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981.
Louis A. Florence Edward C. Kinzel Robert L. Olmon James C. Ginn Markus B. Raschke Glenn D. Boreman 《Infrared Physics & Technology》2012,55(6):449-453
Tapered slot antennas (TSAs) consist of a planar non-resonant structure which couples incident radiation to a propagating waveguide mode. They are commonly used at microwave and radio frequencies because they are fundamentally broadband and have small profiles. Because of their planar layout and broadband response they have recently been scaled to infrared frequencies where they have advantages for sensing and energy harvesting. We use scattering-type scanning near-field optical microscopy (s-SNOM) to study the mode transformation of two types of TSA operating in the thermal infrared (λ0 = 10.6 μm) with respect to electric field amplitude and phase. The results agree well with simulation showing both the phase reversal across the tapered slot and the traveling of wave fronts along the tapered slot, yet they also reveal high sensitivity of device performance to inhomogeneities in the geometry or illumination. This study will aid future design and analysis of practical non-resonant antennas operating at optical and infrared frequencies. 相似文献
982.
Ultrastrong coupling is studied in a modulation-doped parabolic potential well coupled to an inductance-capacitance resonant circuit. In this system, in accordance to Kohn's theorem, strong reduction of the energy level separation caused by the electron-electron interaction compensates the depolarization shift. As a result, a very large ratio of 27% of the Rabi frequency to the center resonance frequency as well as a polariton gap of width 2π × 670 GHz are observed, suggesting parabolic quantum wells as the system of choice in order to explore the ultrastrong coupling regime. 相似文献
983.
984.
Florian Bruckner Christoph Vogler Michael Feischl Dirk Praetorius Bernhard Bergmair Thomas Huber Markus Fuger Dieter Suess 《Journal of magnetism and magnetic materials》2012
3D magnetostatic Maxwell equations are solved using the direct Johnson–Nédélec FEM–BEM coupling method and a reduced scalar potential approach. The occurring BEM matrices are calculated analytically and approximated by H-matrices using the ACA+ algorithm. In addition a proper preconditioning method is suggested that allows to solve large-scale problems using iterative solvers. 相似文献
985.
Hamacek J Poggiali D Zebret S El Aroussi B Schneider MW Mastalerz M 《Chemical communications (Cambridge, England)》2012,48(9):1281-1283
A new tripodal ligand has been designed by connecting pyridine-based coordination units to a rigid triptycene moiety. Its reaction with europium(III) provides three-dimensional tetranuclear edifices, whose structural and photophysical characteristics as well as host-guest interactions are discussed in this contribution. 相似文献
986.
Jiang L Yan Y Drechsler M Huang J 《Chemical communications (Cambridge, England)》2012,48(59):7347-7349
We present here a host-guest approach to construct enzyme-triggered assembly systems on the basis of surfactant-cyclodextrin complexes and α-amylase. We realized enzyme-responsive model self-assembly systems including monolayers, micelles, and vesicles. The host-guest approach is expected to be extended to more complicated assembly systems with widespread applications. 相似文献
987.
Cruz H Fanselow M Holbrey JD Seddon KR 《Chemical communications (Cambridge, England)》2012,48(45):5620-5622
Using in situ viscosity measurement, the rate of cellulose dissolution in a number of ionic liquids has been determined allowing their performance as solvents to be quantitatively assessed. 1-Butyl-3-methylimidazolium ethanoate was shown to dissolve cellulose faster than analogous ionic liquids with chloride or dimethylphosphate anions. Analysis of the data highlights the influence of both anion basicity and relative concentration on the rate of dissolution. 相似文献
988.
Grammel M Dossa PD Taylor-Salmon E Hang HC 《Chemical communications (Cambridge, England)》2012,48(10):1473-1474
Orthogonal amino acid reporters allow the selective labeling of different cell types in heterogeneous populations through the expression of engineered aminoacyl tRNA synthetases. Here, we demonstrate that para-ethynylphenylalanine (PEP) can be used as an orthogonal amino acid reporter for efficient selective labeling of an intracellular bacterial pathogen during infection. 相似文献
989.
Schneider MN Fahrnbauer F Rosenthal T Döblinger M Stiewe C Oeckler O 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(4):1209-1218
The isostructural phases 39R‐Ge0.067Sb0.667Te0.266 (R$\bar 3The isostructural phases 39R-Ge(0.067)Sb(0.667)Te(0.266) (R3m, a=4.2649(1), c=75.061(2) ?) and 39R-Sn(0.067)Sb(0.667)Te(0.266) (R3m, a=4.2959(1), c=75.392(2) ?) were prepared by quenching stoichiometric melts of the pure elements and subsequent annealing at moderate temperatures. Their structures are comparable to "superlattices" synthesized by layer-by-layer deposition onto a substrate. These structures show no stacking disorder by electron microscopy. The structure of the metastable layered phases are similar to that of 39R-Sb(10)Te(3) (equivalent to Sb(0.769)Te(0.231)), which contains four A7 gray-arsenic-type layers of antimony alternating with Sb(2)Te(3) slabs. Joint refinements on single-crystal diffraction data using synchrotron radiation at several K edges were performed to enhance the scattering contrast. These refinements show that the elemental distributions at some atom positions are disordered whereas otherwise the structures are long-range ordered. The variation of the elemental concentration correlates with the variation in interatomic distance. Z-contrast scanning transmission electron microscopy (HAADF-STEM) on 39R-Ge(0.067)Sb(0.667)Te(0.266) confirms the presence of concentration gradients. The carrier-type of the isostructural metal (A7-type lamellae)-semiconductor heterostructures (Ge/Sn-doped Sb(2)Te(3) slabs) varies from n-type (Ge(0.067)Sb(0.667)Te(0.266)) to p-type (Sn(0.067)Sb(0.667)Te(0.266)). Although the absolute values of the Seebeck coefficient reached about 50-70 μV/K and the electrical conductivity is relatively high, the two isotypic phases exhibit a maximal thermoelectric figure of merit (ZT) of 0.06 at 400 °C as their thermal conductivity (κ≈8-9.5 W/mK at 400 °C) lies interestingly in between that of antimony and pure Sb(2)Te(3). 相似文献
990.
Dr. Chang‐Qi Ma Dr. Elena Mena‐Osteritz Dr. Markus Wunderlin Dr. Gisela Schulz Prof. Dr. Peter Bäuerle 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(40):12880-12901
The synthesis of generational dendritic oligothiophenes (DOTs) has been successfully achieved by a divergent/convergent approach that involves halogenation, boronation, and palladium‐catalyzed Suzuki coupling reactions. The key point in the presented synthetic approach is the use of trimethylsilyl (TMS) protecting groups, which allow for the core‐lithiation and subsequent boronation of the dendrons and for the peripheral ipso‐substitution with iodine monochloride or N‐bromosuccimide. In addition, the TMS protecting groups can be completely removed by using tetrabutylammonium fluoride, thus yielding only‐thiophene‐based dendrons and dendrimers. Due to their highly branched structure, all these synthesized DOTs are soluble in organic solvents. Chemical structures were confirmed by NMR spectroscopic, mass spectrometric, and elemental analysis. Concentration‐dependent 1H NMR spectroscopic investigations revealed that the higher generation compounds tend to aggregate in solution. Such an aggregation behavior was further confirmed by measuring with MALDI‐TOF MS. Both MALDI‐TOF MS and gel‐permeation chromatography (GPC) analyses confirmed the monodispersity of the DOTs. Furthermore, GPC results revealed that these DOT molecules adopt a condensed globular molecular shape. Their optical and electronic properties were also investigated. The results indicated that these DOTs comprise various conjugated α‐oligothiophenes with different chain lengths, which results in the higher generation compounds showing broad and featureless UV/Vis absorption spectra and ill‐defined redox waves. 相似文献