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排序方式: 共有93条查询结果,搜索用时 15 毫秒
71.
碳杂金属镍微球的制备及对葡萄糖的电催化氧化性能 总被引:1,自引:0,他引:1
以葡萄糖酸钠与硝酸镍为起始原料,通过水热合成法,制备了碳杂Ni(OH)2复合微球(C-Ni(OH)2),Ni2+的沉淀剂OH-是由葡萄糖酸钠水解提供的;以制得的C-Ni(OH)2微球为前驱体,在N2气氛围中下焙烧8 h,制得了碳杂金属镍(C-Ni)微球,通过场发射扫描电子显微镜(FE-SEM)、X射线衍射(XRD)、X射线能谱(EDS)和N2气吸附脱附实验等测试技术对其进行了分析,结果表明,C-Ni微球具有较大的比表面积和孔容,分别为276 m2/g和0.248 cm3/g;对葡萄糖氧化有良好的电催化作用。 相似文献
72.
载体对甲烷在镍催化剂上分解反应的影响 总被引:1,自引:0,他引:1
开发洁净廉价的燃料替代石油已成为各国竞相研究的热点。从环境友好的观点出发 ,H2 气是一种理想的洁净燃料 ,其燃烧产物只有H2 O ,对环境无任何污染 ,H2 气将成为未来人类主要的能源。因此 ,近年来各国竞相开发大规模廉价的制氢和储氢技术。目前 ,碳及碳氢化合物制合成气法[1 ,2 ] 以其成本低和技术成熟已成为当前大规模制氢最常用的方法 ,包括碳氢化合物的水蒸气重整、CO2 重整、催化部分氧化法和自热重整[1~ 4] 。近年来又兴起了甲烷催化分解制氢[5,6] 。以上各方法均包含甲烷在镍催化剂上的分解过程[7,8] 。Rostrup Ni… 相似文献
73.
Shao-Yi Wu Hua-Ming Zhang Pei Xu Shan-Xiang Zhang 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(1):230-234
The defect structure for Cu2+ in CdSe nanocrystals is theoretically studied by analyzing the spin Hamiltonian parameters of this impurity center. This center is ascribed to Cu2+ occupying the octahedral interstitial site, rather than the tetrahedral substitutional Cd2+ site proposed by previous work. The Cu2+ center exhibits slight tetragonal elongation distortion (characterized by the elongation parameter ρ ≈ 0.03) due to the Jahn–Teller effect. The theoretical spin Hamiltonian parameters and optical transition show good agreement with the experimental data. The above unusual defect structure (occupation and symmetry) for Cu2+ in CdSe nanocrystals is discussed, as compared with the conventional trigonally distorted tetrahedral Cu2+ centers in bulk II–VI semiconductors. 相似文献
74.
Hua-Ming Wang 《Journal of Theoretical Probability》2018,31(2):619-642
We study a random walk with unbounded jumps in random environment. The environment is stationary and ergodic, uniformly elliptic and decays polynomially with speed \(Dj^{-(3+\varepsilon _0)}\) for some \(D>0\) and small \(\varepsilon _0>0.\) We prove a law of large numbers under the condition that the annealed mean of the hitting time of the lattice of the positive half line is finite. As the second part, we consider a birth and death process with bounded jumps in stationary and ergodic environment whose skeleton process is a random walk with unbounded jumps in random environment. Under a uniform ellipticity condition, we prove a law of large numbers and give the explicit formula of its velocity. 相似文献
75.
The electron paramagnetic resonance g factors and the local structure for Ni3+ in LaAl0.9Ni0.1O3 (LAN), La0.75Y0.25Al0.99Ni0.01O3 (LYAN) and YAl0.9Ni0.1O3 (YAN) are theoretically studied from the perturbation formulas of the g factors for a 3d7 ion of low spin (S = 1/2) in tetragonally elongated octahedra. In these formulas, the contributions to the g factors from the tetragonal distortion, characterized by the tetragonal field parameters Ds and Dt are taken into account. According to the calculations, the ligand octahedra around Ni3+ are suggested to suffer 2% relative elongation along the [001] (or C4) axis due to the Jahn-Teller effect. 相似文献
76.
The local structure and the g factors for the tetragonal Ru3+ center in PbTiO3 are theoretically studied from the perturbation formulas of the g factors for a 4d5 ion in tetragonally distorted octahedra. From the studies, the distance between the impurity Ru3+ and the center of the oxygen octahedron is found to be about 0.283 Å, which is smaller than that (≈0.3 Å) for the host Ti4+ site. It appears that the impurity may not occupy exactly the host Ti4+ site but suffer a slight inward shift toward the center of the oxygen octahedron. The calculated g factors based on the above local structure show good agreement with the experimental values. 相似文献
77.
采用柠檬酸法制备了LaMnO3、LaFeO3、La0.5Sr0.5MnO3、La0.5Sr0.5FeO3, 通过负载纳米Pt合成了Pt负载钙钛石催化剂, XRD与IR数据表明合成的催化剂具有钙钛石相, TEM数据表明合成的纳米Pt粒径为~3 nm, 均匀分散在钙钛石上。在CO氧化反应中, 发现钙钛石的氧化-还原性能是影响其活性的重要因素, 因而, Mn系钙钛石表现出较高的CO氧化活性。负载纳米Pt后, Fe系钙钛石则显示出更优异的CO氧化活性, CO完全转化的温度从350 ℃降至120 ℃。吸附实验表明钙钛石上氧空位对促进O2的吸附起着非常重要的作用, 也是影响CO低温氧化的重要因素之一。 相似文献
78.
WAN Hua-Ming LUO Hai-Mei WANG Yi-Fan 《理论物理通讯》2005,44(12)
Based on the maximum entropy principle, we present a density matrix of mesoscopic RLC circuit to make it possible to analyze the connection of the initial condition with temperature. Our results show that the quantum state evolution is closely related to the initial condition, and that the system evolves to generalized coherent state if it is in ground state initially, and evolves to squeezed state if it is in excited state initially. 相似文献
79.
研究了氘代氯仿中N-丁基马来酰亚胺(NBMI)和苯乙烯(St)的络合性能。以十二烷基硫酸钠(SDS)和正戊醇(PTL)为复合乳化剂,配制了含有NBMI(M1)和St(M2)的O/W微乳液。用过硫酸钾引发该体系进行微乳液共聚合。固定乳化剂的浓度为〔SDS〕=0.21mol/L,〔PTL〕=0.28mol/L,详细研究了聚合温度、单体配比和引发剂用量对共聚合动力学的影响。用元素分析法确定共聚物的组成, 相似文献