Alzheimer''s disease histologically proven studied by MRI and MRS: Two cases

Two patients affected by severe Alzheimer's disease (AD) were investigated by MRI and image-guided ³¹P MRS. In one case, ¹H MRS was additionally performed. In both cases the diagnosis of AD was confirmed, post mortem, by the pathologist. The spectral parameters of the ³¹P MR spectra were estimated by fitting the ³¹P MR signals in the time domain. Our ³¹P MRS results suggest that it is possible to detect the membrane catabolism, as indexed with the level of PDE resonances visible in in vivo ³¹P MRS, at least in severe AD cases. The ¹H spectrum from AD brain showed a marked decrease of NAA signal respect to choline.     

通过宽线固体核磁共振氢谱研究半晶高分子的相结构

宽线固体核磁共振氢谱（¹H NMR）是一种研究半晶高分子相结构的经典方法.本文以半晶聚乙烯的宽线固体¹H NMR谱为例，探讨了通过Gaussian/Sinc、Gaussian和Lorentzian函数组合对宽线固体¹H NMR谱图进行拟合的方案，并根据半晶聚乙烯的相结构成分对拟合得到的各信号成分进行归属.并在此基础上探讨了各个相结构中分子链运动与信号线型的相关性，以及利用宽线固体¹H NMR谱测量半晶高分子结晶度存在的困难.     

宿萼假耧斗菜有效组分的NMR研究

利用1D、2D NMK和差谱等方法研究二个化合物:ent-kauran-16β,17-diol和假耧斗菜素(paraquilgin)的化学位移和立体结构,对其¹H和¹³C NMR谱进行了全归属。     

Ga(OTf)3催化合成苯并二氮杂卓及其结构解析

以邻苯二胺和丙炔酸酯为原料,Ga(OTf)3催化一锅法合成了一类新型的1,5-苯并二氮杂卓衍生物,超声波辅助加快了反应的进行,该反应条件温和,反应时间短. 利用¹H NMR、¹³C NMR 确定了该产物的结构,并通过DEPT、¹H-¹H COSY、HMQC、HMBC等2D NMR谱,对化合物的¹H NMR和¹³C NMR数据进行了详细的归属,讨论了化合物的质谱裂解规律,进一步确证了该化合物的结构.     

白桦酯酸7',8'一二羟基肉桂酸脂的2D NMR研究

从产于甘肃的高山绣线菊植物中分离出一种新的化合物:白桦酯酸7',8'-二羟基肉桂酸脂.利用MS,IR,1D和2D NMR技术,其中包括¹H-¹H COSY,¹H-¹³C COSY,¹H-¹³C COLOC等对¹H和¹³C谱进行了归属.     

利用相位步进脉冲消除探头13C NMR背景信号

由静态探头线圈外有机材料产生的¹³C NMR背景信号强度大，化学位移范围广（δ_C 20~250），此背景信号在交叉极化实验中还可被增强，并随着样品信号的累积而累积，严重影响谱图分析.将相位步进脉冲引入交叉极化实验（称为PIPCP）中可以有效去除经交叉极化增强的¹³C NMR背景信号，但样品信号不受影响.这是由于经过相位步进脉冲后，线圈外相位严重畸变，而且线圈外锁定场强度急剧降低，来自探头材料的¹³C NMR背景信号无法有效地进行交叉极化.而对于被测样品甘氨酸来说，由于I核和S核之间强烈的偶极耦合作用，所加相位步进脉冲对锁定场强度的影响只有1.4%.     

德拉沙星葡甲胺波谱学数据解析

本文采用元素分析、紫外吸收光谱、红外吸收光谱、质谱和核磁共振（NMR）波谱（包含¹H NMR、¹³C NMR、DEPT、¹H-¹H COSY、¹H-¹³C HSQC和¹H-¹³C HMBC）等方法对德拉沙星葡甲胺进行了结构分析,确证了德拉沙星葡甲胺的结构,分析了其IR谱图特征吸收峰对应的基团,对其¹H和¹³C NMR信号进行了完整归属.并通过差示扫描量热法、热重分析及粉末X-射线衍射分析对德拉沙星葡甲胺的晶型进行了初步研究.     

一个A环开环型芳基萘内酯类木脂素2D NMR全归属

采用二维核磁共振技术(¹H-¹H COSY, DEPT, HSQC, HMBC, NOESY)和CD光谱,确定了A环开环型芳基萘内酯类木脂素3′, 4′-O, O-demethylene-4-O- demethylpodophyllotoxin (1)的结构. 首次对化合物1的¹³C NMR数据进行了全归属.     

H MAS and H[Na] double resonance NMR studies on the modification of surface hydroxyl groups of γ-alumina by sodium

The modification of surface hydroxyl groups with sodium in a series of Na₂CO₃-γ-Al₂O₃ catalysts was investigated as a function of both the Na₂CO₃ loading and the calcination temperature by means of ¹H magic angle spinning (MAS) and ¹H[²³Na] spin-echo double resonance NMR techniques. The ¹H NMR experiments revealed that sodium ions are homogeneously distributed over the alumina surface and closely coordinated with the surface hydroxyl groups. In the catalysts calcined at 250 °C, the acidic hydroxyl groups (with a chemical shift of 2.0 ppm) are preferentially associated with sodium ions at low Na₂CO₃ coverages (5 and 10%), while both the acidic and the basic (0 ppm) hydroxyl groups are accessible for sodium ions at high coverages (15 and 20%). The coordination causes a low-field shift of about 2 ppm in the ¹H MAS spectra, and a broad signal at 4.5 ppm appears. It is interesting that the 4.5 ppm signal is completely suppressed in the ¹H[²³Na] MAS experiments, providing direct evidence that a strong interaction exists between adsorbed sodium ions and the surface hydroxyl groups. Increasing the calcination temperature to 450 °C results in preferential removal of the acidic hydroxyl groups, and only the most basic hydroxyl groups remain when the calcination temperature is raised to 600 °C. This is attributed to the formation of the coordinated species which enhances the acidity of the surface hydroxyl groups and prompts their dehydroxylation, especially at high calcination temperature. Correlation of the ¹H MAS NMR results and catalytic activity measurements indicates that the basic hydroxyl groups are essential for the carbonyl sulfide hydrolysis reaction.     

盐酸马尼地平的核磁共振数据解析

盐酸马尼地平是第三代合成降压新药．本文利用一维、二维核磁共振（NMR）技术,包括¹H NMR、¹³C NMR DEPT-135、¹H-¹H NOESY、¹H-¹H COSY、¹H-¹³C HSQC和¹H-¹³C HMBC,对其¹H和¹³C NMR信号进行了全归属,进一步确证了其分子结构．同时,对其¹H NMR和¹³C NMR谱中一些异常信号进行了讨论．     

大鼠粪样中几种糖类物质的结构确定

粪样代谢组能够反映宿主和肠道菌群相互作用的共代谢信息,然而粪样中糖类物质的归属信息迄今仍不完善. 该研究使用1D NMR技术检测到大鼠粪样中木糖、阿拉伯糖、半乳糖等单糖以及由阿拉伯糖和木糖组成的寡聚糖. 在使用固相萃取（SPE）方法进行分离富集的基础上,结合使用2D NMR实验技术（¹H-¹H COSY,¹H-¹H TOCSY,¹H-¹³C HSQC,¹H-¹³C HMBC以及DOSY）确定了这些糖类物质的结构,并对其1H NMR和¹³C NMR谱峰进行了归属.     

丁氟螨酯的波谱学数据解析与结构确证

丁氟螨酯是一种新型杀螨剂,具有高效、低残留的特点.本文对其红外吸收光谱（IR）、紫外吸收光谱（UV）、质谱（MS）及核磁共振（NMR）波谱（包括¹H NMR、¹³C NMR、DEPT、¹H-¹H COSY、¹H-¹³C HSQC、¹H-¹³C HMBC）进行了测定,分析了其UV和IR谱图特征吸收峰对应的基团,并对其¹H和¹³C NMR信号进行了归属,确证了丁氟螨酯的结构.该研究将为丁氟螨酯的其他相关研究提供参考.     

Measurement of spin-lattice relaxation times of C in organic solids

A transient nuclear Overhauser effect (NOE) makes measurements of the ¹³C spin-lattice relaxation times in organic solids complicated. Extended Solomon equations are applied in order to describe ¹³C spin-lattice relaxation with ¹H r.f. field irradiation. Spin-lattice relaxation under r.f. irradiation is shown to be generally a triple-exponential process, but it can be reduced to be single-exponential under stronger r.f. field irradiation as well as in the absence of ¹H initial magnetizations. Based on numerical calculations, the difference between spin-lattice relaxation curves obeying T₁^C < T₁^H and those obeying T₁^C < T₁^H is clearly indicated. The methyl group resonances in solid-state -valine are examined, and the experimental results agree well with the theoretical results.     

盐酸贝西沙星的波谱学数据与结构确证

盐酸贝西沙星是一种新型的氟喹诺酮类抗菌药物,对盐酸贝西沙星的紫外吸收光谱（UV）、红外吸收光谱（IR）、质谱（MS）、核磁共振（NMR）波谱（包括¹H NMR、¹³C NMR、DEPT、HSQC、HMBC、COSY和NOESY）数据进行了解析,对其所有的¹H和¹³C NMR信号进行了归属,通过多种波谱学技术确证了盐酸贝西沙星的结构.     

二维核磁共振波谱在阐明一种三萜多糖皂苷结构中的应用

从毛茛科铁破锣属(Beesia)铁破锣[Beesia calthaefolia (Maxim.) Ulbr.］根茎的 正丁醇萃取物中分离得到一种齐墩果酸型三萜皂苷（1）; 其化学结构通过化学方法和波谱分析(IR, ESI-MS, ¹H NMR, ¹³C NMR, ¹H-¹H COSY, ¹H-¹H TOCSY, HMQC, HMQC-TOCSY, HMB C) 鉴定为齐墩果酸-3-O-β-D-吡喃葡萄糖（1→3）-α-L吡喃鼠李糖(1→2)-α -L-吡喃阿拉伯糖-28-O-α-L-吡喃鼠李糖(1→4)-β-D-吡喃葡萄糖(1→6)-β- D-吡喃葡萄糖酯苷. 本文具体介绍上述几种二维核磁共振技术在解析这一结构复杂的天然产物中的应用.     

Visualization of residual anisotropic interactions in crosslinked natural rubbers by dipolar local field measurements and H natural abundance NMR spectroscopy

An extension of the exploitation of indirect observation of ¹H nuclei through ¹³C resonances is presented in the case of crosslinked elastomers. It is demonstrated that, by using this method in vulcanized elastomers above T_g a direct visualization of residual dipolar interactions on different functional groups as well as their dependence on motional constraints is available. It is also shown that ²H natural abundance NMR spectra of elastomers provide similar information on motional constraints by way of residual quadrupolar interactions.     

卡泊三醇的核磁共振谱解析

利用核磁共振氢谱（¹H NMR）、碳谱（¹³C NMR）、同核位移相关谱（¹H-¹H COSY）、异核单量子相干谱（HSQC）和异核多键相关谱（HMBC）等多种核磁研究方法对抗银屑病药物卡泊三醇的¹H、¹³C信号进行完全归属.     

铕离子对tRNAPhe结构影响的NMR研究

采用NMR波谱方法研究了溶液中铕离子对酵母苯丙氨酸转移核糖核酸(phenylalanine transfer ribonucleic acid,简称tRNA^Phe)结构和构象变化的影响.Eu³⁺离子对tRNA^Phe亚胺质子范围的¹H NMR谱具有特殊的影响,酵母tRNA^Phe亚胺质子谱作为Eu³⁺浓度函数的研究表明位于扩大二氢尿嘧啶螺旋(D-螺旋)的端梢三级碱基对G₁₅·C₄₈明显地受加入Eu³⁺的影响(向低场位移0.85);堆积在G₁₅·C₄₈上的U₈·A₁₄碱基对在存有1~2个Mg²⁺离子下亦受加入Eu³⁺的影响.酵母tRNA^Phe中可能受到Eu³⁺影响的另一亚胺质子为G₁₉·C₅₆三级碱基对,由于G₁₉·C₅₆的亚胺质子共振位于高度叠加的12.6与12.2之间,其归属仅供参考.该碱基对有助于D-环对TΨC环的联接.配位Eu³⁺引起tRNA分子构象的变化并且导致一些谱峰向高场或低场位移.     

以NMR手段为主进行结构分析一则

某固体化合物极易溶于水但未能制得其单晶.为测定其结构可充分发挥NMR的特长.利用NMR的多种技术,包括常规¹H谱、¹³C谱,一维、二维谱,确定脂肪链X-CH₂-CH₂-CH₂-Y与芳香基团Y的存在;利用¹³C-¹H长程耦合相关谱(用反相探头)可确定脂肪链与芳香基团间的联接关系,于是立即可确定该物的有机主体骨架应为X-CH₂-CH₂-CH₂-Y.从IR谱得知该物除存在C-N基团外,还存在-SO₃-基团等.从元素成分分析和M8谱,包括FAB-MS谱等分析结果,最终推断该固体化合物为丙磺酸吡啶内鎓盐,它的分子结构应为:      

大鼠尿液中N-氧化烟酰胺和伪尿嘧啶核苷的NMR分析

N-氧化烟酰胺和伪尿嘧啶核苷是尿液代谢组的两种重要组成成分,但是其核磁共振信号的归属仍不完善.该文采用多种2D NMR谱(1H-1H COSY,1H-1H TOCSY,1H-1H J-RES,1H-13C HSQC和1H-13C HMBC)对尿液中N-氧化烟酰胺和伪尿嘧啶核苷的结构进行了确定,并对其1H和13C的化学位移进行了归属.