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31.
经Opuntia dilenii haw植物提取液绿色合成制备的纳米铝酸锌的催化性质(英文) 总被引:1,自引:0,他引:1
C.Ragupathi J.Judith Vijaya S.Narayanan L.John Kennedy Seeram Ramakrishna 《催化学报》2013,34(10):1951-1958
Various nanosized zinc aluminate(ZnAl2O4) samples were prepared by a conventional and a mi- crowave method both with and without using Opuntia dilenii haw plant extract,and were charac- terized by X-ray diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),high resolution scanning electron microscopy(HRSEM),energy dispersion scanning(EDX),temperature dependent conductance measurements, thermoelectric power measurements, ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy,and photoluminescence spectroscopy.The formation of a pure ZnAl2O4 phase was confirmed by XRD and FT-IR.A change in morphology from nanosized plates to nanosized sheets with,respectively,the conventional and microwave heating methods was clearly shown by HRSEM.UV-Vis diffusion reflectance spectroscopy measured the band gaps of ZnAl2O4 nanosized plates and nanosized sheets as 3.5 and 3.9 eV,respectively.The synthesized ZnAl2O4 was single crystalline and has three photoluminescence emissions at 482,528,and 540 nm.ZnAl2O4 nanosized sheets prepared by the microwave method showed higher catalytic activity for the oxida- tion of benzyl alcohol(85% conversion) than ZnAl2O4 nanosized plates prepared by the convention- al method(60% conversion). 相似文献
32.
Raunak Tamrakar Vikas Dubey N. Kumar Swamy Ratnesh Tiwari S. V. N. Pammi P. V. Ramakrishna 《Research on Chemical Intermediates》2013,39(8):3919-3923
The present paper reports thermoluminescence (TL) glow curves of Eu3+-doped Y2O3 phosphor with different ultraviolet (UV) exposure times. The glow peak shows second-order kinetics of Eu3+-doped Y2O3, and corresponding kinetic parameters were evaluated using the peak shape method. Calculations of trap depth were carried out using different methods. The kinetics order, activation energy, and frequency factor were calculated. The recorded glow curve shifts towards higher intensity with longer UV exposure. The heating rate used for recording TL was 3.0 °C s?1. Particle size and structure were verified by X-ray diffraction (XRD) pattern and morphology by scanning electron microscopy (SEM) imaging. 相似文献
33.
Galla Raju Rajesh NomulaKallaganti V.S. Ramakrishna Palakodety Radha Krishna 《Tetrahedron letters》2014
The first total synthesis of (6Z,9S)-3,4-trans-9-hydroxy-3-methyldodec-cis-6-en-4-olide and (6Z)-3,4-trans-9-oxo-3-methyldodec-cis-6-en-4-olide was achieved in a convergent pathway. The salient features of our synthesis include Ohira–Bestmann reaction, regioselective alkyne addition to terminal epoxide, TEMPO/BAIB mediated oxidative lactonization, and partial hydrogenation. 相似文献
34.
Ramakrishna Dileep Badekai Ramachandra Bhat T.H. Suresha Kumara 《Green Chemistry Letters and Reviews》2014,7(1):32-36
Palladium (Pd)-catalyzed carbonylation of alcohols proceeds in ionic liquid (IL) media (1-ethyl-3-methylimidazolium hexafluorophosphate). Carbonylation of primary/secondary alcohols to aldehydes/ketones was greatly accelerated by the use of a Pd-based catalyst in the presence of NaOCl as an oxidant. The catalyst was more easier to recycle in the IL [Emim]PF6 with an equal-proportioned CH2Cl2 than in the single CH2Cl2 or IL. 相似文献
35.
We generalize the concepts of alignment and 3D alignment by moderately intense laser pulses to control both the overall rotations and the torsional motions of polyatomic molecules. Torsional control is applied to manipulate charge transfer events, hence introducing a potential route to light controlled molecular switches. Potential applications in areas such as molecular assembly, molecular spectroscopies, energy transfer, and molecule-based junctions are envisioned. 相似文献
36.
Comment on "negative refraction at optical frequencies in nonmagnetic two-component molecular media"
Ramakrishna SA 《Physical review letters》2007,98(5):059701; discussion 059702
37.
Charge carrier decay and diffusion in organic–inorganic CH3NH3PbI3–xClx perovskite based solar cell 下载免费PDF全文
In recent years, organic–inorganic lead halides attracted widespread interest, mainly due to their impressive photoconversion properties and low‐cost solution processing. In this study, we employed small amplitude transient photovoltage and photocurrent spectroscopy to investigate charge transport and recombination properties of perovskite CH3NH3PbI3–xClx solar cell under realistic light harvesting conditions (<1 sun). Cell structure resembles outlay commonly found in organic photovoltaics, with perovskite absorber being sandwiched between two thin layers of organic polymers. Tested device displayed high power conversion efficiency (10.3%), good fill factor and negligible hysteresis effect. Fundamental device parameters were characterized at various open‐circuit voltages (Voc) by examination of small voltage and current perturbations created by the low intensity pulsed laser excitations. The obtained results exhibit long charge carrier lifetimes and fast charge transport over the full range of applied optical bias, as well as remarkable diffusion lengths exceeding 1 μm. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
38.
Gold Decorated Graphene by Laser Ablation for Efficient Electrocatalytic Oxidation of Methanol and Ethanol 下载免费PDF全文
V. Lakshman Kumar R. S. Sai Siddhardha Adarsh Kaniyoor Ramakrishna Podila Muralikrishna Molli Sai Muthu Kumar V K. Venkataramaniah S. Ramaprabhu A. M. Rao Sai Sathish Ramamurthy 《Electroanalysis》2014,26(8):1850-1857
A well‐known limitation in the fabrication of metal‐graphene composite has been the use of surfactants that strongly adsorb on the surface and reduce the performance of the catalyst. We demonstrate here a novel one‐pot synthesis of gold nanoparticles by laser ablation of gold strip and in‐situ decoration on graphene substrate. Not only the impregnation of nanoparticles was linker free, but also the synthesis by itself was surfactant‐free. The composite materials were well characterized morphologically and functionally using electron microscopy, X‐ray and electron diffraction, Raman spectroscopy, Zeta potential, electrochemical measurements and UV‐Visible spectroscopic techniques. This linker‐free gold‐graphene based composite has been employed for catalytic applications pertaining to electrooxidation. We have explored the use of this composite as a binder‐free electrode in electrocatalytic oxidation of methanol and ethanol in alkaline medium. Additionally, the onset potential for ethanol oxidation was found to be more negative, ?100 mV, an indication of its promising application in direct ethanol fuel cells. 相似文献
39.
M. Penchal Reddy W. Madhuri K. Sadhana I. G. Kim K. N. Hui K. S. Hui K. V. Siva Kumar R. Ramakrishna Reddy 《Journal of Sol-Gel Science and Technology》2014,70(3):400-404
Magnetic nickel ferrite (NiFe2O4) was prepared by sol–gel process and calcined in the 2.45 GHz singlemode microwave furnace to synthesize nickel nanopowder. The sol–gel method was used for the processing of the NiFe2O4 powder because of its potential for making fine, pure and homogeneous powders. Sol–gel is a chemical method that has the possibility of synthesizing a reproducible material. Microwave energy is used for the calcining of this powder and the sintering of the NiFe2O4 samples. Its use for calcination has the advantage of reducing the total processing time and the soak temperature. In addition to the above combination of sol–gel and microwave processing yields to nanoscale particles and a more uniform distribution of their sizes. X-ray diffraction, energy dispersive X-ray spectroscopy, transmission electron microscopy and vibrating sample magnetometer were carried out to investigate structural, elemental, morphological and magnetic aspects of NiFe2O4. The results showed that the mean size and the saturation magnetization of the NiFe2O4 nanoparticles are about 30 nm and 55.27 emu/g, respectively. This method could be used as an alternative to other chemical methods in order to obtain NiFe2O4 nanoparticles. 相似文献
40.
Karim Khanmohammadi Chenab Beheshteh Sohrabi Amir Jafari Seeram Ramakrishna 《Materials Today Chemistry》2020
Global efforts for engineering desired materials which are able to treat the water sources still are ongoing in the bench level methods. Considering adsorbent and photocatalytic materials as the main reliable candidates still are encountering with struggles because of many challenges that restrict their large-scale application. This review comprehensively considered the recent advanced materials water treatment methods which involve to magnetic, activated carbon, carbon nanotubes (CNTs), graphene (G), graphene oxide (GO), (Graphene) quantum dots, carbon nanorods, carbon nano-onions, and reduced graphene oxide (RGO), zeolite, silica and clay-based nanomaterials. The adsorption and photocatalytic properties of these nanomaterials introduced them as highly potent option for heavy metal ions and organic dyes removal and photocatalytic degradation. High specific surface area in conjugation with presenting higher kinetics of adsorption and decomposition are the main characteristics of these materials which make them appropriate to treat wastewater even in ultralow concentration of the pollutants. Considering the mechanistic aspects of the adsorption and photocatalytic decomposition process, challenges and opportunities were other subjects that have been highlighted for the discussed nanomaterials. In term of the adsorption approaches, the mechanism of adsorptions and their influence on the maximum adsorption capacity were discussed and also for photocatalyst approach the radical active spices and their role in kinetic and efficiency of the organic pollutant decomposition were provided a deep discussion. 相似文献