全文获取类型
收费全文 | 105篇 |
免费 | 3篇 |
国内免费 | 3篇 |
专业分类
化学 | 58篇 |
晶体学 | 5篇 |
力学 | 2篇 |
数学 | 1篇 |
物理学 | 45篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 6篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 7篇 |
2013年 | 10篇 |
2012年 | 6篇 |
2011年 | 9篇 |
2010年 | 6篇 |
2009年 | 3篇 |
2008年 | 5篇 |
2007年 | 6篇 |
2006年 | 2篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1981年 | 1篇 |
排序方式: 共有111条查询结果,搜索用时 677 毫秒
41.
高重复频率飞秒脉冲激光辐照钼酸镝玻璃表面后,通过显微拉曼测试,发现在辐照区域内形成了含有MoO4四面体结构的β′-Dy2(MoO4)3晶体和含有MoO6八面体结构的α-MoO3晶体。通过电子能谱(EDS)测量辐照前后样品中钼(Mo)元素的含量,发现在辐照中心位置形成α-MoO3晶体相的区域内出现了明显的Mo元素缺失现象,表明了在高温场作用下,微爆现象引起了材料中心密度的降低。此外,随着辐照时间的增加辐照中心位置还出现了由Dy2(MoO4)3相向MoO3晶体α相的相变。这说明随着激光作用程度的加剧,中心区域Mo元素浓度降低,使得钼氧结构由MoO4四面体向MoO6八面体转变,导致在Mo元素浓度较低的区域更容易形成八面体结构的α-MoO3。 相似文献
42.
C.T. dos Santos C. Bormio-Nunes L. Ghivelder A.R. Belarmino 《Journal of magnetism and magnetic materials》2008,320(14):e183-e185
In the present work we study the magnetostriction of Fe91Sn9 and Fe80Sn20 polycrystalline samples produced by arc melting and heat treated at temperatures of 1153 K for 6 h and 1023 K for 24 h, looking for high values of magnetostriction as in Fe–Ga alloys. Magnetostriction, as well as saturation magnetization measurements, was carried out at temperatures close to 203 K in the magnetic field interval 0 to 1.5 T. Results of magnetostriction on sample Fe91Sn9, which has almost pure -phase, show magnitude and behavior similar to pure Fe. The two additional Fe80Sn20 samples have a combination of -phase plus either Fe5Sn3 or Fe3Sn2 and show a peculiar behavior of the magnetostriction. For μ0H<0.3 T the magnetostriction grows from zero to saturation of the -phase. Following, for μ0H>0.3 T, the magnetostriction starts again to grow linearly with the field, but saturation was not observed up to 5 T. This behavior was attributed to the presence of Fe5Sn3 or Fe3Sn2 phases in these samples that are also ferromagnetic as the -phase is. 相似文献
43.
44.
Y2BaCuO5YBa2Cu3O7-x
(Y211/Y123) interfaces in melt-processed YBa2Cu3O7-x
were studied by high-resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. Yttrium enrichment and barium depletion were observed locally at the Y211/Y123 interfaces where Y123 (001) facets were present. This effect may be interpreted as the result of lattice substitution of Ba by Y near these interfaces. Cation nonstoichiometry was found near Y211/Y123 interfaces where liquid phases (Cu-Ba-O) were present. This chemical disorder introduces numerous point defects in the Y123, and these defects may act as additional pinning sites alongwith stacking faults. A comparison of grain boundary (GB) chemical composition in polycrystalline YBa2Cu3O7-x
and YBa2Cu4O8(Y124), studied using nanoprobe parallel-detection electron energy-loss spectroscopy (EELS), is presented. The studies of Y124 show that stoichiometric grain boundaries can also form weak links between superconducting grains. It is suggested that weak-link behavior is determined largely by misorientation at grain boundaries. 相似文献
45.
电子探针X射线能谱法测定黄金饰品的成色 总被引:3,自引:0,他引:3
本文介绍电子探针能谱法测定含金量50%~99%黄金饰品的成色,该法无损、快速、准确,对束流稳定性要求不高且操作简便。 相似文献
46.
47.
The paper gives an overview of the problems of Standardless analysis of bulk specimens by energy dispersive spectrometry (EDS) in scanning electron microscopes (SEM). The interest is concentrated on the present (and future) developments. The influence of the fluorescence excited by the continuum is discussed. Some improvements are proposed for the ionization cross-section. The difficulties due to the Coster-Kronig radiationless transitions are mentioned for the L lines. Emphasis is put on the necessity of an accurate modelling of the detector window, in order to be able to calculate reliably the efficiency of detection, mainly for the ultra-light elements. It is shown that some hypotheses such as the continuity of the fluorescence yield with the atomic number, which are currently accepted for heavier elements, could be wrong in the field of ultra-light elements. The capability of Standardless analysis in special situations is discussed: analysis at oblique electron beam incidence, analysis of specimens with a thin conductive coating, analysis of stratified specimens. 相似文献
48.
Graphene has attracted the attention of the scientists and researchers because of its peculiar properties. Because of various unique properties, graphene can be used in sensing device applications, solar cells and liquid crystal display devices etc. In this research paper, we present a chemical route towards bulk production of r-GO (reduced graphene oxide). We have employed a modified method to achieve better results which is often termed as modified Hummer's and Offeman method. It is modified in terms of filtration technique. We have also attached silver nanoparticles (Ag-NP) to as synthesised r-GO. After successful growth, silver nanoparticles have been attached to r-GO by suitable treatment with AgNO3 (aq.) N/50 solution. The as grown samples were characterised by FESEM, Raman Spectroscopy and EDS to make sure that r-GO and r-GO–Ag-NP have been successfully synthesised. The electrical and optical studies of the as grown samples were performed by dc conductivity measurements and UV visible spectroscopy. The conductivity was found to have increased with attachment of Ag-NP. The optical transmittance also improved to 90% as against 70% before Ag-NP attachment. The reduced graphene oxide attached with silver nanoparticles could find promising applications in synthesis of transparent electrode materials and optoelectronic devices. 相似文献
49.
In the present article, we have studied the effect of post annealing treatment on microstructural, optical and photoelectrochemical (PEC) properties of MoBi2S5 thin films synthesized by microwave assisted technique. The synthesized thin films are vacuum annealed for 4 h at 473 K temperature. The X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and UV–Vis–NIR spectrophotometer techniques were used for characterization of the as deposited and annealed MoBi2S5 thin films. The XRD patterns confirm the synthesized and annealed thin films have nanocrystalline nature with rhombohedral-orthorhombic crystal structure. SEM micrographs indicate that, nanoflowers exhibit sharper end after annealing. The optical absorption study illustrates that the optical band gap energy has been decrease from 2.0 eV to 1.75 eV with annealing. Finally, applicability of synthesized thin films has been checked for PEC property. The J-V curves revealed that synthesized thin film photoanodes are suitable for PEC cell application. As well, used simple, economical method has great potential for synthesis of various thin film materials. 相似文献
50.
《Arabian Journal of Chemistry》2020,13(11):7707-7719
The Ni-Co alloy co-electrodeposit from a sulfate bath including two new ionic liquids 1-methyl-3-(2-oxo-2-((2,4,5 trifluorophenyl) amino) ethyl)-1H-imidazol-3-ium iodide [MOFIM]I and 1-(4-fluorobenzyl)-3-(4-phenoxybutyl) imidazol-3-ium bromide [FPIM]Br as additives was characterized using the SEM, EDS, EDS mapping, XRD, AFM and microhardness measurement techniques. The resultant surface morphologies in acidic sulfate baths on a copper substrate demonstrated that both the [MOFIM]I and [FPIM]Br additives served as effective leveling agents. The Ni-Co alloy co-deposit morphology in the [MOFIM]I bath was more enhanced (non-grained coating, Ra of 28 nm and Rt of 35.5 nm) than that in the [FPIM]Br bath (grain size 225 nm, Ra of 51. 1 nm and Rt of 65.7 nm) owing to the molecular structure. The co-deposition of Co and Ni from the acidic baths was of the anomalous type. Moreover, the anomalous behavior of the Ni-Co co-deposition was alleviated after [MOFIM]I and [FPIM]Br were introduced in the bath. To determine the optimal bath conditions, the cathodic current efficiency (CCE%) value was calculated during the Ni-Co alloy co-electrodeposition process under three different compositions and different operating conditions. Under the composition of Ni 70% and Co 30% (Ni70%-Co30% alloy deposit), the CCE% values increased considerably, with maximum values of 99.8% and 97.07% in the baths including [MOFIM]I and [FPIM]Br, respectively. 相似文献