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排序方式: 共有198条查询结果,搜索用时 171 毫秒
21.
Angelina T. Georgieva Vijay Pappu Vijay Krishna Pando G. Georgiev Ion Ghiviriga Paul Indeglia Xin Xu Z. Hugh Fan Ben Koopman Panos M. Pardalos Brij Moudgil 《Journal of nanoparticle research》2013,15(7):1-18
Characterization of C60 polyhydroxyfullerenes (PHF) prepared in alkaline media, preparation facilitated by phase-transfer catalyst, presents challenges in determining the chemical structure resulting from the possibility of multiple isomers or analogs with greater or fewer hydroxyl groups from a single reaction mixture. This paper presents the utilization of analytical methods employed in tandem, especially X-ray photoelectron spectroscopy, nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy for semi-quantitative analysis on the number of hydroxyl groups present in PHF. Capillary Electrophoresis was used for purity estimation of the material. Multiple spectra and electropherograms were analyzed using a new simultaneous curve fitting method. The most accurate estimate of hydroxyl groups for C60 polyhydroxy fullerenes obtained is between 16 and 18 allylic hydroxyl groups by combining analytical methods’ results with 5 % accuracy. High precision (reproducibility) of the experiments is observed. Purity of 98 % is estimated by capillary electrophoresis. The size of PHF nanoparticles or aggregates has been determined by atomic force microscopy to be 7.4–14.2 nm. According to the elemental analysis the average probable empirical formula for the most pure PHF at pH 7.1 is C60O17H12Na5(NaHCO3)3(H2O)13 and the average formula weight is 1,605.9 g/mol. This is the first thorough characterization of PHF in terms of purity. 相似文献
22.
Pittner Angelina Wendt Sebastian Zopf David Dathe André Grosse Norman Csáki Andrea Fritzsche Wolfgang Stranik Ondrej 《Analytical and bioanalytical chemistry》2019,411(8):1537-1547
Analytical and Bioanalytical Chemistry - In this work we describe a very fast and flexible method for fabrication of plasmon-supporting substrates with micro-patterning capability, which is... 相似文献
23.
Angelina V. Biitseva Olha V. Hordiyenko Volodymyr A. Sukach Myhailo V. Vovk Konstantin A. Pichugin Irina S. Konovalova Oleg V. Shishkin 《Monatshefte für Chemie / Chemical Monthly》2008,43(4):939-943
The condensation of binucleophilic 3-amino-1-arylimino-1H-isoindoles with bifunctional 1-chloro-benzylisocyanates occurs regioselectively resulting in 3,4-dihydro-1,3,5-triazino[2,1-a]isoindol-2-one derivatives. The structures of the synthesized compounds were unambiguously established by NOE experiments. 相似文献
24.
Dr. Nimisha Jain Angelina Mary Tanu Singh Srushti Gadiyaram Dr. Jyoti Joshi Dr. D. Amilan Jose Dr. Abbas Raja Naziruddin 《欧洲无机化学杂志》2023,26(26):e202300210
We report heteroleptic ruthenium complexes of terpyridine (tpy) ligands with directly linked carboxylic acid anchors. These complexes feature methyl or methoxy-substituted 4′−Phtpy as donor ligands. We prepared these heteroleptic complexes from the ruthenium (II) precursor via a milder route to preclude the homoleptic complex formation. The donor−acceptor arrangement of tpy ligands in these ruthenium complexes renders visible light absorption giving metal and ligand-to-ligand charge transfer excitations at c.a. 490 nm. We evaluate the effect of the tpy donor substituents on the light-harvesting ability in Dye-Sensitized Solar Cells (DSSCs) and compare their photosensitizing ability with heteroleptic complexes bearing phenyl spacer at the acceptor end. Further, scrutinizing their photovoltaic performance, we studied their electron transfer kinetics in DSSCs using electrochemical impedance spectroscopy. This paper presents the structure-photosensitization relationship of these heteroleptic ruthenium complexes through a combined experimental and computational approach. 相似文献
25.
Chen J Russo R Chao W Margerum LD Malachowski MR White R Thawley Z Thayer A Rheingold AL Zakharov LN 《Dalton transactions (Cambridge, England : 2003)》2007,(24):2571-2579
A series of biphenyl-based N(3)O ligands, 2, 4, 6, and 8 were synthesized and their Cu(II) complexes prepared. These complexes were characterized by a combination of elemental analysis, FAB-MS, UV-vis spectroscopy and electrochemistry. The structure of [Cu(N(3)O-mpy-NO2)Cl2], 12 [N(3)O-mpy = 2-(3-pyridylmethylimino)-2'-(2-methylaminophenol)biphenyl], was solved and showed that the ligand coordinates through the three nitrogens with the phenol oxygen uncoordinated. Titration of azide anion into solutions of the complexes in methanol resulted in the appearance of a new band between 485-495 nm at the expense of the starting peak at 380 nm. Cyclic voltammetry studies indicated that the complexes undergo quasi-reversible one-electron reductions in acetonitrile at potentials between 0.13-0.58 V vs. Ag/AgCl. The complexes were found to be weakly active for the oxidation of di-tert-butyl catechol (DTBC). 相似文献
26.
Emulsion stabilization and inversion using a pH- and temperature-sensitive amphiphilic copolymer 总被引:1,自引:0,他引:1
Marchal F Roudot A Pantoustier N Perrin P Daillant J Guenoun P 《The journal of physical chemistry. B》2007,111(46):13151-13155
We describe how a versatile amphiphilic diblock copolymer can form oil-in-water (o/w) or water-in-oil (w/o) emulsions depending on pH and temperature. At high pH and temperature, this copolymer is mostly hydrophobic and forms w/o emulsions. Its spontaneous curvature is greatly increased upon pH and/or temperature lowering (due to protonation and/or hydration, respectively), which allows the formation of o/w emulsions. Conductivity measurements and confocal fluorescence micrographs evidence the two kinds of structures obtained over a wide range of pH and temperature. We also show how the emulsion type can be reversibly switched along a temperature scan under stirring. The lower stability of the w/o emulsions as compared to the o/w ones is attributed to a lack of electrostatic repulsion. The importance of the copolymer architecture and conformation with regards to droplet stability is discussed. 相似文献
27.
Ana Rita Soares Mateus Sílvia Barros Angelina Pena Ana Sanches Silva 《Molecules (Basel, Switzerland)》2021,26(19)
Pistachios are one of the types of tree nut fruits with the highest mycotoxin contamination, especially of aflatoxins, worldwide. This study developed a Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method that was followed by Ultra-High Performance Liquid Chromatography combined with Time-of-Flight Mass Spectrometry (UHPLC–ToF-MS) for the determination of mycotoxins in pistachios. Different approaches to dispersive solid phase extraction as a clean-up method for high lipid matrices were evaluated. For this, classic sorbents such as C18 (octadecyl-modified silica) and PSA (primary secondary amine), and new classes of sorbents, namely EMR-Lipid (enhanced matrix removal-lipid) and Z-Sep (modified silica gel with zirconium oxide), were used. The QuEChERS method, followed by Z-Sep d-SPE clean-up, provided the best analytical performance for aflatoxins (AFB1, AFB2, AFG1 and AFG2), ochratoxin A (OTA), zearalenone (ZEA), toxin T2 (T2) and toxin HT-2 (HT2) in pistachios. The method was validated in terms of linearity, sensitivity, repeatability, interday precision and recovery; it achieved good results according to criteria imposed by Commission Regulation (EC) no. 401/2006. The method was applied to real samples and the results show that pistachios that are available in Portuguese markets are safe from mycotoxins that are of concern to human health. 相似文献
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Raúl Colorado‐Peralta Cristina A. Lpez‐Rocha Sonia A. Snchez‐Ruiz Rosalinda Contreras Angelina Flores‐Parra 《Heteroatom Chemistry》2011,22(1):59-71
The structure and reactivity of a series of new ethylaminedithiazinanes and bis‐diethylaminedithiazinanes synthesized from formaldehyde, NaSH, and N,N‐dimethyl‐ethylene‐diamine ( 1 ), N‐methyl‐ethylene‐diamine ( 2 ), and N‐ethyl‐ethylene‐diamine ( 3 ) are reported. Compound 1 afforded 2‐([1,3,5]‐dithiazinan‐5‐yl)‐ethylene‐N,N‐dimethyl‐amine ( 4 ). The reaction of 4 with dry CH2Cl2 gave N‐{2‐([1,3,5]dithiazinan‐5‐yl)‐ethylene}‐N‐chloromethyl‐N,N‐dimethyl‐ammonium chloride ( 5 ) in high yield, whereas in wet CH2Cl2 and DMSO provided a mixture of 5 with N‐{2‐([1,3,5]‐dithiazinan‐5‐yl)‐ethylene}‐N,N‐dimethyl‐ammonium hydrochloride ( 6 ).bis‐{2‐([1,3,5]‐Dithiazinan‐5‐yl)‐ethylene‐N‐alkyl‐amino}‐methylene‐disulfides ( 7 ) and ( 8 ) formed by two dithiazinanes linked through the chain (CH2)2 NRCH2 S S CH2 NR (CH2)2‐ ( 7 R = methyl, 8 R = ethyl) reacted with CH2Cl2 giving after neutralization of the hydrolysis products the ethylaminedithiazinanes with different pendant N‐groups [ (CH2)2NMeH2+( 9 ); (CH2)2NEtH2+ ( 10 ); (CH2)2NMeH ( 11 ); (CH2)2NEtH ( 12 ); (CH2)2NMeHBH3 ( 13 ) (CH2)2NEtHBH3 ( 14 ). (CH2)2NMe2BH3 ( 15 ), and (CH2)2NEtMeBH3.( 16 )]. The x‐ray diffraction analyses of compounds 5 , 6 , 9 , and 10 are reported. Variable temperature NMR experiments afforded the Δ G≠ of the ring interconversion of the six‐membered heterocycles 6 , 9 , and 10 . © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:59–71, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20657 相似文献