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501.
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503.
Kerstin Schulze‐Matthi Jürgen Bendig Petra Neubauer Burkhard Ziemer 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):e257-e258
The bonding geometry of sulfur in the cations of the title compounds, C8H11S+·CF3SO3? and C13H13S+·CF3SO3?, respectively, is similar and is independent of the ratio of the Me/Ph substituents. As expected, in both cations, the S—Ph bonds are somewhat shorter than the S—Me bonds. In both crystal structures, the interaction between cations and anions is similar. 相似文献
504.
Karsten Gloe Bieluonwu A. Uzoukwu Otto Rademacher 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(12):e580-e581
The title compound, C12H12O2N2·H2O, is described. Although the keto–enol form of the ligand in solution is known, the compound crystallized in the orthorhombic space group P212121 with only the monohydrated 1,3‐diketo form. The intermolecular hydrogen bond between the imino N—H group of the ligand and O atom of the water molecule recorded an H?O distance of 1.73 (3) Å. 相似文献
505.
ČtyrokÝ JiŘÍ Abdelmalek Fethi Ecke Wolfgang Usbeck Kerstin 《Optical and Quantum Electronics》1999,31(9-10):927-941
The operation of a novel device – a waveguide surface plasmon resonance sensor with a UV-written Bragg grating – is theoretically analysed using two methods. In the simple perturbation approach, the metal/dielectric layer system supporting the resonance excitation of the surface plasma wave is considered to be a perturbation of the original dielectric waveguide with Bragg grating that is analysed using a coupled-mode theory. The second approach consists of the rigorous method of bi-directional mode expansion and propagation using the Floquet mode formalism developed recently for the analysis of waveguide grating structures. The results of both approaches are mutually compared, and the operation characteristics of this novel sensing device are briefly described. 相似文献
506.
Christina Allmeling Kerstin Reimers‐Fadhlaoui Peter M. Vogt 《Chemie in Unserer Zeit》2007,41(6):428-434
The experimental data show that the production of artificial nerve grafts with spider silk is a potential alternative therapy. The biologically favourable properties of the fibres from the spider Nephila clavipes should be used in human nerve reconstruction. The biological fibres promote the proliferation of cells. They are immunologically tolerated and not rejected. The muscle attraction line is kept intact which prevents muscle degeneration to a large extent. The spider fibres accelerate the migration of peripheral schwann cells into the nerve construct and promote the alignment of the nerve cells. For surgical interventions the biomechanical stability of spider silk and the composition from essential amino acids make the spider silk fibres interesting as a matrix for the cellular regeneration and in particular as a guiding structure for nerve regeneration. 相似文献
507.
508.
Bianca Antonioli David J. Bray Jack K. Clegg Katrina A. Jolliffe Kerstin Gloe Karsten Gloe Leonard F. Lindoy 《Polyhedron》2007
Three copper(II) complexes derived from 2-(hydroxymethyl)pyridine (LH) have been synthesised and a comparative X-ray investigation of their respective crystal structures undertaken. In the absence of added base, LH reacts with copper(II) chloride or nitrate to yield the five-coordinate [Cu(LH)2Cl]Cl and six-coordinate [Cu(LH)2(NO3)2] species. In the chloro complex the coordination geometry is distorted trigonal bipyramidal, with the pyridyl nitrogens occupying the axial position and two hydroxyl oxygens from the bidentate ligands together with a chloro group occupying the equatorial sites. The structure of the nitrate species, published previously, has been reinvestigated at low temperature in order to specify the weak interactions in the crystal; it contains two molecules of bidentate LH bound trans in the equatorial plane while monodentate nitrato ligands occupy the axial sites. In each of these complexes the hydroxyl protons act as hydrogen bond donors, interacting with the non-coordinated chloride anion in [Cu(LH)2Cl]Cl and the coordinated nitrato groups in [Cu(LH)2(NO3)2] to form bridged, hydrogen-bonded, copper(II)-organic arrays in each case; offset face-to-face π-stacking in the latter produces a two dimensional structure. Further weak CH?Cl, CH?O interactions stabilise both arrangements. The X-ray structure of the complex [Cu(L)2] · 4H2O containing the deprotonated ligand is also described. The presence of the latter results in the above hydrogen bonding arrangements being ‘switched off’ and instead a new two-dimensional network involving bridging tetrameric water clusters hydrogen bound to adjacent ligand hydroxo groups to give extended sheets is generated; offset face-to-face π-stacking occurs between sheets to yield a three dimensional array. 相似文献
509.
Starting from Merrifield resin, 2-formylbenzoic acids were immobilized on solid supports. Reactions between immobilized 2-formylbenzoic acids and different organometallic reagents (Grignard reagents, zinc reagents, allyl silanes via Sakurai type reactions) furnished secondary alcohols which cyclized depending on the metal counter ion and reaction conditions, forming benzoannelated lactones. Asymmetric synthesis was possible on the resin using chiral [2.2]paracyclophane ligands. While the reaction of immobilized ortho-carboxy benzaldehydes with primary amines at elevated temperatures yielded 3-hydroxyisoindolinones, a reaction at ambient temperature allowed imine formation, which underwent 1,2-addition-cleavage reaction with various nucleophiles, yielding isoindolinones with three points of diversity. 相似文献
510.
Gasperov V Gloe K Lindoy LF Mahinay MS 《Dalton transactions (Cambridge, England : 2003)》2004,(22):3829-3834
Host-guest formation between 1,4,8,11-tetrabenzyl-1,4,8,11-tetraazacyclodecane (1) and lipophilic organic carboxylic acids in chloroform has been investigated and the effect of such ligand assembly on the solvent extraction of copper(II) and silver(I) has been probed. NMR titration experiments in the absence of a metal ion confirm the formation of weak 1:1 and 1:2 (macrocycle:carboxylic acid) assemblies in CDCl(3) between 1 and palmitic (hexadecanoic) acid or 4-tert-butylbenzoic acid while difunctional salicylic acid showed a 1 [ratio] 2 interaction that is somewhat stronger. The interaction between the former two acids and the tetra-N-benzylated macrocycle is significantly less than that reported previously for its non-substituted parent, cyclam; a result that likely reflects the presence of the less-basic, more sterically hindered tertiary nitrogens in 1 relative to the secondary nitrogens present in cyclam. Carboxylic acid-containing assemblies of this type have been used as extractants in a series of solvent extraction (water/chloroform) experiments. From both previous observations as well as from entropy considerations, it was anticipated that the use of a host-guest assembly of the above type for metal-ion complexation might contribute to enhanced metal ion binding (and concomitant enhanced metal ion extraction). Such behaviour is postulated to arise from the components of the coordination sphere being, at least in part, assembled for complex formation. In accord with this, the use of the ligand assembly involving palmitic acid/macrocycle 1 was found to lead to enhanced (synergistic) extraction of copper(II) at a metal ion concentration of 10(-3) mol dm(-3) while, for silver(I), synergism was somewhat marginal at this concentration but was clearly apparent under related conditions when the silver concentration was reduced to 10(-4) mol dm(-3). Similar behaviour towards silver was also observed when 4-tert-butylbenzoic acid was substituted for palmitic acid, while the use of salicylic acid resulted in enhanced (synergistic) extraction at both metal ion concentrations. 相似文献