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481.
El?bieta ZambrzyckaDorota Roszko Barbara Le?niewskaAgnieszka Z. Wilczewska Beata Godlewska-?y?kiewicz 《Spectrochimica Acta Part B: Atomic Spectroscopy》2011,66(7):508-516
The examination of the effect of interfering ions on the analytical signal of ruthenium measured by electrothermal atomic absorption spectrometry was initially performed in this work. The complexes of ruthenium(III) with thiosemicarbazide (TSd) and acetaldehyde thiosemicarbazone (AcTSn) were prepared and imprinted in polymeric network. The ion-imprinted polymers were synthesized by copolymerization of methacrylic acid, as functional monomer and ethylene glycol dimethacrylate, as crosslinking agent in the presence of 2,2-azobisisobutyronitrile as initiator. The effects of sample volume, pH, and flow rate on the extraction of analyte were studied in dynamic mode. The optimum pH for quantitative retention of ruthenium on each of the studied sorbents was 7.5 ± 0.5. The elution of analyte was completed with 0.2 mol L−1 thiourea in 0.2 mol L−1 HCl. The effect of matrix ions on ruthenium(III) separation process was studied. The analytical performance of the Ru-TSd polymer in the presence of competing ions was better than Ru-AcTSn polymer, considering recovery of analyte, reproducibility of results, selectivity coefficients, and sorbent capacity. The detection limit of the proposed method (0.16 ng mL−1 on Ru-TSd and 0.25 ng mL−1 on Ru-AcTSn) is lower in comparison with the previously published methods. The developed separation method was successfully applied to the determination of trace amounts of ruthenium in spiked water samples, sludge, grass, and human hair. 相似文献
482.
483.
Szczepanik B Styrcz S 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(3):451-455
The effect of cyano substituents on acidity in ground and excited states of mono- and dicyanophenols was investigated. The equilibrium dissociation constants of 3,4-dicyanophenol in ground and lowest excited states in water solution and the change of these constants in the excited state during the transfer to the ground state for o-, m-, p-cyanophenol and 3,4-dicyanophenol in alcohol and water solutions were determined. It was shown that the cyano substitution increases the acidity of ortho-, meta- and dicyano-derivative in ground state in comparison to the phenol, which makes the anions of these derivatives appear in solutions from methanol to 1-butanol. In the excited state the acidity of investigated compounds changes significantly in comparison to the ground state. 3,4-Dicyanophenol is the strongest acid in the lowest excited singlet state, while p-cyanophenol is the weakest one in both alcohol and water solutions. The distribution of the electronic charge and dipole moments of all investigated cyanophenols in ground and excited states were determined on the basis of ab initio calculations using the GAMESS program. 相似文献
484.
We study polynomial iterative roots of polynomials and describe the locus of complex polynomials of degree 4 admitting a polynomial
iterative square root. 相似文献
485.
Tomasz Girek Tomasz Goszczyński Beata Girek Wojciech Ciesielski Janusz Boratyński Piotr Rychter 《Journal of inclusion phenomena and macrocyclic chemistry》2013,75(3-4):293-296
The design of proteins whose structure and function can be manipulated by binding with specific ligands such as cyclodextrins, has been of great interest in the field of protein engineering and also could be used as drug delivery systems in targeted cancer therapy (Loftsson and Duchêne, Int. J. Pharm. 329:1–11, 1; Loftsson et al., Expert. Opin. Drug Deliv. 2:335–351, 2). CD/proteins conjugates are synthesized using original high temperature method in which mono-6-O-formyl-β-CD reacts with two proteins: basic pancreatic trypsin inhibitor and lysozyme. The proposed synthesis method has a high reproducibility which makes it useful for pharmaceutical purposes. That method allows to obtain the conjugate without losing protein’s biological and enzymatic activity which will used in the reaction, and without violating the chemical structure of cyclodextrin molecules. 相似文献
486.
Vittorio Canale Magdalena Kotaska Anna Dziubina Matylda Stefaniak Agata Siwek Gabriela Starowicz Krzysztof Marciniec Patryk Kasza Grzegorz Sataa Beata Duszyska Xavier Bantreil Frdric Lamaty Marek Bednarski Jacek Sapa Pawe Zajdel 《Molecules (Basel, Switzerland)》2021,26(13)
The complex pathophysiology of depression, together with the limits of currently available antidepressants, has resulted in the continuous quest for alternative therapeutic strategies. Numerous findings suggest that pharmacological blockade of α2-adrenoceptor might be beneficial for the treatment of depressive symptoms by increasing both norepinephrine and serotonin levels in certain brain areas. Moreover, the antidepressant properties of 5-HT7 receptor antagonists have been widely demonstrated in a large set of animal models. Considering the potential therapeutic advantages in targeting both α2-adrenoceptors and 5-HT7 receptors, we designed a small series of arylsulfonamide derivatives of (dihydrobenzofuranoxy)ethyl piperidines as dually active ligands. Following green chemistry principles, the designed compounds were synthesized entirely using a sustainable mechanochemical approach. The identified compound 8 behaved as a potent α2A/5-HT7 receptor antagonist and displayed moderate-to-high selectivity over α1-adrenoceptor subtypes and selected serotonin and dopaminergic receptors. Finally, compound 8 improved performance of mice in the forced swim test, displaying similar potency to the reference drug mirtazapine. 相似文献
487.
A new ruthenium ion imprinted polymer was prepared from the Ru(III) 2-thiobarbituric acid complex (the template), methacrylic acid or acrylamide (the functional monomers), and ethylene glycol dimethacrylate (the cross-linking agent) using 2,2′-azobisisobutyronitrile as the radical initiator. The ion imprinted polymer was characterized and used as a selective sorbent for the solid phase extraction of Ru(III) ions. The effects of type of functional monomer, sample volume, solution pH and flow rate on the extraction efficiency were studied in the dynamic mode. Ru(III) ion was quantitatively retained on the sorbents in the pH range from 3.5 to 10, and can be eluted with 4 mol L?1 aqueous ammonia. The affinity of Ru(III) for the ion imprinted polymer based on the acrylamide monomer is weaker than that for the polymer based on the methacrylic acid monomer, which therefore was used in interference studies and in analytical applications. Following extraction of Ru(III) ions with the imprint and their subsequent elution from the polymer with aqueous ammonia, Ru(III) was detected by electrothermal atomic absorption spectrometry with a detection limit of 0.21 ng mL?1. The method was successfully applied to the determination of trace amounts of Ru(III) in water, waste, road dust and platinum ore (CRM SARM 76) with a reproducibility (expressed as RSD) below 6.4 %. Figure
The new ion imprinted polymer was prepared and used for the separation of ruthenium from water and most complex environmental samples, such as road dust and platinum ore (CRM SARM 76) prior ETAAS determination. 相似文献
488.
Beata Koszarna Rafał Matczak Maciej Krzeszewski Olena Vakuliuk Jan Klajn Mariusz Tasior Jan T. Nowicki Daniel T. Gryko 《Tetrahedron》2014
Derivatized indolizines efficiently prepared via direct arylation, exhibit violet, blue or green fluorescence depending on the nature of substituents. By attaching two electron-withdrawing groups to five-membered ring it is possible to access a range of multi-substituted stable indolizine-based fluorophores. Compounds featuring this scaffold display advantageous combination of optical properties including reasonable fluorescence quantum yield combined with large Stokes shifts. 相似文献
489.
Jesper J. H. B. Sattler Ines D. Gonzalez‐Jimenez Lin Luo Brien A. Stears Andrzej Malek David G. Barton Beata A. Kilos Mark P. Kaminsky Tiny W. G. M. Verhoeven Eline J. Koers Marc Baldus Bert M. Weckhuysen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(35):9405-9410
A novel catalyst material for the selective dehydrogenation of propane is presented. The catalyst consists of 1000 ppm Pt, 3 wt % Ga, and 0.25 wt % K supported on alumina. We observed a synergy between Ga and Pt, resulting in a highly active and stable catalyst. Additionally, we propose a bifunctional active phase, in which coordinately unsaturated Ga3+ species are the active species and where Pt functions as a promoter. 相似文献
490.
Detection of Oxidative Damage of Synthetic Oligonucleotides Caused by Thallium(III) Complexes 下载免费PDF全文
Anna M. Nowicka Beata Krasnodebska‐Ostrega Beata Wrzosek Magdalena Jastrzebska Monika Sadowska Marcin Mackiewicz Zbigniew Stojek 《Electroanalysis》2014,26(2):340-350
Biologically important short sequences of DNA were treated with Tl(III) complexes. The chloride complex releases the Tl(III) cation and therefore oxidizes DNA components and at concentrations higher than 50 nM cuts the strands. The cuts are well seen in the EQCM plots. The change in the strand structure is well seen at CD and UV‐Vis spectra. The chelate complexes of Tl(III) do not damage the DNA strands. The SERS spectra were particularly useful in demonstration of the chemical changes and orientation vs. the surface changes of particular groups in the strands after interaction with TlCl4?. 相似文献