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An improved method is described for the measurement of total, soluble and insoluble dietary fibre as non-starch polysaccharides (NSP). An established procedure is modified to allow more rapid removal of starch and hydrolysis of NSP. In its present form the procedure is simpler and more robust than those previously published. In the modified method starch is removed enzymically within 50 min and NSP is precipitated with ethanol and then hydrolysed by treatment with sulfuric acid for 2 h. The constituent sugars can in turn be measured by gas-liquid chromatography, high-performance liquid chromatography or more rapidly by colorimetry. The improved procedure described here for the removal of starch and hydrolysis of NSP applies to all three techniques, but only the method for measurement of sugars by gas-liquid chromatography is described here in full. 相似文献
3.
Grand canonical Monte Carlo simulations are performed to study the adsorption of water in single-walled (6:6), (8:8), (10:10), (12:12), and (20:20) carbon nanotubes in the 248-548 K temperature range. At room temperature the resulting adsorption isotherms in (10:10) and wider single-walled carbon nanotubes (SWCNs) are characterized by negligible water uptake at low pressures, sudden and complete pore filling once a threshold pressure is reached, and wide adsorption/desorption hysteresis loops. The width of the hysteresis loops decreases as pore diameter narrows and it becomes negligible for water adsorption in (8:8) and (6:6) SWCNs. Results for the isosteric heat of adsorption, density profiles along the pore axis and across the pore radii, order parameter across the pore radii, and x-ray diffraction patterns are presented. Layered structures are observed when the internal diameter of the nanotubes is commensurate to the establishment of a hydrogen-bonded network. The structure of water in (8:8) and (10:10) SWCNs is ordered when the temperature is 298 and 248 K, respectively. By simulating adsorption isotherms at various temperatures, the hysteresis critical temperature, e.g., the lowest temperature at which no hysteresis can be detected, is determined for water adsorbed in (20:20), (12:12), and (10:10) SWCNs. The hysteresis critical temperature is lower than the vapor-liquid critical temperature for bulk Simple Point Charge-Extended (SPCE) water model. 相似文献
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Abachi S Abbott B Abolins M Acharya BS Adam I Adams DL Adams M Ahn S Aihara H Alvarez G Alves GA Amos N Anderson EW Antipov Y Aronson SH Astur R Avery RE Baden A Balamurali V Balderston J Baldin B Bantly J Bartlett JF Bazizi K Behnke T Bendich J Beri SB Bezzubov V Bhat PC Bhatnagar V Biswas N Blazey G Blessing S Boehnlein A Borcherding F Borders J Bozko N Brandt A Brock R Bross A Buchholz D Burtovoi V Butler JM Callot OH Castilla-Valdez H Chakraborty D Chekulaev S Chen J Chen L Chen W 《Physical review letters》1994,72(14):2138-2142
6.
Espy MA Dehnhard D Edwards CM Palarczyk M Langenbrunner JL Davis B Burleson GR Blanchard S Gibbs WR Lail B Nelson B Park BK Zhao Q Cummings WJ Delheij PP Jennings BK Henderson R Häusser O Thiessen D Brash E Jones MK Larson B Brinkmöller B Maeda K Morris CL O'Donnell JM Penttilä S Swenson D Tupa D Bennhold C Kamalov SS 《Physical review letters》1996,76(20):3667-3670
7.
Nanoparticles have been an area of active research in recent years due to their properties, which can be greatly different from the bulk. In this work, we study the sintering of TiO2 nanoparticles using molecular dynamics simulations. Such sintering occurs in flame reactors where nanotitania is prepared via the chloride process. Decrease in free energy due to reduction in surface area is the main driving force for sintering of particles. Simulations, at various starting temperatures and orientations, indicate that the process of sintering is strongly affected by temperature and initial orientation. Extremely high diffusion of ions in the neck region of sintering nanoparticles supports the idea that solid-state diffusion is significant in metal-oxide nanoparticle sintering. It is found that the dipole-dipole interaction between sintering nanoparticles plays a very important role at temperatures away from the melting point. The duration of the simulation is not enough to observe the complete sintering process, but important initial stages are well studied. 相似文献
8.
Cummings EA Linquette-Mailley S Mailley P Cosnier S Eggins BR McAdams ET 《Talanta》2001,55(5):1015-1027
In this paper a comparison between three commercially-available, screen-printable graphite inks for the construction of phenolic biosensors is made. The enzyme tyrosinase was immobilised within a polymer matrix and the substrate catechol was used to characterise the bio-electroanalytical response of each electrode. Biosensors fabricated from Gwent graphite inks exhibited the greatest sensitivity (5740 mA mol cm(-2)) compared to Dupont and Acheson graphite-based inks. This difference in sensitivity was attributed to a combination of a larger electroactive surface area, and thus a greater number of immobilised enzyme molecules. However, the dynamic range was considerably smaller (0.025-14 muM) indicating that the enzyme molecules were easily accessible to the substrate catechol. The surface properties of the biosensors were characterised using ac impedance, which indicated that the presence of the polymer on the electrode surface not only increased the charge-transfer kinetics of the three biosensors, but also increased the surface roughness of biosensors fabricated from Gwent inks. On the basis of these results Gwent graphite-based inks were used for analysis of phenolic compounds in lager beers by flow-injection analysis. The biosensor displayed favourable response characteristics, but cannot differentiate between the various phenolic compounds present in the samples. Nevertheless, the biosensor maybe suitable for indicating the phenolic status of beer or brew samples compared to time-consuming traditional methods, e.g. colorimetric or chromatographic methods. 相似文献
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