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601.
P.A.Závodszky B.Arend D.Cole J.DeKamp M.Doleans G.Machicoane F.Marti P.Miller J.Moskalik W.Nurnberger J.Ottarson M.Steiner J.Stetson J.Vincent X.Wu A.Zeller Q.Zhao 《中国物理 C》2007,31(Z1):18-22
Since the last ECR Workshop,NSCL/MSU has been involved in a vigorous ECR ion source R&D program,which resulted in the construction of an off-line test ECR ion source(ARTEMIS-B)for new beam development and ion optics studies.Also the design and partial completion of a 3rd generation,fully superconducting ECR ion source,SuSI has been accomplished.This paper is an overview of the construction projects and the different R&D activities performed with the existing ion sources.These activities include development of metallic ion beam production methods using evaporation with resistive and inductive ovens and sputtering of very refractory metals.Ion optics developments include testing different focusing elements(magnetic solenoid lens,electrostatic quadrupole triplet lens,Einzel lens,electrostatic double doublet quadrupole combined with an octupole lens),and different beam forming and diagnostics devices.The detailed results will be presented at the workshop in separate talks and posters. 相似文献
602.
G. V. Astakhov T. Kiessling D. R. Yakovlev E. A. Zhukov M. Bayer W. Ossau B. P. Zakharchenya G. Karczewski T. Wojtowicz J. Kossut 《physica status solidi b》2006,243(4):858-862
We report on spin memory relaxation time τ s of free electrons in CdTe‐based quantum wells which is found to be in the nanosecond range. In these studies two different techniques have been exploited: (i) the Hanle effect under cw excitation and (ii) the time‐resolved pump‐&‐probe Kerr rotation measured under excitation by 1.8‐ps optical pulses. These independent techniques give very close results τ s ns and τ s = 14 ns, respectively. To our knowledge this is by two orders of magnitude longer than the electron spin relaxation times reported for CdTe‐based quantum wells so far. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
603.
First data the on X-ray-induced luminescence (RL) and thermoluminescence (TL) spectra in the range 10 to 300 K of K2ZnCl4 and Rb2ZnCl4 are reported. For both the materials, two main emission bands peaking at 280 and 545 nm are observed in the RL spectra. They are proposed to be associated to intrinsic electron–hole recombination processes. The TL spectra show the most intense glow peaks near 205 K for both, K2ZnCl4 and Rb2ZnCl4. The wavelength spectrum of the TL peaks essentially consists of the same bands appearing in the RL spectrum measured at the same temperature. Therefore, the glow peaks should also have their origin in the same electron–hole recombinations. 相似文献
604.
G. Dasbach D. Frhlich H. Stolz R. Klieber D. Suter M. Bayer 《physica status solidi b》2003,238(3):541-547
The long‐ and short‐range exchange interaction for the quadrupole allowed transition to the yellow 1S orthoexciton in Cu2O is derived. While the three orthoexciton states still remain degenerate, when treating the exchange up to the order of K ‐linear terms, a fine structure arises when K ‐quadratic terms are included. This splitting is investigated experimentally by high resolution spectroscopy. Exchange contributions of few μeV are resolved and compared to theory. The impact of strain on the exciton fine structure is discussed and evaluated. 相似文献
605.
Results on the X-ray induced luminescence (RL), after-glow (AG), and thermoluminescence (TL) spectra in the range 10 to 300 K of {(CH3)4N}2ZnCl4 single crystals are presented and compared with previous results for Rb2ZnCl4 and K2ZnCl4. The emissions for the three cases are proposed to be associated to intrinsic electron-hole recombination processes. 相似文献
606.
It has frequently been observed that certain roof tiles and bricks, especially from relatively modern European buildings, do not contain enough quartz grains in a suitable grain size range to permit dose reconstruction using thermoluminescence (TL) or optically stimulated luminescence (OSL) methods. In this paper the feasibility of using infrared-stimulated luminescence (IRSL) on the feldspar fraction of such bricks and tiles has been investigated. Appropriate preheating treatments were employed in order to select the most stable signals, and procedures were developed to enhance the signal to noise ratio. The possible effect of anomalous fading under application of these procedures was tested. In the dose range above 100 mGy, it has been demonstrated that using IRSL on the feldspar fraction of such material provides a feasible alternative to the use of green-light-stimulated luminescence (GLSL) on the quartz fraction, for the purposes of retrospective dosimetry. Furthermore, since the use of IRSL as described in this paper involves the measurement of polymineral fine grain fractions of bricks, a technique for the calibration of the built-in β source against the γ source in Secondary Standard Dosimetry facilities for routine use of the technique is described. 相似文献
607.
Cs2ZnBr4, Cs2CdBr4, and Cs2HgBr4 are at room temperature isomorphous with β-K2SO4 (Pnma, Z = 4). X-ray diffraction and 81Br NQR measurements show that this structure is stable down to T = 5 K for Cs2ZnBr4. In Cs2CdBr4 and Cs2HgBr4 a new phase sequence is observed: Pnma (Z = 4) ↔ incommensurate phase ↔ P21/n (Z=4) ↔ unknown low temperature phase. The incommensurate phase is modulated in the x-direction with q = δa*, the lock-in transition into the P21/n phase occurs at the centre of the Pnma Brillouin zone. 相似文献
608.
[NH3-(CH2)n-NH3]MnCl4 compounds with n = 2, …, 5 are chloride perovskite layer structures. The room temperature phase of members with odd numbers of carbon atoms is orthorhombic, whereas even numbers lead to monoclinic structures. Structural phase transitions were found in all compounds with n > 2. The magnetic behaviour is similar to the (CnH2n+1NH3)2MnCl4-family. 相似文献
609.
The technique of two-photon-absorption spectroscopy with polarized laser-light is applied to localized excitations of 4f-electrons in crystals. The relevant selection rules are discussed. A method is outlined for the unique determination of the relative magnitude of partial transition-probabilities with different types of symmetry using linear and circular polarization of the incident light. The anisotropy of the two-photon absorption has been measured in single crystals of cubic CaF2:Eu2+ at five different wavenumbers. The relative intensities of transitions belonging to the three different types of symmetry active in two-photon absorption are constant in the range of the e-band (26,000 to 29,000 cm−1) but differ from these values at 37,700 cm−1 in the range between the e- and the t-band. This result is discussed in the frame of existing interpretations of the 4f65d-configuration of Eu2+ in CaF2. 相似文献
610.
The optical absorption of (CH3NH3)2CuCl4 has been investigated at 300 K in the spectral range between 0.2 and 40 μm and down to 4.2 K between the optical absorption edge and 2.5 μm. Absorption has also been measured with polarized light, parallel or perpendicular to the crystal axes or a magnetic field. In addition the magnetic linear dichroism and the Faraday rotation has been investigated in function of frequency, magnetic field strength and temperature, as well above as below TC = 8.9 K. From the Faraday rotation one can evaluate the magnetization for T < TC and the susceptibility for T > TC. The discussion is made in terms of critical exponents of the susceptibility. A cross-over region could be determined above, but close to TC. The system changes from three dimensionality to two dimensional Ising. At higher temperatures only molecular field behavior is observed. 相似文献