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81.
Mats Johansson Mikael Trollss Anders Hult 《Journal of polymer science. Part A, Polymer chemistry》1992,30(10):2203-2210
A series of allyl ether-maleate functional star-shaped esters with from one to four arms has been synthesized. The structures that have been made are an analogous series with increasing molecular weight and functionality where the increase in molecular weight has been made nonlinear, i.e., star-shaped. The resins are monodisperse in the sense that each arm has a well-defined structure and that, within a certain sample, only one type of molecule exists. The viscosity and rheological behavior of the resins have been studied. The curing kinetics of the star-shaped (branched) resins and the properties of the films formed have also been studied. These properties have been related to differences in functionality and to differences in the molecular architecture of the resins. © 1992 John Wiley & Sons, Inc. 相似文献
82.
A new polyoxomolybdate complex HNa7[Mo36O112(H2O)16]·47H2O 1 has been prepared in the beaker solution and characterized by single-crystal X-ray diffraction and elemental analyses. Crystal data: H127Mo36Na7O175, Mr = 6542.79, monoclinic, C2/c, a = 40.891(6), b =17.900(3), c = 25.580(4) (A), β = 125.673(2)°, V = 15210(4)(A)3, Z = 4, Dc = 2.857 g/cm3, F(000) =12464, μ = 3.013 mm-1, R = 0.0633 and wR = 0.1654 (I> 2σ(Ⅰ)). With the bridging sodium cations,the [Mo36O112(H2O)16]8- units in compound 1 are linked to form a one-dimensional structure, on the basis of which a three-dimensional architecture is further constructed via other sodium cations and complicated hydrogen bonds. 相似文献
83.
蔡丽 《宁波大学学报(理工版)》2006,19(2):257-259
通过对中国传统建筑体系的再认识和反思,认清中国建筑的现状,走出认识的误区,思索中国现代建筑的发展方向. 相似文献
84.
In this paper, we introduce a mixed- analog-to-digital converter (ADC) architecture for massive multiple-input multiple-output (MIMO) systems and study the system’s performance mainly includes the achievable spectral efficiency and energy efficiency. In principle, the mixed-ADC architecture permits the one part of antennas at the base station (BS) are connected to speed and expensive full-resolution ADCs and the remaining part of the antennas are connected to the cheap low-resolution ADCs. By applying the general maximum-ratio combining detector, a tractable approximate expression for the achievable SE is obtained. Leveraging on the derived results, the effects of the number of BS antennas and the percent of the full-resolution ADCs on the achievable SE are investigated. Results show that the achievable SE increases with the percent of the full-resolution ADCs and the number of BS antennas. Based on a realistic power consumption model, we evaluate the energy efficiency for the considered mixed-ADC architecture. Moreover, under the certain achievable SE constraint, we maximize the energy efficiency by adjusting the number of low-resolution ADCs and the resolution bits of the corresponding ADC device. Numerical results showcase that the energy efficiency can be improved by enhancing the average transmitted power, and there exists an optimal number of resolution bits and the number of antennas to maximize the energy efficiency, which indicates that the application of mixed-ADC architecture has a great potential in future mobile communication system. 相似文献
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88.
Jureepan Piromchom Jintana Othong Jaursup Boonmak Ilpo Mutikainen Sujittra Youngme 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(12):1057-1061
The design and synthesis of metal coordination and supramolecular frameworks containing N‐donor ligands and dicyanidoargentate units is of interest due to their potential applications in the fields of molecular magnetism, catalysis, nonlinear optics and luminescence. In the design and synthesis of extended frameworks, supramolecular interactions, such as hydrogen bonding, π–π stacking and van der Waals interactions, have been exploited for molecular recognition associated with biological activity and for the engineering of molecular solids.The title compound, [Ag(CN)(C12H12N2)]n, crystallizes with the AgI cation on a twofold axis, half a cyanide ligand disordered about a centre of inversion and half a twofold‐symmetric 5,5′‐dimethyl‐2,2′‐bipyridine (5,5′‐dmbpy) ligand in the asymmetric unit. Each AgI cation exhibits a distorted tetrahedral geometry; the coordination environment comprises one C(N) atom and one N(C) atom from substitutionally disordered cyanide bridging ligands, and two N atoms from a bidentate chelating 5,5′‐dmbpy ligand. The cyanide ligand links adjacent AgI cations to generate a one‐dimensional zigzag chain. These chains are linked together via weak nonclassical intermolecular interactions, generating a two‐dimensional supramolecular network. 相似文献
89.
Self-assembly of Zn(NO3)2·6H2O and 2,3,5,6-tetrabromoterephthalic acid(H2TBTA) gave rise to two new zinc metal-organic frameworks,Zn(HTBTA)2(phen)2·H2O(1) and Zn(TBTA)1/2(μ2-OH)(H2O)·0.25EtOH(2).Complex 1 is a mononuclear molecule.The hydrogen bonding interactions further connect the mononuclear molecules to generate a 2D supramolecular architecture.Complex 2 is a 2D organic-inorganic hybrid layer framework constructed from 1D rod-shaped secondary building units. 相似文献
90.
Judit E. Puskas Yaohong Chen Kevin Kulbaba Gabor Kaszas Ali Soleymannezhad 《Journal of polymer science. Part A, Polymer chemistry》2006,44(5):1770-1776
This article discusses the characterization of arborescent (hyperbranched) polyisobutylenes (arb‐PIBs) by size exclusion chromatography and differential scanning calorimetry, in comparison with linear PIB standards. The radius of gyration (〈r〉1/2 = Rz), measured from the angle dependence of light scattering of high‐molecular‐weight arb‐PIBs, was significantly larger than the hydrodynamic radius (Rh) from size exclusion chromatography/viscometry, and the Rh values were significantly smaller than Rh of linear PIBs. The glass‐transition temperature of arb‐PIBs having a branch molecular weight higher than the critical entanglement molecular weight was dependent on both the total number‐average molecular weight and BR up to BR ~ 15. A modified Fox–Flory equation is proposed to describe the effect of architecture on the thermal transition. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1770–1776, 2006 相似文献