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61.
Journal of Thermal Analysis and Calorimetry - The structural relaxation of Na2O–K2O–CaO–ZrO2–SiO2 (NKCZ), Na2O–K2O–ZnO–ZrO2–SiO2 (NKzZ),... 相似文献
62.
Dey S Pal C Nandi D Giri VS Zaidlewicz M Krzeminski M Smentek L Hess BA Gawronski J Kwit M Babu NJ Nangia A Jaisankar P 《Organic letters》2008,10(7):1373-1376
3,3'-Bipyrroles 3 could be synthesized using a double Michael addition reaction involving diaroyl acetylene 1 and the appropriate 1,3-dicarbonyls 2 using ammonium acetate as a nitrogen source. The axial chirality of bipyrrole was anticipated from the X-ray crystal structure and DFT calculations and confirmed by separating the racemates on a chiral column and subsequent CD spectra of the enantiomers. The absolute configuration of the enantiomers was achieved by theoretical CD spectra calculation using the ZINDO method. 相似文献
63.
The application of a new kind of technique involving solid-phase extraction coupled with thermal desorption (SPE-TD) to the
qualitative analysis of water used in pharmaceutical products was evaluated. Comparative analyses performed by the purge and
trap (PT) technique were also conducted. The application of this SPE-TD technique resulted in the isolation of a large number
of compounds from the water sample. The SPE-TD technique is applied to less volatile compounds, whereas the PT technique is
used for more volatile and nonpolar ones. These two techniques should be applied in order to achieve complete identification
and quantitative determination. Additionally, an attempt to identify organic compounds in pharmaceutical products was also
conducted. The compounds present in such products include aldehydes, ketones, hydrocarbons, alcohols, esters. The influence
of storage on the quality of water was also investigated. For samples characterized by a longer storage time, qualitatively
richer chromatograms were obtained, which confirmed that components were released from the packaging (especially polyethylene)
which entered the stored product. 相似文献
64.
Gelatinous solidified layers of the photographic film were used for the immobilization of analytical reagents for detection and determination of reductants and primary aromatic amines. It was shown, that the films with immobilized iron(III)-Dipy or iron(III)-Phen complexes as test films for reductants and films with immobilized aldehydes (vanillin, p-dimethylaminobenzaldehyde) as the test films for primary aromatic amines can be used. The improving of reagents immobilization in the presence of sodium dodecylsulfate micelles was obtained. Metrological characteristics of visual detection and photometric determination using test films were evaluated on the basis of statistical approach and investigation of detection probability distribution in the concentration range of unreliable reaction. The suggested test films for the determination of ascorbic acid, analgin (dipyrone), novocaine and streptocide in drugs were examined successfully. 相似文献
65.
Giovanni Neri Giuseppe Rizzo Lidia De Luca Andrea Donato Maria Grazia Musolino Rosario Pietropaolo 《Reaction Kinetics and Catalysis Letters》2008,93(2):193-202
Selective catalytic reduction of campholenic aldehyde to naturanol was investigated over Sn-and Fe-doped SiO2, and Fe2O3-supported Pd catalysts. On Pd/SiO2 and Pd-Sn/SiO2 only saturated campholenic aldehyde is formed. Addition of Fe increases the C=O hydrogenation rate producing the corresponding
unsaturated alcohol with a good selectivity. Also Fe2O3-supported catalysts were found to be more selective towards carbonyl hydrogenation. Addition of tin to Pd/Fe2O3 contributes to a further selectivity enhancement towards naturanol. 相似文献
66.
Połeć-Pawlak K Abramski JK Ferenc J Foteeva LS Timerbaev AR Keppler BK Jarosz M 《Journal of chromatography. A》2008,1192(2):323-326
Varying the counter-ion is a highly supportive practice in tackling the problem of poor water-solubility of metal complexes of pharmaceutical importance. As a matter of fact, the relevant structural modification may alter the metabolic pathways and possibly the mode of action of a drug. To prove that this does not take place for one of the lead anticancer metal-based developmental compounds, indazolium trans-[RuCl(4)(1H-indazole)(2)] (KP1019), its reactivity toward human serum proteins was assessed under simulated physiological conditions and compared to that of a much more soluble analogue, sodium trans-[RuCl(4)(1H-indazole)(2)] (KP1339). For such kinetic assaying, capillary electrophoresis (CE) interfaced online with inductively coupled plasma mass spectrometry (ICP-MS) to specifically monitor changes in the metal speciation following the formation of ruthenium-protein adducts was applied. The rate constants of interaction with albumin and transferrin were determined at pharmacologically fitting drug-to-protein ratios as on average 0.0319+/-0.0021 min(-1) and 0.0931+/-0.0019 min(-1) (KP1019) and 0.0316+/-0.0018 min(-1) and 0.0935+/-0.0053 min(-1) (KP1339), respectively. The results of this brief study showed that changing from organic to inorganic counter-ion at the stage of formulation could commonly be recommended for improving ruthenium-based drug solubility and bioavailability. 相似文献
67.
Joshua Roldan-Kalil Lidia Zueva Janaina Alves Vassiliy Tsytsarev Priscila Sanabria Mikhail Inyushin 《Photochemistry and photobiology》2023,99(4):1092-1096
One of the known important functions of hair is protection from extensive sunlight. This protection is accomplished in large part due to natural hair pigmentation which is known to reflect the number of melanin granules (melanosomes) in the hair shaft, and melanin variants. Melanin takes in excessive light energy and converts it to heat in a process called absorption; heat is then dissipated into the environment as infrared radiation, thereby protecting the underlying skin. We used transmission electron microscopy (TEM) to visualize the melanosome counts in samples of human hair, and used thermal microscopy to measure the temperature changes of the samples when exposed to green and blue light lasers. In our experiments green light conversion to heat was highly correlated to the number of melanosomes, whereas blue light conversion to heat was less correlated, which may be because the reddish melanosomes it contains are less effective in absorbing energy from the blue spectrum of light. Anyway, we have shown the metals accumulation in the melanin can be easily visualized with TEM. We confirmed that the amount of melanin granules in human hair defines the conversion to heat of light energy in the visible spectrum. 相似文献
68.
Lidia Angeleri Hü gel Silvana Bazzoni Dolors Herbera 《Transactions of the American Mathematical Society》2008,360(5):2409-2421
Let be a commutative domain. We prove that an -module is projective if and only if for any torsion module . This answers in the affirmative a question raised by Kaplansky in 1962.
69.
Zhang Z McCallum SA Xie J Nieto L Corzana F Jiménez-Barbero J Chen M Liu J Linhardt RJ 《Journal of the American Chemical Society》2008,130(39):12998-13007
We report the first chemoenzymatic synthesis of the stable isotope-enriched heparin from a uniformly labeled [(13)C,(15)N]N-acetylheparosan (-GlcA(1,4)GlcNAc-) prepared from E. coli K5. Glycosaminoglycan (GAG) precursors and heparin were formed from N-acetylheparosan by the following steps: chemical N-deacetylation and N-sulfonation leading to N-sulfoheparosan (-GlcA(1,4)GlcNS-); enzyme-catalyzed C5-epimerization and 2-O-sulfonation leading to undersulfated heparin (-IdoA2S(1,4)GlcNS-); enzymatic 6-O-sulfonation leading to the heparin backbone (-IdoA2S(1,4)GlcNS6S-); and selective enzymatic 3-O-sulfonation leading to the anticoagulant heparin, containing the GlcNS6S3S residue. Heteronuclear, multidimensional nuclear magnetic resonance spectroscopy was employed to analyze the chemical composition and solution structure of [(13)C,(15)N]N-acetylheparosan, precursors, and heparin. Isotopic enrichment was found to provide well-resolved (13)C spectra with the high sensitivity required for conformational studies of these biomolecules. Stable isotope-labeled heparin was indistinguishable from heparin derived from animal tissues and is a novel reagent for studying the interaction of heparin with proteins. 相似文献
70.
The Role of Ligand Topology in the Decomplexation of Luminescent Lanthanide Complexes by Dipicolinic Acid
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Dr. Federica Mian Dr. Gregorio Bottaro Dr. Roberta Seraglia Dr. Marco Cavazzini Dr. Silvio Quici Prof. Lidia Armelao 《Chemphyschem》2016,17(20):3229-3236
In this study, we present the aqueous solution behavior of two luminescent lanthanide antenna complexes (Eu3+? 1 , Dy3+? 9 ) with different ligand topologies in the presence of dipicolinic acid (DPA, pyridine‐2,6‐dicarboxylic acid). Macrocyclic (1,4,7,10‐tetraazacyclododecane‐1,4,7‐triacetic acid, DO3A, 9 ) and acyclic (1,4,7‐triazaheptane‐1,1,7,7‐tetraacetic acid, DTTA, 1 ) ligands have been selected to form a ratiometric pair in which Dy3+? 9 acts as a reference and Eu3+? 1 acts as a probe for the recognition of DPA. The pair of luminescent complexes in water reveals the capability to work as a DPA luminescent sensor. The change of emission intensity of Eu3+ indicates the occurrence of a new sensitization path for the lanthanide cation through excitation of DPA. NMR evidence implies the presence of free 1 and mass spectrometry shows the formation of emitting [EuDPA2]? as a result of a ligand exchange reaction. 相似文献