全文获取类型
收费全文 | 203篇 |
免费 | 16篇 |
国内免费 | 7篇 |
专业分类
化学 | 154篇 |
力学 | 11篇 |
数学 | 9篇 |
物理学 | 52篇 |
出版年
2024年 | 3篇 |
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 28篇 |
2020年 | 16篇 |
2019年 | 17篇 |
2018年 | 16篇 |
2017年 | 15篇 |
2016年 | 12篇 |
2015年 | 12篇 |
2014年 | 10篇 |
2013年 | 18篇 |
2012年 | 14篇 |
2011年 | 13篇 |
2010年 | 9篇 |
2009年 | 3篇 |
2008年 | 6篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 1篇 |
2002年 | 1篇 |
1991年 | 1篇 |
1988年 | 2篇 |
1983年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有226条查询结果,搜索用时 15 毫秒
91.
Photocatalytic activity of TiO2 nanoparticles in the visible light region was enhanced. TiO2–CdSe and TiO2–CdSe/CdS nanohybrids were supported on the reduced graphene oxide. These nanohybrid materials were applied as photocatalyst toward oxidation of aromatic alcohols under a mild condition and the molecular oxygen as oxidant. A plausible mechanism for the photocatalytic oxidation was also proposed. Desired nanohybrids were obtained via in situ fixation of CdSe/CdS on the surface of nanosheets of reduced graphene oxide (rGO). Finally, it was modified by TiO2 sol nanoparticles through a hydrothermal method. The obtained nanomaterials, were characterized by SEM, TEM imaging, XRD, EDAX, DRS and XPS analyses. The size of nanohybrids materials were distributed mostly in a narrow range of 50–65 and 60–75 nm for TiO2–rGO–CdSe and TiO2–rGO–CdSe/CdS, respectively. These photocatalysts showed high catalytic activity under visible light irradiation in a short reaction time and even higher selectivity rather than UV irradiation. The yield of catalytic oxidation increased at least 25–30% for TiO2–CdSe/CdS on rGO, which could be related to its higher light sensitivity and lower energy band gap. The photocatalysts were recycled and reused 8 times without significant loss of their activities due to their stability under visible light. 相似文献
92.
93.
Sajjad Damiri Hamid Reza Pouretedal Amin Heidari 《International journal of environmental analytical chemistry》2016,96(11):1059-1073
An electrochemical oxidation route was developed for sensitive and selective assay of nitrotriazolone (NTO) explosive in some environmental samples on a multi-walled carbon nanotube (MWCNTs)/TiO2 nanocomposite paste electrode, for prevention of the analytical interference of conventional reducible energetic compounds. Detailed evaluations were made for the electrochemical behaviour of NTO on the modified electrode by adsorptive stripping voltammetry, electrochemical impedance spectroscopy (EIS) and chronoamperometry techniques in the pH range of 2.0–10.0. Parameters such as diffusion coefficient constant of NTO were calculated, and various experimental conditions were also optimised. Under optimal conditions the calibration curve had two linear dynamic ranges of 130.0–3251.5 μg L?1 and 6.5–26.0 mg L?1 with a detection limit of 26.0 μg L?1 (0.2 μmol L?1) and precision of <3%. This electrochemical sensor was further applied to determine NTO in real soil and water samples with satisfactory results. 相似文献
94.
95.
96.
97.
98.
Molecular Diversity - Spirocyclic compounds fascinate the synthetic chemists due to their privileged ring system and efficacy in drug discovery. Many natural compounds comprise spirocyclic moiety... 相似文献
99.
100.
Ion acoustic solitary waves in a quantum plasma, which is slowly rotating around an axis at an angle θ with the direction of magnetic field, are investigated. Quantum hydrodynamic model is under consideration with the effects of rotations which are included via Coriolis force. Fermions are degenerate and have different spin density states, that is, up and down characterized via parameter α. Linear analysis is performed by applying Fourier transformation to derive dispersion relation. For nonlinear analysis, we apply reductive perturbation method to derive Korteweg de Vries equation (KdV). The effects of variations of Coriolis force, spin polarization, and quantum parameter on characteristics of solitary structure are discussed. These results are applicable to astrophysical and laboratory plasmas. 相似文献