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991.
992.
应用有效折射率微扰法结合二维/三维平面波方法研究了施主和受主缺陷型H1微腔的性质, 使用修正后的有效折射率可以准确地计算微腔的腔模频率, 与三维全矢量时域有限差分法的计算结果很相近. 对于施主型H1微腔, 以介质带边为匹配标准修正的有效折射率计算的微腔腔模频率误差最小, 而对于受主型H1微腔, 匹配标准则应设置为中间带. 有效折射率微扰法既可以将计算的维度从三维降到二维, 大大减少计算所需的计算机内存和时间, 又可以保持计算结果的准确性, 这对于光子晶体微腔的广泛应用具有非常重要的价值. 相似文献
993.
994.
V. S. Ekel’chik 《Mechanics of Composite Materials》2007,43(6):487-502
A survey of various methods for determining the complex elasticity and shear moduli from the resonant frequencies of flexural
and torsional vibrations of rectangular rods cut out from a plate of an orthotropic composite is presented. The errors in
the computed values of dynamic shear moduli caused by inaccuracies in the experimental determination of resonance frequencies
are examined. A new variant of the resonance method is developed, which permits one to find three complex shear moduli of
a composite from the resonant frequencies and the damping of torsional vibrations of three rods oriented along three symmetry
axes of the material. For computing the moduli in the case of an overdetermined system, an algorithm of nonlinear optimization
based on the least-squares method is recommended. From the results obtained it follows that, for determining the interlaminar
shear moduli with a necessary accuracy, the rods must be sufficiently thick. It is shown that a good agreement alone between
calculated and experimental frequencies of flexural and torsional vibrations of rods does not ensure a reliable determination
of the moduli of interlaminar shear if experiments are carried out on wide test specimens cut out from a thin plate. Recommendations
are given for the choice of geometrical sizes of test specimens for resonance experiments.
__________
Translated from Mekhanika Kompozitnykh Materialov, Vol. 43, No. 6, pp. 721–744, November–December, 2007. 相似文献
995.
Baolu Shi Qing Cao Dingjiang Xie Weikang Peng Ningfei Wang 《Proceedings of the Combustion Institute》2019,37(4):4329-4336
To utilize sustainable biofuel, the current study proposes a novel combustion technique that directly burns liquid ethanol without a spray system. Two swirling air flows are induced by tangentially injected the gas from two concentric tubes at different stages. The liquid ethanol is fed by a liquid tank at the center. At the beginning methane flame assists in preheating the system to vaporize liquid ethanol and ignite the vapor. Thereafter methane is switched off, and liquid ethanol can be continuously vaporized through self-burning released heat. The heat and mass transfer processes are examined to illustrate such self-sustained burning–heating–evaporating system. The ethanol flow rate is gradually increased to provide different heat output. The flame structures, temperature distributions and pollutant emissions are carefully examined. The results show that the ethanol can be steadily burned to provide heat output between 0.7 and 2.5?kW. Generally a blue flame is obtained, and the NOx and CO concentrations are ultralow. By increasing ethanol flow rate to exceed 8?mL/min, an unsteady, sooting flame is observed owing to incomplete evaporation and poor mixing. A parametric study is conducted to evaluate the influences of liquid tank position, flow rate and tip structure on the combustion characteristics. Additionally, an optimal operation condition is proposed. The current study provides a promising method to burn low-boiling liquid fuel in a clean, efficient and compact way. 相似文献
996.
In this paper, we study cyclic codes over the rings Z
2 + uZ
2 and Z
2 + uZ
2 + u
2
Z
2 . We find a set of generators for these codes. The rank, the dual, and the Hamming distance of these codes are studied as
well. Examples of cyclic codes of various lengths are also studied.
相似文献
997.
Based on the topological structure of gauge theory, an effective dual version of QCD has been reviewed and analyzed for the phase structure and color confining properties of QCD by invoking the dynamical magnetic symmetry breaking. The multi-flux-tube configuration of condensed QCD vacuum has been explored and associated glueball masses and inter-quark potential have been derived. Thermal response of QCD vacuum has been analyzed using path-integral formalism alongwith the mean-field approach and associated thermodynamical potential is used to derive thermal form of glueball masses, monopole condensate, inter-quark potential and monopole density which then lead to an estimate of the critical temperature of QCD phase transition. During its thermal evolution, a smooth transition of hadronic system via a weakly bound QGP phase to the fully deconfined phase is established and the thermal evolution profiles of various parameters are shown to indicate a second-order deconfinement phase transition and the restoration of magnetic symmetry. Monopole density calculations have been shown to lead to gradual evaporation of magnetic condensate into thermal monopoles during QCD phase transition. 相似文献
998.
S. Helhel 《International Journal of Infrared and Millimeter Waves》2006,27(4):615-629
Confined dual frequency hydrogen plasma discharge has been investigated with microwave interferometer method and radial profiles
are taken by Abel inversion technique. Dual radio-frequency sources, operating at 27.12MHz and 1.94MHz, are coupled to each
other through the plasma. 27.12MHz RF power is used to enhance plasma density and 1.94MHz power is used to enhance ion acceleration
energy to the electrode. Radial density profiles has been taken for comparing the effects of low frequency source that the
secondary RF source causes reduction in plasma density due to the sheath expansion. Instead radial density profile is assumed
as flat by most of the models, there is about 2.5eV of potential drop occurs from centre to boundary at 40W of primary source
power. It has been observed that increasing sheath width (increasing the secondary source power to primary source power) reduces
the bulk plasma volume and makes potential profile flattening in y direction. While the high frequency power is dissipated
by electrons in the bulk plasma; low frequency power is mostly dissipated by ions in the sheath region. Using both high and
low frequency power, we may control plasma density and ion acceleration energy to the electrode simultaneously. 相似文献
999.
Süleyman Demir 《Central European Journal of Physics》2007,5(4):487-506
In this paper, a new representational model based on dual quaternionic matrices is proposed for classical electromagnetism.
After demonstrating the isomorphic matrix representations of dual quaternions, Maxwell’s equations and the constitutive relations
for electromagnetism are expressed in terms of dual quaternionic matrices. For this purpose, new 8 × 8 matrices connected
with quaternion basis elements have been introduced.
相似文献
1000.
In this article, we utilize the semiinfinite versions of Guignard's constraint qualification and Motzkin's theorem of the alternative to establish a set of Karush–Kuhn–Tucker-type necessary optimality conditions for a nonsmooth and nonconvex semiinfinite programming problem. Furthermore, we discuss some sufficient optimality conditions and duality relations for our semiinfinite programming problem. 相似文献