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991.
Osmotic coefficients of binary mixtures containing an ionic liquid, (1-butyl-3-methylimidazolium tetrafluoroborate, [BMIm]BF4, 1-ethyl-3-methylimidazolium ethyl sulfate, [EMIm]ES, and 1-butyl-3-methylimidazolium methyl sulfate, [BMIm]MS) with water were measured until about 3 molal concentrations using vapor pressure osmometry method (VPO) at temperature ranges 298.15–328.15 K and modeled using different electrolyte excess Gibbs free energy models including electrolyte non-random two liquids (NRTL), modified NRTL (MNRTL), mean spherical approximation NRTL (MSA-NRTL), non random factor (NRF), and extended Wilson models. The results show that osmotic coefficient data increase with increasing temperature. The calculated standard deviations of the studied systems show that the applicability of these models for the correlation of VLE properties of ionic liquid solutions. The average standard deviations for the models have the order σ(?) MNRTL < σ(?) Wilson < σ(?) NRTL < σ(?) MSA-NRTL < σ(?)NRF. The results show MNRTL model is able to reproduce experimental osmotic coefficients of aqueous solution of studied ionic liquids with good precision. 相似文献
992.
Zohreh Dahaghin Hassan Zavvar Mousavi Ehsan Mirparizi Parand Haghighat 《Chemical Papers》2018,72(6):1451-1459
In this work for the first time, Fe3O4@SiO2 core–shell nanoparticles functionalized with isatin groups as a magnetic nanosorbent was applied for the simultaneous extraction of trace amounts of cadmium(II), nickel(II), lead(II), and zinc(II). The characterization of this nanosorbent was studied using Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectrometry, X-ray diffraction, vibrating sample magnetometer and thermogravimetric analysis. The effect of several factors such as pH, amount of sorbent, extraction time, type and volume of the eluent, sample volume, sorption capacity, and potentially interfering ions was investigated. In the selected conditions, it was observed that the limits of detection were 0.11 ng mL?1 for Cd(II), 0.28 ng mL?1 for Ni(II), 0.47 ng mL?1 for Pb(II), and 0.21 ng mL?1 for Zn(II), and the maximum sorption capacity of this suggested magnetic nanosorbent was 120, 112, 100, and 100 mg g?1 for Cd(II), Ni(II), Pb(II), and Zn(II), respectively. Also, the precision of the method (RSD%) for ten replicate measurements was found 2.5, 2.5, 2.8, and 3.1%, for Cd(II), Ni(II), Pb(II), and Zn(II) ions, respectively. Finally, the suggested procedure was applied for determination of cadmium(II), nickel(II), lead(II), and zinc(II) at trace levels in different water and agricultural products with satisfactory results. 相似文献
993.
Removal of chromate from aqueous solution by reduction with nanoscale Fe–Al layered double hydroxide
Leila Alidokht Shahin Oustan Alireza Khataee Mohammadreza Neyshabouri Adel Reyhanitabar 《Research on Chemical Intermediates》2018,44(4):2319-2331
Nanoscale layered double hydroxides of FeII and AlIII (Fe–Al LDH) have been applied for removal of chromate (CrVI) from aqueous solution. Given the reaction stoichiometry, CrVI was completely reduced to CrIII and coprecipitated with FeIII and AlIII oxyhydroxides. The extent of CrVI removal decreased with increasing initial pH and decreasing molar ratio of CrVI/structural FeII in the LDH. The chromate reduction rate at different initial concentrations of CrVI was well described by the pseudo-second-order model with reaction rate constant ranging from 197.4 to 13.53 (mmol min)?1. Initial pH and substitution of various amounts of FeIII in the LDH structure had little effect on the reaction rate. Backtransformation of CrIII to CrVI by birnessite Mn oxide (δ-MnO2) after 40 days of reaction was less than 1% of the initial Cr (as CrIII solid), indicating high stability of the final reaction products and high efficiency of nanoscale Fe–Al LDHs for removal of chromate from aqueous solution. 相似文献
994.
Ali Zamani Reza Ghiasi Mirabdollah Seyed Sadjadi Mohammad Yousefi 《Russian Journal of Inorganic Chemistry》2018,63(7):906-910
In this study, we report substituent effect on aryl group migration in (para-C6H4X)Mn(CO)5 complexes using mpw1pw91 quantum chemical calculations. These calculations reveal good linear relationships between barrier energy (ΔE), activation energy (ΔH?), activation free energy (ΔG?) values and rate constants with Hammett constants of X-substituents. The occupancy values of Mn–COcis and Mn–C(O)-(para-C6H4X) bonds in reactant, transition state and product were calculated by Natural bond orbital (NBO) method. 相似文献
995.
Mina Yarazavi Ebrahim Noroozian Mehdi Mousavi 《Journal of the Iranian Chemical Society》2018,15(11):2593-2603
Sol–gel coating technology for the preparation of solid-phase microextraction fibers involves a single-step procedure and allows for in situ creation of chemically bonded coatings which are characterized by high thermal and solvent stabilities. A novel titania sol–gel coating was prepared for the first time on a stainless steel fiber and applied for the headspace solid-phase microextraction (HS-SPME) of menthol with gas chromatography and flame ionization detection. Important parameters influencing the efficiency of SPME process, such as extraction time, extraction temperature and ionic strength, were optimized by central composite design. An extraction time of 40 min at 60 °C gave maximum extraction efficiency, when NaCl (10% w/v) was added to the aqueous sample. The analytical characteristics of the proposed method were comparable with other reported fibers. Under optimized conditions, the linearity was between 0.05 and 100 µg mL??1. The relative standard deviations (RSDs) determined at 0.5 µg mL??1 concentration level (n?=?5) were as follows: intra-day RSD 7.26%; inter-day RSD 10.87%; fiber-to-fiber RSD 9.05%. The relative recoveries determined after spiking a mint distillate sample at three concentration levels from 0.067 to 50.0 µg mL??1 varied from 86 to 102%. The proposed method was successfully applied for the analysis of menthol in peppermint samples. 相似文献
996.
Maryam Maleki Seyed Meysam Baghbanian Mahmood Tajbakhsh 《Journal of the Iranian Chemical Society》2018,15(2):359-368
A new magnetic oxidation catalyst was prepared using immobilization of tungstophosphoric acid on poly(N-vinylimidazole) entrapped magnetic nanozeolite and characterized by FTIR, TGA, XRD, SEM, TEM, EDX, VSM, and ICP-OES. The resulting heterogeneous catalyst displays high catalytic performance for selective oxidation of alcohols compared to the other catalysts. The catalyst could be reused eight times without any loss of catalytic activity. 相似文献
997.
M. Yousef Elahi H. Heli S. Z. Bathaie M. F. Mousavi 《Journal of Solid State Electrochemistry》2007,11(2):273-282
The electrocatalytic oxidation of glucose was investigated on a nickel-basedchemically modified electrode (Ni(II)-curcumin) prepared by electropolymerization of Ni-curcumin complex (curcumin=1,7-bis[4-hydroxy-3-methoxyphenyl]-1,6-heptadiene-3,5-dione) in alkaline solution. Reaction kinetic and mechanism were investigated by using cyclic voltammetry (CV) and chronoamperometry (CA) techniques and steady-state polarization measurements. Cyclic voltammetry studies indicated that in the presence of glucose the anodic peak current of surface redox mediator was increased, followed by decrease in the corresponding cathodic current. This indicates that glucose was oxidized at the surface of this modified electrode. The results were explained based on the concept of electrocatalytic reactions that occur in this chemically modified electrode. The diffusion coefficient of glucose and the rate constant of the catalytic oxidation of glucose were found to be 6.7×10−6 cm2 s−1 and 6.5×103 M−1 s−1, respectively. It has shown that by using the Ni-curcumin modified electrode, glucose can be determined with good response and low detection limit. 相似文献
998.
Artificial neural networks (ANNs) have been used to dynamically model crossflow ultrafiltration of milk. It aims to predict permeate flux, total hydraulic resistance and the milk components rejection (protein, fat, lactose, ash and total solids) as a function of transmembrane pressure and processing time. Dynamic modelling of ultrafiltration performance of colloidal systems (such as milk) is very important for designing of a new process and better understanding of the present process. Such processes show complex non-linear behaviour due to unknown interactions between compounds of a colloidal system, thus the theoretical approaches were not being able to successfully model the process. In this work, emphasis has been focused on intelligent selection of training data, using few training data points and small network. Also it has been tried to test the ANN ability to predict new data that may not be originally available. Two neural network models were constructed to predict the flux/total resistance and rejection during ultrafiltration of milk. The results showed that there is an excellent agreement between the validation data (not used in training) and modelled data, with average errors less than 1%. Also the trained networks are able to accurately capture the non-linear dynamics of milk ultrafiltration even for a new condition that has not been used in the training process. 相似文献
999.
Mojtaba Shamsipur Sayed Habib Kazemi Abdolhamid Alizadeh Mir Fazlollah Mousavi Mark S. Workentin 《Journal of Electroanalytical Chemistry》2007,610(2):218-226
An electroactive self-assembled monolayer (SAM) was fabricated by covalent attachment of a novel hydroquinone-terminated dodecanethiol onto the gold surface and its electrochemical behavior was investigated using cyclic voltammetry and electrochemical impedance spectroscopy. The capability of the designed SAM in immobilization of organic molecules onto the gold surface was studied utilizing the Michael-addition as a model reaction. The results obtained from cyclic voltammetry, electrochemical impedance and grazing incidence Fourier transform infrared (GI-FTIR) spectroscopy revealed that, upon applying an anodic potential to the Au-SAM electrode system in the presence of glutathione, the electrochemically generated p-quinone participated in a Michael-addition reaction with glutathione and the corresponding Michael adduct was formed at the solid–liquid interface. The kinetic parameters were then derived for this interfacial Michael-addition reaction. 相似文献
1000.
A metallophthalocyanine complex with zirconium(IV) ion in the center (as an oxo-zirconium, Zr=O, group) was used in poly vinyl chloride (PVC) membranes for the selective detection of 5-sulfosalicylic acid (SSA). The resulting electrodes demonstrate Nernstian responses over a wide range of sulfosalicylic acid concentration (10−6 to 10−1 mol dm−3) with a slope of about −29 mV per decade. The influence of lipophilic ion-exchanger sites on the response properties of the electrodes was investigated. The optimal potentiometric response was observed for the electrode in the presence of about 150 mol% of cationic additive (relative to ionophore) in the phase membrane. The electrodes have a fast response time, micromolar detection limit and good long-term stability (more than 2 months). The feasibility of the application of these sensors for the potentiometric titration of iron in solutions that were prepared from magnetite samples was investigated. 相似文献