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11.
Photophysics of Calix[4]biscrown-Based Ditopic Receptors of Caesium Containing One or Two Dioxocoumarin Fluorophores 总被引:1,自引:0,他引:1
The ditopic receptors Calix-COU1 and Calix-COU2 consist of a calix[4]biscrown containing one or two dioxycoumarin fluorophores, respectively, inserted into the crown. They can form 1:1 and 2:1 (metal:ligand) complexes with caesium ions. The photophysical properties of the 1:1 complexes can be explained by (i) cation tunneling through the tube-shaped cavity (composed of the four phenyl rings) of the calix[4]biscrown, (ii) photodisruption of the interaction between the bound cation and the oxygen atoms belonging to both the coumarin moiety and the crown, (iii) photoinduced motions of the cation. 相似文献
12.
Dmytro Strilets Dr. Shixin Fa Arthur Hardiagon Dr. Marc Baaden Prof. Tomoki Ogoshi Dr. Mihail Barboiu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(51):23413-23419
Artificial water channels mimicking natural aquaporins (AQPs) can be used for selective and fast transport of water. Here, we quantify the transport performances of peralkyl-carboxylate-pillar[5]arenes dimers in bilayer membranes. They can transport ≈107 water molecules/channel/second, within one order of magnitude of the transport rates of AQPs, rejecting Na+ and K+ cations. The dimers have a tubular structure, superposing pillar[5]arene pores of 5 Å diameter with twisted carboxy-phenyl pores of 2.8 Å diameter. This biomimetic platform, with variable pore dimensions within the same structure, offers size restriction reminiscent of natural proteins. It allows water molecules to selectively transit and prevents bigger hydrated cations from passing through the 2.8 Å pore. Molecular simulations prove that dimeric or multimeric honeycomb aggregates are stable in the membrane and form water pathways through the bilayer. Over time, a significant shift of the upper vs. lower layer occurs initiating new unexpected water permeation events through toroidal pores. 相似文献
13.
Natalia Selivanova Aidar Gubaidullin Pavel Padnya Ivan Stoikov Yuriy Galyametdinov 《Liquid crystals》2019,46(3):415-421
Supramolecular organised materials were prepared from nonionic surfactants and the following macrocyclic ionic liquids: n-tert-butylthiacalix[4]arenes containing quaternary ammonium fragments with amino acid substituents. Tetraethylene glycol monododecyl ether and decadiethylene glycol monododecyl ether were used as nonionic surfactants. They form lamellar and hexagonal mesophases in aqueous media, respectively. Liquid crystal and structural properties of these systems were studied. Intermolecular interactions of system components leading to formation of lyomesophases were estimated. Molecular structure of thiacalixarene contributes to the formation of a hydrogen bonding with surfactants. This process, in turn, initiates formation of a denser packed hexagonal structure. 相似文献
14.
Calixarenesareregardedasthethirdgenerationofh0stmoleculesbecauseoftheirinclusionabilitytocati0ns,anionsandneutralmoleculesI'2.Duringthepastdecademosteff0rtshavebeentakenonthefunctionalizati0n0fcalixareness0thattheycanbeappliedn0tonlyastheionoph0resintheextractionprocess','andassensitivematerialsforionelectrodes"',butalsoastheenZymemimicscatalyzingthecleavageofphosphatediesters"'.Inordertoenablethemtoincludeandrecognizelargerchemicalspecies,manyappr0acheshavebeenusedtoc0nstructoIigo-calixarene… 相似文献
15.
16.
A novel photochromic Schiff base derivative, 5,17-N,N′-(5,5′-di-methoxyl-benzlaldehyde)diimine-25,27-dipropoxy-calix[4]arene has been synthesized through incorporation of two imine groups into the upper rims of calix[4]arene. The experiments showed that the addition of Dy3+ or Er3+ ions to compound 4 results in the solution color change, but other metal ions caused less change. It indicated that the synthetic receptor can selectively recognize Dy3+ and Er3+ ion by naked eye over other lanthanide cations. Thus, these systems can be applied as chemosensor for Dy3+ and Er3+ ion in analytical chemistry. 相似文献
17.
Yong S. Chong Dr. William R. Carroll William G. Burns Mark D. Smith Ken D. Shimizu Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(36):9117-9126
An atropisomeric molecular balance was developed to study face‐to‐face arene–arene interactions. The balance has a large central 1,4,5,8‐naphthalene diimide surface that forms intramolecular arene–arene interactions with two pendent arms. The balance adopts distinct syn and anti isomers with varying numbers of intramolecular interactions. Thus, the strength of the arene–arene interaction could be quantitatively measured by NMR spectroscopy from the anti/syn ratios. The size of the arene arms was easily varied, which allowed examination of the relationship between arene size and strength of the interaction. A nonlinear size dependence was observed in solution with larger arene arms having a disproportionately stronger arene–arene interaction. The intramolecular arene–arene interactions were also characterized in the solid state by X‐ray crystallography. These studies were facilitated by the kinetic stability of the syn and anti isomers at room temperature due to the high isomerization barrier (ΔG=27.0 kcal mol?1). Thus, the anti isomer could be selectively isolated and crystallized in its folded conformation. The X‐ray structures confirmed that the anti isomers formed two strong intramolecular arene–arene interactions with face‐to‐face geometries. The solid‐state structure analysis also reveals that the rigid framework may contribute to the observed nonlinear size trend. The acetate linker is slightly too long, which selectively destabilizes the balances with smaller arene arms. The larger arene arms are able to compensate for the longer linker and form effective intramolecular arene–arene interactions. 相似文献
18.
Chong Wu Jiang-Lin Zhao Xue-Kai Jiang Xin-Long Ni Xi Zeng Carl Redshaw Takehiko Yamato 《Analytica chimica acta》2016
A new type of chemosensor-based approach to the detection of 2,4,6-trinitrophenol (TNP) is described in this paper. Two hexahomotrioxacalix[3]arene-based chemosensors 1 and 2 were synthesized through click chemistry, which exhibited high binding affinity and selectivity toward TNP as evidenced by UV–vis and fluorescence spectroscopy studies. 1H NMR titration analysis verified that CH?O hydrogen bonding is demonstrated as the mode of interaction, which possibly facilitates effective charge-transfer. 相似文献
19.
An efficient, straightforward and environmentally benign process has been developed for the synthesis of fluorenone and 1-tetralone derivatives using cyclic 1,3-dione, malononitrile and dialkylacetylenedicarboxylate as starting materials in aqueous medium. The reaction is favoured in presence of resorcin[4]arene which is effective as a reusable organocatalyst. The catalyst has been easily synthesized and characterized by 1H, 13C NMR, IR, XRD and HRMS analyses. Resorcin[4]arene afforded the resulted products in a shorter time and in good yields. The recyclability of the catalyst was established up to 6th cycle by FT-IR and SEM images. 相似文献
20.
Access to the Bis‐benzene Cobalt(I) Sandwich Cation and its Derivatives: Synthons for a “Naked” Cobalt(I) Source? 下载免费PDF全文
Stefan C. Meier Albina Holz Jan Kulenkampff Alexei Schmidt Dr. Daniel Kratzert Dr. Daniel Himmel Dominik Schmitz Dr. Ernst‐Wilhelm Scheidt Prof. Dr. Wolfgang Scherer Dr. Christine Bülow Martin Timm Dr. Rebecka Lindblad Dr. Scott T. Akin Dr. Vicente Zamudio‐Bayer Prof. Dr. Bernd von Issendorff Prof. Dr. Michael A. Duncan Prof. Dr. J. Tobias Lau Prof. Dr. Ingo Krossing 《Angewandte Chemie (International ed. in English)》2018,57(30):9310-9314
The synthesis and structural characterization of the hitherto unknown parent Co(bz)2+ (bz=benzene) complex and several of its derivatives are described. Their synthesis starts either from a CoCO5+ salt, or directly from Co2(CO)8 and a Ag+ salt. Stability and solubility of these complexes was achieved by using the weakly coordinating anions (WCAs) [Al(ORF)4]? and [F{Al(ORF)3}2]? {RF=C(CF3)3} and the solvent ortho‐difluorobenzene (o‐DFB). The magnetic properties of Co(bz)2+ were measured and compared in the condensed and gas phases. The weakly bound Co(o‐dfb)2+ salts are of particular interest for the preparation of further CoI salts, for example, the structurally characterized low‐coordinate 12 valence electron Co(PtBu3)2+ and Co(NHC)2+ salts. 相似文献