全文获取类型
收费全文 | 364篇 |
免费 | 14篇 |
国内免费 | 2篇 |
专业分类
化学 | 199篇 |
晶体学 | 3篇 |
力学 | 10篇 |
数学 | 125篇 |
物理学 | 43篇 |
出版年
2023年 | 3篇 |
2022年 | 15篇 |
2021年 | 9篇 |
2020年 | 9篇 |
2019年 | 12篇 |
2018年 | 11篇 |
2017年 | 9篇 |
2016年 | 22篇 |
2015年 | 7篇 |
2014年 | 23篇 |
2013年 | 25篇 |
2012年 | 35篇 |
2011年 | 27篇 |
2010年 | 21篇 |
2009年 | 20篇 |
2008年 | 15篇 |
2007年 | 17篇 |
2006年 | 13篇 |
2005年 | 22篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 7篇 |
1999年 | 2篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1976年 | 2篇 |
1974年 | 1篇 |
排序方式: 共有380条查询结果,搜索用时 15 毫秒
11.
12.
Kristina D. Radosavljević Jelena D. Lović Dušan Ž. Mijin Slobodan D. Petrović Milka B. Jadranin Aleksandar R. Mladenović Milka L. Avramov Ivić 《Chemical Papers》2017,71(7):1217-1224
The electrodegradation of azithromycin was studied by its indirect oxidation using dimensionally stable Ti/RuO2 anode as catalyst in the electrolyte containing methanol, 0.05 M NaHCO3, sodium chloride and deionized water. The optimal conditions for galvanostatic electrodegradation for the azithromycin concentration of 0.472 mg cm?3 were found to be NaCl concentration of 7 mg cm?3 and the applied current of 300 mA. The differential pulse voltammetry using glassy carbon electrode was performed for the first time in the above-mentioned content of electrolyte for the nine concentration of azithromycin (0.075–0.675 mg cm?3) giving the limits of azithromycin detection and of quantification as: LOD 0.044 mg cm?3 and LOQ 0.145 mg cm?3. The calibration curve was constructed enabling the electrolyte analysis during its electrodegradation process. The electrolyte was analyzed by high-performance liquid chromatography and electrospray ionization time-of-flight mass spectrometry. The electrooxidation products were identified and after 180 min there was no azithromycin in the electrolyte while TOC analysis showed that 79% of azithromycin was mineralized. The proposed degradation scheme is presented. 相似文献
13.
Aleksandar Kremenovi Predrag Vuli 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(3):256-259
The X‐ray powder diffraction pattern that corresponds to the disordered state of kalsilite (potassium aluminium orthosilicate), KAlSiO4, is investigated. The directionality of (Al,Si)O4 tetrahedra within single six‐membered tetrahedral ring building units (S6R) could not be defined. With equal probability for the directionality of each tetrahedra within one S6R [free apex pointing up (U) or down (D)], an undefined sequence of U and D directionalities is needed to describe the S6R building units. The extinction conditions of disordered kalsilite are also different compared to ordered kalsilite within the space group P63. In disordered kalsilite, h0l and hhl reflections with l = 2n + 1 are systematically absent. 相似文献
14.
15.
Miloš Dubajić Aleksandar Daničić Nikola Vuković Vitomir Milanović Jelena Radovanović 《Optical and Quantum Electronics》2018,50(10):373
In this work we theoretically investigate a possibility to use cubic nitride based multi-layer periodic nanostructure as a semiconductor metamaterial. The structure design is based on an active region of a quantum cascade laser optimized to achieve optical gain in the Terahertz (THz) spectral range. In particular, we test the GaN/AlGaN quantum well configurations, which should exhibit important advantages compared to GaAs-based structures, namely room temperature operation without the assistance of magnetic field and lower doping densities. Our numerical rate-equations model is solved self-consistently and it takes into account electron-longitudinal optical phonon scattering between all the relevant states among the adjacent periods of the structure. A global optimization routine, specifically genetic algorithm is then used to generate new gain-optimized structures. This work confirms the advantages of cubic GaN designs over GaAs ones, namely feasibility of negative refraction at room temperature without the assistance of magnetic field while keeping the doping densities of the same order of magnitude. 相似文献
16.
17.
Dušica B. Stojanović Milorad Zrilić Radmila Jančić‐Heinemann Irena Živković Aleksandar Kojović Petar S. Uskoković Radoslav Aleksić 《先进技术聚合物》2013,24(8):772-776
New forms of hybrid multiaxial nanocomposites with enhanced mechanical and stab resisting properties are presented. This study is motivated by the lack of knowledge in the study of the multiaxial fabric nanocomposites with two modified thermoplastic matrices for antiballistic protection. Introduction of 5 wt.% silica nanoparticles in the composite of polyurethane/p‐aramid/poly (vinyl butyral) leads to significant improvement in mechanical properties, and the addition of silane as a coupling agents and glutaraldehyde as a crosslinking agents yielded maximal values of storage modulus, tensile modulus and anti‐stabbing properties for hybrid nanocomposites. Ballistic resistance testing and penetration depth of the hybrid nanocomposites were visualized using image analysis. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
18.
Aleksandar T. Dimitrov Ana Tomova Anita Grozdanov Orce Popovski Perica Paunović 《Journal of Solid State Electrochemistry》2013,17(2):399-407
The subject of this study is production of carbon nanotubes (CNTs) using an original procedure of reduction of lithium molten salts onto graphite cathode; their structural characterization and application as support material for electrocatalysts aimed for hydrogen evolution. As-produced CNTs were characterized by means of scanning and transmission electron microscopy (SEM and TEM), Raman spectroscopy, and thermogravimetric and differential thermal analysis (DTA). SEM and TEM images have shown that nanotubes are mostly of curved shape with length of 1–20 μm and diameter of 20–40 nm. Raman peaks indicate that the crystallinity of produced nanotubes is rather low. The obtained results suggest that formed product contains up to 80 % multiwalled carbon nanotubes (MWCNTs), while the rest being non-reacted graphite and fullerenes. DTA curves show that combustion process of the nanotubes takes place in two stages, i.e., at 450 and 720 °C. At the lower temperature, combustion of MWCNTs occurs, while at higher one, fullerenes and non-reacted graphite particles burn. As-produced MWCNTs were used as electrocatalyst’s support materials and their performance was compared with that of traditional carbon support material Vulcan XC-72. MWNTs have shown almost twice higher real surface area, and electrocatalyst deposited on them showed better catalytic activity than corresponding one deposited on Vulcan XC-72. 相似文献
19.
20.
Application of Novel Zn‐Ferrite Modified Glassy Carbon Paste Electrode as a Sensor for Determination of Cd(II) in Waste Water
下载免费PDF全文
![点击此处可从《Electroanalysis》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dalibor M. Stanković Sandra Škrivanj Nenad Savić Aleksandar S. Nikolić Predrag Vulić Dragan D. Manojlović 《Electroanalysis》2014,26(7):1536-1543
This paper describes the preparation of a new sensor based on Zn‐ferrite modified glassy carbon paste electrode and its electrochemical application for the determination of trace Cd(II) ions in waste waters using differential pulse anodic stripping voltammetry (DPASV). Different Zn/Ni ferrite nanoparticles were synthesized and characterized using scanning electron microscopy (SEM) and X‐ray powder diffraction (XRPD). The prepared ferrite nanoparticles were used for the preparation of Zn‐ferrite‐modified glassy carbon paste electrode (ZnMGCPE) for determination of Cd(II) at nanomolar levels in waste water at pH 5. The different parameters such as conditions of preparation, Zn2+/Ni2+/Fe2+ ratio and electrochemical parameters, percentage of modifier, accumulation time, pH and accumulation potential were investigated. Besides, interference measurements were also evaluated under optimized parameters. The best voltammetric response was observed for ZnFe2O4 modifier, when the percentage of modifier was 3 %, accumulation time 9 min, pH of supporting electrolyte 5 and accumulation potential ?1.05 V. Thus prepared electrode displays excellent response to Cd(II) with a detection limit of 0.38 ppb, and selective detection toward Cd(II) was achieved. 相似文献