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201.
202.
Robert D. Van De Grampel Jan Van Geldrop Jozua Laven Rob Van Der Linde 《应用聚合物科学杂志》2001,79(1):159-165
This study aimed at reducing the surface energy of coatings by copolymerization of commonly used monomers with fluorine‐containing monomers. Copolymers of 1,1‐dihydroperfluoroheptyl methacrylate (FHMA) and methyl methacrylate (MMA) or butyl acrylate (BA) are prepared by low‐conversion polymerization in solution. Using 1H‐NMR data and nonlinear least‐squares data fitting, reactivity ratios of these systems at 80°C are determined to be rFHMA = 1.31, rMMA = 0.76, and rFHMA = 3.15, rBA = 0.38, respectively. We assume that the penultimate unit effect plays an important role in these systems. Introduction of the perfluoroalkyl side chain lowers the polymer surface energy significantly; copolymers of MMA and FHMA show a reduction in total surface energy of about 50 % at a content of 15 mol % FHMA as compared with pure PMMA. The attainable reduction in surface energy is much larger than with, for example, Teflon. This is due to the preferential adsorption of the —CF3 groups of the fluoroalkyl side chain, if compared to that of the —CF2— groups of Teflon. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 159–165, 2001 相似文献
203.
Hafida Harrar‐Ferfera 《应用聚合物科学杂志》2008,107(6):3963-3973
Copolymerizations of methyl methacrylate (MMA) with 4‐vinylpyridine (4VP) were performed from different monomer feed ratios in 1,4‐dioxan at 30°C under free radical initiation experimental conditions, using Ni(II)α‐Benzoinoxime complex as initiator. The obtained copolymers (PMMA4VP) were examined by FTIR and 1H NMR spectroscopies. The composition of these copolymers was calculated, using 1H NMR spectra and elemental analysis. Monomer reactivity ratios were estimated from Fineman–Ross (FR, rm = 0.550, rv = 1.165) and Kelen–Tudos (KT, rm = 0.559, rv = 1.286) linearization methods, as well as nonlinear error in variables model (EVM) method using the RREVM computer program (RREVM, rm = 0.559, rv = 1.264). These values suggest that MMA‐4VP pair copolymerizes randomly. 1H NMR spectra provide information about the stereochemistry of the copolymers in terms of sequence distributions and configurations. These results showed that the age of the Ni complex has an impact not only on its activity towards polymerization reactions but also on the features of the corresponding copolymers, whereas the chemical composition was insensitive to this prominent factor. The mechanism of MMA‐4VP copolymerization is consistent with a radical process as supported by microstructure and molecular weight distribution studies. Thermal behaviours of these copolymers were investigated by differential scanning calorimetry and thermogravimetric analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 相似文献
204.
205.
Oscar Valdés Dagmar Monett Lissette Agüero Dionisio Zaldívar Larissa Alexandrova Issa Katime 《应用聚合物科学杂志》2008,108(3):1680-1688
206.
In this study, the decomposition conditions of limestone particles (0.25-0.50 mm) for CO2 capture in a steam dilution atmosphere (20-100% steam in CO2) were investigated by using a continuously operating fluidized bed reactor. The results show that the decomposition conversion of limestone increased with the steam dilution percentage in the CO2 supply gas. At a bed temperature of 920 °C, the conversions were 72% without steam dilution and 98% with 60% steam dilution. The conversion was 99% with 100% steam dilution at 850 °C of the bed temperature. Steam dilution can decrease not only the decomposition temperature of limestone, but also the residence time required for nearly complete decomposition of CaCO3. The hydration and carbonation reactivities of the CaO produced were also tested and the results show that both the reactivities increased with the steam dilution percentage for decomposing limestone. 相似文献
207.
Charles L. Perrin 《Israel journal of chemistry》2016,56(1):46-52
This article presents a personal view of the field of physical organic chemistry (broadly construed), its history, its current status, and what it may become in the future. 相似文献
208.
S. M. Sayyah S. S. Abd El‐Rehim S. M. Kamal M. M. El‐Deeb R. E. Azooz 《应用聚合物科学杂志》2011,119(1):252-264
209.
This paper describes a simple and rapid photocatalytic pretreatment procedure that removes contaminants from glassy carbon (GC) surfaces. The effectiveness of TiO2 mediated photocatalytic pretreatment procedure was compared to commonly used alumina polishing procedure. Cyclic voltammetric and chronocoulometric measurements were carried out to assess the changes in electrode reactivity by using four redox systems. Electrochemical measurements obtained on photocatalytically treated GC electrodes showed a more active surface relative to polished GC. In cyclic voltammograms of epinephrine, Fe(CN)63−/4− and ferrocene redox systems, higher oxidation and reduction currents were observed. The heterogeneous electron transfer rate constants (ko) were calculated for Fe(CN)63−/4− and ferrocene which were greater for photocatalytic pretreatment. Chronocoulometry was performed in order to find the amount of adsorbed methylene blue onto the electrode and was calculated as 0.34 pmol cm−2 for photocatalytically pretreated GC. The proposed photocatalytic GC electrode cleansing and activating pretreatment procedure was more effective than classical alumina polishing. 相似文献
210.
Chin‐Sheng Chao Yu‐Fang Yen Wei‐Cheng Hung Kwok‐Kong Tony Mong 《Advanced Synthesis u0026amp; Catalysis》2011,353(6):879-884
Solvent participation in a one‐pot glycosylation strategy (SPOG) was developed on the basis of the low concentration β‐selective glycosylation method. This strategy enables the production of a β‐glycosidic bond in a one‐pot oligosaccharide synthesis without or with minimal use of any C‐2 participating function. 相似文献