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101.
102.
Ferrocenyl bridged bisaminopyridines were synthesized from 2‐bromopyridine or 2‐bromo‐4‐methylpyridine and 1,1'‐diaminoferrocene using palladium catalysed aryl amination. X‐ray crystal structure analysis of the two bisaminopyridines revealed the formation of dimers in the solid state. The formation of the dimers occurs via four H‐bonds between the amino N‐H function and the pyridine nitrogen atoms. 相似文献
103.
Isocyanato‐ ( 1a ), 1,1′‐di(isocyanato)‐ ( 2a ), isothiocyanato‐ ( 1b ), 1,1′‐di(isothiocyanato)‐ ( 2b ), isoselenocyanato‐ ( 1c ) and 1,1′‐di(isoselenocyanato)ferrocene ( 2c ) were prepared and studied by 1H, 13C and 14N NMR spectroscopy. Isocyanatoferrocene ( 1a ) trimerizes upon chromatography on alumina to give 3a . The molecular structures of 2c and 3a were determined by X‐ray analysis, and almost undistorted ferrocene‐like structures were found in both cases. 相似文献
104.
Heidi M. French Mark J. Henderson A. Robert Hillman Eric Vieil 《Journal of Electroanalytical Chemistry》2001,500(1-2)
A combined electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD) instrument was used to monitor the mobile species transfers associated with the redox processes of thin (Γ100–150 nmol cm−2) α- and β-nickel hydroxide films exposed to aqueous LiOH solution. A comparison of the measured PBD signal with the predicted PBD profiles, calculated by temporal convolution analysis of the current and mass responses, enabled the contributions to redox switching of anion (OH−) and solvent (H2O) transfers to be discriminated quantitatively. The responses from the combined instrument are reconciled in terms of H+ deintercalation/intercalation within the nickel hydroxide structure as OH− ions enter/exit the film. Hydroxide ion movement is associated with a counterflux of water. Thin nickel hydroxide films show a gradual α→β phase transformation with continuous voltammetric cycling, especially when the films are exposed to high concentrations of electrolyte. α-Films are characterised by OH− transfers that dominate the H+ and H2O movements; β-films are characterised by an increased participation of water and protons to the exchange dynamics. 相似文献
105.
106.
Seland JG Bruvold M Anthonsen H Brurok H Nordhøy W Jynge P Krane J 《Magnetic resonance imaging》2005,23(2):353-354
We have used combined D-T1 and T1-T2 correlation experiments to explore water compartments in rat heart tissue (myocardium). The results show that two main compartments can be identified, which we assign to extracellular (ec) and intracellular (ic) water. The exchange rate of water across the cell membrane was found to be on the order of 0.1 Hz. In addition, the T1-T2 correlation measurements indicate that the ic compartment contain two T2 populations. 相似文献
107.
Vankrunkelsven S Clicq D Pappaert K Ranson W De Tandt C Ottevaere H Thienpont H Baron GV Desmet G 《Electrophoresis》2004,25(10-11):1714-1722
We report on a series of preliminary experiments investigating the applicability of a novel method for the size separation of nano- and microsized particles and cells. The working principle is based on the application of a shear-driven flow through stepwise tapered micro- or nanochannels. Size separations of mixtures of 0.5 and 1.0 microm carboxylated polystyrene beads as well as of binary mixtures of Staphylococcus aureus and Saccharomyces cerevisiae cells and of S. cerevisiae and Escherichia coli cells are demonstrated. 相似文献
108.
Over a range of conditions, lipid and surfactant monolayers exhibit coexistence of discrete solid domains in a continuous liquid. The surface shear viscosity, mu(s), of such monolayers collapses onto a single curve: mu(s)/mu(so) = [1-(A/A(c))](-1), in which mu(so) is the viscosity of the liquid phase, A is the area fraction of the solid phase measured by fluorescence microscopy, and A(c) is a critical solid phase fraction. This scaling relationship is directly analogous to that of three-dimensional dispersion of spheres in a solvent with long-range repulsive interactions, with area fraction replacing volume fraction. 相似文献
109.
Aquatic flow over a submerged vegetation canopy is a ubiquitous example of flow adjacent to a permeable medium. Aquatic canopy
flows, however, have two important distinguishing features. Firstly, submerged vegetation typically grows in shallow regions.
Consequently, the roughness sublayer, the region where the drag length scale of the canopy is dynamically important, can often
encompass the entire flow depth. In such shallow flows, vortices generated by the inflectional velocity profile are the dominant
mixing mechanism. Vertical transport across the canopy–water interface occurs over a narrow frequency range centered around
f
v
(the frequency of vortex passage), with the vortices responsible for more than three-quarters of the interfacial flux. Secondly,
submerged canopies are typically flexible, coupling the motion of the fluid and canopy. Importantly, flexible canopies can
exhibit a coherent waving (the monami) in response to vortex passage. This waving reduces canopy drag, allowing greater in-canopy velocities and turbulent stresses.
As a result, the waving of an experimental canopy reduces the canopy residence time by a factor of four. Finally, the length
required for the set-up and full development of mixing-layer-type canopy flow is investigated. This distance, which scales
upon the drag length scale, can be of the same order as the length of the canopy. In several flows adjacent to permeable media
(such as urban canopies and reef systems), patchiness of the medium is common such that the fully developed condition may
not be representative of the flow as a whole. 相似文献
110.
A rut is a depression or groove formed into the ground by the travel of wheels and tracks. Ruts can cause severe influences on soil and vegetation, and reduce vehicle mobility. In this paper, rut depth and rut width were used as the main indicators to quantify a rut. A new indicator, rut index, was proposed, combining rut depth and rut width. A Light Armored Vehicle (LAV) and a High Mobility Multi-purpose Wheeled Vehicle (HMMWV) were used for testing the influence of turning radius on rut depth, rut width and rut index. The LAV and the HMMWV were operated in spiral patterns at different speeds. Differential GPS data for the vehicles were collected every second during the spiral. Rut measurements were manually taken every 4-7 m along each of the spiral tracks. The results of field tests indicate that rut depth, rut width and rut index increase with the decrease of turning radius, especially when turning radius is less than 20 m. Velocity influences rut formation for the LAV but not HMMWV. 相似文献