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高速魔角旋转下基于组合π脉冲的射频驱动重耦同核双量子固体NMR相关实验研究
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作者 宋佩君 易迎彦 +1 位作者 王秀梅 张正逢 《分析测试学报》 CAS CSCD 北大核心 2024年第6期898-904,共7页
该文提出了一种改进固体核磁共振(NMR)实验中射频驱动重耦(RFDR)序列的方法。以组合π脉冲替代传统的单一矩形π脉冲作为RFDR序列的基本构成单元,并选择若干个适用于高速魔角旋转条件的组合π脉冲,在RFDR双量子实验中进行全面研究,通过... 该文提出了一种改进固体核磁共振(NMR)实验中射频驱动重耦(RFDR)序列的方法。以组合π脉冲替代传统的单一矩形π脉冲作为RFDR序列的基本构成单元,并选择若干个适用于高速魔角旋转条件的组合π脉冲,在RFDR双量子实验中进行全面研究,通过数值模拟分析了影响RFDR双量子实验性能的两个关键因素——共振偏置和射频场不均匀性,并根据模拟结果确定了性能最优的组合π脉冲。结合六氟硅酸钠和L-组氨酸的一维和二维^(19)F或1H固体NMR实验,验证了在高速魔角旋转条件下选择适当的组合π脉冲的RFDR序列的优势。该方法不仅能确保较高的同核双量子激发效率,还能提高激发带宽,并且对射频场不均匀性更加不敏感。稳定高效的RFDR同核双量子相关实验为采用固体NMR分析强自旋耦合体系的核间相互作用提供了重要的技术支持。 展开更多
关键词 固体核磁共振 魔角旋转 组合脉冲 偶极重耦 双量子-单量子相关 射频驱动重耦(RFDR)
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Applications of Floquet-Magnus and Fer Expansion Approaches during Cross Polarization Radiation in Solid State NMR
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作者 Eugene Stephane Mananga Thibault Charpentier 《Journal of Modern Physics》 2023年第7期1136-1156,共21页
This paper investigates the concept of Cross Polarization (CP) experiment in addition to revisiting the two potential expansion schemes recently developed in the field of solid-state nuclear magnetic resonance (SSNMR)... This paper investigates the concept of Cross Polarization (CP) experiment in addition to revisiting the two potential expansion schemes recently developed in the field of solid-state nuclear magnetic resonance (SSNMR): namely, the Floquet-Magnus expansion and the Fer expansion. We use the aforementioned expansion schemes for the calculation of effective Hamiltonians and propagators when the spin system undergoes Cross Polarization radiation. CP is the gateway experiment into SSNMR. An in-depth comprehension of the underlying mechanics of spin dynamics during the cross-polarization experiment is pivotal for further experimental developments and optimization of more complex solid-state NMR experiments. The main contribution of this work is a prospect related to spin physics;particularly regarding to generalization of the calculation. This work reports original yet interesting novel ideas and developments that include calculations performed on the CP experiment. In fact, the approach presented could play a major role in the interpretation of several fine NMR experiments in solids, which would in turn provide significant new insights in spin physics. The generality of the work points towards potential applications in problems related in solid-state NMR and theoretical developments of spectroscopy as well as interdisciplinary research areas as long as they include spin dynamics concepts. 展开更多
关键词 Cross Polarization solid-State nmr Floquet-Magnus Expansion Fer Expansion Spin Dynamics
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Polymeric Structure and Solid ^(31)P, ^(113)Cd NMR Spectra of Cadmium(II) Dialkyldithiophosphate (Alkyl = n-butyl and i-butyl)
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作者 Ye Gao YIN Willis FORSLING +3 位作者 Dan BOSTROM Oleg ANTZUTKIN Mats LINDBERG Alexander IVANOV 《Chinese Chemical Letters》 SCIE CAS CSCD 2003年第2期188-190,共3页
Two polymeric complexes, [Cd(BTP)2]n 1 and [Cd(i-BTP)2]n 2, were prepared and investigated by solid 31P and 113Cd NMR spectroscopies. The crystal structure of 2 was determined by X-ray diffraction.
关键词 Cadmium(II) complex dialkyldithiophosphate crystal structure solid nmr.
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Solid State NMR Study of Polystyrene Nanolatex Particles(I) ^(13)C Spin-Lattice Relaxation Time
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作者 Ya Lin TANG Xiao Zhong QU +1 位作者 Liu Sheng CHEN Xi Gao JIN 《Chinese Chemical Letters》 SCIE CAS CSCD 2001年第4期353-354,共2页
C spin-lattice relaxtion times for polystyrene nanolatex particles have been investigated. It was found that the dramatic increase at 80℃ annealing temperature is well below the Tg temperature of bulk polystyrene, t... C spin-lattice relaxtion times for polystyrene nanolatex particles have been investigated. It was found that the dramatic increase at 80℃ annealing temperature is well below the Tg temperature of bulk polystyrene, the increase of relaxation time of aromatic carbons is larger than that of for aliphatic carbons at transition annealing temperature. 展开更多
关键词 Polystyrene nanolatex particles solid state nmr spin-lattice relaxation time
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Solid State NMR and Fluorescence Studies of Conjugated Polymer Nanocomposties
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作者 Chao Jun JING Liu Sheng CHEN +1 位作者 Yi SHI Xi Gao JIN 《Chinese Chemical Letters》 SCIE CAS CSCD 2005年第11期1519-1522,共4页
^13C spin-lattice relaxation times (T1) of a conjugated polymer MEH-PPV in polymer/ layered silicate nanocomposites together with the steady state fluorescence emission and transient fluorescence decay measurements ... ^13C spin-lattice relaxation times (T1) of a conjugated polymer MEH-PPV in polymer/ layered silicate nanocomposites together with the steady state fluorescence emission and transient fluorescence decay measurements have been investigated. The T1 values of the conjugated carbons decrease dramatically according to the reduction of polymer concentration in the nano composites, while the fluorescence life times (τ) show a linear prolonging tendency. The results are explained from the point of view of molecular dynamics. 展开更多
关键词 Conjugated polymer NANOCOMPOSITES FLUORESCENCE solid state ^13C nmr
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Study of the coordinative nature of alkylaluminum modified Phillips CrO_x/SiO_2 catalyst by multinuclear solid-state NMR
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作者 Zhang Qin-Hui Yan Fang +1 位作者 Xia Wei Liu Chenguang 《Petroleum Science》 SCIE CAS CSCD 2013年第4期577-583,共7页
Solid-state nuclear magnetic resonance spectroscopy was used to investigate the coordinative states of surface Al species on various alkylaluminum-modified Phillips CrOx/SiO2 catalysts.The alkylaluminum-modified Phill... Solid-state nuclear magnetic resonance spectroscopy was used to investigate the coordinative states of surface Al species on various alkylaluminum-modified Phillips CrOx/SiO2 catalysts.The alkylaluminum-modified Phillips CrOx/SiO2 catalysts were examined via ethylene homopolymerization.1H and 27Al magic angle spinning(MAS) nuclear magnetic resonance(NMR) spectra clearly demonstrated that the existing states of surface Al species in alkylaluminum-modified catalysts strongly depended on the type of alkylaluminum cocatalyst,concentration of alkylaluminum and the calcination temperature.1H MAS NMR spectra of alkylaluminum-modified Phillips CrOx/SiO2 catalysts,calcined at two different temperatures,exhibited similar trends in peak shift.1H spectra showed that with an increase of Al/Cr ratio and calcination temperature,the main peak shifted to high field,indicating that the dominant surface proton species changed from hydroxyl to ethoxyl and ethyl groups.27Al MAS NMR spectra showed the presence of three different coordination states(6-,5-,and 4-coordinated Al species) in the alkylaluminummodified Phillips catalysts.In comparison of different alkylaluminum cocatalysts,it was found that the reactivity of alkylaluminum modified Phillips catalyst decreased in the order of TEA〉DEAH〉DEAE.The amount of 4-coordinated Al species of Phillips catalysts modified by TEA,DEAE and DEAH also decreased in the order of TEA〉DEAH〉DEAE,indicating that the presence of 4-coordinated Al species is related to the polymerization activity. 展开更多
关键词 Phillips catalyst ALKYLALUMINUM ethylene polymerization solid-state nmr
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固体NMR研究MOFs吸附和分离过程中的主客体相互作用 被引量:1
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作者 贺彩艳 肖宇情 +2 位作者 李申慧 徐君 邓风 《波谱学杂志》 CAS 北大核心 2023年第2期192-206,共15页
固体核磁共振(NMR)因对结构和化学环境敏感,已广泛应用于研究金属有机框架材料(MOFs)在吸附分离应用上的主客体相互作用机制.多核、多维、变温固体NMR实验可以用来研究低碳碳氢化合物、CO_(2)在MOFs孔道内的吸附行为(包括优先吸附位点... 固体核磁共振(NMR)因对结构和化学环境敏感,已广泛应用于研究金属有机框架材料(MOFs)在吸附分离应用上的主客体相互作用机制.多核、多维、变温固体NMR实验可以用来研究低碳碳氢化合物、CO_(2)在MOFs孔道内的吸附行为(包括优先吸附位点、动力学性质、扩散快慢等).固体NMR也可用来直接测定低碳烷烃/烯烃在MOFs中的分离选择性,并观测低碳烷烃/烯烃在MOFs孔道内的竞争优先吸附.此外,固体NMR还可用来揭示常见化学品与MOFs的主客体相互作用模式.这些研究的开展将有助于人们理解MOFs在吸附和分离过程中存在的内在构效关系. 展开更多
关键词 固体核磁共振 金属有机框架材料 主客体相互作用 吸附和分离
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Unveiling chain–chain interactions in CO2-based crystalline stereocomplexed polycarbonates by solid-state NMR spectroscopy and DFT calculations
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作者 Zhenchao Zhao Pengju Ren +3 位作者 Ye Liu Kangbo Zhao Xiao-Bing Lu Weiping Zhang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2018年第2期361-366,共6页
CO2-based stereocomplexed polycarbonates derived from the intermolecularly interlocked interaction between the enantiopure polymers with the opposite configuration exhibit high crystallinity, excellent thermal and mec... CO2-based stereocomplexed polycarbonates derived from the intermolecularly interlocked interaction between the enantiopure polymers with the opposite configuration exhibit high crystallinity, excellent thermal and mechanical stabilities. Deep insights into the mechanism of stereocomplexation are of particular importance to the design and manufacture of new promising and sustainable polycarbonates with enhanced physicochemical properties. Our solid-state NMR experiments linking with DFT computations clearly reveal the specific chain-chain interactions in a typical stereocomplexed poly(4,4-dimethyl-3,5,8-trioxabicyclo[5.1.0] octane carbonate)(PCXC).13C CP/MAS NMR,1H DUMBO MAS NMR and 13C/1H relaxation-time measurements indicate that the formation of stereocomplex reduces the local mobilities of carbonyl, methine and methylene groups in each chain of PCXC significantly. Through a combination of two-dimensional 1H-13C HETCOR NMR and DFT calculation analysis, the cis-/trans-conformations and packing models of PCXC chains in the amorphous, enantionpure isotactic and stereocomplexed polycarbonates are identified. The splitting of 13C and 1H NMR chemical shifts of methine groups in the backbone carbon region demonstrates the ordered interlock interactions between the R-and S-chain in the stereocomplexed PCXC. 展开更多
关键词 Stereocomplexed polycarbonates Crystalline carbonate polymers Stacking interaction solid-state nmr DFT
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Solid-State NMR Spectroscopic Approaches to Investigate Dynamics, Secondary Structure and Topology of Membrane Proteins
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作者 Shadi Abu-Baker Gary A. Lorigan 《Open Journal of Biophysics》 2012年第4期109-116,共8页
Solid-state NMR spectroscopy is routinely used to determine the structural and dynamic properties of both membrane proteins and peptides in phospholipid bilayers [1-26]. From the perspective of the perpetuated lipids,... Solid-state NMR spectroscopy is routinely used to determine the structural and dynamic properties of both membrane proteins and peptides in phospholipid bilayers [1-26]. From the perspective of the perpetuated lipids, 2H solid-state NMR spectroscopy can be used to probe the effect of embedded proteins on the order and dynamics of the acyl chains of phospholipid bilayers [8-13]. Moreover, 31P solid-state NMR spectroscopy can be used to investigate the interaction of peptides, proteins and drugs with phospholipid head groups [11-14]. The secondary structure of 13C = O site-specific isotopically labeled peptides or proteins inserted into lipid bilayers can be probed utilizing 13C CPMAS solid-state NMR spectroscopy [15-18]. Also, solid-state NMR spectroscopic studies can be utilized to ascertain pertinent informa- tion on the backbone and side-chain dynamics of 2H- and 15N-labeled proteins, respectively, in phospholipid bilayers [19-26]. Finally, specific 15N-labeled amide sites on a protein embedded inside oriented bilayers can be used to probe the alignment of the helices with respect to the bilayer normal [2]. A brief summary of all these solid-state NMR ap- proaches are provided in this minireview. 展开更多
关键词 solid-STATE nmr Structure and DYNAMICS Membrane PROTEINS
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二甲基胺阳离子掺杂甲胺铅溴钙钛矿材料的固体NMR研究
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作者 马开阳 乔文成 +1 位作者 王雪璐 姚叶锋 《波谱学杂志》 CAS 北大核心 2023年第1期10-21,共12页
本文利用氘核磁共振((2)^H NMR)技术对阳离子掺杂铅溴钙钛矿MA_(0.6)DMA_(0.4)PbBr_(3)中内嵌阳离子的运动状态进行了较为深入的研究.通过对二甲基胺(DMA)和甲胺(MA)阳离子的选择性氘代,我们实现了对上述材料中不同内嵌阳离子的选择性NM... 本文利用氘核磁共振((2)^H NMR)技术对阳离子掺杂铅溴钙钛矿MA_(0.6)DMA_(0.4)PbBr_(3)中内嵌阳离子的运动状态进行了较为深入的研究.通过对二甲基胺(DMA)和甲胺(MA)阳离子的选择性氘代,我们实现了对上述材料中不同内嵌阳离子的选择性NMR观测.研究结果显示,在低温下,该材料中的DMA与MA阳离子都接近于双重旋转模型;随着温度升高,DMA与MA阳离子的运动自由度增加,其运动逐步转变为快速各向同性运动.且在相同温度时,DMA阳离子比MA阳离子运动更快,表明该材料中阳离子运动状态不一致.在对阳离子运动研究的基础上,我们对该材料相结构转变的分子机制进行了探讨. 展开更多
关键词 固体氘核磁共振 分子运动 选择性观测 阳离子掺杂钙钛矿 二甲基胺阳离子
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SOLID-STATE HIGH RESOLUTION NMR STUDY ON POLY (2, 6-DIMETHYL-1,4-PHENYLENE OXIDE)
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作者 晏欣 胡建治 +2 位作者 姚树人 叶朝辉 张宝真 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 1995年第3期252-258,共7页
Experiments including C-13 spin-lattice relaxation, C-13 heteronuclear dipolar dephasing and H-1 spin diffusion are performed on poly (2,6-dimethyl-1,4-phenylene oxide) (PPO). The results show that the rotation of the... Experiments including C-13 spin-lattice relaxation, C-13 heteronuclear dipolar dephasing and H-1 spin diffusion are performed on poly (2,6-dimethyl-1,4-phenylene oxide) (PPO). The results show that the rotation of the methyl groups in solid PPO is partially restricted, which results in a surprisingly efficient spin diffusion between the aromatic proton and methyl proton characterized by a diffusion time of 150 mu s. The results also show that the aromatic ring in solid PPO is rigid and twisted, which causes all aromatic carbons to be chemically unequivalent. 展开更多
关键词 solid-STATE HIGH RESOLUTION nmr C-13 SPIN-LATTICE RELAXATION C-13 HETERONUCLEAR DIPOLAR DEPHASING H-1 SPIN DIFFUSION POLY (2 6-DINIETHYL 1 4-PHENYLENE OXIDE)
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SYNTHESIS AND NMR CHARACTERIZATION OF PRECURSORS OF EPOXY NETWORK AS POLYMER HOST FOR SOLID ELECTROLYTE
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作者 巴恒飞 彭新生 +1 位作者 陈东霖 王佛松 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 1992年第1期32-43,共12页
To raise the room temperature ionic conductivity and improve the mechanical strength of a PEO-based polymer electrolyte, a noncrystalline two-component epoxy electrolyte system has been prepared. The diglycidyl ether ... To raise the room temperature ionic conductivity and improve the mechanical strength of a PEO-based polymer electrolyte, a noncrystalline two-component epoxy electrolyte system has been prepared. The diglycidyl ether of polyethylene glycols as precursors of the system were synthesized by a two-step process. The presumed structure of the product was characterized, by ^(13)C, ~1H NMR and IR spectroscopy. It was found that a side-reaction occurred between the secondary hydroxyl group of PEG-chlorohydrin and epichlorohydrin in some degree, resulting in a by- product containing—CH_2Cl side group. By selecting a characteristic signal, which is undistorted by the increase in the length of CH_2 CH_2—O segment, a ~1H NMR approach of determining the equivalent epoxy weight (EEW) was proposed. The method is valid to specimens even though the EEW is as high as 2,000. The examination of the specimens by DSC showed that epoxidation greatly depressed the crystallinity of the PEG's, whereas the T_g was raised. 展开更多
关键词 Polymer solid electrolyte Polyethylene glycol epoxy network ^(13)C and ~1H nmr characterization ~1H nmr method of determining epoxide equivalent weight
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不同金属离子交换的FAU型分子筛的超极化^(129)Xe NMR研究 被引量:9
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作者 徐舒涛 张维萍 +1 位作者 韩秀文 包信和 《催化学报》 SCIE CAS CSCD 北大核心 2009年第9期945-950,共6页
采用连续流动的激光诱导超极化129Xe为探针分子,利用高分辨固体核磁共振技术研究了不同电子结构的金属阳离子(Na+,Ag+,Cu2+,Cu+,Cs+)交换的FAU型分子筛与超极化129Xe之间的相互作用.结果表明,超极化129Xe能够很灵敏地检测不同电子结构... 采用连续流动的激光诱导超极化129Xe为探针分子,利用高分辨固体核磁共振技术研究了不同电子结构的金属阳离子(Na+,Ag+,Cu2+,Cu+,Cs+)交换的FAU型分子筛与超极化129Xe之间的相互作用.结果表明,超极化129Xe能够很灵敏地检测不同电子结构的金属离子对限阈空间中电场梯度的影响.Na+对超笼内电场梯度的影响很小,NaX与NaY分子筛中Xe的化学位移表现出相似的行为.对于具有nd10电子结构的Ag+或Cu2+经自还原生成的Cu+,其与Xe的5d0轨道形成dπ-dπ键,导致Xe的化学位移明显向高场方向位移.Cu2+由于具有一定的顺磁性,使得129XeNMR谱展宽,甚至无法观测.Cs+的电子结构与Xe原子相同,它能吸附更多的Xe原子,导致Xe的化学位移明显向低场方向偏移. 展开更多
关键词 超极化129Xe核磁共振 固体核磁共振 离子交换 FAU型分子筛
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用固体高分辨NMR研究聚(L-丙氨酸)-聚乙二醇单甲醚双嵌段共聚物的微相结构与链段运动 被引量:10
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作者 伍国琳 孙平川 马建标 《高等学校化学学报》 SCIE EI CAS CSCD 北大核心 2003年第8期1515-1518,共4页
利用固体高分辨 1 3 C CP/MAS及二维 WISE核磁共振技术研究了聚 (L-丙氨酸 ) -聚乙二醇单甲醚双嵌段共聚物 (MPEG-b-PLA)在固态下的微相结构和链段运动行为 .结果表明 ,聚乙二醇链段在形成嵌段共聚物后结晶度明显下降 ,同时存在晶区和... 利用固体高分辨 1 3 C CP/MAS及二维 WISE核磁共振技术研究了聚 (L-丙氨酸 ) -聚乙二醇单甲醚双嵌段共聚物 (MPEG-b-PLA)在固态下的微相结构和链段运动行为 .结果表明 ,聚乙二醇链段在形成嵌段共聚物后结晶度明显下降 ,同时存在晶区和非晶区 ,从而表现出两种不同的运动状态 .而聚乙二醇链段的引入对聚 L-丙氨酸链段影响不大 ,嵌段共聚物中聚 L-丙氨酸链段高度结晶 ,同时含有大量的α螺旋结构 ,分子链运动严重受限 ,估计聚 L-丙氨酸链段的相区尺寸很小 . 展开更多
关键词 固体高分辨 nmr 聚(L-丙氨酸)-聚乙二醇单甲醚 双嵌段共聚物 微相结构 链段运动 固体核磁共振
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采用固体NMR研究MPEG-PLA双嵌段共聚物的固态相区结构 被引量:5
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作者 伍国琳 孙平川 +1 位作者 张国林 马建标 《波谱学杂志》 CAS CSCD 北大核心 2003年第1期1-7,共7页
采用固体核磁共振方法 ,研究了AB型聚 (L 丙氨酸 ) 聚乙二醇嵌段共聚物 (MPEG b PLA)的固态微相结构 .1 3C核的交叉极化与直接极化实验表明 ,MPEG中存在晶态和非晶态两种相区结构 ,PLA则含有大量的α螺旋与少量的 β折叠二级结构 .由... 采用固体核磁共振方法 ,研究了AB型聚 (L 丙氨酸 ) 聚乙二醇嵌段共聚物 (MPEG b PLA)的固态微相结构 .1 3C核的交叉极化与直接极化实验表明 ,MPEG中存在晶态和非晶态两种相区结构 ,PLA则含有大量的α螺旋与少量的 β折叠二级结构 .由交叉极化过程下的1 3C自旋 晶格弛豫时间 (T1 )测定结果进一步表明 ,MPEG链段由于嵌段结构使结晶过程受抑制 ,结晶度明显下降 .PLA链段以结晶态形式存在 ,并由于大量α螺旋和β折叠有序结构的存在 ,链段非常刚性 ,运动严重受限 ,而β位甲基因为可以自由旋转 。 展开更多
关键词 固态相区结构 固体nmr 聚氨基酸 核磁共振 MPEG-PLA双嵌段共聚物 聚醚
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不同骨架硅铝比Y分子筛热改性过程的固体NMR表征 被引量:6
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作者 要旸 肖强 +3 位作者 李丽颖 陈铁红 孙平川 丁大同 《南开大学学报(自然科学版)》 CAS CSCD 北大核心 2004年第2期102-106,共5页
不同次邻近铝含量可导致改性后Y分子筛酸中心性质的较大差别,较高Si/Al比Y分子筛焙烧脱羟时可能出现三配位铝.随骨架Si/Al比不同,Y型分子筛脱铝形成的非骨架铝性质也有所不同.以化学环境敏感的四极核Na+为探针,证实了改性产生的非骨... 不同次邻近铝含量可导致改性后Y分子筛酸中心性质的较大差别,较高Si/Al比Y分子筛焙烧脱羟时可能出现三配位铝.随骨架Si/Al比不同,Y型分子筛脱铝形成的非骨架铝性质也有所不同.以化学环境敏感的四极核Na+为探针,证实了改性产生的非骨架Al对骨架阳离子位的环境有较大影响,这可能是B,L酸协同作用后出现增强酸性的证据. 展开更多
关键词 Y分子筛 热改性 固体核磁共振
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高分辨固体NMR研究不饱和聚酯/聚乙二醇-聚丙二醇-聚乙二醇三嵌段共聚物共混体系的相容性及局域分子运动 被引量:5
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作者 李新娟 党琴琴 +5 位作者 林海 王亦农 孙平川 李宝会 金庆华 丁大同 《高分子学报》 SCIE CAS CSCD 北大核心 2006年第4期636-639,共4页
An nanostructured thermoset blend of unsaturated polyester(UPR) and PEO-PPO-PEO triblock copolymer was prepared and characterized by solid-state NMR and other techniques.It is concluded that the blend is microphase se... An nanostructured thermoset blend of unsaturated polyester(UPR) and PEO-PPO-PEO triblock copolymer was prepared and characterized by solid-state NMR and other techniques.It is concluded that the blend is microphase separated and the determined long period is 20 nm.A distinct dynamic difference between the cured-UPR matrix and block copolymers was observed by 1D and 2D NMR experiments,the formation of PEO crystalline domains was inhibited in the blend.The PEO blocks are partially miscible with the cured-UPR matrix.Upon curing, part of the mobile PEO was locally expelled from the cured-UPR matrix and formed dispersed microphase together with the mobile PPO,the residual immobilized PEO blocks were intimately mixed with the partially cured-UPR, and they formed an interphase region. 展开更多
关键词 嵌段共聚物 不饱和聚酯 热固性共混物 固体核磁共振
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施用蚓粪对滨海盐碱地土壤有机碳库及其稳定性的影响
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作者 卢云 秦天扬 +7 位作者 陈玮峰 蔡健 许益伟 李云龙 左文刚 陈硕桐 单玉华 柏彦超 《土壤》 CAS CSCD 北大核心 2024年第4期817-825,共9页
为探讨施用蚯蚓粪后滨海盐碱地土壤有机碳库及其稳定性的变化,选择江苏省南通市如东县栟茶镇方凌垦区的滨海盐碱地,于2019年10月将蚯蚓粪以0、25、50、100、200 t/hm^(2)施用量一次性施于田间,2022年10月采集耕层(0~20 cm)土壤样品,测... 为探讨施用蚯蚓粪后滨海盐碱地土壤有机碳库及其稳定性的变化,选择江苏省南通市如东县栟茶镇方凌垦区的滨海盐碱地,于2019年10月将蚯蚓粪以0、25、50、100、200 t/hm^(2)施用量一次性施于田间,2022年10月采集耕层(0~20 cm)土壤样品,测定其可溶性有机碳、钙结合有机碳、易氧化有机碳、颗粒态及矿物结合态有机碳的含量,计算碳库管理指数,并采用固体核磁共振波谱分析土壤有机碳的官能团结构。结果表明:与不施用蚯蚓粪相比,施用超过50 t/hm^(2)的蚯蚓粪后,土壤有机碳库变化显著,土壤有机碳含量增加了35%~97%,可溶性有机碳含量增加了27%~104%,钙结合有机碳含量增加了19%~26%,易氧化有机碳含量增加了6%~94%,颗粒态和矿物结合态有机碳分别增加了14%~124%和37%~85%,土壤碳库管理指数提高了6%~92%;土壤中脂肪族碳与芳香族碳的比值减小,烷基碳/O-烷基碳以及疏水碳/亲水碳的比值增大,表明土壤有机碳的结构稳定性有所提升。综上,施用蚯蚓粪对提高滨海盐碱地土壤有机碳库及其稳定性具有显著作用,且在50和100 t/hm^(2)施用量下效果最佳。 展开更多
关键词 蚯蚓粪 滨海盐碱地 土壤有机碳库 碳库管理指数 固体核磁共振
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高聚物微观结构的固体NMR研究 被引量:3
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作者 孙平川 陈铁红 +3 位作者 伍国琳 李宝会 金庆华 丁大同 《波谱学杂志》 CAS CSCD 北大核心 2004年第1期141-147,共7页
核磁共振波谱是研究高聚物结构和动力学的有效手段,特别是固体高分辨NMR实验方法的不断发展及谱仪技术的进步,使这方面的研究不断深入。文中简述了若干固体高分辨NMR技术在固态高聚物结构研究中的应用和重要进展。部分实验工作在Varian ... 核磁共振波谱是研究高聚物结构和动力学的有效手段,特别是固体高分辨NMR实验方法的不断发展及谱仪技术的进步,使这方面的研究不断深入。文中简述了若干固体高分辨NMR技术在固态高聚物结构研究中的应用和重要进展。部分实验工作在Varian UNITY-plus 400MHz NMR谱仪的固体单元上完成。 展开更多
关键词 高聚物 微观结构 固体核磁共振 谱编辑技术 化学位移 结晶行为 分辨率
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固体核磁共振样品制备系统的自主研制
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作者 陈阳 周萌 +1 位作者 李勇 杨海军 《波谱学杂志》 CAS 2024年第1期77-86,共10页
近年来,国内多个科研单位引进了固体核磁共振波谱仪.由于目前固体核磁共振波谱仪还没有国产化,完全依赖进口,因此仪器及配套的样品制备系统价格昂贵.转子是魔角旋转核磁共振实验的关键耗材,其尺寸精密度要求极高,加工难度大.通过分析进... 近年来,国内多个科研单位引进了固体核磁共振波谱仪.由于目前固体核磁共振波谱仪还没有国产化,完全依赖进口,因此仪器及配套的样品制备系统价格昂贵.转子是魔角旋转核磁共振实验的关键耗材,其尺寸精密度要求极高,加工难度大.通过分析进口成品3.2mm固体核磁共振转子及其配套样品制备工具的特性和实际应用需求,改进转子各零部件之间的连接方式,优化转子的密封性,成功实现了固体核磁共振转子和配套样品制备工具箱的自主研制.测试结果表明,自主研制的转子能在12kHz转速下正常运行,满足常规固体核磁共振实验需求,且配套的样品制备工具箱操作简单,安全可靠. 展开更多
关键词 固体核磁共振 转子 样品制备工具 自主研发
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