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151.
A novel synthetic approach for the preparation of PbS micro-nanostructures with different morphologies has been reported. PbS micro-nanostructures with various morphologies such as stars, dendrites, hexapods, and cubes were synthesized by thermal decomposition of lead acetate and thiourea in ethylene glycol at 120 °C, in air, in the absence of any surfactant. The PbS micro-nanostructures were characterized using different analytical techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, diffuse reflectance spectroscopy, and photoluminescence spectroscopy. The effect of different synthetic parameters such as [Pb2+:S2?] ratio, decomposition temperature, time, and source of sulfur on the morphologies of PbS was investigated and the mechanism for the formation of micro-nanostructures with different morphologies has also been proposed. 相似文献
152.
153.
Rita M. A. Nayeem Gaur Diwakar G. B. Rout B. K. Pandey A. K. Sarangi 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(3):1413-1415
Geological rock samples collected from Narwapahar uranium mines, UCIL, Jaduguda were analysed for the estimation of uranium concentration (U3O8) by beta–gamma method which is a physical technique and same set of samples were analysed by pellet fluorimetry technique which is a chemical technique. 28 samples were analysed by beta–gamma method and values varied between 240 and 2,500 ppm. Samples were analysed by pellet fluorimetry and values varied between 260 and 2,300 ppm. The results obtained were well comparable by both the techniques. 相似文献
154.
Reetu Yadav Mulayam Singh Gaur Seema Bhadauria Anna N. Berlina Boris B. Dzantiev 《International journal of environmental analytical chemistry》2018,98(6):570-581
This article deals with the detection of Co(II) in real water sample using aptamer – reactant platform combination with activated Ag–Au alloy nanoparticles (NPs) by chemiluminescence (CL) method. CL is attributed to a catalytically enhanced decomposition of H2O2 by aptamer conjugated Ag–Au alloy NPs to produce reactive oxygen species. The Ag–Au alloy NPs were prepared by chemical method using double reducing agent (i.e. trisodium citrate and polyethylenimine) and used for detection of Co(II) from water by CL method. CL experiments were carried out with the variation of different parameters such as pH, concentration of luminol, concentration of H2O2 and Ag–Au alloy NPs. We found that Ag–Au alloy NPs have very good efficiency towards Co(II) detection. Analytical parameters and kinetics were studied in detail to know the nature and mechanism of CL in presence of aptamer conjugated Ag–Au alloy NPs. The linear range of the CL sensor of Co(II) is covered concentration from 0.01 to 10 µg/L with detection limit of 0.001 µg/L. The relative standard deviation for determination of Co(II) was 6.65 in 10 replicated measurements. CL method is first time applied to detect the Co(II) in real water samples at very low level using aptamer conjugated Ag–Au NPs as a catalyst. 相似文献
155.
We have investigated the specific heat, thermal expansion and thermodynamic properties of BaRuO3 in rhombohedral, hexagonal and cubic phase using the modified rigid ion model (MRIM) by incorporating the effect of lattice distortions. The calculated Debye temperature, specific heat and other thermal properties reproduce well with the available experimental data, implying that MRIM represents properly the nature of the perovskite-type BaRuO3. Besides, we have reported the thermal expansion (α), bulk modulus (B), cohesive energy (?), molecular force constant (f), Reststrahlen frequency (υ), Debye temperature (θ D), and Gruneisen parameter (γ). 相似文献
156.
Kiran Singh Rajneesh Mohan Nupinder Kaur N.K. Gaur Manglesh Dixit Vilas Shelke R.K. Singh 《Physica C: Superconductivity and its Applications》2006,450(1-2):124-128
The effects of Cu doping in MgB2 superconductor has been studied at different processing temperatures. The polycrystalline samples of Mg1−xCuxB2 with x = 0.05 were synthesized through the in-situ solid sate reaction method in argon atmosphere at different temperature range between 800–900 °C. The samples were characterized through X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and low temperature R–T measurement techniques for the phase verification, microstructure and superconducting transition temperature, respectively. The XRD patterns of Mg1−xCuxB2 (x = 0.05) do not exhibit any impurity traces of MgB4 or MgB6 and they show the sharp transition in the samples prepared at 850 °C. The onset transition temperature of the prepared samples is around 39 K, which is almost the same as that for the pure MgB2. This indicates that Cu doping in MgB2 does not affect the transition temperature. The SEM micrograph of Mg0.95Cu0.05B2 has shown that the sample is dense with grain size smaller than 1 μm. 相似文献
157.
158.
The temperature dependence of Gibb's free energy difference (ΔG), entropy difference (ΔS) and enthalpy difference (ΔH) between the undercooled melt and the corresponding equilibrium solid phases of bulk metallic glass (BMG) forming melts has been proved to be very useful in the study of their thermodynamical behavior. The present study is made by calculating ΔG, ΔS and ΔH in the entire temperature range Tm (melting temperature) to Tg (glass transition temperature) for three Zr-based samples of BMGs: Zr57Cu15.4Ni12.6Al10Nb5, Zr41.2Ti13.8Ni10Cu12.5Be22.5 and Zr58.5Cu15.6Ni12.8Al10.3Nb2.8. The study is made on the basis of Taylor's series expansion and a comparative study is also performed between the present result and the result obtained in the framework of expansions proposed by earlier workers, and also with the experimental results. An attempt has also been made to study the glass forming ability for BMGs. 相似文献
159.
We present here the effect of degradation on electronic properties of polymer solar cells. Investigations were performed on two types of solar cells based on the bulk‐heterojunction network of poly(3‐hexylthiophene) and phenyl [6,6] C61 butyric acid methyl ester, one with slow degradation whereas other with faster degradation. Samples were prepared in identical conditions with controlled atmosphere, but for faster degradation, one of the samples was exposed to ambient air (rich in O2 and H2O molecules) before deposition of top metal electrode. The sample with slow degradation showed linear degradation in short circuit current density (Jsc), whereas the sample with faster degradation exhibited exponential degradation in Jsc. Linear degradation happens due to degradation in the active layer only whereas the exponential degradation is because of through degradation of the solar cell. The effect of degradation is investigated on different diode parameters. Because of different degradation processes in the two samples, the variations in diode parameters with time are different. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
160.
Dhananjay Kumar Bhanu Prakash Lalit K. Pandey J. P. Gaur 《Applied biochemistry and biotechnology》2010,160(8):2475-2485
The present study characterises sorption of two pesticides, namely, paraquat (PQ) and 2,4-dichlorophenoxyacetic acid (2,4-D)
by an Oscillatoria sp.-dominated cyanobacterial mat. Sorption of PQ onto the test mat was not significantly affected by the pH of the solution
within the pH range 2–7. However, 2,4-D sorption was strongly influenced by the solution pH and was maximum at pH 2. Whereas
PQ sorption increased with increase in temperature, 2,4-D sorption showed an opposite trend. The sorption of PQ and 2,4-D
achieved equilibrium within 1 h of incubation, independent of concentration of pesticide and mat biomass in the solution.
The pseudo-second-order kinetic model better defined PQ sorption than the pseudo-first-order model, whereas 2,4-D sorption
was well defined by both the models. Sorption isotherms of both the pesticides showed L-type curve. Freundlich model more
precisely defined PQ sorption than Langmuir model, thereby suggesting heterogeneous distribution of PQ binding sites onto
the biomass surface. However, the Langmuir model more correctly defined 2,4-D sorption, thus, indicating homogeneous distribution
of 2,4-D binding sites onto the biomass surface. The test biomass is a good sorbent for the removal of PQ because it could,
independent of pH of the solution, sorb substantial amount of PQ (q
max = 0.13 mmol g−1). 相似文献