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51.
Effect of Te doping on superconductivity and charge-density wave in dichalcogenides 2H-NbSe2-xTex (x = 0, 0.1, 0.2) 下载免费PDF全文
Single crystals of Te-doped dichalcogenides 2H-NbSe2-xTex (x ---- 0, 0.10, 0.20) were grown by vapour transport method. The effect of Te doping on the superconducting and charge-density wave (CDW) transitions has been investigated. The sharp decrease of residual resistance ratio, RRR = R(3OOK)/R(SK), with increasing Te content was observed, indicating that the disorder in the conducting plane is induced by Te doping. Meanwhile the superconducting transition temperature, Tc, decreases monotonically with Te content. However, the CDW transition temperature, TCDW, shown by a small jump in the temperature dependence of the resistivity near 30 K, increases slightly. The results show that the suppression of superconductivity might be caused by the enhancement of CDW ordering. The disorder has little influence on the CDW ordering. 相似文献
52.
Rana Saha A.K. Bera Y. Sundarayya S.M. Yusuf A. Sundaresan C.N.R Rao 《Journal of solid state chemistry》2011,184(3):494-9532
Magnetic properties of the Al1−xGaxFeO3 family of oxides crystallizing in a non-centrosymmetric space group have been investigated in detail along with structural aspects by employing X-ray and neutron diffraction, Mössbauer spectroscopy and other techniques. The study has revealed the occurrence of several interesting features related to unit cell parameters, site disorder and ionic size. Using first-principles density functional theory based calculations, we have attempted to understand how magnetic ordering and related properties in these oxides depend sensitively on disorder at the cation site. The origin and tendency of cations to disorder and the associated properties are traced to the local structure and ionic sizes. 相似文献
53.
M. Boschmans 《Phase Transitions》2013,86(1-4):237-244
A new experimental technique is described for the measurement of local birefringence and molecular orientation in liquid crystals. This technique consists in analyzing the local channeled spectra obtained by optical polarising microscopy. 相似文献
54.
55.
We propose a formalism for the study of mean resistance of a one dimensional chain of random potentials. We obtain the resistance
as a function of the length of the chain. In the asymptotic limit, this is related to the wavefunction envelope. The formalism
demands loss of translational symmetry, but is general enough to include potentials with spatial correlations which are not
long ranged and also those whose randomness is inhomogeneous. 相似文献
56.
Beverly Brooks Hinojosa 《Journal of solid state chemistry》2010,183(1):262-4974
To clarify the role of A2O′ and B2O6 networks on cation displacement observed in Bi2Ti2O′O6, we used density functional theory calculations to examine the effect of sulfur substitution on the O′ and O sites on lone pair formation and resulting atomic displacement observed in Bi2Ti2O′O6. Cation displacement in bismuth titanate is suppressed only when S is substituted on the O′ site. Analysis of the electronic structure shows that S substitution on the O′ site suppresses the formation of the asymmetric p-type lone pair by modifying the Bi-anion hybridization. Lone pair formation is favored in Bi2Ti2O′S6 and the atomic displacement is larger than that observed in Bi2Ti2O′O6. This enhanced displacement is due to weaker Bi-S versus Bi-O interactions leading to significantly stronger hybridization between the Bi and O′ states in Bi2Ti2O′S6. We also induced lone pair formation in a metallic bismuth pyrochlore oxide (Bi2Ru2O′O6) by modifying the Bi-O interactions through S substitution on the B2O6 network, indicating atomic displacement on the A2O′ network may be achieved by modifying the B2O6 network. 相似文献
57.
The boron atom in C22H15BO5 is O,O’-chelated by the anions in a tetrahedral geometry, with the planar five-and six-membered chelate rings being orthogonal to each other. The molecule lies on a two-fold rotation axis. The molecule is disordered with respect to another molecule in a 93:7 ratio; the treatment of the ‘whole-molecule disorder’ by employing a large number of restraints is described. Crystal data: C22H15BO5, monoclinic C2/c, a = 17.1804(5), b = 12.9409(4), c = 9.8842(3) , β = 124.832(2)o, V = 1803.82(9) 3 at –173 K. 相似文献
58.
J. B. Gosk 《Crystal Research and Technology》2010,45(5):465-478
To investigate the one‐dimensionally disordered structures (ODDS) in the close packed (cp) crystals, the Monte Carlo computer simulation technique has been applied. Calculations of the diffraction intensity distributions along the 10.L reciprocal lattice row from the 6H(33) structure with the four different kinds of the stacking faults (SFs): growth, deformation, layer displacement and extrinsic fault are presented. In particular, using the simple frequency functions of the fault to fault distances, both random and non‐random distributions of the SFs are considered. Distinctive features of the diffraction patterns corresponding to the chosen examples of the transformations from the parent 6H(33) structure into another small‐period polytypes are discussed in detail. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
59.
We study the connection between the martingale and free-boundary approaches in sequential detection problems for the drift of a Brownian motion, under the assumption of exponential penalty for the delay. By means of the solution of a suitable free-boundary problem, we show that the reward process can be decomposed into the product between a gain function of the boundary point and a positive martingale inside the continuation region. 相似文献
60.
采用时域有限差分法数值求解Maxwell方程组,分析了平面随机介质中光波模式的频谱时间演化特性.随机介质的特征可以用散射颗粒的随机构形、介质参数(如颗粒的尺寸和填充率等)以及介质形态等因素来描述.这些因素决定了随机介质在准稳态下模式的频率特性与数量,但具有不同因素的随机介质中模式的产生、选择与演化,具有大致相同的特征与速度.平面随机介质的这些冷腔特性,与传统光腔中模式的产生、选择和演化的特征非常相似.
关键词:
激光物理
随机激光器
无序介质中的光学特性 相似文献