全文获取类型
收费全文 | 1666篇 |
免费 | 44篇 |
国内免费 | 83篇 |
专业分类
化学 | 1139篇 |
晶体学 | 24篇 |
力学 | 47篇 |
数学 | 2篇 |
物理学 | 581篇 |
出版年
2023年 | 102篇 |
2022年 | 43篇 |
2021年 | 44篇 |
2020年 | 51篇 |
2019年 | 34篇 |
2018年 | 42篇 |
2017年 | 52篇 |
2016年 | 58篇 |
2015年 | 54篇 |
2014年 | 74篇 |
2013年 | 91篇 |
2012年 | 84篇 |
2011年 | 152篇 |
2010年 | 111篇 |
2009年 | 211篇 |
2008年 | 146篇 |
2007年 | 127篇 |
2006年 | 102篇 |
2005年 | 53篇 |
2004年 | 52篇 |
2003年 | 30篇 |
2002年 | 17篇 |
2001年 | 13篇 |
2000年 | 16篇 |
1999年 | 11篇 |
1998年 | 6篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
排序方式: 共有1793条查询结果,搜索用时 31 毫秒
41.
Ryszard Krzyminiewski Bernadeta Dobosz Grzegorz Schroeder Joanna Kurczewska 《Physics letters. A》2018,382(44):3192-3196
The paper shows the application of a new method – Magnetic Nanoparticles Focusing 3D, MNF-3D – for focusing of magnetic nanoparticles at any point in a three-dimensional space between the rotating magnet system. The results of focusing process of nanoparticles in water, human blood, human serum and polyurethane sponge are presented. Additionally, blood flow was also considered. The effectiveness of nanoparticle focusing was monitored optically and quantitatively by electron spin resonance method. The method enabled focusing of magnetic nanoparticles within a few minutes in different environments. A good efficiency of focusing process was observed for all the samples. 相似文献
42.
《Comptes Rendus Chimie》2016,19(10):1310-1314
Irregularly shaped and inorganic fullerene-like MoS2 compounds were characterized by Resonance Raman spectroscopy using an exciting line at 633 nm. It was shown that the relative intensity of the longitudinal acoustic mode at 226 cm−1 and its overtone strongly depends on the MoS2 crystallite size but not on the size of the particles made of agglomerated crystallites. This technique appeared as a promising probe to characterize in situ very small crystallites that are not observed by XRD. 相似文献
43.
Production of palladium nanoparticles supported on multiwalled carbon nanotubes by gamma irradiation
J.V. Rojas C.H. Castano 《Radiation Physics and Chemistry》2012,81(1):16-21
Palladium nanoparticles were produced and supported on multiwalled carbon nanotubes (MWCNT) by gamma irradiation. A solution with a specific ratio of 2:1 of water-isopropanol was prepared and mixed with palladium chloride and the surfactant sodium dodecyl sulfate (SDS). The gamma radiolysis of water ultimately produces Pd metallic particles that serve as nucleation seeds. Isopropanol is used as an ion scavenger to balance the reaction, and the coalescence of the metal nanoparticles was controlled by the addition of SDS as a stabilizer. The size and distribution of nanoparticles on the carbon nanotubes (CNT) were studied at different surfactant concentrations and radiation doses. SEM, STEM and XPS were used for morphological, chemical and structural characterization of the nanostructure. Nanoparticles obtained for doses between 10 and 40 kGy, ranged in size 5-30 nm. The smaller nanoparticles were obtained at the higher doses and vice versa. Histograms of particle size distributions at different doses are presented. 相似文献
44.
《Journal of Macromolecular Science: Physics》2013,52(3):625-637
Abstract This study was focused on the pervasion process of sulfion in a PVA–Zn2+ complex film. A diffusion equation for this process, based on the Fick first diffusion law, is suggested, which was in good agreement with the experimental results. The diffusion constant was 9.92 × 10?6 cm2/sec, calculated by combining the model and the experimental results. 相似文献
45.
Selenization of Fe2O3 with NaHSe led to Se/Fe3O4. The unexpected generation of Fe3O4 attributed to the reduction conditions of the reaction, and the resulted magnetic features of the material facilitated its separation in practical applications. Owning to the synergistic effect of Se with Fe, the material was especially active to catalyze the oxidative C=C scission using O2 as mild oxidant. The technique has been successfully applied in polyene degradation project, which is of profound practical values for the treatment of the polyene pigment pollution and may be applied in the food and pharmaceutical industry. 相似文献
46.
Subir Panja Debasish kundu Sabir Ahammed Brindaban C. Ranu 《Tetrahedron letters》2017,58(35):3457-3460
A highly chemoselective reduction of aryl, heteroaryl, acyl and sulfonyl azides to the corresponding amines has been achieved by Fe(0) nanoparticles in water at room temperature in the absence of external hydride source. Several readily reducible functionalities including alkene, alkyne, S-S linkage, OTBDMS remain unaffected during reduction. 相似文献
47.
Alexandra FriedmanNina Perkas Yuri KoltypinAharon Gedanken 《Applied Surface Science》2012,258(7):2368-2372
The inner and the outer walls of hollow tubing with an inner diameter of 0.4-0.9 cm and an outer diameter of 0.6-1.3 cm were coated with silver nanoparticles (NPs) by a one-step process using ultrasound irradiation. The structure and morphology of the nanoparticles (NPs) inside the hollow tubing and on the outer surface were characterized using methods such as XRD, TEM, HR-TEM, and HRSEM. The inner surface of the tubing was found to be coated with more silver than the outer surface. The coating was done on tubing made of rubber, PVC, Teflon and polyethylene. Sonochemistry is demonstrated as a method for depositing nanoparticles on the inner wall of a tube. 相似文献
48.
Ying-Xia Wang Chuan-Fei Liu Man-Li Yang Xi-Hui Zhao Zhi-Xin Xue Yan-Zhi Xia 《中国化学快报》2017,28(1):60-64
Concave nanostructures may be developed to improve the specific mass activity of a catalyst for formic acid and methanol electro-oxidation. In this work, we report the elctrocatalytic oxidation of methanol and formic acid in acid medium over concave Pt-Cu-Fe ternary nanocubes (NCs), obtained by the galvanic exchange of Pt and Fe on Cu NCs. The concave Pt-Cu-Fe NCs exhibited improved electrooxidation performance contrasted to Pt-Cu NCs and purchased commercial Pt/C as demonstrated by their improved durability, lower onset potential, and more preferable anti-poisoning properties. These properties are believed to originate from the tailored concave structure of the catalyst and possible synergetic effects among the components of the Pt-Cu-Fe NCs. 相似文献
49.
Nanoparticles usually exhibit pronounced anisotropic properties, and a close insight into the atomic-scale deformation mechanisms is of great interest. In present study, atomic simulations are conducted to analyse the compression of bcc nanoparticles, and orientation-dependent features are addressed. It is revealed that surface morphology under indenter predominantly governs the initial elastic response. The loading curve follows the flat punch contact model in [1 1 0] compression, while it obeys the Hertzian contact model in [1 1 1] and [0 0 1] compressions. In plastic deformation regime, full dislocation gliding is dominated in [1 1 0] compression, while deformation twinning is prominent in [1 1 1] compression, and these two mechanisms coexist in [0 0 1] compression. Such deformation mechanisms are distinct from those in bulk crystals under nanoindentation and nanopillars under compression, and the major differences are also illuminated. Our results provide an atomic perspective on the mechanical behaviours of bcc nanoparticles and are helpful for the design of nanoparticle-based components and systems. 相似文献
50.
Emma Sotelo-Gonzalez María T. Fernandez-ArgüellesJose M. Costa-Fernandez Alfredo Sanz-Medel 《Analytica chimica acta》2012
Quantum dot (QD) nanoparticles (NPs) are increasingly used as highly valuable fluorescent biomarkers and as sensitive (bio)chemical probes. Interestingly, if certain metal impurities are incorporated during the NPs synthesis, phosphorescent QDs with analytical potential can be obtained. 相似文献