维普中文期刊产品整合服务
12篇 您的检索式:作者名="David G.EVANS"
    题名 作者 年代 出处 被引量
1超声浸渍法制备Pd/Al_2O_3催化剂及其催化蒽醌加氢性能显示文摘以球形-γAl2O3和-θAl2O3为载体,分别采用超声浸渍和普通浸渍方法制备了Pd含量为0.3%的负载型催化剂,并将其用于蒽醌加氢反应.采用X射线衍射、N2吸附和透射电镜等手段对催化剂的理化性质和孔结构进行了分析,考察了浸渍方法对催化剂活性金属分散度的影响.结果表明,与普通浸渍法相比,超声浸渍法制备的负载型Pd催化剂金属分散度明显提高,因而对蒽醌加氢反应表现出较高的催化活性.以960℃焙烧的球形-θAl2O3为载体,通过超声浸渍制备的负载型Pd催化剂具有较高的Pd分散度和较大的孔径,在蒽醌加氢反应中对反应物的扩散阻力较小,因而表现出更高的催化活性,而且反应中催化剂的稳定性良好.杨永辉 林彦军 冯俊婷 David G.Evans 李殿卿 2006催化学报2006,27,4:29
2γ-Al_2O_3表面原位合成Ni-Al-CO_3 LDHs研究显示文摘Ni-Al-CO3 LDHs/γ-Al2O3 have been prepared using an in-situ synthesis technique. NH3·H2O was chosen as activation agent of Al on the γ-Al2O3 surface as well as precipitant. Ni-Al-CO3 LDHs/γ-Al2O3 was synthesized by controlling the reaction conditions such as temperature, concentration of Ni2+ and initial pH. The crystalline structure, chemical composition and porous structure were characterized by means of XRD, FT-IR, TG-DTA, 27Al MAS-NMR and N2 adsorption-desorption. The resulting sample of Ni-Al-CO3 LDHs/γ-Al2O3 possesses higher specific area and narrower pore distribution, in which Ni-Al-CO3 LDHs are located on the surface of γ-Al2O3 and share the same Al-O bonds with the γ-Al2O3 lattice. Finally a possible structural model was proposed to account for the porous characters of Ni-Al-CO3 LDHs/γ-Al2O3.毛纾冰 李殿卿 张法智 David G.Evans 段雪 2004无机化学学报2004,20,5:15
3柠檬酸溶胶凝胶法制备LiCoO_2电极材料及其表征显示文摘LiCoO2 precursors of the cathode material for lithium ion batteries were prepared from lithium hydroxide, basic cobalt carbonate and citric acid by a sol gel method. The LiCoO2 samples were obtained by sintering the gel precursors at different temperatures and for different times. The thermal decomposition behavior of the gel precursors was examined by means of thermo gravimetric analysis and differential thermal analysis using a PCT IA thermal analyzer system. Their structures and morphologies were characterized by powder XRD and SEM techniques. It was found that using citric acid realized that the formation of LiCoO2 crystal can be clearly differentiated to the nucleation and growth processes of the crystals; furthermore, the crystal size can be controlled. Electrochemical tests using the LAND BT1 10 test system showed the electrochemical performance of the material is affected by its integrity and stability.王兴杰 杨文胜 卫敏 David G.Evans 段雪 2003无机化学学报2003,19,6:13
4新型层状农药缓/控释材料-草甘膦插层双金属氢氧化物的超分子结构与缓释性能显示文摘以镁铝双金属氢氧化物(MgAllayereddoublehydroxide:MgAl—LDH)为主体,以草甘膦(Glyphosate:GLY)为客体,通过控制反应pH值,由共沉淀法组装得到两种不同结构的GLY插层MgAl-LDH缓/控释材料.考察了该缓/控释材料在Na2CO3溶液中的缓释性能,其缓释历程为客体阴离子与介质中CO32-的离子交换过程,客体阴离子在插层化合物层间及晶粒间隙的扩散,即粒内扩散过程为释放速率控制步.低pH合成GLY插层产物较大的层间距、层间客体GLY阴离子单层垂直的定位方向及较高的堆积密度使其较高pH合成材料展示出更为显著的缓释能力,其原因归结为超分子结构对释放速率控制步的影响.该研究指出了层状双金属氢氧化物在农药缓/控释领域的应用潜力.孟锦宏 张慧 David G.Evans 段雪 2005科学通报2005,50,3:12
5磷酸二氢根插层水滑石的制备及其选择性红外吸收性能显示文摘采用成核/晶化隔离法制备了镁铝碳酸根型水滑石(MgAl-CO3-LDHs),以其为前驱体,在酸性条件下通过离子交换将磷酸二氢根阴离子组装到水滑石层间,制备了具有超分子插层结构的MgAl-H2PO4-LDHs,并采用XRD、FTIR、TG-DTA-DTG、SEM和ICP等手段进行了表征。采用母粒工艺将MgAl-CO3-LDHs和MgAl-H2PO4-LDHs添加到聚乙烯(PE)中制备了LDHs/PE薄膜,研究其红外吸收性质发现,添加MgAl-H2PO4-LDHs的PE薄膜在7~25μm特别是9~11μm范围的红外吸收率明显高于添加MgAl-CO3-LDHs的薄膜,表现出显著的选择性红外吸收性能。王丽静 徐向宇 David G.Evans 李殿卿 2010无机化学学报2010,26,6:9
6磁性药物-无机纳米复合材料的结构设计与表征显示文摘以镁铁氧体为磁性粒子, 层状锌铝双金属氢氧化物为主体层板, 分别以卡托普利(Captopril: Cpl)和5-氨基水杨酸(5-aminosalicylic acid: 5-ASA)为客体药物分子, 采用共沉淀法组装得到超分子结构磁性卡托普利及5-氨基水杨酸插层锌铝双金属氢氧化物 Cpl-LDHs/MgFe2O4和 5-ASA-LDHs/MgFe2O4. 研究表明, 该超分子结构磁性复合材料具有良好的晶相结构, Cpl-LDHs 及 5-ASA-LDHs 通过 Zn-O-Mg 和Al-O-Mg 键连接于 MgFe2O4表面形成核壳结构, 且该药物-无机纳米复合材料具有明显的磁性能.孙辉张慧 David G.Evans 段雪 2004科学通报2004,49,24:5
7球形TiO_2-Al_2O_3的制备、结构和理化性能研究显示文摘将Ti(SO4)2溶于稀盐酸合成酸性钛溶胶,再将其与铝溶胶和六次甲基四胺溶液混合后采用油柱成型法制备了球形TiO2-Al2O3复合氧化物。通过XRD、低温氮吸附-脱附与NH3-TPD等手段对样品进行表征,结果表明600℃焙烧得到的球形TiO2-Al2O3中TiO2以无定型形式存在;随TiO2含量的增加,球形TiO2-Al2O3的比表面积、孔容和平均孔径呈增加趋势;TiO2的引入没有对球形TiO2-Al2O3的强酸和弱酸中心的强度产生影响,弱酸中心数量显著增加,强酸中心数量稍有增加;球形TiO2-Al2O3的堆密度和压碎强度随TiO2含量的增加而减小,颗粒直径基本保持不变。刘鹏程 林彦军 徐向宇 David G.Evans 李殿卿 2007无机化学学报2007,23,10:4
8Co^2+含量对CoAl-LDHs焙烧产物结构、组成及其生长碳纳米管的影响显示文摘采用成核晶化隔离法将Co2+引入层状双金属氢氧化物(LDHs),得到了含不同Co2+/Al3+物质的量的比为1∶1,2∶1,3∶1的二元钴铝碳酸根型LDHs(CoAl-LDHs)。通过X射线衍射(XRD)、透射电镜(TEM)、扫描电镜-能量散射谱(SEM-EDS)、拉曼光谱(Raman)、程序升温还原(TPR)及X射线光电子能谱(XPS)等方法对CoAl-LDHs焙烧产物的结构、组成及其化学气相沉积(CCVD)催化生长多壁碳纳米管(CNTs)进行了研究。结果表明:CoAl-LDHs前体中钴的含量可以明显改变焙烧产物的组成分布和还原性能,并最终影响CNTs的生长,其中以nCo2+/nAl3+比为2/1的LDHs作为催化剂前体可以得到管径均匀和石墨化程度高的CNTs,这与还原得到的纳米活性Co颗粒均匀分散有关。Halidou I.Hima 项顼 张璐 李峰 David G.Evans 2008无机化学学报2008,24,6:2
9原位氧化插层法制备层状LiMnO_2及其机理与性能显示文摘以Mn(OH)2作为反应前驱体, LiOH为锂化剂, (NH4)2S2O8为氧化剂, 采用原位氧化插层反应方法, 在缓和的实验条件下合成出层状正交结构LiMnO2. 采用X射线粉末衍射(XRD)、电感耦合等离子体原子发射光谱(ICP)、透射电子显微镜(TEM)及核磁共振(7Li-NMR)等手段对样品进行了表征, 结果表明, 使用该方法可以获得单一相、晶型较好、纯度较高的样品. 电化学测试表明该方法合成样品具有较好的电化学性能: 首次放电容量达到208 mAhg-1, 30周循环后放电容量仍保持在180 mAhg-1.李晓丹 杨文胜 David G.Evans 段雪 2004科学通报2004,49,19:2
10Preparation and photochromic properties of NiAl-NO_3-LDHs/LDPE composite显示文摘Nanoscale NiAl-NO3-LDHs with good crystallinity have been synthesized by a method, Separate Nucleation and Aging Steps (SNAS). An NiAl-NO3-LDHs/LDPE composite was prepared by blending NiAl-NO3-LDHs and LDPE in a heated double-roller mixer. The color of this composite changed from olive green to steel gray under UV irradiation. After heating at 80oC for 2 h, the color returned to olive green. The effect of varying the amount of added NiAl-NO3-LDHs and UV exposure time on the photochromic properties of the composite has been investigated. The results showed that the photochromic phenomenon becomes more apparent with increasing amount of NiAl-NO3-LDHs. When the amount reaches 5%, the composite exhibits good photochromic properties and reproducibility. The color change rate of the composite reaches a maximum when the irradiation time exceeds 20 min. The addition of LDPE improves the photochromic cyclability of NiAl-NO3-LDHs significantly. The addition of nanoscale NiAl-NO3-LDHs also improves the mechanical properties of LDPE to some extent.CHO Kyuhaeng David G.EVANS 2007Chinese Science Bulletin2007,52,7:1
11Tris(8‐hydroxyquinoline‐5‐sulfonate)aluminum Intercalated Mg–Al Layered Double Hydroxide with Blue Luminescence by Hydrothermal Synthesis显示文摘ShuangdeLi JunLu MinWei David G.Evans XueDuan 2010Adv Funct Mater2010,,17:1
12轨梁轧机的润滑及工作辊轴承寿命的改进显示文摘本文介绍了通过改进轴承的安装方法和检修作业、开发新的干油分配、应用和控制系统等措施所取得的主要效益,这些效益包括降低轴承损耗、减少干油消耗和成本等。John F.Tauschman Robert L.Wingrove David G.Evans Thomas M.Mayrosh James B.Lynn 潘志军 1994一重技术1994,,2:0
返回顶部 每页显示:
共1页 首页 上一页 第1页 下一页 末页 /1 跳转

网站首页 | 关于我们 | 联系我们 | 产品服务 | 客服中心 | 广告服务 | 版权声明 | 网站联盟 | 友情链接 | 售卡网点

版权所有© 渝B2-20050021-1 渝公网安备 50019002500403号 违法和不良信息举报中心

互联网出版许可证 新出网证(渝)字10号 全国400电话 - 免长途话费