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161.
In this study, the adsorption of hydrogen and methane on the Zn2(NDC)2(diPyTz) [(NDC = 2,6-naphthalenedicarboxylate, diPyTz = di-3,6-(4-pyridyl)-1,2,4,5-tetrazine)] metal–organic framework (MOF) and the effect of its doping with alkali metal cations (Li+, Na+, K+) were investigated using Grand Canonical Monte Carlo simulations. The results indicated that the triply catenating Zn2(NDC)2(diPyTz), possessing small pores preferentially adsorbed hydrogen. Doping of Zn2(NDC)2(diPyTz) with alkali metal cations enhanced the hydrogen adsorption on the MOF. However, this enhancement became weaker as the atomic number of metal cation increased. The simulation results showed that the hydrogen adsorption on the Li+-doped Zn2(NDC)2(diPyTz) was almost 2.35 times greater than that of the corresponding undoped MOF at low pressure and room temperature. This suggests that the doping of MOFs with alkali metal cations especially lithium is a desired strategy for hydrogen storage. Furthermore, the results revealed that the adsorption of hydrogen on the Zn2(NDC)2(diPyTz) was higher than that of methane at room temperature. 相似文献
162.
An efficient algorithm is derived for solving the quantile regression problem combined with a group sparsity promoting penalty. The group sparsity of the regression parameters is achieved by using a \(\ell _{1,\infty }\) -norm penalty (or constraint) on the regression parameters. The algorithm is efficient in the sense that it obtains the regression parameters for a wide range of penalty parameters, thus enabling easy application of a model selection criteria afterwards. A Matlab implementation of the proposed algorithm is provided and some applications of the methods are studied. 相似文献
163.
Saleh Shahin Pirouzfar Vahid Alihosseini Afshar 《Journal of Thermal Analysis and Calorimetry》2019,136(4):1817-1830
Journal of Thermal Analysis and Calorimetry - In this study, a refrigeration cycle was simulated with different refrigerants in a petrochemical plant in Iran. Using Aspen HYSYS Software, necessary... 相似文献
164.
Aisa Sendijarevi Vahid Sendijarevi Kurt C. Frisch Branka Koruga-Lazarevi Enes Torli 《Journal of polymer science. Part A, Polymer chemistry》1990,28(13):3603-3615
The synthesis and properties of thermoplastic urethane-modified polyimides, based on different isocyanates, with different concentrations of hard segments and different ratios of imide and urethane groups, were studied. The effect of catalysts, isocyanates, and temperature was investigated on model reactions leading to formation of monoimides, bisimides, and polyimides. A polymer based on 2,4-TDI, poly(oxytetramethylene) glycol of 1000 molecular weight and pyromellitic dianhydride, with 75% of imide in the hard segments, retained about 50% of the original tensile strength at 120°C and about 30% at 150°C. Increasing the temperature up to 150°C had very little effect on the elongation of this copolymer. In general, increasing the imide concentration in the polymer structure provided better retention of stress-strain properties at elevated temperatures. 相似文献
165.
Givargis T. Vahid F. Henkel J. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2002,10(4):416-422
In this work, we provide a technique for efficiently exploring the power/performance design space of a parameterized system-on-chip (SOC) architecture to find all Pareto-optimal configurations. These Pareto-optimal configurations will represent the range of power and performance tradeoffs that are obtainable by adjusting parameter values for a fixed application that is mapped on the SOC architecture. Our approach extensively prunes the potentially large configuration space by taking advantage of parameter dependencies. We have successfully applied our technique to explore Pareto-optimal configurations of our SOC architecture for a number of applications. 相似文献
166.
Hajrija ehovi Aia Sendijarevi Vahid Sendijarevi Kurt C. Frisch 《Journal of polymer science. Part A, Polymer chemistry》1987,25(10):2729-2736
The reaction of butyl isocyanate with phenylglycidyl ether was selected as a model reaction for the synthesis of aliphatic isocyanate-based poly(2-oxazolidones). The selectivity of different metal halides and aluminum trichloride/triphenylphosphine oxide (AlCl3 TPPO) and aluminum hexamethylphosphoramide (AlCl3 HMPA) complexes were investigated for oxazolidone formation. Both FTIR and mass spectrographic methods were employed for characterization of the reaction products. The kinetics of the model reaction was studied using AlCl3 TPPO in o-dichlorobenzene at 120 and 140°C. 相似文献
167.
新型磺酸功能化吡啶盐酸盐离子液体催化剂用于六氢喹啉合成(英文) 总被引:1,自引:0,他引:1
Ardeshir Khazaei Mohammad Ali Zolfigol Ahmad Reza Moosavi-Zare Javad Afsar Abdolkarim Zare Vahid Khakyzadeh Mohammad Hassan Beyzavi 《催化学报》2013,34(10):1936-1944
Sulfonic acid functionalized pyridinium chloride [pyridine-SO3 H]Cl has been synthesized as a novel Brnsted acidic ionic liquid and characterized on the basis of its FT-IR,1H and 13C NMR,MS,ther-mogravimetry,and derivative thermogravimetry data.The material has also been used as a highly efficient,homogeneous,and reusable catalyst for the preparation of hexahydroquinolines according to the one-pot multi-component condensation of arylaldehydes,dimedone(5,5-dimethylcyclohexane-1,3-dione),β-ketoesters,and ammonium acetate under solvent-free conditions. 相似文献
168.
Asad Asadujjaman Vahid Ahmadi Antoine Michel Claude Franc Annabelle Bertin 《Journal of polymer science. Part A, Polymer chemistry》2019,57(19):2064-2073
A novel copolymer based on supramolecular motif 2,6‐diaminopyridine and water‐soluble acrylamide, poly[N‐(6‐acetamidopyridin‐2‐yl) acrylamide‐co‐acrylamide], was synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization with various monomer compositions. The thermoresponsive behavior of the copolymers was studied by turbidimetry and dynamic light scattering (DLS). The obtained copolymers showed an upper critical solution temperature (UCST)‐type phase transition behavior in water and electrolyte solution. The phase transition temperature was found to increase with decreasing amount of acrylamide in the copolymer and increasing concentration of the solution. Furthermore, the phase transition temperature varied in aqueous solutions of electrolytes according to the nature and concentration of the electrolyte in accordance with the Hoffmeister series. A dramatic solvent isotope effect on the transition temperature was observed in this study, as the transition temperature was almost 10–12 °C higher in D2O than in H2O at the same concentration and acrylamide composition. The size of the aggregates below the transition temperature was larger in D2O compared to that in H2O that can be explained by deuterium isotope effect. The thermoresponsive behavior of the copolymers was also investigated in different cell medium and found to be exhibited UCST‐type phase transition behavior in different cell medium. Such behavior of the copolymers can be useful in many applications including biomedical, microfluidics, optical materials, and in drug delivery. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2064–2073 相似文献
169.
Mohammad Ali Zolfigol Vahid Khakyzadeh Ahmad Reza Moosavi-Zare Abdolkarim Zare Seyedeh Bahareh Azimi Zhila Asgari Alireza Hasaninejad 《Comptes Rendus Chimie》2012,15(8):719-736
In this work, some novel sulfonic acid functionalized imidazolium salts (SAFIS), as a new category of ionic liquids, are synthesized by eco-friendly and simple procedures, and used as highly efficient and reusable catalysts to promote the following one-pot multicomponent organic transformations under solvent-free conditions: (i) the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes from β-naphthol (2 eq.) and arylaldehydes (1 eq.), (ii) the preparation of tetrahydrobenzo[a]xanthene-11-ones from β-naphthol, arylaldehydes and dimedone, and (iii) the synthesis of 1,8-dioxo-octahydroxanthenes from dimedone (2 eq.) and aromatic aldehydes (1 eq.). Environmentally benign, simple methodologies, easy workup procedure, clean reaction, short reaction time, high yield and easy preparation of the catalysts are some advantages of this work. 相似文献
170.
Marzieh Vafaee Mostafa M. Amini Ezzatollah Najafi Omid Sadeghi Vahid Amani 《Journal of Sol-Gel Science and Technology》2012,64(2):411-417
Different nanoporous silica materials, MCM-41, MCM-48 and SBA-15, were modified by pyridine and their applications for oral drug delivery system were evaluated. These pyridine functionalized nanoporous silicas were loaded with a water insoluble diorganotin(IV) dichloride complex as an antitumor drug model and its release from them were investigated by changing pH. An efficient pH-responsive carrier system was constructed by coordination of the pyridine group in modified nonoporous materials to tin complex. In vitro, releasing of loaded tin complex was studied in three different kinds of fluids, including a simulated gastric medium and a simulated body fluid. The loading and releasing of the diorganotin(IV) dichloride from various modified nanoporous silicas and also a non-porous silica (SiO2) were investigated, and the results were compared. In addition, the effect of some factors such as pH, time of loading and releasing were investigated through this study. 相似文献