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13C-

13C-

13C-

13C-

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Aim : nuclear magnetic resonance spectrum of calycosin was studied , and its chemical shifts of 13C NMR were attributed .

目的：研究了毛蕊异黄酮的核磁共振波谱学，并对其 13CNMR 进行归属。

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This caused a massive release of 12C-rich methane into the atmosphere , explaining the initial drop in 13C concentrations .

这导致 12C 被大规模释放到大气中，也解释了 13C 浓度最初下降的原因。

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The structures of the new intermediates and target compounds are confirmed by 1H NMR, 13C NMR, IR, and MS spectra .

所有的目标化合物和一些中间体化合物的结构都经过 1HNMR 、13CNMR 、IR 及 MS 得到了确认。

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Non-radioactive carbon comes in two forms : 12C and the heavier (and much rarer form ) 13C.

非放射性碳以两种形式存在：12C 还有较重（并且更罕见）的 13C 。

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The structures of the intermediates and the target compound were confirmed by MS, 1H NMR and 13C NMR spectra in our experiments.

关键中间体及最终化合物的结构经质谱、核磁共振氢谱及碳谱得到确证。

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No apparent toxicity was observed in 13C-octanoic acid abnormal toxicity test .

13C-辛酸异常毒性试验未见明显毒副反应。

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Methods 13C-octanoic acid was synthesized with Grignard method .

方法 13C-辛酸采用格利雅方法合成标记。

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The chemical shifts of 1H and 13C have been calculated with ab initio and DFT, all of which are compared with the experimental results .

用从头算法和密度泛函方法计算了碳和氢的化学位移，并与实验结果进行了比较。

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Methods 13C-labelled urea breath test (13C-UBT) was conducted in 2512 health-examined individuals .

方法对 2512 例健康体检人员进行 13C 尿素酶呼气试验（13C-UBT ）检测分析。

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Results The structure of the target molecule was identified by 1H NMR, 13C NMR and element analysis .

结果最终产物由核磁共振谱和元素分析进行结构鉴定。

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abstract: Objective To observe the effect of xylitol on the texture of reagents used in13C- urea breath test and the value of DOBtest.

目的观察木糖醇对 13C-尿素呼气试验检测试剂的口感及 DOB 检测值的影响。

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The routine chemical analysis means and 13CNMR spectra were employed to learn the relations of structure and quality of UF resin .

采用常规化学分析和 ^13C 核磁共振相结合的方法，分析研究了脲醛树脂胶粘剂性能与结构的关系。

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The method is also suitable to label plant with 13C and 15N isotope .

该方法亦适合于采用 14C 、15N 等同位素对植物进行标记和示踪。

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It can aid people to elucidate the 13C-NMR spectra of steroidal natural products effectively .

能有效地辅助人们对甾体类天然产物 ~（13 ）C-NMR 图谱的解析。

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Average temperature of a month is 7-13C (45-55F) that is higher than its nearby cities , such as Chengdu , Chongqing and Kunming .

月平均温度是 7到13 摄氏度，很明显高于附近的成都，重庆，昆明等城市。

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