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四次非谐势下的能隙呼吸子和三次非谐势的影响 被引量:1
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作者 田强 李宓善 周倩 《北京师范大学学报(自然科学版)》 CAS CSCD 北大核心 2005年第6期582-585,共4页
在局域非简谐近似(LAA)和旋转波近似(RWA)下,研究具有K2-K3-K4相互作用势的一维双原子链晶格振动的能隙呼吸子.数值计算得到以重原子为中心的对称呼吸子(HS模)振动图像,特别是不同三次非谐势的HS模振动图像.结果表明,一维K2-K3-K4双原... 在局域非简谐近似(LAA)和旋转波近似(RWA)下,研究具有K2-K3-K4相互作用势的一维双原子链晶格振动的能隙呼吸子.数值计算得到以重原子为中心的对称呼吸子(HS模)振动图像,特别是不同三次非谐势的HS模振动图像.结果表明,一维K2-K3-K4双原子链中能隙呼吸子的HS模,一般只存在于四次软非简谐势(soft anharmonicity)的情况下.三次非谐势对局域振动模有显著的影响.当三次非谐势由零变为非零,轻原子的振动明显增强;随着三次非谐势的进一步增大,轻原子的振动又很快减弱.同时,DGB中心重原子的振幅随三次非谐势的变化不明显. 展开更多
关键词 吸子 K2-K3-K4双原 四次非谐势 二次非谐势
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吸湿回干种子处理对小麦萌发期抗盐性的影响 被引量:13
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作者 牛海山 旭日 +1 位作者 王淑芬 宋炳煜 《内蒙古大学学报(自然科学版)》 CAS CSCD 1999年第1期79-84,共6页
研究吸湿回干种子处理是否能提高小麦在萌发期及幼苗期的抗盐性.在盐胁迫下,处理种子的发芽率低于未处理种子,然而如果继续培养,观察其正常幼苗的比率,情况却截然不同,尤其在高盐胁迫下(15g/LNaCl),处理种子正常苗比... 研究吸湿回干种子处理是否能提高小麦在萌发期及幼苗期的抗盐性.在盐胁迫下,处理种子的发芽率低于未处理种子,然而如果继续培养,观察其正常幼苗的比率,情况却截然不同,尤其在高盐胁迫下(15g/LNaCl),处理种子正常苗比率显著高于未处理种子.随氯化钠浓度升高,处理幼苗的根数基本上呈上升趋势,而对照幼苗根数却在15g/LNaCl条件下急剧下降.处理幼苗的总根长、苗高也在高盐胁迫条件下(15g/LNaCl)显著大于未处理.另外,处理种子的发芽率对吸涨萌发0~24h内给予的氯化钠胁迫最敏感. 展开更多
关键词 湿回 处理 抗盐性 小麦 萌发期
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抽吸剥离子在甲状腺Miccoli术式中的应用 被引量:4
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作者 张宇 杨涛 +3 位作者 梅静 侯东旭 李敏娟 蔡源源 《中国微创外科杂志》 CSCD 北大核心 2018年第2期121-123,共3页
目的探讨Miccoli术式中用抽吸剥离子替代腔镜抓钳和吸引装置的可行性。方法我院2014年1月~2015年11月Miccoli术式80例甲状腺良性病变患者按照术前告知、自愿选择的方式分为观察组(使用抽吸剥离子,n=40)和对照组(使用腔镜抓钳和吸引装置,... 目的探讨Miccoli术式中用抽吸剥离子替代腔镜抓钳和吸引装置的可行性。方法我院2014年1月~2015年11月Miccoli术式80例甲状腺良性病变患者按照术前告知、自愿选择的方式分为观察组(使用抽吸剥离子,n=40)和对照组(使用腔镜抓钳和吸引装置,n=40)。比较2组术中拭镜次数、切口拥堵次数、手术时间、切口长度、切口牵拉损伤情况。结果 80例均完成Miccoli手术,与对照组相比,观察组术中拭镜次数少[(6.8±1.0)次vs.(8.9±1.3)次,t=-8.007,P=0.000],切口拥堵次数少[(2.6±0.7)次vs.(3.8±0.8)次,t=-7.494,P=0.000],手术时间短[(80.3±8.7)min vs.(84.8±7.8)min,t=-2.451,P=0.016],切口短[(25.7±3.8)mm vs.(27.6±4.0)mm,t=-2.248,P=0.027],切口牵拉损伤少(2例vs.8例,χ~2=4.114,P=0.043)。结论在Miccoli术式中虽不能以抽吸剥离匙完全替代腔镜抓钳及吸引装置,但其应用能明显改善术中切口拥堵情况,减少术中拭镜次数,缩短手术时间,减少切口牵拉损伤。 展开更多
关键词 甲状腺 Miccoli手术 抽剥离
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内吸式鼻中隔剥离子的研制与应用
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作者 张丽君 高举 +1 位作者 曲玲 樊忠 《山东大学基础医学院学报》 2003年第5期316-316,共1页
关键词 式鼻中隔剥离 医疗装置 鼻中隔矫正术 鼻内窥镜 手术方法
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吸气罩流场的分区边界积分法求解
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作者 殷少有 关志强 夏春麟 《华东工业大学学报》 CAS 1997年第4期53-58,共6页
将吸气罩流场计算区域分成两个子区域,分别推导出各子区域边界积分方程,并将各子区域方程组合成一个方程,利用边界元法进行求解.
关键词 边界元法 区域 吸子 边界积分 数值计算
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Characteristic analysis of 1.06μm long-cavity diode lasers based on asymmetric waveguide structures
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作者 ZHAO Ren-Ze GAO Xin +3 位作者 FU Ding-Yang ZHANG Yue SU Peng BO Bao-Xue 《红外与毫米波学报》 SCIE EI CAS CSCD 北大核心 2024年第4期557-562,共6页
In long-cavity edge-emitting diode lasers,longitudinal spatial hole burning(LSHB),two-photon ab⁃sorption(TPA)and free carrier absorption(FCA)are among the key factors that affect the linear increase in out⁃put power a... In long-cavity edge-emitting diode lasers,longitudinal spatial hole burning(LSHB),two-photon ab⁃sorption(TPA)and free carrier absorption(FCA)are among the key factors that affect the linear increase in out⁃put power at high injection currents.In this paper,a simplified numerical analysis model is proposed for 1.06μm long-cavity diode lasers by combining TPA and FCA losses with one-dimensional(1D)rate equations.The ef⁃fects of LSHB,TPA and FCA on the output characteristics are systematically analyzed,and it is proposed that ad⁃justing the front facet reflectivity and the position of the quantum well(QW)in the waveguide layer can improve the front facet output power. 展开更多
关键词 diode lasers longitudinal spatial hole burning free carrier absorption two-photon absorption
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Dynamics of Nonlinear Waves in(2+1)-Dimensional Extended Boiti-Leon-Manna-Pempinelli Equation
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作者 SUN Junxiu WANG Yunhu 《应用数学》 北大核心 2024年第4期1103-1113,共11页
Based on the Hirota bilinear method,this study derived N-soliton solutions,breather solutions,lump solutions and interaction solutions for the(2+1)-dimensional extended Boiti-Leon-Manna-Pempinelli equation.The dynamic... Based on the Hirota bilinear method,this study derived N-soliton solutions,breather solutions,lump solutions and interaction solutions for the(2+1)-dimensional extended Boiti-Leon-Manna-Pempinelli equation.The dynamical characteristics of these solutions were displayed through graphical,particularly revealing fusion and ssion phenomena in the interaction of lump and the one-stripe soliton. 展开更多
关键词 Hirota bilinear method N-soliton solutions Breather solutions Lump solutions Interaction solutions (2+1)-dimensional extended Boiti-Leon-Manna-Pempinelli equation
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一类二维映象分形流域边界的性质
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作者 李佳云 《哈尔滨师范大学自然科学学报》 CAS 2000年第1期39-41,共3页
本文用微扰法研究了一类二维映象的流域边界 ,构造了流域边界的解析形式 ,从而可以方便地研究流域边界的结构和解析性质 ,并实现了用解析法计算 Lyapunov指数 .
关键词 二维映象 奇怪吸子 分形流域边界 解析性质
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Preparation and Characterization of lonic Conductive Eutectogels Based on Polyacrylamide Copolymers with Long Hydrophobic Chain
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作者 Minhao Zhang Qiang Zhou +3 位作者 Jiaqing He Yongjun Xie Haiyang Yang Weidong He 《Chinese Journal of Chemical Physics》 SCIE EI CAS CSCD 2024年第5期685-695,I0101,共12页
With the blooming development of electronic technology,the use of electron conductive gel or ionic conductive gel in preparing flexible electronic devices is drawing more and more attention.Deep eutectic solvents are ... With the blooming development of electronic technology,the use of electron conductive gel or ionic conductive gel in preparing flexible electronic devices is drawing more and more attention.Deep eutectic solvents are excellent substitutes for ionic liquids because of their good biocompatibility,low cost,and easy preparation,except for good conductivity.In this work,we synthesized a reactive quaternary ammonium monomer(3-acrylamidopropyl)octadecyldimethyl ammonium bromide with a hydrophobic chain of 18 carbons via the quaternization of 1-bromooctadecane and N-dimethylaminopropyl acrylamide at first,then we mixed quaternary ammonium with choline chloride,acrylic acid and glycerol to obtain a hydrophobic deep eutectic solvent,and initialized polymerization in UV light of 365 nm to obtain the ionic conductive eutectogel based on polyacrylamide copolymer with long hydrophobic chain.The obtained eutectogel exibits good stretchability(1200%),Young's modulus(0.185 MPa),toughness(4.2 MJ/m^(3)),conductivity(0.315 S/m).The eutectogel also shows desireable moisture resistance with the maximum water absorption of 11.7 wt%after one week at 25℃and 60%humidity,while the water absorption of eutectogel without hydrophobic long chains is 24.0 wt%.The introduction of long-chain hydrophobic groups not only improves the mechanical strength of the gels,but also significantly improves moisture resistance of the eutectogel.This work provides a simpler and more effective method for the preparation of ionic conductive eutectogels,which can further provide a reference for the applications of ionic conductive eutectogels in the field of flexible electronic devices. 展开更多
关键词 Hydrophobic long-chain copolymer Deep eutectic solvent Ionic conductive eutectogel Moisture resistance
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Adsorption behavior and adsorption mechanism of Cu(Ⅱ) ions on amino-functionalized magnetic nanoparticles 被引量:8
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作者 李卉 肖得力 +2 位作者 何华 林锐 左朋礼 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第9期2657-2665,共9页
Amino-functionalized magnetic nanoparticle (NH2-MNP) were prepared by a sol-gel approach. The adsorption behavior of Cu(II) ions on NH2-MNP was discussed systematically by batch experiments. The effects of initial... Amino-functionalized magnetic nanoparticle (NH2-MNP) were prepared by a sol-gel approach. The adsorption behavior of Cu(II) ions on NH2-MNP was discussed systematically by batch experiments. The effects of initial Cu(II) ions concentration, time, pH and temperature were investigated. In kinetic studies, the pseudo-second-order model was successfully employed, and the pseudo-first-order model substantiated that Cu(II) adsorption on NH2-MNP was a diffusion-based process. Langmuir model and Dubinin-Radushkevich model (R2〉0.99) were more corresponded with the adsorption isotherm data of Cu(II) ions than Freundlich model. The adsorption capacity was increased with the increment of temperature and pH. NH2-MNP remains excellent Cu(II) recoveries after reusing five adsorption and desorption cycles, making NH2-MNP a promising candidate for repetitively removing heavy metal ions from environmental water samples. According to the results obtained from adsorption activation energy and thermodynamic studies, it can be inferred that the main adsorption mechanism between absorbent and Cu(II) ions is ion exchange-surface complexation. 展开更多
关键词 amino-functionalized magnetic nanoparticles Cu(Ⅱ) ions ADSORPTION ion exchange-surface complexation
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Adsorption and activation of copper ions on chalcopyrite surfaces:A new viewpoint of self-activation 被引量:9
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作者 邓久帅 文书明 +2 位作者 刘建 吴丹丹 丰奇成 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第12期3955-3963,共9页
The adsorption behaviors of copper ions on chalcopyrite surfaces were investigated based on zeta potential measurements, X-ray photoelectron spectroscopy, copper ion adsorption experiments, first-principles calculatio... The adsorption behaviors of copper ions on chalcopyrite surfaces were investigated based on zeta potential measurements, X-ray photoelectron spectroscopy, copper ion adsorption experiments, first-principles calculations, and Hallimond tube cell flotation experiments. The results show that copper ions activate the chalcopyrite as a result of the interactions between copper ions and sulfur on the chalcopyrite surface. This adsorption increases the flotation rate under certain conditions, and this is beneficial for the flotation of chalcopyrite. The copper ions in the flotation pulp are mainly derived from surface oxidation dissolution and the release of fluid inclusions, and these effects enable chalcopyrite to be activated. 展开更多
关键词 CHALCOPYRITE copper ions ADSORPTION SELF-ACTIVATION
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Impact of Salt Stress on Growth and Ion Uptake of Different Parts of Oil Sunflower Seedlings 被引量:7
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作者 杨晓翠 李文建 +1 位作者 曲颖 张天虎 《Agricultural Science & Technology》 CAS 2011年第3期354-358,共5页
[Objective] The purpose was to discuss the effects of different NaCl concentrations on fresh weight and dry weight,ion absorption and distribution in oil sunflower seedlings. [Method] Under the simulated salt environm... [Objective] The purpose was to discuss the effects of different NaCl concentrations on fresh weight and dry weight,ion absorption and distribution in oil sunflower seedlings. [Method] Under the simulated salt environment by using NaCl solutions at different concentrations,the dry weight,fresh weight and ion content of oil sunflower seedlings were determined. [Result] With the increase of NaCl concentration,the growth rate of oil sunflower seedling was inhibited. In addition,its fresh weight and dry weight also decreased; the fresh weight of leaf decreased most significantly by 60%,and that of cotyledon decreased most slightly by 13% at 200 mmol/L NaCl concentration. The dry weight of root,stem,leaf and cotyledon decreased by 35%,39%,55% and 8% respectively,showing a similar decreasing trend with fresh weight. Under NaCl stress,Na+ content in root and stem of oil sunflower seedling increased while K+ decreased. Na+ content was mainly concentrated in roots and stems much more than in leaves; K+ content in roots decreased most significantly by 21% compared with control,and it was relatively high in leaf. Ca2+ and Mg2+ content was decreased slightly in roots and stems; Ca2+ content in leaves and cotyledons was stable; Mg2+ content was slightly increased. [Conclusion] Oil sunflower maintained high mineral ion absorptionunder salt stress,that maybe the part reason for high salt tolerance of oil sunflower seedlings. 展开更多
关键词 Oil sunflower seedlings NACL Ion absorption
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Leaching characteristics of ion-adsorption type rare earths ore with magnesium sulfate 被引量:26
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作者 肖燕飞 陈迎迎 +4 位作者 冯宗玉 黄小卫 黄莉 龙志奇 崔大立 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第11期3784-3790,共7页
Magnesium sulfate was proposed to be leaching agent to deal with the ion-adsorption type rare earths ore to reduce or even eliminate ammonia?nitrogen emissions. The effects of temperature, particle size and stirring s... Magnesium sulfate was proposed to be leaching agent to deal with the ion-adsorption type rare earths ore to reduce or even eliminate ammonia?nitrogen emissions. The effects of temperature, particle size and stirring speed on rare earth leaching process and the leaching behaviors of the single rare earth element were investigated in order to reveal the rare earth leaching characteristics. Besides, the comparison of leaching effects between magnesium sulfate and ammonium sulfate was also studied. The results showed that the rare earth leaching process could be well described with inner diffusion control model and the apparent activation energy was 9.48 kJ/mol. The leaching behaviors of the single rare earth element were brought into correspondence with rare earths. Moreover, when the concentration of leaching agent was 0.20 mol/L, the rare earth leaching efficiency could all reach above 95% and the leaching efficiency of aluminum impurities could be restrained by 10% using magnesium sulfate compared with ammonium sulfate. 展开更多
关键词 rare earth leaching agent kinetics magnesium sulfate ion-adsorption type rare earths ore
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X-ray Spectroscopically Probing Mo_(2)C@MoSe_(2)Heterojunction Electrodes
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作者 CAO Yu-yang WEI Shi-qiang +5 位作者 JIANG Wei Peter Joseph Chimtali YAN Zi-wei ZHOU Quan CHEN Shuang-ming SONG Li 《分析测试学报》 CAS CSCD 北大核心 2024年第10期1618-1625,共8页
Due to their high electrical conductivity and layered structure,two dimensional MXene materials are re⁃garded as promising candidates for energy storage applications.However,the relatively low stability and specific c... Due to their high electrical conductivity and layered structure,two dimensional MXene materials are re⁃garded as promising candidates for energy storage applications.However,the relatively low stability and specific ca⁃pacity of MXene materials limit their further utilization.In this study,these issues are addressed using a heterostruc⁃ture strategy via a one-step selenization method to form Mo_(2)C@MoSe_(2).Synchrotron radiation X-ray spectroscopic and high-resolution transmission electron microscopy(HRTEM)characterizations revealed the heterostructure consisting of in-situ grown MoSe_(2)on Mo_(2)C MXene.Electrochemical tests proved the heterojunction electrode’s superior rate perfor⁃mance of 289.06 mAh·g^(-1)at a high current density of 5 A·g^(-1)and long cycling stability of 550 mAh·g^(-1)after 900 cycles at 1 A·g^(-1).This work highlights the useful X-ray spectroscopic analysis to directly elucidate the heterojunction structure,providing an effective reference method for probing heterostructures. 展开更多
关键词 X-ray spectroscopic MXene HETEROJUNCTION X-ray absorption fine structure lithium-ion batteries
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Purification and Characterization of Flammulin,a Basic Protein with Anti-tumor Activities from Flammulina velutipes 被引量:10
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作者 陈畅 薛久刚 +3 位作者 周凯松 李彦 张晗星 张长铠 《Journal of Chinese Pharmaceutical Sciences》 CAS 2003年第2期60-65,共6页
Aim To purify and characterize flammulin, a basic protein with anti-tumoractivities. Methods Ammonium sulfate, ethanol fractionation and column chromatography were used forseparation and purification. Electrophoretic ... Aim To purify and characterize flammulin, a basic protein with anti-tumoractivities. Methods Ammonium sulfate, ethanol fractionation and column chromatography were used forseparation and purification. Electrophoretic analysis, amino acid analysis, and MS of flammulin werecarried out. Results Flammulin was purified to electrophoretic homogeneity and crystallized. With amolecular mass of 19891.13 Da, pI 8.9, λ_(max) = 276 - 278 nm, λ_(min) = 250 nm, flammulin wascharacterized by its lack of methionine. Fingerprint mapping of flammulin was determined by MALDI-MSfollowing in-gel protease digestion; no close matches were identified. Conclusion Flammulin waspurified to electrophoretic homogeneity, and its characteristics are discussed for the first time. 展开更多
关键词 anti-tumor activities flammulin flammulina velutipes PURIFICATION CHARACTERIZATION mass spectrometry
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Synthesis of Li^+ adsorbent(H_2TiO_3) and its adsorption properties 被引量:9
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作者 石西昌 张志兵 +3 位作者 周定方 张丽芬 陈白珍 余亮良 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第1期253-259,共7页
H2TiO3 was obtained from the acid-modified adsorbent precursor Li2TiO3,which was synthesized by a solid-phase reaction between TiO2 and Li2CO3.The extraction ratio of Li+ from Li2TiO3 was 98.86%,almost with no Ti4+ ... H2TiO3 was obtained from the acid-modified adsorbent precursor Li2TiO3,which was synthesized by a solid-phase reaction between TiO2 and Li2CO3.The extraction ratio of Li+ from Li2TiO3 was 98.86%,almost with no Ti4+ extracted.The effects of lithium titanium ratio,calcining temperature and time were investigated on the synthesis of Li2TiO3.Li2TiO3,H2TiO3 and the adsorbed Li+ adsorbent were characterized by XRD and SEM.The lithium adsorption properties were investigated by the adsorption kinetics and adsorption isotherm.The results indicate that H2TiO3 has an excellent adsorptive capacity for Li+.Two simplified kinetic models including the pseudo-first-order and pseudo-second-order equations were selected to follow the adsorption processes.The rate constants of adsorption for these kinetic models were calculated.The results show that the adsorption process can be described by the pseudo-second-order equation,and the process is proved to be a chemical adsorption.The adsorption process that H2TiO3 adsorbs Li+ in LiCl solution well fits the Langmuir equation with monolayer adsorption. 展开更多
关键词 Li+ adsorbent Li2TiO3 adsorption property kinetic models monolayer adsorption TIO2 Li2CO3
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Influence of copper ions and calcium ions on adsorption of CMC on chlorite 被引量:7
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作者 冯其明 冯博 卢毅屏 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第1期237-242,共6页
The effects of copper ions and calcium ions on the depression of chlorite using CMC(carboxymethyl cellulose) as a depressant were studied through flotation tests,adsorption measurements,ζ potential tests and co-pre... The effects of copper ions and calcium ions on the depression of chlorite using CMC(carboxymethyl cellulose) as a depressant were studied through flotation tests,adsorption measurements,ζ potential tests and co-precipitation experiments.The results show that the electrostatic repulsion between the CMC molecules and the chlorite surfaces hinders the approach of the CMC to the chlorite while the presence of copper ions and calcium ions enhances the adsorption density of CMC.The action mechanisms of these two types of ions are different.Calcium ions can not adsorb onto the mineral surfaces,but they can interact with the CMC molecules,thus reducing the charge of the CMC and enhancing adsorption density.Copper ions can adsorb onto the mineral surfaces,which facilitates the CMC adsorption through acid/base interaction.The enhanced adsorption density is also attributed to the decreased electrostatic repulsion between the CMC and mineral surfaces as copper ions reduce the surface charge of both the mineral surfaces and the CMC molecules. 展开更多
关键词 CHLORITE carboxymethyl cellulose copper ions calcium ions ADSORPTION
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Determination of Chromium and Zinc in Soil by Microwave Digestion and Flame Atomic Absorption Spectrometry 被引量:4
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作者 王天顺 牙禹 +4 位作者 何洁 莫磊兴 林波 李松 朱俊杰 《Agricultural Science & Technology》 CAS 2015年第9期1962-1964,共3页
[Objective] The aim was to develop a rapid, simple method for determination of chromium and zinc in soil samples by flame atomic absorption spectrometry.[Method] The method for determination of Cr and Zn in soil by co... [Objective] The aim was to develop a rapid, simple method for determination of chromium and zinc in soil samples by flame atomic absorption spectrometry.[Method] The method for determination of Cr and Zn in soil by combined flame atomic absorption spectrometry and microwave digestion was used. [Result] The concentration curve was linear within the range of 0-0.8 mg/L for Cr and 0-0.8 mg/L for Zn, the detection limits of Cr and Zn was 0.0025 mg/L and 0.002 3 mg/L, respectively. Recoveries of 102.4%-103.2% for Cr and 97.7%-98.3% for Zn were obtained for there soil samples. [Conclusion] The proposed method has the advantages of simple operation, high sensitivity, and high efficiency; it was successfully used for determination of Cr and Zn in soil samples. 展开更多
关键词 Microwave digestion Flame Atomic absorption spectrometry CHROMIUM ZINC SOIL
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Determination the Vigor of Rice Seed with Different Degrees of Aging with Ultraweak Chemiluminescence During Early Imbibition 被引量:12
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作者 陈文利 邢达 何永红 《Acta Botanica Sinica》 CSCD 2002年第11期1376-1379,共4页
用高灵敏度的单光子计数系统探测人工老化 (40℃ ,相对湿度 90 % ) 0、7、14和 2 1d的水稻种子吸胀初期的超弱化学发光强度变化 ,首次观测到水稻 (OryzasativaL .)种子吸胀初期超弱化学发光强度与其老化程度有关。加水激活水稻种子的超... 用高灵敏度的单光子计数系统探测人工老化 (40℃ ,相对湿度 90 % ) 0、7、14和 2 1d的水稻种子吸胀初期的超弱化学发光强度变化 ,首次观测到水稻 (OryzasativaL .)种子吸胀初期超弱化学发光强度与其老化程度有关。加水激活水稻种子的超弱化学发光 ,其强度依赖于种子的老化程度。实验结果表明水稻种子的人工老化时间越短 ,则吸胀初期 (2 0~ 30min)超弱化学发光的强度越强 ,萌发率越高。水稻种子萌发率与超弱化学发光强度呈显著正相关。观测水稻种子吸胀初期超弱化学发光强度的变化可望成为检测种子老化程度的一种快速、简便、无损伤的新方法。 展开更多
关键词 rice seeds ultraweak chemiluminescence early imbibition accelerated aging
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Multi-branched carbazole derivatives for two-photon absorption and two-photon excited fluorescence 被引量:1
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作者 钱鹰 黄维 +3 位作者 路志锋 孟康 吕昌贵 崔一平 《Journal of Southeast University(English Edition)》 EI CAS 2008年第2期234-237,共4页
Carbazole-core multi-branched chromophores 9-ethyl- 3, 6-bis ( 2- { 4- [ 5- (4-tert-butyl-phenyl) - [ 1, 3, 4 ] oxadiazol-2-yl ] - phenyl }-vinyl) -carbazole(3) and 9-ethyl-3-( 2- {4-[ 5-(4-tert-butyl- phenyl... Carbazole-core multi-branched chromophores 9-ethyl- 3, 6-bis ( 2- { 4- [ 5- (4-tert-butyl-phenyl) - [ 1, 3, 4 ] oxadiazol-2-yl ] - phenyl }-vinyl) -carbazole(3) and 9-ethyl-3-( 2- {4-[ 5-(4-tert-butyl- phenyl) -[ 1, 3, 4 ] oxadiazol-2-yl ] -phenyl }-vinyl ) -carbazole ( 2 ) are synthesized through Wittig reaction and characterized by nuclear magnetic resonance(NMR)and infrared(IR). The two- photon absorption properties of chromophores are investigated. These chromophores exhibit large two-photon absorption crosssections and strong blue two-photon excited fluorescence. The cooperative enhancement of two-photon absorption(TPA) in the multi-branched structures is observed. This enhancement is partly attributed to the electronic coupling between the branches. The electronic push-pull structures in the arm and their cooperative effects help the extended charge transfer for TPA. 展开更多
关键词 two-photon absorption two-photon excited fluorescence multi-branched chromophores carbazole derivatives
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