全文获取类型
收费全文 | 582篇 |
免费 | 213篇 |
国内免费 | 85篇 |
专业分类
化学 | 440篇 |
晶体学 | 13篇 |
力学 | 4篇 |
综合类 | 3篇 |
物理学 | 420篇 |
出版年
2024年 | 1篇 |
2023年 | 10篇 |
2022年 | 12篇 |
2021年 | 16篇 |
2020年 | 52篇 |
2019年 | 33篇 |
2018年 | 42篇 |
2017年 | 29篇 |
2016年 | 52篇 |
2015年 | 44篇 |
2014年 | 69篇 |
2013年 | 71篇 |
2012年 | 76篇 |
2011年 | 77篇 |
2010年 | 50篇 |
2009年 | 52篇 |
2008年 | 34篇 |
2007年 | 48篇 |
2006年 | 38篇 |
2005年 | 22篇 |
2004年 | 15篇 |
2003年 | 13篇 |
2002年 | 11篇 |
2001年 | 7篇 |
2000年 | 2篇 |
1999年 | 4篇 |
排序方式: 共有880条查询结果,搜索用时 15 毫秒
1.
Degradation of rhodamine B photocatalyzed by Eu-doped CdS nanowires illuminated by visible radiation
Anukorn Phuruangrat Siwat Thungprasert Thawatchai Sakhon Budsabong Kuntalue Titipun Thongtem Somchai Thongtem 《印度化学会志》2022,99(2):100349
CdS nanowires doped with different contents of Eu dopant were synthesized by solvothermal method. XRD, SEM, TEM and Raman analyses certified that the as-synthesized samples were hexagonal CdS uniform nanowires. The pure CdS nanowires were 1–3 ?μm long and 80 ?nm diameter with the 1st and 2nd order longitudinal phonon modes at 298 and 594 ?cm?1. The 3% Eu-doped CdS wires were 800 ?nm–2.5 ?μm long and 75 ?nm diameter with the 1st and 2nd order longitudinal phonon modes at 296 and 593 ?cm?1. CdS nanowires grew along the [001] direction due to the surface energy effect. The photocatalytic properties of CdS and Eu-doped CdS nanowires were investigated for the degradation of rhodamine B (RhB) illuminated by visible radiation. In this research, Eu dopant played the role in promoting the photocatalytic kinetics because Eu3+ ions act as an electron acceptor to promote charge separation and photocatalytic activity. Both ●OH and ●O2? were the main active radicals used to transform RhB molecules into CO2, H2O and other intermediates. 相似文献
2.
《Journal of Saudi Chemical Society》2022,26(4):101514
A facile, single-step hydrothermal route is followed to prepare ZnS nanowires with large aspect ratios. The obtained ZnS nanowires deposited on nickel foam (ZnS/Ni-foam) exhibit a specific capacitance of 781 F/g at a current density of 0.5 A/g. An asymmetric supercapacitor fabricated from ZnS/Ni-foam as a positive electrode and jute derived activated carbon coated on Ni-foam (JAC/Ni-foam) as a negative electrode attains a high specific capacitance of 573 F/g at a current density of 0.5 A/g, with an accompanying high energy density of 51 Wh/kg at a power density of 200 W/kg in an extensive operating potential window of 1.2 V. In addition, the ZnS//JAC asymmetric supercapacitor reveals long-term cyclic stability, after 10,000 GCD cycles the device sustain around ~87 % of the initial specific capacitance. These results shed enlighten a new opportunity for promising electrode materials in supercapacitors. 相似文献
3.
Shunrui Luo Kostiantyn Turcheniuk Ah‐Young Song Aashray Narla Doyoub Kim Alexandre Magasinsky Gleb Yushin 《Angewandte Chemie (International ed. in English)》2020,59(1):403-408
Technologically important composites with enhanced thermal and mechanical properties rely on the reinforcement by the high specific strength ceramic nanofibers or nanowires (NWs) with high aspect ratios. However, conventional synthesis routes to produce such ceramic NWs have prohibitively high cost. Now, direct transformation of bulk Mg‐Li alloys into Mg alkoxide NWs is demonstrated without the use of catalysts, templates, expensive or toxic chemicals, or any external stimuli. This mechanism proceeds through the minimization of strain energy at the boundary of phase transformation front leading to the formation of ultra‐long NWs with tunable dimensions. Such alkoxide NWs can be easily converted in air into ceramic MgO NWs with similar dimensions. The impact of the alloy grain size and Li content, synthesis temperature, inductive and steric effects of alkoxide groups on the diameter, length, composition, ductility, and oxidation of the produced NWs is discussed. 相似文献
4.
Haozhou Yang Deren Yang Prof. Dr. Xun Wang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(36):15657-15661
Utilizing sustainable energy for chemical activation of small molecules, such as CO2, to produce important chemical feedstocks is highly desirable. The simultaneous production of CO/H2 mixture (syngas) from photoreduction of CO2 and H2O is highly promising. However, the relationships between structure, composition, crystallinity, and photocatalytic performance are still indistinct. Here, amorphous ultrathin CoO nanowires and polyoxometalate incorporated nanowires with even lower crystallinity were synthesized. The POM-incorporated ultrathin nanowires exhibit high photocatalytic syngas production activity, reaching H2 and CO evolution rates of 11555 and 4165 μmol g−1 h−1 respectively. Further experiments indicate that the ultrathin morphology and incorporation of POM both contribute to the superior performance. Multiple characterizations reveal the enhanced charge–hole separation efficiency of the catalyst would facilitate the photocatalysis. 相似文献
5.
Nhat Anh Thi Thieu Minh Canh Vu Dae Hoon Kim Won Kook Choi Sung‐Ryong Kim 《先进技术聚合物》2020,31(10):2351-2359
The composites comprising vertically aligned network of copper nanowires (CuNWs) in the presence of cellulose nanofibers were fabricated by using the freeze‐templating method and the effect of aspect ratio (A/R) of CuNWs on the thermal conductivity of epoxy composites was investigated. The thermal conductivity of epoxy composites increased to 0.79 W m?1 K?1 at 1.12 vol% of high A/R CuNWs loading, corresponding to the thermal conductivity enhancement of 365% as compared to the pure epoxy. The thermal conductivity of vertically aligned higher A/R CuNWs/epoxy, which is 38.5% and 51.9% higher than those of the lower A/R CuNWs and the randomly aligned CuNWs, respectively. The application of the epoxy composites in heat dissipation was demonstrated by the temperature changes of composites on a hot plate with the increase of heating time. These results indicate that the thermally conductive composites in this study could be applied for thermal dissipating materials in electronic devices. 相似文献
6.
Jianyu Wang Huabin Sun Yun Sheng Fan Gao Yao Yin Yun Li Lijia Pan Youdou Zheng Yi Shi Takashi Sekiguchi 《固体物理学:研究快报》2015,9(8):466-469
Surface‐diffusion‐induced spontaneous Ga incorporation process is demonstrated in ZnO nanowires grown on GaN substrate. Crucially, contrasting distributions of Ga atoms in axial and radial directions are experimentally observed. Ga atoms uniformly distribute along the ~10 μm long ZnO nanowire and show a rapidly gradient distribution in the radial direction, which is attributed substantially to the difference between surface and volume diffusion. The understanding on the incorporation process can potentially modulate doping and properties in semiconductor nanomaterials.
7.
以过硫酸铵为氧化剂,通过氧化苯胺和鲁米诺混合溶液合成了聚(苯胺-鲁米诺)复合纳米线。相对于鲁米诺425 nm处的最大荧光发射波长,复合纳米线中聚鲁米诺的最大荧光发射波长明显红移到465 nm处。采用简单的滴凃方式将聚(苯胺-鲁米诺)复合纳米线修饰于石墨电极表面,形成一层稳定的聚(苯胺-鲁米诺)复合纳米线膜。此聚(苯胺-鲁米诺)纳米线膜修饰电极呈现出良好的电化学发光特性,H2O2对化学合成的聚(苯胺-鲁米诺)纳米线电化学发光呈现出增敏效应。在优化实验条件下,修饰电极的电化学发光信号与H2O2在5.0×10#9~1.0×10#5mol/L范围内呈线性关系,检出限为2×10#9mol/L。 相似文献
8.
Fatima Dayton J. Vogel Yulun Han Talgat M. Inerbaev Nuri Oncel 《Molecular physics》2019,117(17):2293-2302
ABSTRACTIn this research, ground-state electronic structure and optical properties along with photoinduced electron dynamics of Si nanowires oriented in various directions are reviewed. These nanowires are significant functional units of future nano-electronic devices. All observables are computed for a distribution of wave vectors at ambient temperature. Optical properties are computed under the approximation of momentum conservation. The total absorption is composed of partial contributions from fixed values of momentum. The on-the-fly non-adiabatic couplings obtained along the ab initio molecular dynamics nuclear trajectories are used as parameters for Redfield density matrix equation of motion. The main outcomes of this study are transition energies, light absorption spectra, electron and hole relaxation rates, and electron transport properties. The results of these calculations would contribute to the understanding of the mechanism of electron transfer process on the Si nanowires for optoelectronic applications. 相似文献
9.
Comparative study on transport properties of N-, P-, and As-doped SiC nanowires: Calculated based on first principles 下载免费PDF全文
According to the one-dimensional quantum state distribution, carrier scattering, and fixed range hopping model, the structural stability and electron transport properties of N-, P-, and As-doped SiC nanowires(N-SiCNWs, P-SiCNWs, and As-SiCNWs) are simulated by using the first principles calculations. The results show that the lattice structure of NSiCNWs is the most stable in the lattice structures of the above three kinds of doped SiCNWs. At room temperature,for unpassivated SiCNWs, the doping effect of P and As are better than that of N. After passivation, the conductivities of all doped SiCNWs increase by approximately two orders of magnitude. The N-SiCNW has the lowest conductivity. In addition, the N-, P-, As-doped SiCNWs before and after passivation have the same conductivity–temperature characteristics,that is, above room temperature, the conductivity values of the doped SiCNWs all increase with temperature increasing.These results contribute to the electronic application of nanodevices. 相似文献
10.
Yingjun Sun Dr. Yingjie Li Yingnan Qin Prof. Lei Wang Prof. Shaojun Guo 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(18):4032-4038
Searching for new anti-poisoning Pt-based catalysts with enhanced activity for alcohol oxidation is the key in direct alcohol fuel cells (DAFCs). However, in the traditional strategy for designing bimetallic or multimetallic alloy is still difficult to achieve a satisfactory heterogeneous electrocatalyst because the activity often depends on only the surface atoms. Herein, we fabricate the multicomponent active sites by creating a sulfide structure on 1D PtNiCo trimetallic nanowires (NWs), to give a PtNiCo/NiCoS interface NWs (IFNWs). Owing to the presence of sulfide interfaces, the PtNiCo/NiCoS IFNWs enable an impressive methanol/ethanol oxidation reaction (MOR/EOR) performance and excellent anti-CO poisoning tolerance. They have the MOR and EOR mass activities of 2.25 Amg-1Pt and 1.62 Amg-1Pt, around 1.26, 3.21 and 1.46, 2.96 times higher than those of PtNiCo NWs and commercial Pt/C, respectively. CO-stripping and XPS measurements further demonstrate that the new interfacial structure and optimal bonding of Pt−CO can result in accelerating the removal of surface adsorbed carbonaceous intermediates. Moreover, such a unique structure has also demonstrated a much-improved ability for the electrochemical detection of some important molecules (H2O2 and NH2NH2). 相似文献