used－silical capillary columns containing heptakis（2、3、6－tri－o－pentyl）-β-cyclodextrinand dibenzo-18-crown-6 were prepared．By studying the selectivity of mixed stationary phases forsome solute pairs.as well a...used－silical capillary columns containing heptakis（2、3、6－tri－o－pentyl）-β-cyclodextrinand dibenzo-18-crown-6 were prepared．By studying the selectivity of mixed stationary phases forsome solute pairs.as well as comparing with the heptakis（2．3、6-tri-O-pentyl）-β-cyclodextrin and thedibenzo-18-crown-6 used as individual stationary phase、the synergistic effects were observed.These effects were affected by the column temperature．mixed ratio and linear velocity of carrier gas．展开更多
The effects of different x values on the dielectric properties in the Ba6-3xSm8+2xTi18O54 microwave dielectric ceramics(0.3≤x≤0.7) were studied. The results showed that the major crystal phase was BaSm2Ti4O12 and th...The effects of different x values on the dielectric properties in the Ba6-3xSm8+2xTi18O54 microwave dielectric ceramics(0.3≤x≤0.7) were studied. The results showed that the major crystal phase was BaSm2Ti4O12 and the sintering temperature of the ceramics was 1340 ℃ when the x value was 0.67. The dielectric properties were better: εr≈79, tanδ≈1×10-4(1 MHz); εr≈80, Q·f=9230 GHz(3.97 GHz), τf=-17 ppm·℃-1.展开更多
the regioselectivity in the oxidation of different types of ketone compounds 1--6 with an oxidative reagent system,KH/O_2/18- Crown-6/THF is described.From these oxidative products,the various lactones have been prepa...the regioselectivity in the oxidation of different types of ketone compounds 1--6 with an oxidative reagent system,KH/O_2/18- Crown-6/THF is described.From these oxidative products,the various lactones have been prepared.展开更多
目的合成环己酮3-氯-1,2-丙二醇缩酮。方法采用浸渍法制备了H6P2W18O62/TiO2-SiO2催化剂,并采用FT-IR、XRD、SEM对其进行了表征。以环己酮和3-氯-1,2-丙二醇为原料,催化合成环己酮3-氯-1,2-丙二醇缩酮,采用FT-IR、1 H NMR、13 C NMR等...目的合成环己酮3-氯-1,2-丙二醇缩酮。方法采用浸渍法制备了H6P2W18O62/TiO2-SiO2催化剂,并采用FT-IR、XRD、SEM对其进行了表征。以环己酮和3-氯-1,2-丙二醇为原料,催化合成环己酮3-氯-1,2-丙二醇缩酮,采用FT-IR、1 H NMR、13 C NMR等表征手段来分析合成产物为环己酮3-氯-1,2-丙二醇缩酮。结果在酮醇摩尔比为1∶1.4,带水剂环己烷用量8mL,催化剂用量为反应物总质量的2.0%,反应时间1.0h的条件下,缩酮收率可达85.0%。催化剂重复使用5次后收率有72.6%。结论 H6P2W18O62/TiO2-SiO2催化剂对合成环己酮3-氯-1,2-丙二醇缩酮不仅反应时间短,催化剂用量少,而且产品收率高。展开更多
文摘used－silical capillary columns containing heptakis（2、3、6－tri－o－pentyl）-β-cyclodextrinand dibenzo-18-crown-6 were prepared．By studying the selectivity of mixed stationary phases forsome solute pairs.as well as comparing with the heptakis（2．3、6-tri-O-pentyl）-β-cyclodextrin and thedibenzo-18-crown-6 used as individual stationary phase、the synergistic effects were observed.These effects were affected by the column temperature．mixed ratio and linear velocity of carrier gas．
文摘The effects of different x values on the dielectric properties in the Ba6-3xSm8+2xTi18O54 microwave dielectric ceramics(0.3≤x≤0.7) were studied. The results showed that the major crystal phase was BaSm2Ti4O12 and the sintering temperature of the ceramics was 1340 ℃ when the x value was 0.67. The dielectric properties were better: εr≈79, tanδ≈1×10-4(1 MHz); εr≈80, Q·f=9230 GHz(3.97 GHz), τf=-17 ppm·℃-1.
文摘the regioselectivity in the oxidation of different types of ketone compounds 1--6 with an oxidative reagent system,KH/O_2/18- Crown-6/THF is described.From these oxidative products,the various lactones have been prepared.
文摘目的合成环己酮3-氯-1,2-丙二醇缩酮。方法采用浸渍法制备了H6P2W18O62/TiO2-SiO2催化剂,并采用FT-IR、XRD、SEM对其进行了表征。以环己酮和3-氯-1,2-丙二醇为原料,催化合成环己酮3-氯-1,2-丙二醇缩酮,采用FT-IR、1 H NMR、13 C NMR等表征手段来分析合成产物为环己酮3-氯-1,2-丙二醇缩酮。结果在酮醇摩尔比为1∶1.4,带水剂环己烷用量8mL,催化剂用量为反应物总质量的2.0%,反应时间1.0h的条件下,缩酮收率可达85.0%。催化剂重复使用5次后收率有72.6%。结论 H6P2W18O62/TiO2-SiO2催化剂对合成环己酮3-氯-1,2-丙二醇缩酮不仅反应时间短,催化剂用量少,而且产品收率高。
