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121.
N. S. Gajbhiye Sayan Bhattacharyya G. Balaji R. S. Ningthoujam Raj Kumar Das Susmita Basak J. Weissmüller 《Hyperfine Interactions》2005,165(1-4):153-159
Nanocrystalline MFe2O4 (M?=?Co, Ni) particles are synthesized by citrate precursor technique. Mössbauer and magnetic studies are carried out with the CoFe2O4 samples having particle sizes of 9, 14 and 30 nm and the NiFe2O4 samples having particle sizes of 9, 21 and 30 nm. The intrinsic magnetic parameters are found to vary with the particle size. The magnetic interactions and cation distribution present in these systems influence the room temperature Mössbauer parameters. Ferrimagnetic sextets are observed for all the different particle sizes. The observed reduction of the magnetic hyperfine field values with the decrease in the size of MFe2O4 particles are attributed to the intrinsic size effect and the canted spin structure at the surface of the nanoparticles. 相似文献
122.
Montmorillonite clay (N) based nanocomposites were prepared using three different grades of acrylonitrile butadiene rubber (NBR) (19%, 34%, and 50% acrylonitrile contents), styrene butadiene rubber (SBR), and polybutadiene rubber (BR). Rheological study was carried out on these nanocomposites at three different temperatures (110 °C, 120 °C, and 130 °C) over a range of shear rates for comparison. The results showed that the shear viscosity decreased with increasing shear rate and incorporation of the unmodified (N) and the modified (OC) fillers up to a certain loading, when the results were compared with the gum rubber. This effect became more prominent with increasing polarity of the rubber. The die swell, on the other hand, decreased with loading of N and OC. With increasing filler volume fraction, the die swell further decreased. Decrease of viscosity with concomitant decrease of die swell is unique in such systems. Consecutive runs of the same sample over different shear rates increased the viscosity. The results were explained with the help of X‐Ray Diffraction (XRD) data and Transmission Electron Microscopy (TEM).© 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1854–1864, 2005 相似文献
123.
A. Podder B. P. Mukhopadhyay N. Saha A. Saha B. Stensland 《Journal of chemical crystallography》1989,19(1):71-76
The title compound crystallizes in space groupP21/n witha=10.651(3),b=11.082(2),c=8.993(3) Å,=106.79(3)°;R=0.064 andR
w=0.074 for 3399 observed reflections (I3(I)) from 3674 measured. The structure was solved by direct methods and refined by least squares. The Ni atom of the complex is located at a center of inversion, and is surrounded by four nitrogen atoms of the two ligands in square-planar geometry. The oxygen atoms of the two centrosymmetrically related water molecules complete the coordination around the metal ion to form an elongated octahedron. 相似文献
124.
Sudip?Biswas Susmita?Pradhan Hemanta?Naskar Rajib?Bandyopadhyay Panchanan?PramanikEmail author 《Mikrochimica acta》2018,185(11):513
Titanium dioxide nanoparticles (NPs) were synthesized by a sol-gel method from hexafluorotitanic acid using poly(ethylene glycol) as a capping agent. The crystal structure and morphology of the NPs were characterized by X-ray diffraction, FESEM, and TEM. The NPs were used to modify a graphite paste electrode for simultaneous determination of uric acid (UA) and guanine (GU). The effect of calcination temperature on crystal structure and electrocatalytic activity was investigated. The electrochemical responses to UA and GU at bare GP, TiO2–350/GP, and TiO2–600/GP electrodes were compared. The DPV oxidation peaks of UA and GU were found to be strongest at around 304 and 673 mV, respectively, against Ag/AgCl reference electrode, and this are well separated for effective simultaneous determination. UA and GU can be simultaneously determined by this method. Response is linear within the range 0.1–500 μM and 0.1–40 μM for UA and GU, respectively. The detection limits are 70 nM for UA and 50 nM for GU (at an S/N? ratio of?3). The TiO2–600/GP electrode showed excellent analytical performance when analyzing spiked urine and serum samples. 相似文献
125.
Secondary benzylation with benzyl alcohols catalyzed by a high-valent heterobimetallic Ir-Sn complex
A highly efficient secondary benzylation procedure has been demonstrated using a high-valent heterobimetallic complex [Ir2(COD)2(SnCl3)2(Cl)2(mu-Cl)2] 1 as the catalyst in 1,2-dichloroethane to afford the corresponding benzylated products in moderate to excellent yields. The reaction was performed not only with carbon nucleophiles (arenes and heteroarenes) but also with oxygen (alcohol), nitrogen (amide and sulfonamide), and sulfur (thiol) nucleophiles. Mechanistic investigation showed the intermediacy of the ether in this reaction. An electrophilic mechanism is proposed from Hammett correlation. 相似文献
126.
de Rooy SL El-Zahab B Li M Das S Broering E Chandler L Warner IM 《Chemical communications (Cambridge, England)》2011,47(31):8916-8918
Herein we report the synthesis of a fluorescent organic salt through anion exchange and the subsequent fabrication of 1D-nanostructures via a facile templating method. 相似文献
127.
128.
We analyse the origin of the multiple long time scales associated with the long time decay observed in non-polar solvation
dynamics by linear stability analysis of solvent density modes where the effects of compressibility and solvent structure
are systematically incorporated. The coupling of the solute-solvent interactions at both ground and excited states of the
solute with the compressibility and solvent structure is found to have important effects on the time scales. The present theory
suggests that the relatively longer time constant is controlled by the solvent compressibility, while the solvent structure
at the nearest-neighbour length scale dominates the shorter time constant.
相似文献
129.
The effects of discontinuously time-varying perturbations on the dynamics of a particle moving in harmonic, symmetric double well and symmetric triple well potentials, are investigated both classically and quantum mechanically. The quantum dynamics is followed using the time-dependent Fourier grid Hamiltonian (TDFGH) method while the classical dynamics is analyzed within the framework of classical Hamiltonian mechanics. Depending on the spatial symmetry of the perturbation and the characteristic features of the reversal time , different types of ‘phase space’ structures are observed in each of the potentials. For symmetric double and triple well potentials, quantum dynamics reveals that complete destruction of tunnelling (CDT) can be achieved in the presence of a time-dependent spatially asymmetric perturbing field that is continuous in time. Any discontinuity in time-variation of the perturbation may induce over the barrier transition. The relevance of these results in the context of (i) tunnelling control and (ii) quantum computing with 3-state or 2-state quantum registers is briefly discussed. 相似文献
130.
Potassium dihydrogen phosphate (KDP) doped with different mole concentrations of Urea and KCl were grown using low temperature solution growth technique. X‐ray diffraction studies were carried out on the grown crystals using a Shimadzu X‐ray diffractometer with CuKD radiation. X‐ray study revealed that the structures of the doped crystals are slightly distorted compared to the pure KDP crystal. This may be attributed to strains on the lattice by the adsorption of urea and KCl. 相似文献