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991.
An isomorphism between fully quantized fermion and boson fluids and classical polymer mixtures is used as a point of departure to initiate an analytic treatment of quantum fluids. 相似文献
992.
Giovanni Ricci Aldo Boglia Tiziano Motta Fabio Bertini Antonella Caterina Boccia Lucia Zetta Enrica Alberti Antonino Famulari Paolo Arosio Stefano Valdo Meille 《Journal of polymer science. Part A, Polymer chemistry》2007,45(22):5339-5353
The (E) isomer in mixtures of (E) and (Z) 1,3‐hexadiene was polymerized with the system CoCl2(PiPrPh2)2‐MAO, a highly active and stereospecific catalyst for the preparation of 1,2 syndiotactic polybutadiene. A new crystalline polymer with a melting point of 109 °C was obtained. The polymer was characterized by IR, NMR (13C, 1H in solution and 13C in the solid‐state), X‐ray diffraction, DSC, GPC and it was found to have a trans‐1,2 syndiotactic structure with a 5.18 ± 0.04 Å fiber periodicity. Since only the (E) isomer was polymerized, at the end of the reaction we were able to separate the (Z) isomer, which was ultimately polymerized with CpTiCl3‐MAO at low temperature, obtaining a low molecular weight, stereoregular polymer that, characterized by IR and NMR methods, was found to exhibit a cis‐1,2 syndiotactic structure, never reported before. Molecular mechanics calculations were carried out on the trans‐1,2 syndiotactic polymer and structural models consistent with the X‐ray diffraction data are proposed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5339–5353, 2007 相似文献
993.
994.
An exact three-dimensional analysis is developped for an axisymmetric loading acting on the surface of a semi-infinite medium composed by two transversely isotropic materials. The loading is assumed to be parallel to the elastic symmetry axis of the upper layer. The solutions of a concentrated force and a uniform loading distributed on a circle are obtained by exact integral expressions. The numerical results are performed to show the anisotropic effect with isovalue curves of stress. To cite this article: C. Ruimy, M. Dahan, C. R. Mecanique 330 (2002) 469–473. 相似文献
995.
原子模型势理论中径向微分算符矩阵元的计算 总被引:1,自引:1,他引:0
本文推广[7,8]的工作,导出了多电子原子模型势理论中含径向微分算符的矩阵元通式,可直接用于以“速度”及“加速度”形式跃迁振子强度计算。 相似文献
996.
M. Elkurdi P. Boucaud S. Sauvage G. Fishman O. Kermarrec Y. Campidelli D. Bensahel G. Saint-Girons G. Patriarche I. Sagnes 《Physica E: Low-dimensional Systems and Nanostructures》2003,16(3-4):450
We have investigated the interband and the intraband absorption properties of Ge/Si self-assembled islands. The investigated structure consists of a p–i–n junction containing Ge/Si self-assembled islands embedded in a Si0.98Ge0.02 waveguiding layer. The variation of transmission associated with carrier injection under forward bias is monitored both in the near-infrared and in the mid-infrared spectral ranges. We show that the carrier injection leads to an absorption resonant at 185 meV which is polarized along the growth axis of the islands. This transition corresponds to an intraband optical transition from the island ground states to the two-dimensional wetting layer states. This assignment is supported by a two-dimensional band structure calculation performed in a 14 band k·p formalism. Meanwhile, the carrier injection leads to a bleaching of the interband absorption. We show that this electroabsorption spectroscopy is a useful tool for the study of self-assembled islands that is complementary of standard photoluminescence, electroluminescence or absorption spectroscopies. 相似文献
997.
We present an efficient self-consistent method for approaching quantum transport through atomic-scale structures. Using the recursion-transfer-matrix (RTM) method with a separable form of nonlocal pseudopotentials, scattering waves propagating between metallic electrodes through nano-bridged structures are efficiently calculated on the basis of the density-functional formalism. We performed calculations with this method of the conductance of Al atomic wires with various kinds of single atoms mixed at the contact to one electrode. We found that the transport properties are considerably affected by the bonding nature of the atom at the contact. The conductance is largely determined by the atomic species at the contact and does not change much as the length of the atomic wire increases. 相似文献
998.
H. Pan T. H. Lin 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(3):299-303
The supercurrent through an Aharonov-Bohm interferometer containing
two parallel quantum dots connected with two superconductor leads is
investigated theoretically. The possibility of controlling the
supercurrent is explored by tuning the quantum dot energy levels and
the total magnetic flux. By tuning the energy levels, both quantum
dots can be in the on-resonance or off-resonance states, and thus
the optimal modulation of the supercurrent can be achieved. The
supercurrent sign does not change by simply varying the quantum dot
energy levels. However, by tuning the magnetic flux, the
supercurrent can oscillate from positive to negative, which results
in the π-junction transition. 相似文献
999.
P. Navez 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(2):219-228
We describe a cryptographic protocol consisting of two entangled beams of squeezed light which makes use of statistical tests
to deduce the secret key bit. The sender (Alice) encrypts a secret key by modulating the phase of the beam sent in public
by the receiver (Bob) who keeps the other beam private. The knowledge of the degree of non classical correlation between the
beam quadrature components measured in private and in public allows only Bob to decrypt the secret key. With a view towards
absolute security, we formally prove that any external intervention from an eavesdropper (Eve) during the communication process
introduces necessarily some modification susceptible to be detected. Statistical confidentiality tests are proposed to detect
the presence of Eve.
Received 12 July 2001 and Received in final form 11 November 2001 相似文献
1000.
利用量子代数SU(2)q,s的双参数变形自旋相干态,通过引入量子代数SU(2)q,s的不可约表示张量积空间的Bargmann表示,导出了这一表示中不可约表示基底、双参数变形自旋相干态以及算符的表达式.最后导出了量子代数SU(2)q,s在双参数变形自旋相干态下的Clebsch-Gordan系数. 相似文献