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101.
102.
The lattice dynamics of transition metal oxides has been investigated in detail with threebody force shell model which is a successful extension of the shell model and includes the effect of electron shell displacements as well as deformations. The phonon dispersion relations along three principal symmetry directions obtained from this model have been compared with neutron data and found to give better agreement as compared to other models. The complete phonon spectra have also been computed and used to derive the temperature dependence of Debye temperature, and the second-order Raman and infrared spectra. The derived data agree fairly well with the observed ones wherever available. 相似文献
103.
104.
Pradeep Kumar 《Physics letters. A》1978,66(6):487-488
The contribution of the textures in the B-phase of superfluid 3He to the specific heat has been calculated. The specific heat is found to be divergent near Tc. 相似文献
105.
Investigation of the role of NaBH<Subscript>4</Subscript> in the chemical synthesis of gold nanorods
Akshaya K. Samal Theruvakkattil S. Sreeprasad Thalappil Pradeep 《Journal of nanoparticle research》2010,12(5):1777-1786
An improvement in the previously reported seed-mediated chemical synthesis of gold nanorods (GNRs) is reported. Monodisperse
GNRs have been synthesized in a one-step protocol. The addition of controlled quantity of sodium borohydride (NaBH4) directly into the growth solution produced uniform GNRs, formed by in situ nucleation and growth. In order to arrive at
the conclusion, we studied the formation of GNRs with various seeds, of metals of widely differing crystal structures, and
there were no variations in the properties of the GNRs formed. The role of NaBH4 in the growth of GNR, which has not been covered in previous reports, is discussed in detail. The dependence of longitudinal
plasmon peak on the concentration of NaBH4 is compared with the dependence of residual concentration of NaBH4 in the seed solution, which is added to the growth solution in seed-mediated synthesis. The study shows that NaBH4 plays an important role in the formation of GNRs. This proposed protocol offers a number of advantages: one-step preparation
of GNRs, significant reduction in the preparation time to 10 min, high monodispersity of GNRs, and tailorability of the aspect
ratio depending on NaBH4 concentration. It is suggested that NaBH4 added to the growth solution leads to in situ formation of the seed particles of the size of 3–5 nm which enables the growth
of GNRs. The growth of GNRs suggested here is likely to have an impact on the preparation of other anisotropic structures.
Our single-pot methodology makes the procedure directly adaptable for commercial-scale production of GNRs and for their synthesis
even in undergraduate laboratories. 相似文献
106.
Kumar P Yan Z Xu L Mazza MG Buldyrev SV Chen SH Sastry S Stanley HE 《Physical review letters》2006,97(17):177802
Using molecular dynamics simulations, we investigate the relation between the dynamic transitions of biomolecules (lysozyme and DNA) and the dynamic and thermodynamic properties of hydration water. We find that the dynamic transition of the macromolecules, sometimes called a "protein glass transition," occurs at the temperature of dynamic crossover in the diffusivity of hydration water and also coincides with the maxima of the isobaric specific heat C_{P} and the temperature derivative of the orientational order parameter. We relate these findings to the hypothesis of a liquid-liquid critical point in water. Our simulations are consistent with the possibility that the protein glass transition results from crossing the Widom line, which is defined as the locus of correlation length maxima emanating from the hypothesized second critical point of water. 相似文献
107.
Abstract The experimental observables of a vibrational spectrum are depicted either in the form of their positions, i.e., frequency relating the energy required in a given quantum transition, or as the intensities of absorption and scattering related to their transition probabilities. Expressed in terms of molecular parameters, the frequencies depend on the geometry, atomic masses, and intramolecular forces [11 while the band intensities [2] reflect changes in dipole moment (infrared) or polarizabilities (Raman) which are caused during a vibrational displacement and are related to movement of electronic charges within the individual bonds. The mathematical basis for determining vibrational frequencies was well established as early as 1940 by Wilson [3] and others [4, 51. Applying the interpretation of vibrational spectra has become routine in the multitudinous disciplines of chemical literature [6–26]. Accounts of infrared and Raman spectra [27–29], collection of literature [30], and reasonable sets of intramolecular forces [31, 321 are now available for the prediction of normal frequencies of hydrocarbons. 相似文献
108.
A. Durga Devi R. Gladwin Pradeep V.K. Chandrasekar 《Journal of Nonlinear Mathematical Physics》2013,20(1):78-93
In this paper we develop a straightforward procedure to construct higher dimensional isochronous Hamiltonian systems. We first show that a class of singular Hamiltonian systems obtained through the Ω-modified procedure is equivalent to constrained Newtonian systems. Even though such systems admit isochronous oscillations, they are effectively one degree of freedom systems due to the constraints. Then we generalize the procedure in terms of Ω i -modified Hamiltonians and identify suitable canonically conjugate coordinates such that the constructed Ω i -modified Hamiltonian is nonsingular and the corresponding Newton's equation of motion is constraint free. The procedure is first illustrated for two dimensional systems and subsequently extended to N-dimensional systems. The general solution of these systems are obtained by integrating the underlying equations and is shown to admit isochronous as well as amplitude independent quasiperiodic solutions depending on the choice of parameters. 相似文献
109.
Haridas J. Kharat Kishor P. Kakde Dhammanand J. Shirale Vikas K. Gade Pradeep D. Gaikwad Padmakar A. Savale 《Fiber and Integrated Optics》2013,32(6):411-422
Evanescent wave configuration has been extensively used in the development of fiber-optic sensor for different biomedical applications. In the present investigation we have theoretically proposed the designing of single-mode and multimode optical fiber sensing probes, which can be prepared by removing a few centimeters of cladding near the distal end of the step index optical fiber. In this theoretical study, we found that the removal of cladding causes V-number mismatching and this has led to the loss of signal acquisition from the sensing region. Therefore, to minimize these losses we have proposed to reduce the radius by step etch and tapering technique. It was found that step etching and tapering enhances the strength and penetration depth of the evanescent wave significantly. 相似文献
110.
A series of bile acid based receptors having triazole unit along with some additional heteroatom containing moieties as coordinating units for transition metal ion recognition has been synthesized. The UV–Vis studies revealed that these receptors show significant multiple binding affinity for Hg2+, Cd2+, Pb2+ and Cu2+ ions. 相似文献