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排序方式: 共有391条查询结果,搜索用时 15 毫秒
91.
Ran RAN Guo Xing XIONG* Yu Hong ZHANG Shi Shan SHENG Wei Shen YANG State Key Laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences P.O.Box Dalian 《中国化学快报》2001,(3)
Partial oxidation of methane (POM) has several advantages over the traditional industrial method of steam reforming, such as much higher space velocity, reduced capital and operation cost and optimized the ratio of the products (H2/CO). Many investigators are interested in the POM reaction over monolith now1-3. Monolith is a kind of ceramic-like metal oxide material. It has relative high surface to volume ratio compared to commercial pellets, low pressure drop during the reaction process2,… 相似文献
92.
Aurelio L Box JS Brownlee RT Hughes AB Sleebs MM 《The Journal of organic chemistry》2003,68(7):2652-2667
N-Methyl amino acids occur in many natural products. Experimental strategies are presented for a unified approach to the synthesis of N-methyl derivatives through 5-oxazolidinones of the 20 common l-amino acids. The amino acids with reactive side chains that required protecting groups or devoted syntheses for side chain construction for N-methylation to proceed included serine, threonine, tyrosine, cysteine, methionine, tryptophan, asparagine, histidine, and arginine. The studies have provided improved methods for the preparation of N-methyl serine, threonine, and tyrosine. All 20 of the common l-amino acids are now available in suitable forms for solid or solution-phase peptide synthesis. 相似文献
93.
羧甲基交联魔芋葡甘聚糖微球的制备与表征 总被引:6,自引:0,他引:6
采用交联魔芋葡甘聚糖颗粒(CKGG)合成了羧甲基交联魔芋葡甘聚糖微球(CMCKGG),讨论了羧甲基化过程中的影响因素.用正交设计的方法确定了具有较好交换容量的CMCKGG制备奈件.当碱用量为CKGG量的20%,氯乙酸钠用量为CKGG量的10倍,温度55℃,反应时间8h时,制得的CMCKGG阳离子交换容量为0.7389mmol/g.红外光谱.光学显微镜和扫描电镜的结果表明,该颗粒为蜂窝状多孔微球,粒度均匀. 相似文献
94.
Giulia Caron Guillaume Steyaert Alessandra Pagliara Frdric Reymond Patrizia Crivori Patrick Gaillard Pierre-Alain Carrupt Alex Avdeef John Comer KarlJ. Box HubertH. Girault Bernard Testa 《Helvetica chimica acta》1999,82(8):1211-1222
The objectives of this study were to validate new experimental techniques used to measure the log P of protonated drugs, and to investigate the inter- and intramolecular forces influencing the partitioning behavior of β-blockers in isotropic biphasic solvent systems. The lipophilicity parameters of a number of β-blockers were measured by two-phase titration, centrifugal partition chromatography (CPC), and cyclic voltammetry (CV) in one or more of the following solvent systems: octanol/water, 1,2-dichloroethane/water, and dibutyl ether/water. CV proved to be a promising technique for measuring the lipophilicity of protonated β-blockers. Derived parameters such as Δlog P (difference between log P in two different solvent systems, a parameter valid for a given solute in a given electrical form) and diff (difference between log P of two different electrical forms of a given solute, in the same system) yielded insights into inter- and intramolecular interactions characteristic of β-blockers. The relevance of these parameters in structure-permeation relationships is explored. 相似文献
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