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排序方式: 共有199条查询结果,搜索用时 15 毫秒
91.
Analysis of the magnetic losses in iron-based soft magnetic composites with MgO insulation produced by sol-gel method 总被引:3,自引:0,他引:3
Amir Hossein Taghvaei Azadeh Ebrahimi Kamal Janghorban 《Journal of magnetism and magnetic materials》2010,322(23):3748-3754
This work investigated the magnetic losses of heat treated iron-based soft magnetic composites with a thin MgO insulating layer produced by sol-gel method. The samples were characterized by energy dispersive X-ray spectroscopy, X-ray analysis and Fourier transform infrared spectroscopy. The results show that the surface of the powders contains a thin layer of MgO insulation. The loss results indicate that the hysteresis part for both the core loss and total loss factor was approximately the same for the MgO-insulated compacts and conventional SOMALOYTM samples with phosphate insulation after annealing at 600 °C. But the MgO-insulated compacts exhibited significantly lower eddy current contribution of both core loss and total loss factor with respect to SOMALOYTM samples after annealing. Also the contribution of eddy current in the iron particles for MgO insulated compacts (kp=0.91) was noticeably higher than this contribution for SOMALOYTM samples (kp=0.18) after annealing due to the higher electrical resistivity of the MgO-insulated compacts. 相似文献
92.
Amir Sabet Sarvestani Parviz Abdolmaleki Seyed Javad Mowla Faezeh Ghanati Emran Heshmati Zeinab Tavasoli Azadeh Manoochehri Jahromi 《Micron (Oxford, England : 1993)》2010,41(2):101-104
In order to evaluate the influence of static magnetic fields (SMF) on the progression of cell cycle as a monitor of presumptive genotoxicity of these fields, the effects of a 15 mT SMF on cell cycle progression in rat bone marrow stem cells (BMSC) were examined. The cells were divided into two groups. One group encountered SMF alone for 5 h continuously but the other group exposed with X ray before treatment with SMF. The population of cells did not show any significant difference in the first group but the second group that was exposed with acute radiation before encountering SMF showed a significant increase in the number of cells in G2/M phase. So SMF has intensified the effects of X ray, where SMF alone, did not had any detectable influence on cell cycle.These findings suggest that magnetic fields (MF) play their role by increasing the effects of genotoxic agents and because of the greater concentration of free radicals in the presence of radical pair producers, this effect is better detectable. 相似文献
93.
Azam Aliakbari Mostafa M. Amini Kheirollah Mehrani Hamid Reza Moghadam Zadeh 《Mikrochimica acta》2014,181(15-16):1931-1938
An ion imprinted polymer coated onto magnetite (Fe3O4) nanoparticles is shown to be a useful magnetic sorbent for the fairly selective preconcentration of vanadium. The sorbent was prepared by radical copolymerization of 3-(triethoxysilyl)propyl methacrylate (the monomer), ethylene glycol dimethacrylate (the cross-linker), and the vanadium(IV) complex of 1-(2-pyridylazo-2-naphthol) in the presence of magnetite nanoparticles. The material was characterized by IR spectroscopy, scanning electron microscopy, and thermal analysis. The vanadium(IV) ions were removed from the imprint by a solution containing thiourea and HCl, and the eluent was submitted to AAS. The analytical efficiency and relative standard deviation are 99.4 and ±2.3 %, respectively, under optimum conditions, and the limit of detection is 20 ng mL?1. The method was successfully applied to the preconcentration and determination of vanadium(IV) ions in crude oil. Figure
An ion imprinted polymer is coated on to magnetite nanoparticles as a useful magnetic sorbent for the fairly selective preconcentration of vanadium which can be used for vanadium determination in crude oil. 相似文献
94.
Abasalt Hosseinzadeh Colagar Hamed Memariani Farshad Sohbatzadeh Azadeh Valinataj Omran 《Applied biochemistry and biotechnology》2013,171(7):1617-1629
Nonthermal atmospheric plasma jet, a promising technology based on ionized gas at low temperatures, can be applied for disinfection of contaminated surfaces. In this study, Escherichia coli cells and their macromolecules were exposed to the nonthermal atmospheric argon plasma jet for different time durations. Total protein, genomic DNA, and malondialdehyde (MDA) levels of E. coli were assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining; agarose gel electrophoresis; and measurement of absorbance at 534 nm, respectively. After exposure, the spectroscopic results of liquid samples indicated that the survival reduction of E. coli can reach to 100 % in an exposure time of 600 s. Moreover, inactivation zones of E. coli, DNA degradation, and MDA levels were significantly increased. Additionally, banding patterns of total protein were changed and amino acid concentrations increased following ninhydrin test. The experimental results suggest that the nonthermal plasma could serve as an effective instrument for both sterilizing E. coli and degrading macromolecules from the surface of the objects being sterilized. 相似文献
95.
Reza Maddahian Azadeh Kebriaee Bijan Farhanieh Bahar Firoozabadi 《Archive of Applied Mechanics (Ingenieur Archiv)》2011,81(4):489-501
In this research, the developing turbulent swirling flow in the entrance region of a pipe is investigated analytically by
using the boundary layer integral method. The governing equations are integrated through the boundary layer and obtained differential
equations are solved with forth-order Adams predictor-corrector method. The general tangential velocity is applied at the
inlet region to consider both free and forced vortex velocity profiles. The comparison between present model and available
experimental data demonstrates the capability of the model in predicting boundary layer parameters (e.g. boundary layer growth,
shear rate and swirl intensity decay rate). Analytical results showed that the free vortex velocity profile can better predict
the boundary layer parameters in the entrance region than in the forced one. Also, effects of pressure gradient inside the
boundary layer is investigated and showed that if pressure gradient is ignored inside the boundary layer, results deviate
greatly from the experimental data. 相似文献
96.
Kheyrollah Mehrani Azadeh Mehrani Mostafa M. Amini Omid Sadeghi Najmeh Tavassoli 《Mikrochimica acta》2011,173(3-4):521-527
Nanoporous silicas of the type SBA-15 (Santa Barbara Amorphous) and MCM-48 (Mobile Composition of Material) were modified with dipyridylamine (dipy) and used as solid phases for the extraction of Pd(II) ions. The experimental conditions (pH, sample and eluent flow rates, type and quantity of eluent) were optimized. The recovery values were ~ 99.7 and ~ 93.4% for dipy-MCM-48 and dipy-SBA-15, respectively, the limits of detection were <0.08 and <0.11 ng L?1, the pre-concentration factors were 725 and 550, and the adsorption capacity was >78 mg g?1. The procedure was applied to the preconcentration of Pd(II) in real samples. Figure
Nanoporous silicas of the type SBA-15 and MCM-48 were modified with dipyridylamine and used as solid-phase for the extraction of Pd(II) ions. The experimental conditions were optimized and the recovery values were determined. The procedure was applied to the pre-concentration of Pd(II) in real samples. 相似文献
97.
One of the most important results of Chevalley's extension theorem states that every valuation domain has at least one extension to every extension field of its quotient field. We state a generalization of this result for Prüfer domains with any finite number of maximal ideals. Then we investigate extensions of semilocal Prüfer domains in algebraic field extensions. In particular, we find an upper bound for the cardinality of extensions of a semilocal Prüfer domain. Moreover, we show that any two extensions of a semilocal Prüfer domain are incomparable (by inclusion) in an algebraic extension of fields. 相似文献
98.
Crystallography Reports - A new co-crystal compound of 4,4'-bipyridine and phenylsuccinic acid was synthesized and characterized by elemental analysis, infrared and ultraviolet–visible... 相似文献
99.
Nemati Azadeh Sayyahi Soheil Zare-Shahabadi Vahid Anaraki-Ardakani Hossein 《Research on Chemical Intermediates》2020,46(7):3397-3411
Research on Chemical Intermediates - In this study, we examined the catalytic role of low rhodium embedded onto MOF-5 as a hard template, in the ring opening reaction of epoxides with N3?... 相似文献
100.
Highly ordered mesoporous molecular sieves AlMCM‐41 and a new NiO/AlMCM‐41 nanocomposite were synthesized using a sol–gel method. Fourier transform infrared (FT‐IR) spectroscopy, X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX), and N2 adsorption desorption analyses were used to examine the structure, morphology, size and phase composition of the synthesized NiO/AlMCM‐41 nanocomposites. AlMCM‐41 embedded with NiO nanoparticles was subsequently prepared using different nickel loadings in a direct synthetic route. The results show the successful deposition of NiO nanoparticles onto the framework of AlMCM‐41. AlMCM‐41 provides enormous benefits such as environmentally safe, economic viability and porosity when used as support for NiO nanoparticles. The excellent catalytic activities of AlMCM‐41 and NiO/AlMCM‐41 were investigated for the reduction of nitrophenols (4‐NP, 2‐NP) to aminophenols (4‐AP, 2‐AP) in water at ambient temperature. The best observed performance of reduction of NP with 100% conversion into analogous amino derivatives occurred within 6 min with an estimated rate constant of 0.46 min?1. The efficiency of reduction was observed to increase as a function of NiO enrichment. The NiO/AlMCM‐41 nanocomposite could be recycled and reused up to five times without noticeable change in its structure and activity. These properties make NiO/AlMCM‐41 nanocomposite an ideal platform to study various heterogeneous catalytic processes which can have application in purification, catalysis, sensing devices, and green chemistry. 相似文献