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121.
A. Biber A. Golick M. Tomak 《International Journal of Infrared and Millimeter Waves》2002,23(9):1315-1325
This paper presents the analytical proof of Time-Domain Mapping Method for the spherical resonator made up of uniaxial crystal. In this way, the main types of caustics inside the spherical resonator made up of uniaxial crystal, which were investigated numerically before, are confirmed analytically. It is engraved that the problem of the ray flow inside the spherical resonator can be reduced to the problem of the ray flow inside metal cavity shaped as spheroid. 相似文献
122.
F. Honda A.V. Andreev V. Sechovský Y. Homma Y. Shiokawa 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(3):313-318
Single crystals of U(Ni1-xPdx)2Si2 with x = 0.05, 0.09 and 0.135 have been grown. Magnetization and electrical resistivity measurements were performed in a wide range
of temperatures and magnetic fields in order to study stability of magnetic phases in the solid solutions between UNi2Si2 and UPd2Si2 with a special emphasis on the type of ground state. In UPd2Si2 the simple AFI-type antiferromagnetic structure of U moments is observed at low temperatures. UNi2Si2 adopts the uncompensated AF structure (UAF) with the + + - stacking of U moments along the c-axis and consequently this compound exhibits a spontaneous magnetization corresponding to 1/3 of the U moment. The substitution
of Pd for Ni leads to a rapid decay of the spontaneous magnetization. The evolution of magnetization and electrical resistivity
behavior with Pd doping is tentatively attributed to the coexistence of the AF-I and UAF phases in the ground state of U(Ni0.91Pd0.09)2Si2 and U(Ni0.865Pd0.135)2Si2. In this scenario, the volume fraction of the AF-I phase rapidly grows with Pd doping on account of the UAF. At lowest temperatures
an irreversible transition to the UAF phase is observed when a sufficiently high magnetic field is applied along the c-axis.
Received 28 March 2002 / Received in final form 8 August 2002 Published online 19 December 2002
RID="a"
ID="a"e-mail: sech@mag.mff.cuni.cz 相似文献
123.
The effect of the grain boundary microstructure on the anisotropy and coercivity was investigated in an HDDR Nd-Fe-B permanent
magnetic alloy. Considering the special microstructure of its magnetic powder grain, an anisotropic theoretical model influenced
simultaneously by the structure defect at the grain boundary and the exchange coupling interaction was put forward. The variations
of the structure defect factors based on the nucleation and pinning mechanism with 2r
0/lex (where r
0 and lex are the defect thickness and the length of exchange coupling, respectively) were calculated. The results show that the coercivity
mechanism of an HDDR Nd-Fe-B permanent magnetic alloy is greatly related to its microstructure defect at the grain boundary.
For a fixed lex, when 2r
0/lex < 1.67, the coercivity is controlled by the pinning mechanism; when 2r
0/lex > 1.67, it is determined by the nucleation mechanism. The coercivity reaches the maximum when 2r
0/lex = 1.67. The calculation result is consistent well with the experimental result given by Morimoto et al.
Supported by the National Natural Science Foundation of China (Grant No. 50671055) 相似文献
124.
Fundamental theory presented in Part (I)[8] is used to analyze anisotropic plane stress problems. First we construct the generalized variational principle to enter Hamiltonian
system and get Hamiltonian differential operator matrix; then we solve eigen problem; finally, we present the process of obtaining
analytical solutions and semi-analytical solutions for anisotropic plane stress problems on rectangular area. 相似文献
125.
This paper is mainly concerned with elastic and acoustic properties of vitrous silica besides the computation of phonon frequencies.
Thus the phonon frequencies of vitrous silica have been calculated assuming the electronic bulk modulus,K
e, as equal to zero. New equations have been derived to relate the pressure derivatives of second order elastic constants to
the acoustic Gruneisen’s parameters using both Bhatia-Singh’s parameters and Schofield’s equations. The calculated longitudinal
and transverse Gruneisen’s parameters and the predicted absorption band spectra from Nagendranath’s equation and Bhatia Singh’s
parameters are in good agreement with experiment. The calculated mean acoustic mode Gruneisen’s parameter evaluated from the
pressure derivative of Nagendranath’s equation is also in good agreement with experiment.
An erratum to this article is available at . 相似文献
126.
The purpose of this paper is to investigate the interplay between the chemical shielding anisotropy and quadrupole interaction in MQMAS spectra.
in the compounds Na3Co(NO2)6 and trans-Co[(en2)(NO2)2]NO3 provides model systems for such an investigation. Furthermore, only few results have been reported on the application of the MQMAS method to a spin I=7/2. The possibilities of the MQMAS spectroscopy for determining the relative orientation of the two tensors and its advantage over previous techniques are discussed. Reported experimental spectra at different spinning speeds of Na3Co(NO2)6 are accurately reproduced by our theoretical simulations. The calculations are based on a recent approach, summarized in the present paper, which allows one to perform efficient simulations of MQMAS spectra including all interactions and their time-dependence throughout the experiment. This is necessary for calculating accurate MQMAS spectra including the spinning sideband pattern. In the case of trans-Co[(en2)(NO2)2]NO3 where the quadrupolar interaction and chemical shielding are stronger and their axes are non-coincident, the MQMAS spectrum is strongly distorted due to the unsufficient spinning speed and RF power. In this case, MAS at different spinning speeds is shown to provide valuable information. 相似文献
127.
Alfredo De Rossi Gaetano Assanto Stefano Trillo William E. Torruellas 《Optics Communications》1998,150(1-6):390-398
We have identified a family of (2+1)D spatial solitary waves which can stably propagate in bulk media in the presence of coexisting diffraction, self-focusing Kerr and quadratic nonlinearities. In a conspicuous range of excitation conditions close to the stationary solutions, the emerging wavepackets are immune to the detrimental occurrence of filamentation and collapse, typical of pure Kerr media. The presence of a second-order contribution to the cubic nonlinear response is, therefore, able to prevent optical damage in applications relying on self-guidance. We show that the cross-phase modulation plays an important effect on stability. Our estimate shows that the effects of the cubic susceptibility cannot be neglected below a certain beam size in realistic crystals (e.g. KTP or similar). 相似文献
128.
有横向耦合的束流系统的匹配问题 总被引:1,自引:0,他引:1
分析了不同起始情况的束流通过有横向耦合的束流系统后发射度的变化,给出了束流有效发射度的边界方程式及匹配条件. 相似文献
129.
Twenty high energy nuclear interactions produced in the graphite units of an emulsion chamber were recorded. The emulsion
chamber was exposed to cosmic rays at an atmospheric depth of 10 g cm−2 for about 7 hr over Hyderabad, India. Fourteen interactions which radiated energyΣ E
r⩾1000 GeV in the form ofγ-rays were analysed in detail. The median energy 〈Σ E
r〉 of the interactions was 1600 GeV. Results concerning the multiplicity, the transverse and longitudinal momentum distributions,
and the fractional energy distribution ofγ-rays in these interactions are presented. The average transverse momentum ofπ
0—mesons <pt
π
0> is found to increase very slowly with the primary energyE
0 and it can be approximated by the function <pt
π
0>=0·238E
0
0.06
. 相似文献
130.
There are two main contributions influencing the relative line intensities in a hyperfine pattern of a polycrystalline material:
1) Lattice vibrational anisotropy-Goldanskii-Karyagin effect (GKE) and 2) preferred orientation of the crystallites (texture).
We present the results of experiments and computer calculations of the line-intensity ratios for various orientation distributions.
The two competing effects are hard to distinguish from an experimental point of view, and this evaluation should enable one
to appreciate the magnitude of their respective contributions. A variety of textures is selected and discussed: For instance,
the interesting case where the GKE and the texture produce the same effect on the relative line intensities. Generally speaking,
it seems that in many qualitative discussions of quadrupole line asymmetries the influence of texture is underestimated, especially
for small deviations from randomness. Conversely, the asymmetry in the spectra is often explained by making the ad hoc assumption
of a GKE without realizing that this would require an unrealistic lattice vibration anisotropy.
This work was done in partial fulfillment of the requirement for the degree “Dr. rer. nat.”. 相似文献