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41.
Silva SS Luna SM Gomes ME Benesch J Pashkuleva I Mano JF Reis RL 《Macromolecular bioscience》2008,8(6):568-576
Surface modification of biomaterials is a way to tailor cell responses whilst retaining the bulk properties. In this work, chitosan membranes were prepared by solvent casting and treated with nitrogen or argon plasma at 20 W for 10-40 min. AFM indicated an increase in the surface roughness as a result of the ongoing etching process. XPS and contact angle measurements showed different surface elemental compositions and higher surface free energy. The MTS test and direct contact assays with an L929 fibroblast cell line indicated that the plasma treatment improved the cell adhesion and proliferation. Overall, the results demonstrated that such plasma treatments could significantly improve the biocompatibility of chitosan membranes and thus improve their potential in wound dressings and tissue engineering applications. 相似文献
42.
Husáková L Cernohorský T Srámková J Hubácková K Dolezalová I 《Analytica chimica acta》2008,614(1):38-45
The mixture of palladium (chloride) with citric acid and lithium is proposed as a new chemical modifier for the elimination of interference occurred during the determination of Tl in aqua regia extracts from rocks, soils and sediments by electrothermal atomic absorption spectrometry using instrumentation with deuterium-lamp background correction (D2-ETAAS). Palladium was preferred to rhodium and platinum as to analyte stabilization, citric acid served as an effective reducing agent facilitating formation of Pd-Tl stable covalent bonds playing an important role in the analyte stabilization. Citric acid in addition helps to remove most of interfering chloride at low temperature. The further addition of Li increased significantly the robustness of chemical modifier against strongly interfering ZnCl2 matrix by binding free chlorine into a more stable LiCl molecule. In the presence of the proposed chemical modifier the temperature for the final step of pyrolysis was adjustable up to 1000 °C, without any noticeable loss of volatile Tl species and the interference of the rest chloride matrix was significantly reduced. The application of the modifier to direct determination of Tl in aqua regia extracts from rocks, soils and sediments has ensured the characteristic mass and LOD value for the original sample 13 pg and 0.043 μg g−1, respectively (10-μL aliquots of sample) and has enabled the use of matrix-free standard solutions for attaining accurate analysis. The accuracy was verified by the analysis of certified reference samples and by the comparison of results with those found by an inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometer (ICP-oa-TOFMS) method. 相似文献
43.
44.
Iva ikuten Petra tambuk Jasminka Karoglan Konti Edi Maleti Ivana Tomaz Darko Preiner 《Molecules (Basel, Switzerland)》2021,26(23)
(1) Background: Solid phase microextraction (SPME)-Arrow is a new extraction technology recently employed in the analysis of volatiles in food materials. Grape volatile organic compounds (VOC) have a crucial role in the winemaking industry due to their sensory characteristics of wine.; (2) Methods: Box–Behnken experimental design and response surface methodology were used to optimise SPME-Arrow conditions (extraction temperature, incubation time, exposure time, desorption time). Analyzed VOCs were free VOCs directly from grape skins and bound VOCs released from grape skins by acid hydrolysis.; (3) Results: The most significant factors were extraction temperature and exposure time for both free and bound VOCs. For both factors, an increase in their values positively affected the extraction efficiency for almost all classes of VOCs. For free VOCs, the optimum extraction conditions are: extraction temperature 60 °C, incubation time 20 min, exposure time 49 min, and desorption time 7 min, while for the bound VOCs are: extraction temperature 60 °C, incubation time 20 min, exposure time 60 min, desorption time 7 min.; (4) Conclusions: Application of the optimized method provides a powerful tool in the analysis of major classes of volatile organic compounds from grape skins, which can be applied to a large number of samples. 相似文献
45.
Milojković-Opsenica Dusanka M. Lazarević Kristina Ivačković Vojkan Tešić Zivoslav Lj. 《平面色谱法杂志一现代薄层色谱法》2003,16(4):276-279
JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of nine frequently used water-soluble food dyes has been studied by TLC on RP-18 silica gel.... 相似文献
46.
Determination of extractable chromium from leather 总被引:1,自引:0,他引:1
Abstract People are exposed to chromium ions from leather materials due to everyday contact with different textile objects. The problem
is that Cr(VI) is extremely toxic and may cause contact allergic dermatitis on the skin and may also be a trigger for many
diseases. Huge amounts of chromium ions are released by waste waters to rivers after chromium-tanning processes in the leather
industry; the presence of chromium is not only a problem for human health, but also for the environment. For this reason it
is extremely important to monitor the presence of chromium as Cr(VI) and as total chromium. This study aims to present an
appropriate analytical method for monitoring Cr(VI) and the total chromium present on leather materials. Applying this method
to chromium-tanned leather samples, it was observed that the amounts of total chromium as well as of Cr(VI) are higher than
prescribed and recommended by different regulations. Chromium(VI) exceeded the limit of 3 mg/kg in the majority of tested
materials, while the total chromium exceeded the limit of 50 mg/kg in all tested samples. For this reason, it is recommended
to avoid direct and prolonged contact of those materials with the skin.
Graphical abstract
相似文献
47.
When tin is to be determined in such a complex matrix like aqua regia extracts of environmental samples by electrothermal atomic absorption spectrometry (ETAAS), spectral interferences occur when deuterium-lamp (D2) background correction is used, even using high pyrolysis temperature of 1400 °C achieved with palladium with citric acid chemical modifier. We have found that the further addition of NH4F to palladium with citric acid chemical modifier is essential for overcoming the above-mentioned problems for which aluminium oxide is most probably responsible. It is supposed, that NH4F enables volatilization of the alumina matrix formed by hydrolysis from the chloride salt and interfering in a gas phase via the formation of AlF3 which could be, in contrast to aluminium oxide, removed from the graphite furnace during the pyrolysis stage. Using the proposed chemical modifier, the direct and accurate determination of Sn in aqua regia extracts from rocks, soils and sediments is possible even when using matrix free standard solutions. This presumption was confirmed by the analysis of certified reference samples and by the comparison with inductively coupled plasma time of flight mass spectrometry (ICP-TOFMS) method. Characteristic mass and LOD value for the original sample (10-μL aliquots of sample) was 17 pg and 0.055 μg g−1, respectively. 相似文献
48.
Rowena Held Iva Stavrov Brian VanKoten 《Differential Geometry and its Applications》2009,27(4):464-481
We use reduced homogeneous coordinates to construct and study the (semi-)Riemannian geometry of the octonionic (or Cayley) projective plane , the octonionic projective plane of indefinite signature , the para-octonionic (or split octonionic) projective plane and the hyperbolic dual of the octonionic projective plane . We also show that our manifolds are isometric to the (para-)octonionic projective planes defined classically by quotients of Lie groups. 相似文献
49.
Malitesta C Mazzotta E Picca RA Poma A Chianella I Piletsky SA 《Analytical and bioanalytical chemistry》2012,402(5):1827-1846
This review highlights the importance of coupling molecular imprinting technology with methodology based on electrochemical
techniques for the development of advanced sensing devices. In recent years, growing interest in molecularly imprinted polymers
(MIPs) in the preparation of recognition elements has led researchers to design novel formats for improvement of MIP sensors.
Among possible approaches proposed in the literature on this topic, we will focus on the electrosynthesis of MIPs and on less
common hybrid technology (e.g. based on electrochemistry and classical MIPs, or nanotechnology). Starting from the early work
reported in this field, an overview of the most innovative and successful examples will be reviewed. 相似文献
50.
D. Bucurescu Gh. Căta-Danil I. Căta-Danil M. Ivaşcu N. Mărginean C. Rusu L. Stroe C.A. Ur A. Gizon J. Gizon B. Nyakó J. Timár L. Zolnai A.J. Boston D.T. Joss E.S. Paul A.T. Semple C.M. Parry 《The European Physical Journal A - Hadrons and Nuclei》2001,10(3):255-258
High-spin states in the 96Tc nucleus have been studied with the reactions 82Se(19F,5nγ) at 68 MeV and Zn(36S,αpxn) at 130 MeV. Two γ-ray cascades (irregular bandlike structures) have been observed up to an excitation energy of about 10
MeV and spin 21-22?.
Received: 19 January 2001 / Accepted: 30 March 2001 相似文献