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261.
This report provides spectroscopic evidence to support a single electron transfer pathway to describe the reaction of metal hydrides with alkyl halides by direct EPR observation of the radical formed in the reaction. 相似文献
262.
The effect of added electrolytes on the nature of water molecules in the palisade layer of a Triton X-100 (TX-100) micelle has been investigated using solvation dynamics studies of C153 dye in the presence of different concentrations of NaCl, KCl, and CsCl salts. In all of the cases, the solvation dynamics is found to be biexponential in nature. It is seen that in the presence of added salts the solvation dynamics becomes slower. As previously reported (Charlton et al. J. Phys. Chem. B 2000, 104, 8327; Molina-Bolivar et al. J. Phys. Chem. B 2002, 106, 870), the presence of salt increases micellar hydration (and also size) for TX-100, mainly due to enhancement in the mechanically trapped water content in the palisade layer. Under normal circumstances, increased micellar hydration was expected to cause faster solvation dynamics (Kumbhakar et al. J. Phys. Chem. B 2004, 108, 19246), though in the present work, a reverse trend is in fact observed with the added salts. In accordance with solvation dynamics results, fluorescence anisotropy studies also indicate an increase in microviscosity for the palisade layer of the TX-100 micelle with the added salts. The present results have been rationalized assuming that the ions reside in the palisade layer, and due to the hydration of the ions, especially the cations, the water molecules in the palisade layer undergo a kind of clustering, causing the microviscosity to in fact increase rather than decrease as expected due to increased micellar hydration. A partial collapse of the surfactant chains due to their dehydration as caused by the hydration of the ions in the palisade layer may also add to the increase in microviscosity and the consequent retardation in relaxation dynamics in the presence of salts. 相似文献
263.
We report here measurements of the phonon density of states and the lattice dynamics calculations of strontium tungstate (SrWO4). At ambient conditions this compound crystallizes to a body-centred tetragonal unit cell (space group I41/a) called scheelite structure. We have developed transferable interatomic potentials to study the lattice dynamics of this
class of compounds. The model parameters have been fitted with respect to the experimentally available Raman and infra-red
frequencies and the equilibrium unit cell parameters. Inelastic neutron scattering measurements have been carried out in the
triple-axis spectrometer at Dhruva reactor. The measured phonon density of states is in good agreement with the theoretical
calculations, thus validating the interatomic potential developed.
相似文献
264.
A performance model for counter flow arrangement in concentric tube recuperator that can be used to utilize the waste heat
in the temperature range of 900–1,400°C is presented. The arrangement consists of metallic tubular inner and outer concentric
shell with a small annular gap between two concentric shells. Flue gases pass through the inner shell while air passes through
the annular gap in the reverse direction (counter flow arrangement). The height of the recuperator is divided into elements
and an energy balance is performed on each elemental height. Results give necessary information about surface, gas and air
temperature distribution, and the influence of operating conditions on recuperator performance. The recuperative effectiveness
is found to be increased with increasing inlet gas temperature and decreased with increasing fuel flow rate. The present model
accounts for all heat transfer processes pertinent to a counterflow radiation recuperator and provide a valuable tool for
performance considerations. 相似文献
265.
A self-consistent density-functional approach has been employed to study the structure of an electric double layer formed from a charge-asymmetric (2:l) electrolyte within the restricted primitive model which corresponds to charged hard sphere ions and a continuum solvent. The particle correlation due to hard-core exclusions is evaluated by making use of the universality of the density functionals and the correlation function of the uniform hard sphere fluid obtained through the integral equation theory with an accurate closure relation whereas mean spherical approximation is employed for the electrical contribution. Numerical results on the diffuse layer potential drop, ionic density profile, and the mean electrostatic potential near the electrode surface at several surface charge densities are found to be in quantitative agreement with the available simulation data. 相似文献
266.
T. D. Mishima J. C. Keay N. Goel M. A. Ball S. J. Chung M. B. Johnson M. B. Santos 《Physica E: Low-dimensional Systems and Nanostructures》2004,20(3-4):260
We investigate oriented abrupt steps (OASs), a type of surface defect in InSb/AlxIn1−xSb quantum-well (QW) samples grown on GaAs (0 0 1) substrates. Previous atomic force microscopy studies have reported that the OASs are oriented along the [1 1 0] and
directions and have an inclination angle of 5°–15° with respect to the sample surface. Our plan-view and cross-sectional transmission electron microscopy analyses reveal that the OASs are the terminal edges of threading micro-twins at the sample surface. Hall effect measurements indicate that the density of OASs correlates with the electron mobility in the InSb QWs. 相似文献
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270.
Harshita Shet Manisha Patel Jyoti M. Waikar Dr. Pavan M. More Dr. Yogesh S. Sanghvi Dr. Anant R. Kapdi 《化学:亚洲杂志》2023,18(1):e202201006
The dimethylamino functionality has significant importance in industrially relevant molecules and methodologies to install these efficiently are highly desirable. We report herein a highly efficient, room-temperature dimethylamination of chloroheteroarenes performed via the in-situ generation of dimethylamine using N,N-dimethylformamide (DMF) as precursor wiith a large substrate scope that includes various heteroarenes, purines as well as commercially relevant drugs such as altretamine, ampyzine and puromycin precursor. 相似文献