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Steven M. Swick Tim Gebraad Dr. Leighton Jones Dr. Bo Fu Dr. Thomas J. Aldrich Prof. Kevin L. Kohlstedt Prof. George C. Schatz Prof. Antonio Facchetti Prof. Tobin J. Marks 《Chemphyschem》2019,20(20):2608-2626
Accurate single-crystal X-ray diffraction data offer a unique opportunity to compare and contrast the atomistic details of bulk heterojunction photovoltaic small-molecule acceptor structure and packing, as well as provide an essential starting point for computational electronic structure and charge transport analysis. Herein, we report diffraction-derived crystal structures and computational analyses on the n-type semiconductors which enable some of the highest efficiency organic solar cells produced to date, 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene ( ITIC ) and seven derivatives (including three new crystal structures: 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-propylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene ( ITIC-C3 ), 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(3-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene ( m -ITIC-C6 ), and 3,9-bis(2-methylene-((3-(1,1-dicyanomethylene)-6,7-difluoro)-indanone))-5,5,11,11-tetrakis(4-butylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophene ( ITIC-C4-4F ). IDTT acceptors typically pack in a face-to-face fashion with π–π distances ranging from 3.28–3.95 Å. Additionally, edge-to-face packing is observed with S⋯π interactions as short as 3.21–3.24 Å. Moreover, ITIC end group identities and side chain substituents influence the nature and strength of noncovalent interactions (e. g. H-bonding, π–π) and thus correlate with the observed packing motif, electronic structure, and charge transport properties of the crystals. Density functional theory (DFT) calculations reveal relatively large nearest-neighbor intermolecular π-π electronic couplings (5.85–56.8 meV) and correlate the nature of the band structure with the dispersion interactions in the single crystals and core–end group polarization effects. Overall, this combined experimental and theoretical work reveals key insights into crystal engineering strategies for indacenodithienothiophene (IDTT) acceptors, as well as general design rules for high-efficiency post-fullerene small molecule acceptors. 相似文献
73.
Viko Ladelta George Zapsas Yves Gnanou Nikos Hadjichristidis 《Journal of polymer science. Part A, Polymer chemistry》2019,57(24):2450-2456
New tricrystalline triblock terpolymers, polyethylene‐block‐poly(ε‐caprolactone)‐block‐poly(L‐lactide) (PE‐b‐PCL‐b‐PLLA), were synthesized by ROP of ε‐caprolactone (CL) and L‐lactide (LLA) from linear ω‐hydroxyl polyethylene (PE‐OH) macroinitiators. The linear PE‐OH macroinitiators were prepared by C1 polymerization of methylsulfoxonium methylide (polyhomologation). Tin(II) 2‐ethylhexanoate was used as the catalyst for the sequential ROP of CL and LLA in one‐pot polymerization at 85 °C in toluene (PE‐OH macroinitiators are soluble in toluene at 80 °C). 1H NMR spectra confirmed the formation of PE‐b‐PCL‐b‐PLLA triblock terpolymers through the appearance of the characteristic proton peaks of each block. GPC traces showed the increase in the number average molecular weight from PE‐OH macroinitiator to PE‐b‐PCL, and PE‐b‐PCL‐b‐PLLA corroborating the successful synthesis. The existence of three crystalline blocks was proved by DSC and XRD spectroscopy. © 2019 The Authors. Journal of Polymer Science Part A: Polymer Chemistry published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2450–2456 相似文献
74.
George Victor McIlvaine 《Expositiones Mathematicae》2019,37(3):333-346
This paper reports on findings relating to catenaries since the publication in Expositiones Mathematicae of Denzler and Hinz’s pioneering 1999 paper, Catenaria Vera – the True Catenary. New governing differential equations and explicit solutions are derived for the catenary in positive and negative radial potentials with physical constants incorporated in the derivations. In keeping with precedent by Denzler and Hinz, a measure of historical perspective is offered as homage to Gottfried Wilhelm Leibniz, Christiaan Huygens and Johann Bernoulli, the original first-solvers of the catenary. 相似文献
75.
Robert A. Skutnik Louis Lehmann Sergej Püschel-Schlotthauer George Jackson Martin Schoen 《Molecular physics》2019,117(20):2830-2845
ABSTRACTMonte Carlo simulations in the isothermal-isobaric ensemble are used to investigate the formation of an ordered, biaxial nematic phase in a binary mixture of thermotropic liquid crystals. The orientational dependence of the interaction between molecules of each pure component is the same as in the well-known Maier-Saupe model; each pure component of the mixture is therefore capable of forming a uniaxial nematic phase. For the interaction between molecules of different components, we use the same Maier-Saupe model but change the sign of the coupling constant. As a consequence a T-shaped arrangement of these molecules is energetically favoured. The formation of the biaxial phase occurs in two steps. At higher temperatures T, one of the components forms a uniaxial nematic phase whereas the other is in a quasi two-dimensional restricted isotropic liquid state. We develop a simple theoretical model to understand the high degree of (ostensible) nematic order in the latter. At lower T, the second component becomes nematic and then the entire mixture of the two compounds has biaxial symmetry. The biaxial nematic phase does not demix into domains rich in molecules of one or the other species. 相似文献
76.
In this article, we investigate the artistic puzzle of designing mathematics experiences (MEs) to engage young children with ideas of group theory, using a combination of hands-on and computational thinking (CT) tools. We elaborate on: (1) group theory and why we chose it as a context for young mathematicians’ experiences with symmetry and transformations; (2) our ME design principles of agency, access, surprise and audience; (3) the affordances of CT that complement our design principles; and (4) three ME variations we tested in grades 3–6 classrooms. We then reflect on the ME variations based on our design principles and the affordances of CT, and consider how the MEs may be further adapted and improved. 相似文献
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Borohydride supported on an ion exchange resin selectively reduced α,β-unsaturated nitroalkenes to nitroalkanes in high yields. The isolation of pure products by simple filtration is a key feature of this method. 相似文献