排序方式: 共有42条查询结果,搜索用时 15 毫秒
31.
Alison Hart Sarah A. Kelley Tyler Harless John A. Hood Michael Tagert Julie A. Pigza 《Tetrahedron letters》2017,58(31):3024-3027
We report an efficient two step process for the reduction of non-aromatic esters to the corresponding ethers via the intermediate TMS-protected acetal. The acetal formed after the first step can be carried on directly to the subsequent reduction to the ether without purification. The ester reduction step was monitored using in-situ ReactIR for disappearance of the CO peak, allowing for the exact determination of time and equivalents of the reducing agent. Furthermore, use of TMS-imidazole to form the acetal has allowed us to dramatically reduce the overall reaction time required for the two step procedure. 相似文献
32.
Background
It is well known that both semantic and syntactic information play a role in pronoun resolution in sentences. However, it is unclear what the relative contribution of these sources of information is for the establishment of a coreferential relationship between the pronoun and the antecedent in combination with a local structural case constraint on the pronoun (i.e. case assignment of a pronoun under preposition governing). In a prepositional phrase in German and Dutch, it is the preposition that assigns case to the pronoun. Furthermore, in these languages different overtly case-marked pronouns are used to refer to male and female persons. Thus, one can manipulate biological/syntactic gender features separately from case marking features. 相似文献33.
ICP-AES法测定色漆可溶性金属含量 总被引:1,自引:0,他引:1
用ICP-AES法测定了色漆中的“可溶性”金属铬、镉、铅元素,考察了不同酸度对分析结果的影响,优化了测试条件。进行了回收率和精密度试验。并用原子吸收光谱国标方法进行对照,结果一致。 相似文献
34.
35.
36.
37.
38.
39.
40.