全文获取类型
收费全文 | 219篇 |
免费 | 12篇 |
国内免费 | 26篇 |
专业分类
化学 | 236篇 |
晶体学 | 1篇 |
物理学 | 9篇 |
无线电 | 11篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 9篇 |
2018年 | 4篇 |
2017年 | 10篇 |
2016年 | 13篇 |
2015年 | 13篇 |
2014年 | 9篇 |
2013年 | 9篇 |
2012年 | 15篇 |
2011年 | 12篇 |
2010年 | 14篇 |
2009年 | 24篇 |
2008年 | 17篇 |
2007年 | 16篇 |
2006年 | 10篇 |
2005年 | 12篇 |
2004年 | 13篇 |
2003年 | 13篇 |
2002年 | 9篇 |
2001年 | 2篇 |
2000年 | 5篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 4篇 |
排序方式: 共有257条查询结果,搜索用时 265 毫秒
121.
In this work, we describe the characterization of the complex [Fe(tpy-NH2)2](PF6)2 (tpy-NH2 = bis[4′-(3-aminophenyl)-2, 2′:6′,2″-terpyridine]. The complex was oxidatively electropolymerized on glassy-carbon electrodes in CH3CN/0.1 M tetraethylammonium perchlorate (TEAP) to generate polymer films that exhibit reversible oxidative electrochemical behavior in a wide potential range (0.0–1.6 V), as well as high conductivity and stability/durability. In situ spectrocyclic voltammetry of this modified electrode was carried out on a photodiode array spectrophotometer attached to a potentiostat, which provided UV–Vis absorption spectra of the redox species during the potential sweep. We determined charge transport parameters as a function of time and thickness of the modified electrode, and the results showed that poly-[[Fe(tpy-NH2)2]2+]n can be made to exhibit three regimes of charge transport behavior by manipulation of the film thickness and the experimental time-scale. Morphological characterization of the film was provided by atomic force microscopy. 相似文献
122.
《Electroanalysis》2018,30(3):486-496
Aptasensor for highly sensitive determination of aflatoxin M1 (AFM1) was developed on the base of glassy carbon electrode (GCE) covered with polymeric Neutral red (NR) dye obtained by electropolymerization in the presence of polycarboxylated pillar[5]arene derivative. Aptamer against AFM1 and NR label were then covalently linked to the carboxylic groups of the carrier by carbodiimide binding. At presence of AFM1 the cathodic peak current related to the NR conversion decreases. AFM1 induced also an increase of the charge transfer resistance measured by electrochemical impedance spectroscopy. In optimal conditions, this make it possible to determine from 5 to 120 ng/L AFM1 in standard solutions with limit of detection (LOD) of 0.5 ng/L. The aptasensor was validated on the spiked samples of cow and sheep milk as well as in kefir after their methanol dilution. Reliable detection of the 40–160 ng/kg of mycotoxins was reached. This is below limited threshold value (50 μg/kg) established in EC. 相似文献
123.
124.
The preparation of the monomer and thin films of a new polymeric tetraruthenated porphyrin material and their characterization by spectroscopic and electrochemical techniques, are described. This material is one of the most active electrocatalyst for the oxidation of nitrite ions to nitrate, exhibiting a heterogeneous cross-exchange rate constant (kf=(6.2±0.1×104) M-1 s-1) 30 times higher than that previously described for the electrostatic assembled porphyrin films. The polymeric films were obtained by electropolymerization of the corresponding molecular films, previously prepared by dip-coating. This strategy leads to an increase in the efficiency of the reticulation process while minimizing the amount of monomer necessary for the preparation of the modified electrodes. The conductivity of the thin films close to the E1/2 of the Ru(III/II) redox pair is very good, decreasing rapidly as the applied potential departs from it, as expected for a redox polymer. The conductivity decreases when the surface concentration becomes higher than 1.2×10-8 mol cm−2 also, reflecting a higher impedance for electrolyte diffusion inside the polymeric material. The high electrocatalytic activity associated with the high conductivity make this new nanostructured material suitable for sensor applications. 相似文献
125.
本实验设计以邻苯二胺为功能单体,以双酚A为目标分子,采用简单快速的电聚合方法,制备了对双酚A具有特异性识别能力的分子印迹电极。采用差分脉冲伏安法和石英晶体微天平对印迹电极的特异识别性能进行表征。结果表明,印迹电极对双酚A表现出较高的特异性识别能力。与非印迹电极相比,识别能力提高一个数量级。同时,该电极对100倍浓度的阿特拉津、17β-雌二醇的信号响应仅为十分之一,表明该电极在复杂体系中具有良好的抗干扰能力。此外,该实验方案目标分子选择灵活,能制备针对不同目标分子的印迹电极,可满足自主设计实验的需求。通过该创新实验,可以有效帮助学生深入了解分子间的相互作用,体验在分子层次设计材料的过程。 相似文献
126.
Poly(o‐anisidine) (POA) was formed by successive cyclic voltammetry in monomer solution containing sodium dodecyl sulfate (SDS) at the surface of carbon paste electrode. Then Ni(II) ions were incorporated to electrode by immersion of the polymeric modified electrode having amine group in 0.1 M Ni(II) ion solution. Cyclic voltammetric and chronoamperometric experiments were used for the electrochemical study of this modified electrode; a good redox behavior of Ni(OH)2/NiOOH couple at the surface of electrode can be observed. The capability of this modified electrode for catalytic oxidation of folic acid was demonstrated. The amount of α and surface coverage (Γ*) of the redox species and catalytic chemical reaction rate constant (k) for folic acid oxidation were calculated. The catalytic oxidation peak current of folic acid was linearly dependent on its concentration and a linear calibration curve was obtained in the range of 0.1 to 5 mM with a correlation coefficient of 0.9994. The limit of detection (3σ) was determined as 0.091 mM. This electrocatalytic oxidation was used as simple, selective and precise voltammetric method for determination of folic acid in pharmaceutical preparations. 相似文献
127.
F. Lallemand 《Applied Surface Science》2008,254(11):3318-3323
In the line of elaboration of conducting polymer on oxidizable metal, electropolymerization of 3,4-ethylene-dioxythiophene (PEDOT) was performed in ammonium oxalate aqueous solution on nickel. The advantageous effect of the oxalate ions on the electropolymerization process as well as on the physical characteristics of the resulting polymer film has been evidenced. Among these properties, adhesion has been drastically improved. Hybride nanowires nickel/PEDOT have been elaborated to highlight the nickel-PEDOT adhesion. The protective effect of the PEDOT film against corrosion in NaCl is nevertheless very slight. 相似文献
128.
Omer Yehezkeli Oded Ovits Ran Tel‐Vered Sara Raichlin Itamar Willner 《Electroanalysis》2010,22(16):1817-1823
Au nanoparticles are functionalized with thioaniline electropolymerizable units and mercaptophenyl boronic acid ligands. Flavin adenine dinucleotide (FAD) is linked to the boronic acid ligands and apo‐glucose oxidase, apo‐GOx, is reconstituted on the FAD cofactor units to yield enzymes in a structurally‐aligned configuration in respect to the Au NPs. Electropolymerization of the enzyme‐functionalized Au NPs on a thioaniline‐modified Au electrode yields a three‐dimensional bis‐aniline‐crosslinked Au NPs/reconstituted glucose oxidase matrix on the electrode that reveals effective electrical contacting with the electrode. 相似文献
129.
《Analytical letters》2012,45(8):1297-1310
Eleven glucose biosensors were prepared by cross-linking, entrapment, and layer-by-layer assembly to investigate the influence of these immobilization methods on performance. The effects of separate nanozeolites combined with magnetic nanoparticles and multiwalled carbon nanotubes in the enzyme composition on the performance of glucose biosensors were compared. Cyclic voltammetric studies were carried out on the biosensors. Acrylonitrile copolymer/nanozeolite/carbon nanotube and acrylonitrile copolymer/nanozeolite/magnetic nanoparticle electrodes prepared by a cross-linking method showed the highest electroactivity. These results indicated that a synergistic effect occurred when multiwalled carbon nanotubes, magnetic nanoparticles, and nanozeolites were combined that greatly improved the electron transfer ability of the sensors. Amperometric measurements by the glucose oxidase electrodes were obtained that showed that the acrylonitrile copolymer/nanozeolite/carbon nanotube electrode was the most sensitive (10.959 microamperes per millimolar). The lowest detection limit for this biosensor was 0.02 millimolar glucose, with a linear dynamic range up to 3 millimolar. The response after thirty days was 81 percent of the initial current. 相似文献
130.
《Journal of Coordination Chemistry》2012,65(12):2181-2191
A precursor (H3A) was synthesized by the mono condensation of 2-aminobenzylamine with salicylaldehyde and then a tetradentade Schiff-base ligand (H2L) prepared by using H3A and 3-methoxysalicylaldehyde. The copper(II) complex of this new ligand was prepared and characterized by elemental analysis, electronic absorption, Fourier transform infrared (FT-IR), and magnetic susceptibility. For the ligand, 1H- and 13C-NMR and liquid chromatography mass spectrometry (LC–MS) spectra were obtained. The tetradentate ligand is coordinated to Cu(II) through the phenolic oxygen and azomethine nitrogen. The use of this metal complex in the preparation of a modified electrode is also described. CuL was electropolymerized on a platinum electrode surface in a 0.1 mol dm?3 solution of lithium perchlorate in acetonitrile by cyclic voltammetry between 0 and 1.6 V versus Ag/Ag+. Electrochemical properties of the electroactive polymeric film have been investigated and a surface confined polymerization mechanism was proposed. 相似文献