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91.
Reusable acidic nickel oxide nanoparticles have been synthesized,characterized and applied as a catalyst to convert 2-aminoaryl ketones and β-ketoesters/ketones into the corresponding quinolines in good yields with high selectivity.This could serve as a simple and convenient procedure for the Friedlander annulations. 相似文献
92.
M. S. Bhuvaneswari S. Selvasekarapandian G. Hirankumar R. Baskaran M. Vijayakumar 《Ionics》2005,11(5-6):362-365
Sr stabilized zirconia has been prepared by the co-precipitation method and electrically characterized by using impedance
spectroscopy in the frequency range from 42 Hz to 5 MHz. The charge carrier concentration of the material has been calculated
from the conductance spectra and it is found to be of the order of 1025 cm−3. The conductance spectra show a dc plateau and a dispersive region suggesting correlated hopping motion of the ions. The
impedance analysis shows a depressed semicircle indicating non-Debye nature of the material as well as the broad nature of
modulus peaks indicates non-Debye behaviour. The bulk resistance of the material has been extracted from the impedance spectra
and it is found to be 3.5×107 Ω·cm−1 at 673 K. The low frequency dispersion of the dielectric constant implies the space charge effects arising from the electrodes.
Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28 – 30, 2003. 相似文献
93.
Kiran Y. B. Rambabu G. Vijayakumar V. Barbosa L. C. A. 《Russian Journal of Organic Chemistry》2021,57(7):1158-1166
Russian Journal of Organic Chemistry - A green acetic acid-mediated synthesis of kojic acid derivatives through a multicomponent reaction (MCR) has been developed. This new protocol is simple and... 相似文献
94.
Organic Donor–Acceptor Assemblies form Coaxial p–n Heterojunctions with High Photoconductivity 下载免费PDF全文
Dr. Seelam Prasanthkumar Samrat Ghosh Dr. Vijayakumar C. Nair Dr. Akinori Saeki Prof. Dr. Shu Seki Prof. Dr. Ayyappanpillai Ajayaghosh 《Angewandte Chemie (International ed. in English)》2015,54(3):946-950
The formation of coaxial p–n heterojunctions by mesoscale alignment of self‐sorted donor and acceptor molecules, important to achieve high photocurrent generation in organic semiconductor‐based assemblies, remains a challenging topic. Herein, we show that mixing a p‐type π gelator (TTV) with an n‐type semiconductor (PBI) results in the formation of self‐sorted fibers which are coaxially aligned to form interfacial p–n heterojunctions. UV/Vis absorption spectroscopy, powder X‐ray diffraction studies, atomic force microscopy, and Kelvin‐probe force microscopy revealed an initial self‐sorting at the molecular level and a subsequent mesoscale self‐assembly of the resulted supramolecular fibers leading to coaxially aligned p–n heterojunctions. A flash photolysis time‐resolved microwave conductivity (FP‐TRMC) study revealed a 12‐fold enhancement in the anisotropic photoconductivity of TTV/PBI coaxial fibers when compared to the individual assemblies of the donor/acceptor molecules. 相似文献
95.
P. M. Ratheesh Kumar C. Sudha Kartha K. P. Vijayakumar F. Singh D. K. Avasthi 《辐射效应与固体损伤》2013,168(7):635-644
ZnO thin films, irradiated by 80 MeV Ni+ ions, were analysed with the help of different characterization techniques like X-ray diffraction, optical absorption, transmission, photoluminescence (PL), electrical resistivity, photosensitivity (PS) and thermally stimulated current (TSC) measurements. Crystallinity and absorption edge were hardly affected by irradiation. PL spectrum of pristine sample showed a broad peak at 517 nm, whereas irradiated film had two emissions at 517 and 590 nm. Intensity ratio between these two emissions (I517/I590) decreased with the fluence, and finally at a fluence of 3×1013 ions/cm2, the emission at 517 nm completely disappeared. Electrical resistivity of the sample irradiated with a fluence of 1×1013 ions/cm2 drastically increased. However, on increasing the fluence to 3×1013 ions/cm2, resistivity decreased, probably due the onset of hopping conduction through defects. PS also decreased due to irradiation. TSC measurements on pristine sample could reveal only one defect level at 0.6 eV, due to interstitia1 zinc (ZnI). But, irradiation at a fluence of 1×1012 ions/cm2, resulted in three different defect levels as per TSC studies. Interestingly, the sample irradiated at a fluence of 3×1013 ions/cm2 had only one defect level corresponding to a deep donor. The possible origin of these defect levels is also discussed in the paper. 相似文献
96.
Vijayakumar C Praveen VK Kartha KK Ajayaghosh A 《Physical chemistry chemical physics : PCCP》2011,13(11):4942-4949
Excitation energy migration (EM) and assisted energy transfer (ET) properties of a few oligo(p-phenylenevinylene) (OPV) based organogelators with different end functional groups have been studied using picosecond time-resolved emission spectroscopy (TRES). EM was found to be more efficient in OPV gelators with small end functional groups (OPV3-4) when compared to that of the gelators with bulky end groups (OPV1-2) in the gel state. TRES studies at elevated temperature and in chloroform solution highlight the role of the self-assembled scaffolds in assisting the EM and ET processes. Increase in temperature and solvent polarity leads to the aggregate breaking and hence adversely affects the EM and ET efficiencies. The effect of EM efficiency on the fluorescence resonance energy transfer (FRET) properties of the OPV gels was studied by using OPV1 and OPV3 as the donors and OPV5 as the acceptor. Better transfer of excitation energy was observed in the donor system (OPV3) having higher EM efficiency even at very low concentration (3.1 mol%) of the acceptor molecules, whereas ET efficiency was lower in the donor system (OPV1) with low EM efficiency. 相似文献
97.
Sathya Vijayakumar Srinivasadesikan Venkatesan Lee Shyi-Long Padmini Vediappen 《Journal of fluorescence》2022,32(4):1481-1488
Journal of Fluorescence - Pyridine based organic molecule as probe has been synthesized for the detection of phenylalanine (PA) biomarker. The synthesized probe is characterized by 1H and 13C NMR... 相似文献
98.
Thermal degradation of pentaerythritol phosphate alcohol 总被引:1,自引:0,他引:1
Nagarajan David Mathan Mahendran Arunjunairaj Thangamani Rajkumar Durairaj Ponraju Chinnaswamy Thangavel Vijayakumar 《Journal of Thermal Analysis and Calorimetry》2012,110(3):1133-1141
Intumescent material, 2,6,7-trioxa-1-phosphabicyclo-[2,2,2]-octane-4-methanol phosphate (PEPA), is synthesized and characterized using FTIR, 1HNMR and 13CNMR. The degradation properties of PEPA are studied by employing TG and TG?CMS technique. The activation energies for the degradation process of PEPA are calculated by using TG curves obtained from multiple heating rates (Friedman, Kissinger?CAkahira?CSunose and Flynn?CWall?COzawa methods). The degradation that is occurring in the temperature region 307?C366?°C has the highest activation energy. Eventhough the calculated activation energies for the degradation differ depending on the approximation method employed, the trend in variation of activation energy for degradation is similar. Single ion monitoring technique proved the evolution of H2O, CO/C2H4, HCHO, C2H5OH/HCOOH and trace amounts of C2H7O3P and C4H9O4P from the degrading PEPA. The thermal conductivity and stability of the char formed during the TG analysis are also discussed. 相似文献
99.
Vijayakumar M Li L Nie Z Yang Z Hu J 《Physical chemistry chemical physics : PCCP》2012,14(29):10233-10242
The vanadium(III) cation structure in mixed acid based electrolyte solution from vanadium redox flow batteries is studied by (17)O and (35/37)Cl nuclear magnetic resonance (NMR) spectroscopy, electronic spectroscopy and density functional theory (DFT) based computational modelling. Both computational and experimental results reveal that the V(III) species can complex with counter anions (sulfate/chlorine) depending on the composition of its solvation sphere. By analyzing the powder precipitate it was found that the formation of sulfate complexed V(III) species is the crucial process in the precipitation reaction. The precipitation occurs through nucleation of neutral species formed through deprotonation and ion-pair formation process. However, the powder precipitate shows a multiphase nature which warrants multiple reaction pathways for precipitation reaction. 相似文献
100.
In the present investigation, the reaction mechanism and kinetics of 2-formylcinnamaldehyde (2-FC) with O3 and hydroxyl OH radicals were studied. The reaction of 2-FC with O3 radical are initiated by the formation of primary ozonide, whereas the reaction of 2-FC with the hydroxyl OH radical are initiated by two different ways: (1). H-atom abstraction by hydroxyl OH radical from the –CHO and –CH = CHCHO group of 2-FC (2). Hydroxyl OH addition to the –CH = CHCHO group to the ring-opened 2-FC. These reactions lead to the formation of an alkyl radical. The reaction pathways corresponding to the reactions between 2-FC with O3 and hydroxyl OH radicals have been analysed using density functionals of B3LYP and M06-2X level of methods with the 6-31+G(d,p) basis set. Single-point energy calculations for the most favourable reactive species are determined by B3LYP/6-311++G(d,p) and CCSD(T)/6-31+G(d,p) levels of theory. From the obtained results, the hydroxyl OH addition at C8 position of 2-FC are most favourable than the C9 position of 2-FC. The subsequent reactions of the alkyl radicals, formed from the hydroxyl OH addition at C8 position, are analysed in detail. The individual and overall rate constant for the most favourable reactions are calculated by canonical variational transition theory with small-curvature tunnelling corrections over the temperature range of 278–350 K. The calculated theoretical rate constants are in good agreement with the available experimental data. The Arrhenius plot of the rate constants with the temperature are fitted and the atmospheric lifetimes of the 2-FC with hydroxyl OH radical reaction in the troposphere calculate for the first time, which can be applied to the study on the atmospheric implications. The condensed Fukui function has been verified for the most favourable reaction sites. This study can be regarded as an attempt to investigate the O3-initiated and hydroxyl OH-initiated reaction mechanisms of 2-FC in the atmosphere. 相似文献