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In this paper, superlattice patterns have been investigated by using a two linearly coupled Brusselator model. It is found that superlattice patterns can only be induced in the sub-system with the short wavelength. Three different coupling methods have been used in order to investigate the mode interaction between the two Turing modes. It is proved in the simulations that interaction between activators in the two sub-systems leads to spontaneous formation of black eye pattern and/or white eye patterns while interaction between inhibitors leads to spontaneous formation of super-hexagonal pattern. It is also demonstrated that the same symmetries of the two modes and suitable wavelength ratio of the two modes should also be satisfied to form superlattice patterns. 相似文献
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The mechanism of the famous phase compression is discussed, and it is used to control the chaos in the Hindmarsh-Rose (H-R) model. It is numerically confirmed that the phase compression scheme can be understood as one kind of intermittent feedback scheme, which requires appropriate thresholds and feedback coeffcient, and the intermittent feedback can be realized with the Heaviside function. In the case of control chaos, the output variable (usually the voltage or the membrane potential of the neuron) is sampled and compared with the external standard signal of the electric electrode. The error between the sampled variable and the external standard signal of the electrode is input into the system only when the sampled variable surpasses the selected thresholds. The numerical simulation results confirm that the chaotic H-R system can be controlled to reach arbitrary n-periodical (n = 1, 2, 3, 4, 5, 6,...) orbit or stable state even when just one variable is feed backed into the system intermittently. The chaotic Chua circuit is also investigated to check its model independence and effectiveness of the schemes and the equivalence of the two schemes are confirmed again. 相似文献
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真空溶剂蒸发全二维液相色谱接口及其应用 总被引:2,自引:1,他引:1
以正相色谱(NPLC)为第一维,反相色谱(RPLC)为第二维,建立了真空溶剂蒸发接口的全二维液相色谱系统(VEI-C2DLC)。样品首先在第一维(CN色谱柱)进行正相分离,第一维洗脱产物被交替存储到十通阀上的两个定量环中,与此同时对切割到定量环内的第一维组分进行在线真空蒸发,被分析样品组分保留在定量环内壁内,而溶剂被蒸发除去。十通阀切换后保留在该定量环内的样品组分被洗脱到第二维进行反相分离,如此反复循环使第一维组分完全转移到第二维。采用标准样品和天然植物蛇床子提取液对该全二维液相系统进行了评价。 相似文献
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微波辅助提取GC-MS分析莪术挥发油成分 总被引:3,自引:0,他引:3
1引言 莪术是我国传统中药材,是一种有效的抗癌中药,在防治恶性肿瘤特别是早期宫颈癌方面有较好的疗效.据<本草纲目>记载:莪术辛、苦、温,归肝、脾经,具有行气破血、消积止痛之功效,被称为血中之气药.莪术根茎中含挥发油约1%~2.5%,为多种倍半萜类,其中莪术醇和榄香烯以及莪术酮和莪术二酮具有抗肿瘤、抗病毒的疗效.微波辅助提取具有设备简单、适用范围广、萃取效率高、节省时间和溶剂、污染小等诸多优点,应用范围已从最初的环境样品分析迅速扩展到食品、化工和农业等领域.本研究以莪术为原料,采用微波萃取法提取挥发油,通过紫外分光光度法监测其含量变化,用气相色谱-质谱法(GC-MS)分析最优提取工艺条件下所得挥发油成分,为进一步开发莪术药用价值提供依据. 相似文献
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As one of the next-generation energy-storage devices,Li-O2 battery has become the main research direction for the academic researchers due to its characteristics of environmental friendship,relatively simple structures,high energy density of 3500 Wh/kg and low cost.However,Li-O2 battery cannot be commercialized on a large scale because of the challenging issues including high-efficient electro-catalysts,membranes,Li-based anode and so on.In this review,we focused on the recent development of electrocatalyst materials as cathodes for the non-aqueous Li-O2 batteries which are relatively simpler than other Li-O2 batteries' structures.Electrocatalysts were summarized including noble metals,nano-carbon materials,transition metals and their hybrids.We points out that the challenges of preparation high-efficient catalysts not only require high catalytic activity and conductivity,but also have novel nanoarchitectures with large interface and porous volume for LiOx storage.Furthermore,the further investigation of reaction mechanism and advanced in situ analysis technologies are welcome in the coming work. 相似文献
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沸石和分子筛微孔晶体材料是指以硅酸盐、硅铝酸盐、磷铝酸盐和无机金属磷酸盐为骨架的晶体材料[1,2 ] .最近 ,Yaghi,Williams,Zaworotko,Kitagawa和游效曾等 [3~ 11] 利用刚性和热稳定性较好的有机分子 (如芳香多酸和多碱 )和金属离子作为结构单元 ,制备出了新型无机 -有机杂 相似文献
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将稀土纳米材料Er2O3用于构建葡萄糖生物传感器。Er2O3和氧化石墨烯形成复合基底,将葡萄糖氧化酶(GOD)固载在玻碳电极表面。首先利用SEM和XRD技术对所制备的Er2O3和氧化石墨烯纳米材料进行表征。利用EIS和CV对整个生物传感器制备过程进行表征。Er2O3的存在能有效地保持GOD的生物活性并加速其与电极之间的电子传递。由于Er2O3和氧化石墨烯之间的协同效应,使得制备的传感器在CV图中呈现一对明显的氧化还原峰,证实GOD和电极之间的直接电子传递性能。当用于对葡萄糖的电催化氧化时,传感器的CV响应随着葡萄糖浓度的增加而变弱。在葡萄糖浓度为1~10 mmol·L-1范围内,CV响应值与葡萄糖浓度成线性关系。此外,传感器具有好的稳定性和重现性。 相似文献