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571.
Serrilli AM Ramunno A Amicucci F Chicarella V Santoni S Ballero M Serafini M Bianco A 《Natural product research》2008,22(7):618-622
The monoterpenoid fractions of three endemic Galium ssp. (Rubiaceae) from Sardinia Island were examined and compared with the iridoidic pattern yet known in Galium species. This comparison evidenced theirs endemic characters. In particular, in G.corsicum and in G. glaucophyllum loganic acid was isolated and identified for the first time in Galium genus. In G. schmidii a rare iridoid is present, 10-hydroxy-loganin, whose presence in this genus was evidenced only in G. mollugo and loganin isolated for the first time. 相似文献
572.
Sutter M Oliveira S Sanders NN Lucas B van Hoek A Hink MA Visser AJ De Smedt SC Hennink WE Jiskoot W 《Journal of fluorescence》2007,17(2):181-192
The fluorescent dye Nile red was used as a probe for the sensitive detection of large, denatured aggregates of the model protein
β-galactosidase (E. coli) in solution. Aggregates were formed by irreversible heat denaturation of β-galactosidase below and above the protein’s unfolding
temperature of 57.4°C, and the presence of aggregates in heated solutions was confirmed by static light scattering. Interaction
of Nile red with β-galactosidase aggregates led to a shift of the emission maximum (λ
max) from 660 to 611 nm, and to an increase of fluorescence intensity. Time-resolved fluorescence and fluorescence correlation
spectroscopy (FCS) measurements showed that Nile red detected large aggregates with hydrodynamic radii around 130 nm. By steady-state
fluorescence measurements, it was possible to detect 1 nM of denatured and aggregated β-galactosidase in solution. The comparison
with size exclusion chromatography (SEC) showed that native β-galactosidase and small aggregates thereof had no substantial
effect on the fluorescence of Nile red. Large aggregates were not detected by SEC, because they were excluded from the column.
The results with β-galactosidase demonstrate the potential of Nile red for developing complementary analytical methods that
overcome the size limitations of SEC, and can detect the formation of large protein aggregates at early stages. 相似文献
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574.
Cerium-bismuth oxides have emerged as promising candidates for Diesel soot oxidation. The catalysts are synthesized via automated co-precipitation methods. T50 values, where 50 % of soot is oxidized, and the dynamic oxygen storage capacity (OSCdyn) are used to compare the catalytic activity. The activity is measured by thermogravimetric methods. The synthesized catalysts are characterized through powder X-ray diffraction (PXRD), Raman spectroscopy, and specific surface area (SBET) measurements. This work investigates the influence of the contact mode between soot and catalyst. The literature-known manual contact modes “loose”, “tight”, and “wet” are compared with our developed automated contact mode, using a dual asymmetric centrifuge. The rotation speed rs and mixing time tM have been varied independently. Both factors influence the T50 value. A continuous transition from loose to tight contact mode with increasing rotation speed rs can be shown. Furthermore, the automated contact mode shows better reproducibility behavior compared to manual contact modes. 相似文献
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578.
Hugo R. Lewgoy Cibele B. Zamboni Sabrina Metairon Ilca M. M. A. Medeiros Jose A. G. de Medeiros 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):573-577
This paper discusses preliminary work into the modelling and processing of coincidence measurements, for which a Monte-Carlo simulation and a post-processing program have both been developed. In the current work, a GEANT4 code is used to simulate a pair of NaI(Tl) scintillators, which are used experimentally to both develop the post-processing program and validate the GEANT4 model. This is found to be accurate to within 9 % at a confidence level of 93.0 % for energies from 30 to 3,000 keV. 相似文献
579.
Bonifacio A Beleites C Vittur F Marsich E Semeraro S Paoletti S Sergo V 《The Analyst》2010,135(12):3193-3204
Raman mapping in combination with uni- and multi-variate methods of data analysis is applied to articular cartilage samples. Main differences in biochemical composition and collagen fibers orientation between superficial, middle and deep zone of the tissue are readily observed in the samples. Collagen, non-collagenous proteins, proteoglycans and nucleic acids can be distinguished on the basis of their different spectral characteristics, and their relative abundance can be mapped in the label-free tissue samples, at so high a resolution as to permit the analysis at the level of single cells. Differences between territorial and inter-territorial matrix, as well as inhomogeneities in the inter-territorial matrix, are properly identified. Multivariate methods of data analysis prove to be complementary to the univariate approach. In particular, our partial least squares regression model gives a semiquantitative mapping of the biochemical constituents in agreement with average composition found in the literature. The combination of hierarchical and fuzzy cluster analysis succeeds in detecting variations between different regions of the extra-cellular matrix. Because of its characteristics as an imaging technique, Raman mapping could be a promising tool for studying biochemical changes in cartilage occurring during aging or osteoarthritis. 相似文献
580.
Nicoletta Calace Andrea Casagrande Sabrina Mirante Bianca Maria Petronio Marco Pietroletti 《Microchemical Journal》2010,96(2):218-224
Dissolved (DFA) and particulate (PFA) fulvic acids were studied in some areas of the Ross Sea (Antarctica) characterised by different water masses. Our interest was focused on their distribution in the water column. Moreover, their correlation with fluorescence data and structural characterisation in relation to the water masses was also studied. We found that PFA concentration was mainly influenced by the primary production in surface layers and by stratification of water masses along the water column. Conversely, the DFA are less influenced by primary production and by the stratification of the water masses. An early stage of the humification process can be hypothesised for PFA related to DFA as shown by elemental analyses and spectroscopic data. PFA collected in the bottom depths of the water column showed a relationship with age of water mass (the highest concentration was found for the oldest circulating water mass (CDW)). This relationship was not observed for DFA. Moreover, any significant difference in structure was found in the DFA and PFA extracted from samples collected at bottom depths. 相似文献