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941.
942.
J. M. Hernndez Ana M. Herrera J. García‐Serrano J. F. Rivas‐Silva 《International journal of quantum chemistry》2002,88(3):342-346
Conformations of p‐methacryloylaminophenylarsonic acid (p‐MAPHA) are determined through molecular mechanics and DFT/B3LYP calculations. Solvation effects are studied within the self‐consistent isodensity continuum model (SCI‐PCM). The stationary points were found to correspond to minima as verified by the analysis of vibrational frequencies in the molecule. The molecular optical absorption was obtained by using different solvent environments. The present results are in good agreement with the available experimental data. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 相似文献
943.
An organic-phase optical phenol biosensor coupling enzymatic oxidation with chemical reduction 总被引:1,自引:0,他引:1
This paper presents a recycle amplification optical biosensor to monitor phenol in hydrophobic organic solvents. Tyrosinase was first immobilised by entrapping it in a copolymer membrane of poly(vinyl alcohol)-hydroxyethyl carboxymethylcellulose doped with octadecylsilica particles. The biosensor was then constructed by co-mixing small particles of the immobilised tyrosinase with the adduct of L-ascorbic acid-poly(vinyl alcohol) (AsA-PVA) in conjunction with an optical oxygen transducer. The biosensor was characterised by its amplifying response to phenol, stable biocatalytic activity of entrapped-tyrosinase, free of interference from o-quinone polymerisation, and large water buffer capacity in hydrophobic organic solvents. The working range of the biosensor to phenol was 0.08-40 mmol dm(-3) in the flow mode. The response times (95%) of the biosensor were 4-7 min for phenol. The operational lifetime was more than 40 assays and the shelf lifetime of the biosensor was longer than 3 months. The biosensor has been successfully applied to quantify the phenol contents in some commercial ointment samples. 相似文献
944.
The interaction between gatifloxacin mesylate (GM) and salmon sperm DNA was studied by fluorescence spectrometry and ultra‐violet (UV) spectrometry. Additions of salmon sperm DNA to GM solution resulted in its strong fluorescence quenching and UV absorbance decrease due to the strong interaction between GM and salmon sperm DNA. Both the maximum fluorescence emission wavelength and the maximum UV absorbance wavelength of GM did not change with the increasing concentration of salmon sperm DNA, indicating no intercalative binding existed between them. The Stern‐Volmer plot indicated that the fluorescence‐quenching constant at different temperatures or different salmon sperm DNA concentration ranges was different. Effects of ionic strength and I? on the fluorescence quenching of GM by salmon sperm DNA indicated that electrostatic interaction and groove binding coexisted between them. 相似文献
945.
Poly(malachite green) film modified Nafion‐coated glassy carbon electrodes have been prepared by potentiodynamic cycling in malachite green solution. The pH of polymerisation solution has only minor effect on film formation. Electrochemical quartz crystal microbalance (EQCM) was used to monitor the growth of the poly(malachite green) film. Cyclic voltammogram of the poly(malachite green) film shows a redox couple with well‐defined peaks. The redox response of the modified electrode was found to be depending on the pH of the contacting solution. The peak potentials were shifted to a less positive region with increasing pH and the dependence of the peak potential was found to be 56 mV per pH unit. The electrocatalytic behavior of poly(malachite green) film modified Nafion‐coated glassy carbon electrodes was tested towards oxidation of NADH, dopamine, and ascorbic acid. The oxidation of dopamine and ascorbic acid occurred at less positive potential on poly(malachite green) film compared to bare glassy carbon electrode. In the case of NADH, the overpotential was reduced substantially on modified electrode. Finally, the feasibility of utilizing poly(malachite green) film electrode in analytical estimation of ascorbic acid was demonstrated in flow injection analysis. 相似文献
946.
An ionic liquid-type carbon paste electrode and its polyoxometalate-modified properties 总被引:1,自引:0,他引:1
Hongtao Liu Ping He Zhiying Li Chunyan Sun Lihong Shi Yang Liu Guoyi Zhu Jinghong Li 《Electrochemistry communications》2005,7(12):1357-1363
The replacement of a non-conductive organic binder with a conductive room temperature ionic liquid in fabricating carbon paste electrode has been made. This new electrode due to its enhanced conductivity presented very large current response from electroactive substrates. The novel carbon paste electrode was bulk-modified via the uniform dispersion of Keggin-type phospho polyoxomolybdate (PMo12) in bulky carbons, which possessed excellent electrocatalytic activity for the reduction of nitrite. The pronounced multi-electron catalytic ability was ascribed to the used hydrophobic ionic liquid which constructed an excellent charge-transfer bridge in the bulk of carbon paste electrode, thus facilitated the intake of electrons from reduced PMo12 mediators. In view of their prominent properties, the carbon paste electrode using ionic liquid binder and its bulk-modified electrode take on good prospects of the application in physical chemistry and electroanalytical chemistry fields. 相似文献
947.
948.
Jing Xu Yibao Li Lejia Wang Xiaoyang Zhu Xunwen Xiao Yanfang Geng Ke Deng Qingdao Zeng 《中国化学快报》2019,30(3):767-770
Because of the effect of pyridine on the substituent position on the TTF group, TTF derivatives exhibit different assembly structures at the interface, which will be of great significance to the construction of functional nanostructures from the molecular design point of view. 相似文献
949.
Direct electrochemical and electrocatalytic behavior of hemoglobin (Hb) immobilized on glass carbon electrode (GCE) containing gelatine (Gel) films was investigated. The characteristics of Hb/Gel film modified GC electrode were performed by using SEM microscopy, UV-vis spectroscopy and electrochemical methods. The immobilized Hb showed a couple of quasi-reversible redox peak with a formal potential of −0.38 V (versus SCE) in 0.1 M pH 7.0 PBS. The formal potential changed linearly from pH 4.03 to 8.41 with a slope value of −52.0 mV pH−1, which suggested that a proton transfer was accompanied with each electron transfer (ET) in the electrochemical reaction. The Hb/gelatine/GCE displayed a rapid amperometric response to the reduction of H2O2 and nitrite. 相似文献
950.
Uniform nylon 6 nanofibers with diameters around 200 nm were prepared by electrospinning. Polymorphic phase transitions and crystal orientation of nylon 6 in unconfined (i.e., as-electrospun) and a high T(g) (340 degrees C) polyimide confined nanofibers were studied. Similar to melt-spun nylon 6 fibers, electrospun nylon 6 nanofibers also exhibited predominant, meta-stable gamma crystalline form, and the gamma-crystal (chain) axes preferentially oriented parallel to the fiber axis. Upon annealing above 150 degrees C, gamma-form crystals gradually melted and recrystallized into the thermodynamically stable alpha-form crystals, which ultimately melted at 220 degrees C. Release of surface tension accompanied this melt-recrystallization process, as revealed by differential scanning calorimetry. For confined nanofibers, both the melt-recrystallization and surface tension release processes were substantially depressed; gamma-form crystals did not melt and recrystallize into alpha-form crystals until 210 degrees C, only 10 degrees C below the T(m) at 220 degrees C. After complete melting of nano-confined crystals at 240 degrees C and recrystallization at 100 degrees C, only alpha-form crystals oriented perpendicular to the nanofiber axis were obtained. In the polyimide-confined nanofibers, the Brill transition (from the monoclinic alpha-form to a high temperature monoclinic form) was observed at 180-190 degrees C, which was at least 20 degrees C higher than that in unconfined nylon 6 at approximately 160 degrees C. This, again, was attributed to the confinement effect. 相似文献