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111.
P. Kuppusami K. Muthukkumaran R. Divakar R. Kesavamoorthy E. Mohandas S. Selladurai 《Ionics》2007,13(5):343-348
Microstructural properties of nano-ionic thin films of gadolinia-doped ceria (GDC) prepared by pulsed laser ablation from
sintered targets of gadolinia (5–20 mol%) doped ceria are investigated. The ionic conductivity measurements of the sintered
pellets showed a decrease in the activation energy from 1.1 to 0.65 eV for 5 and 30 mol% gadolinia-doped ceria, respectively.
The microstructural properties of the GDC films as a function of substrate temperature, oxygen partial pressure, and laser
energy show that the films are polycrystalline in the entire range of substrate temperature. The grain size is found to increase
with increasing temperature up to 873 K. Further improved crystallinity is noticed for the films grown with oxygen partial
pressure of 0.1–0.2 mbar. X-ray diffraction and transmission electron microscopy (TEM) reveal nanocrystalline grains with
textured growth along <111> orientation in these films at low substrate temperature and at lower oxygen partial pressure.
TEM study shows a uniform distribution of nanocrystal of 8–10 nm for energies ≤200 mJ/pulse, and nanocrystals embedded in
a large crystalline matrix of doped ceria for energies in the range 400–600 mJ/pulse. Raman spectroscopy also confirms the
defects in these films. The study also reveals that the substrate temperature and oxygen partial pressure could influence
preferred orientation, while the laser energy could significantly influence defect concentration in these films.
Invited paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec.
7–9, 2006. 相似文献
112.
113.
采用基于密度泛函理论第一性原理超软贋势平面波方法系统计算了Ca2Si及P掺杂Ca2Si的电子结构、光学性质,分析了P掺杂对Ca2Si的能带结构、电子态密度、光学性质的影响.计算结果表明:掺入P后Ca2Si的能带向低能方向偏移,禁带宽带为0.557 95eV,价带主要由Si的3p,P的3p以及Ca的4s、3d电子构成,导带主要由Ca的3d电子贡献.通过能带结构和态密度分析了P掺杂正交相Ca2Si的复介电函数、折射率、反射谱、吸收谱和能量损失函数,结果表明P掺杂增强了Ca2Si的光利用率,说明掺杂能够有效改变材料电子结构和光电性能,为Ca2Si材料光电性能的开发、应用提供理论依据. 相似文献
114.
掺杂聚苯胺能带结构和导电机理的研究 总被引:7,自引:1,他引:7
用EHMO-CO方法对质子掺杂聚苯胺进行了模型化理论计算,得到与吸收光谱实验数据一致的能带结构,研究表明,掺杂苯胺中的载流子是极化子,能满意地解释掺杂聚苯胺的导电机制。 相似文献
115.
116.
We report a new result on the characterization of Nd-doped ceria, Ce1−xNdxO2−x/2 (x=0.075-0.675) using positron lifetime spectroscopy (LTS) and coincidence Doppler broadening (CDB) measurements. A systematic increase in lifetime that is attributed to formation of Nd-oxygen vacancy associates is seen from x=0.075-0.4 followed by a sharper increase up to x=0.5. The change in profile of lifetime around x=0.4 suggests drastic increase in the concentration of these associates. Discontinuity in lifetime around x=0.5 is ascribed to ordering of oxygen vacancies. Coincidence Doppler broadening measurements indicate reduction in the overlap of positron wavefunction with oxygen core electrons due to trapping of positrons. Low-temperature (50-300 K) lifetime measurements indicate the presence of Rydberg-like positron states associated with Nd3+ sites. 相似文献
117.
Elena L. Gubanova Vladislav A. Sadykov Andre C. van Veen Claude Mirodatos 《Reaction Kinetics and Catalysis Letters》2009,97(2):349-354
The temporal analysis of products (TAP) technique coupled with the oxygen TPD was used to elucidate the effects of the Pt-supported
fluorite-like doped ceria–zirconia oxide chemical composition and the type of pretreatment on their oxygen bonding strength,
mobility, and reactivity as related to catalytic properties in the partial oxidation of methane into synthesis gas. A rapid
evolution of hydrogen under CH4 pulse observed for oxidized catalysts agrees with the direct route of the methane selective oxidation into syngas. This route
is favored by the Pt-support interaction and a moderate bonding strength of surface oxygen species along with a high lattice
oxygen mobility. 相似文献
118.
新型锗系聚吡咯分子簇络合物的合成、表征及其电子结构的从头算研究刘尚长金旭东闫丽静刘宁徽宋玉林(辽宁大学化学系,沈阳110036)关键词锗配合物;聚吡咯;分子簇配合物;从头算;Gaossion程序.锗及其化合物在半导体、超导体、医药、医疗、保健、化学、... 相似文献
119.
钴前驱体对掺杂TiO2微结构和可见光催化性能的影响 总被引:1,自引:0,他引:1
为发展可见光下破坏污染物的钴掺杂TiO2光催化剂,以CoCl2、Co(NO3)2和CoSO4为钴前驱体,采用溶胶-凝胶法制备了钴掺杂TiO2,通过X射线衍射、扫描电镜、BET表面积测试和紫外-可见吸收光谱对比研究了钴前驱体对样品的微观结构和吸光性能的影响.同时,以苯胺为降解目标物,比较了样品在可见光下的催化活性.结果表明,样品的TiO2晶相、形貌、比表面积和吸光性能都随着钴前驱体的不同而不同,其中以Co(NO3)2为前驱体制备得到的样品其光催化活性最高,特别是1%掺杂且400℃烧结得到的样品,并简要讨论了其可能原因. 相似文献
120.
Rana F. Mehmood Farzana Mehmood Javeed Akhtar S. S. Shah 《Journal of Dispersion Science and Technology》2013,34(2):153-160
Sol-gel silica was doped with N,N-(dipropylcarbamothioyl) thiophene-2-carboxamide to investigate the sorption of cadmium (Cd) ions from aqueous media. In doped sol-gel silica, the large reagent molecules entrap into pores, whereas, small metal ions diffuse into pores where they make complex with doped reagent. This complexation can be accomplished by either ion exchange or chelation. Doped sol-gel sorbent was applied for removal of Cd(II) from aqueous solution in our study. Adsorption kinetics, adsorption isotherm, equilibration time, effect of initial concentration of adsorbate, and pH effect on the metal removal were studied to optimize the conditions. The prepared adsorbent shows rapid equilibrium and high stability toward high temperature and applied medium. In addition, desorption of metal ions was carried out by 1 M HCl and, thereafter, sol-gel silica adsorbent was regenerated and reused periodically. 相似文献