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101.
Vijay K. Stokes 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1989,40(2):201-215
The structure of the principal directions of stress is characterized for the general case of asymmetric stress. It is shown that, for asymmetric stress, the principal directions can comprise either only one direction, or only two directions, or only three directions, or a plane of directions, or a plane of directions together with a direction external to this plane. The asymmetric stress obtained by combining a one-dimensional stress field with a skew-symmetric stress field is analyzed in detail. 相似文献
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We prove that the numerical semigroups associated to the combinatorial configurations satisfy a family of linear, non-homogeneous, symmetric patterns. We use these patterns to prove an upper bound of the conductor and we also give an upper bound of the multiplicity. Also, we compare bounds of the conductor of numerical semigroups associated to balanced configurations, and to configurations with coprime parameters. The proof of the latter involves a bound of the conductor of prime power generated numerical semigroups. 相似文献
107.
108.
David L. Stokes G. D. Griffin Tuan Vo-Dinh 《Analytical and bioanalytical chemistry》2001,369(3-4):295-301
This work demonstrates the detection of E. coli using a 2-dimensional photosensor array biochip which is efficiently equipped with a microfluidics sample/reagent delivery
system for on-chip monitoring of bioassays. The biochip features a 4 × 4 array of independently operating photodiodes that
are integrated along with amplifiers, discriminators and logic circuitry on a single platform. The microfluidics system includes
a single 0.4 mL reaction chamber which houses a sampling platform that selectively captures detection probes from a sample
through the use of immobilized bioreceptors. The independently operating photodiodes allow simultaneous monitoring of multiple
samples. In this study the sampling platform is a cellulosic membrane that is exposed to E. coli organisms and subsequently analyzed using a sandwich immunoassay involving a Cy5-labeled antibody probe. The combined effectiveness
of the integrated circuit (IC) biochip and the immunoassay is evaluated for assays performed both by conventional laboratory
means followed by detection with the IC biochip, and through the use of the microfluidics system for on-chip detection. Highlights
of the studies show that the biochip has a linear dynamic range of three orders of magnitude observed for conventional assays,
and can detect 20 E. coli organisms. Selective detection of E. coli in a complex medium, milk diluent, is also reported for both off-chip and on-chip assays.
Received: 13 October 2000 / Revised: 13 November 2000 / Accepted: 13 November 2000 相似文献
109.
Jan Ilavsky Kristoffer K. Stokes Michael C. Berg Randy A. Mrozek Joseph L. Lenhart Frederick L. Beyer Jan W. Andzelm 《Journal of Polymer Science.Polymer Physics》2011,49(20):1479-1491
Dynamic density functional theory calculations were performed for thermoplastic elastomer gels composed of an ABA triblock copolymer immersed in a B‐attractive solvent. The triblock copolymer model was parameterized for poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS), while the solvent model was parameterized for the hydrocarbon oil tetradecane. The effect of the solvent concentration and S‐EB interaction on the morphology was investigated, where complementary experimental data was used to validate results at χABN ≈ 100. Agreement was observed at solvent volume fractions of 0.2, 0.4, and 0.6, which correspond to the cylindrical, spherical, and spherical phases, respectively. Qualitative agreement was observed for 0.8 volume fraction solvent, where a core‐shell spherical micelle morphology was found. For a 50/50 vol % mixture of polymer/solvent, the effect of solvent molecular weight on the morphology was considered, where a transition between micro and macrophase separation was predicted at a critical solvent molecular weight. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1479–1491, 2011 相似文献
110.
Garcia-Sartal C Taebunpakul S Stokes E Barciela-Alonso Mdel C Bermejo-Barrera P Goenaga-Infante H 《Analytical and bioanalytical chemistry》2012,402(10):3359-3369
Edible seaweed consumption is a route of exposure to arsenic. However, little attention has been paid to estimate the bioaccessibility
and/or bioavailability of arsenosugars in edible seaweed and their possible degradation products during gastrointestinal digestion.
This work presents first use of combined inductively coupled plasma mass spectroscopy (ICP-MS) with electrospray ionization
tandem mass spectrometry (ESI-MS/MS) with two-dimensional HPLC (size exclusion followed by anion exchange) to compare the
qualitative and quantitative arsenosugars speciation of different edible seaweed with that of their bioavailable fraction
as obtained using an in vitro gastrointestinal digestion procedure. Optimal extraction conditions for As species from four
seaweed namely kombu, wakame, nori and sea lettuce were selected as a compromise between As extraction efficiency and preservation
of compound identity. For most investigated samples, the use of ammonium acetate buffer as extractant and 1 h sonication in
a water bath followed by HPLC-ICP-MS resulted in 40–61% of the total As to be found in the buffered aqueous extract, of which
86–110% was present as arsenosugars (glycerol sugar, phosphate sugar and sulfonate sugar for wakame and kombu and glycerol
sugar and phosphate sugar for nori). The exception was sea lettuce, for which the arsenosugar fraction (glycerol sugar, phosphate
sugar) only comprised 44% of the total extracted As. Interestingly, the ratio of arsenobetaine and dimethylarsinic acid to
arsenosugars in sea lettuce extracts seemed higher than that for the rest of investigated samples. After in vitro gastrointestinal
digestion, approximately 11–16% of the total As in the solid sample was found in the dialyzates with arsenosugars comprising
93–120% and 41% of the dialyzable As fraction for kombu, wakame, nori and sea lettuce, respectively. Moreover, the relative
As species distribution in seaweed-buffered extracts and dialyzates was found to be very similar. Collection of specific fractions
from the size-exclusion column to be analysed using anion-exchange HPLC-ESI-MS/MS enabled improved chromatographic selectivity,
particularly for the less retained arsenosugar (glycerol sugar), facilitating confirmation of the presence of arsenosugars
in seaweed extracts and dialyzates. Using this approach, the presence of arsenobetaine in sea lettuce samples was also confirmed. 相似文献