Partial phase diagram of Pd-Ag-Ru-Gd quaternary system
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作者 张康侯 徐云 《广东有色金属学报》 2005年第2期149-155,共7页
On the basis of the Ag-Pd-Gd, Ag-Ru-Gd and Pd-Ru-Gd ternary systems, the partial phase diagram of Pd-Ag-Ru-Gd(Gd<25% atom fraction) quaternary system has been studied by means of X-ray diffraction analysis, diffe... On the basis of the Ag-Pd-Gd, Ag-Ru-Gd and Pd-Ru-Gd ternary systems, the partial phase diagram of Pd-Ag-Ru-Gd(Gd<25% atom fraction) quaternary system has been studied by means of X-ray diffraction analysis, differential thermal analysis, electron probe microanalysis and optical microscopy. The 700℃ isothermal sections of the Ag-Pd-5Ru-Gd, Ag-Pd-20Ru-Gd and Ag-Pd-50Ru-Gd (Gd≤25% atom fraction) phase diagrams were determined respectively. And the 700℃ isothermal section of the Pd-Ag-Ru-Gd (Gd≤25% atom fraction) quaternary system phase diagram was finally inferred. The section consists of four single-phase regions: solid solution Pd(Ag), (Ru), Pd3Gd and Ag 51 Gd 14 ; five two-phase regions: Pd(Ag)+(Ru), Pd(Ag)+ Ag 51 Gd 14 , (Ru)+ Ag 51 Gd 14 , Pd(Ag)+ Pd3Gd and (Ru)+ Pd3Gd; three three-phase regions: Pd(Ag)+ Pd3Gd+(Ru), Pd(Ag)+ Ag 51 Gd 14 +(Ru) and (Ru)+ Ag 51 Gd 14 + Pd3Gd; one four-phase region Pd(Ag)+ (Ru)+ Ag 51 Gd 14 + Pd3Gd. No new quaternary intermetallic phase is found. 展开更多
关键词 合金 二元结构 四位体 金属互化物
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Pt-Pd体系的热力学评估
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作者 张金华 主余亮 +2 位作者 权凯栋 史爱文 刘欣 《贵金属》 CAS 北大核心 2024年第3期46-51,共6页
采用CALPHAD(计算相图)方法首先对Pt-Pd体系各相吉布斯自由能分别建模,通过拟合热力学实验数据,获得两套热力学参数。该参数可用于相组分、相图相变、希尔凝固路径及微观组织结构演化模拟等研究领域,利于高性能合金成分设计。针对Pt-Pd... 采用CALPHAD(计算相图)方法首先对Pt-Pd体系各相吉布斯自由能分别建模,通过拟合热力学实验数据,获得两套热力学参数。该参数可用于相组分、相图相变、希尔凝固路径及微观组织结构演化模拟等研究领域,利于高性能合金成分设计。针对Pt-Pd体系中面心立方相(Fcc)混溶间隙是否存在的争论,基于最新的实验数据,使用Thermo-calc软件中的Parrot模块分别对两种情况进行热力学优化。通过优化获得的两套自洽的热力学参数,计算并比较了两种情况下的吉布斯自由能,证实了实验中发现的混溶间隙处于一种亚稳态。Fcc亚稳相图提供了混溶间隙范围内的相组成信息,平衡相图预测的热力学性质则与实验数据高度一致。 展开更多
关键词 相图 热力学优化 混溶间隙 Pt-pd体系
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乙烯气相法制醋酸乙烯Pd-Au催化剂研究进展
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作者 任栎 张向辉 +5 位作者 王光永 陈鹏 李克兵 丁明月 姚佩 赵安民 《低碳化学与化工》 CAS 北大核心 2024年第3期30-41,共12页
醋酸乙烯(VAc)是重要的化工原料,具有良好的应用价值。随着光伏行业的迅速发展以及环保要求的提升,我国对高品质醋酸乙烯(即乙烯气相法醋酸乙烯)的需求逐年增加,开发高催化活性、高目标产物选择性、高稳定性以及低成本的乙烯气相法制醋... 醋酸乙烯(VAc)是重要的化工原料,具有良好的应用价值。随着光伏行业的迅速发展以及环保要求的提升,我国对高品质醋酸乙烯(即乙烯气相法醋酸乙烯)的需求逐年增加,开发高催化活性、高目标产物选择性、高稳定性以及低成本的乙烯气相法制醋酸乙烯Pd-Au催化剂具有重要意义。首先,综述了乙烯气相法制醋酸乙烯催化剂的发展,概述了Pd-Au催化剂的载体、活性组分以及醋酸钾助剂的作用,分析了乙烯气相法制醋酸乙烯的两种反应机理和Pd-Au催化剂的失活原因,阐述了由浸渍法制得蛋壳型Pd-Au催化剂的制备过程。然后,总结了研究者为进一步提高催化性能、降低催化剂成本在催化剂改进方面的研究成果,包括载体改性和异型化,以及活性组分的浸渍、陈化、还原、水洗及干燥等步骤的改进。最后,提出了未来乙烯气相法醋酸乙烯催化剂的研究方向。 展开更多
关键词 醋酸乙烯 乙烯气相法 pd-Au催化剂 催化剂改进
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离子色谱技术研究进展
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作者 关宁昕 孔淮 王萍丽 《中国无机分析化学》 北大核心 2025年第2期210-217,共8页
离子色谱技术作为分析无机离子的首选方法,还可实现小分子极性化合物、氨基酸、糖类等生物样品的分析。近年来,离子色谱技术快速发展,广泛应用在环境监测、食品分析、生物医药、农业、地质等多个领域。针对离子色谱技术的综述多是探讨... 离子色谱技术作为分析无机离子的首选方法,还可实现小分子极性化合物、氨基酸、糖类等生物样品的分析。近年来,离子色谱技术快速发展,广泛应用在环境监测、食品分析、生物医药、农业、地质等多个领域。针对离子色谱技术的综述多是探讨离子色谱技术在环境、烟草、药品、食品等领域的应用进展,而关注离子色谱技术发展动态的研究报道相对较少。专利文献蕴含科技文献未曾报道的技术研发信息,对于归纳总结前沿技术走向具有重要意义。基于全球范围内离子色谱相关技术专利数据,从淋洗液发生装置、色谱柱固定相、离子色谱抑制器、检测器等方面综述离子色谱分析技术的研究进展,旨为国内离子色谱技术创新发展提供参考与依据。研究表明,全球离子色谱技术研究发展迅速,核心技术及基础研究主要分布在美国和日本,超高压淋洗液发生器、优化供电方式的自动再生电解抑制器及温控稳定的检测器是离子色谱领域新近研究方向,围绕固定相的研究侧重于提高离子交换容量,提高分析速度,改善离子色谱柱效、选择性与亲水性等方面性能。 展开更多
关键词 离子色谱 淋洗液发生装置 色谱柱固定相 抑制器 电导率检测器
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Pd/Al_2O_3液相选择加氢催化剂抗硫性能研究 被引量:14
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作者 黄星亮 宋月芹 沈师孔 《高校化学工程学报》 EI CAS CSCD 北大核心 2002年第5期575-579,共5页
研究了助剂对Pd/Al2O3催化剂裂化汽油液相选择加氢活性及其抗硫性能的影响。着重探讨了Co助剂的作用规律。结果表明,助剂对Pd/Al2O3催化剂的加氢活性有不同影响,其中加入Ag、Cu和Co助剂时,可以提高催化剂加氢活性,而Co助剂的提高最为明... 研究了助剂对Pd/Al2O3催化剂裂化汽油液相选择加氢活性及其抗硫性能的影响。着重探讨了Co助剂的作用规律。结果表明,助剂对Pd/Al2O3催化剂的加氢活性有不同影响,其中加入Ag、Cu和Co助剂时,可以提高催化剂加氢活性,而Co助剂的提高最为明显。通过对催化剂进行XPS和反应后催化剂硫含量的分析,表明Co助剂改善Pd/Al2O3催化剂液相加氢活性的作用有两方面,一是与Pd金属产生电子相互作用,改变其电子状态,减弱对硫化物的吸附;二是Co具有吸硫作用,使部分硫化物吸附在助剂Co上,从而减少了在活性中心Pd上的吸附,导致Pd-Co/Al2O3催化剂具有良好的液相选择加氢活性。 展开更多
关键词 pd/AL2O3 液相选择加氢 抗硫性能 汽油 助剂 二烯烃 炔烃 氧化铝负载钯催化剂
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反相HPLC法测定白花前胡根中有效成分Pd-Ia的含量 被引量:4
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作者 叶文鹏 刘俊亭 +1 位作者 李延兵 刘桂华 《理化检验(化学分册)》 CAS CSCD 北大核心 2002年第6期299-300,共2页
采用反相HPLC法测定白花前胡根中醚提取物的有效成分 [3′(S) 当归酰氧基 ,4′(S) 乙酰氧基 3′ ,4′ 双氢邪蒿内酯 ,Pd Ia]的含量。峰面积与Pd Ia含量在 0 .0 0 15 0 5~ 0 .15 0 5mg·ml-1范围内呈线性关系。回归方程为C(mg... 采用反相HPLC法测定白花前胡根中醚提取物的有效成分 [3′(S) 当归酰氧基 ,4′(S) 乙酰氧基 3′ ,4′ 双氢邪蒿内酯 ,Pd Ia]的含量。峰面积与Pd Ia含量在 0 .0 0 15 0 5~ 0 .15 0 5mg·ml-1范围内呈线性关系。回归方程为C(mg·ml-1) =5 .8× 10 -8A - 5 .0 2 5× 10 -4 。前胡样品中Pd Ia的含量为 0 .0 77%。 展开更多
关键词 测定 有效成分 反相HPLC法 白花前胡 pd-Ia 香豆素 分析 中药材
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Ag-Pd-Ru三元系相图的700℃等温截面 被引量:6
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作者 张康侯 徐云 李曲波 《中国有色金属学报》 EI CAS CSCD 北大核心 2000年第1期1-4,共4页
采用X射线衍射、电子探针和金相显微镜等方法研究了Ag Pd Ru三元系相图的 70 0℃等温截面。发现在该截面上沿着Ag Pd侧有一单相区 (Ag或Pd) ,这个单相区在富Pd区域较宽 ;在该截面的富Ru侧也存在一较小的单相区 (Ru) ;在这两个单相区之... 采用X射线衍射、电子探针和金相显微镜等方法研究了Ag Pd Ru三元系相图的 70 0℃等温截面。发现在该截面上沿着Ag Pd侧有一单相区 (Ag或Pd) ,这个单相区在富Pd区域较宽 ;在该截面的富Ru侧也存在一较小的单相区 (Ru) ;在这两个单相区之间是一个宽阔的二相区 (Ag +Ru)。此外 ,在Ag Pd Ru三元系富Ag Ru侧的部分成分区域 ,由于合金在液态出现分层现象 ,凝固后难于获得均匀合金 ,致使该区域内的相区边界未能测定。 展开更多
关键词 Ag-pd-Ru三元系 相图 等温截面 银合金
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Pd替代对Ti-Zr-Ni准晶合金结构的影响 被引量:2
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作者 黄火根 贾建平 李嵘 《金属学报》 SCIE EI CAS CSCD 北大核心 2009年第10期1272-1276,共5页
针对Ti_(45)Zr_(38)Ni_(17)与Ti_(40)Zr_(40)Ni_(20)准晶合金用X射线衍射仪、透射电子显微镜与金相等手段研究了不同含量的Pd替代对其结构的影响.在吸铸态下,前一个合金形成了二十面体准晶相(IQC)与少量配位数为8的bccβ-(Ti,Zr)相,用2%... 针对Ti_(45)Zr_(38)Ni_(17)与Ti_(40)Zr_(40)Ni_(20)准晶合金用X射线衍射仪、透射电子显微镜与金相等手段研究了不同含量的Pd替代对其结构的影响.在吸铸态下,前一个合金形成了二十面体准晶相(IQC)与少量配位数为8的bccβ-(Ti,Zr)相,用2%Pd(原子分数,下同)对合金的Ti或Zr组元替代,抑制了β-(Ti,Zr)相析出并促使配位数为14的MgZn_2结构的简单六方C14 Laves相生成.而后一个合金中IQC相则与少量简单六方α-(Ti,Zr)共存,在2%Pd替代后α-(Ti,Zr)消失,生成了单一的IQC相,但当Pd替代量增加到6.7%或13.3%时,配位数为12的IQC相急剧减少而C14相大量析出,并在Ti_(40)Zr_(26.7)Ni_(20)Pd_(13.3)合金中生成了单一C14相.结果表明,添加中等尺寸的Pd原子有利于提高Ti-Zr-Ni合金的原子密堆性,使合金趋于生成高配位数的Laves相,这种相的Fermi面与Brillouin区的相互作用不显著,偏离了电子相的稳定机制. 展开更多
关键词 准晶 Ti-Zr-Ni合金 pd添加 LAVES相
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双水相体系中Pd/C催化Suzuki偶联反应的研究 被引量:4
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作者 袁艳琴 王艳 郭圣荣 《化学试剂》 CAS CSCD 北大核心 2010年第5期465-469,共5页
以双水相为反应溶剂,用可重复使用的Pd/C为催化剂,在较低的温度下(78~85℃),芳基硼酸与芳基卤化物进行了Suzuki反应。该方法具有反应时间短、产率较高、选择性较好等特点,为该反应及该类化合物的合成提供了一种新方法。产物通过熔点测... 以双水相为反应溶剂,用可重复使用的Pd/C为催化剂,在较低的温度下(78~85℃),芳基硼酸与芳基卤化物进行了Suzuki反应。该方法具有反应时间短、产率较高、选择性较好等特点,为该反应及该类化合物的合成提供了一种新方法。产物通过熔点测定,核磁共振氢谱、碳谱、质谱等的表征。 展开更多
关键词 双水相 SUZUKI反应 芳基卤化物 钯碳 芳基硼酸
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用改进液相还原法制备炭载Pd催化剂 被引量:6
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作者 陈滢 唐亚文 +3 位作者 高颖 刘长鹏 邢巍 陆天虹 《应用化学》 CAS CSCD 北大核心 2009年第8期985-988,共4页
研究了用改进液相还原法制备用作直接甲酸燃料电池(DFAFC)的炭载Pd(Pd/C)阳极催化剂制备方法,研究发现在滴加还原剂NaBH4之前,在PdCl2溶液中滴加NaOH溶液后,制得的Pd/C催化剂中Pd粒子的平均粒径和相对结晶度均比不加NaOH的小。而且Pd粒... 研究了用改进液相还原法制备用作直接甲酸燃料电池(DFAFC)的炭载Pd(Pd/C)阳极催化剂制备方法,研究发现在滴加还原剂NaBH4之前,在PdCl2溶液中滴加NaOH溶液后,制得的Pd/C催化剂中Pd粒子的平均粒径和相对结晶度均比不加NaOH的小。而且Pd粒子的平均粒径和相对结晶度与加入的NaOH溶液和PdCl2溶液的浓度比有关。在未加NaOH时制得的Pd/C催化剂中Pd粒子的平均粒径和相对结晶度分别为20.2 nm和6.29,当加入的NaOH溶液和PdCl2溶液的浓度比为10时得到的Pd粒子的平均粒径和相对结晶度适中,分别为6.7 nm和3.45,因此,制得的Pd/C催化剂对甲酸氧化的电催化活性和稳定性均要比其它NaOH溶液和PdCl2溶液的浓度比时制得的Pd/C催化剂要好。且该制备方法简单,具有潜在的应用前景。 展开更多
关键词 甲酸 直接甲酸燃料电池 炭载pd催化剂 NAOH 液相还原法
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