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101.
Corrosion and biological behavior of nanostructured 316L stainless steel processed by severe plastic deformation
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K. Hajizadeh H. Maleki‐Ghaleh A. Arabi Y. Behnamian E. Aghaie A. Farrokhi M. G. Hosseini M. H. Fathi 《Surface and interface analysis : SIA》2015,47(10):978-985
Nanostructured metals have different mechanical, chemical, and physical behaviors in comparison with the microstructured ones. Numerous research studies demonstrated that the biological behavior of nanostructured metallic implants was improved significantly. Concerning the nanostructured metals, decreasing the corrosion rate and the releasing of hazardous ions from metallic implants, and thus increasing the biocompatibility of implants are due to improving the native oxide layer. In the present study, nanostructured 316L stainless steel (biomedical grade) was manufactured via equal channel angular pressing (ECAP) method. To do so, the 316L stainless steel (SS) was exposed to the ECAP operation for eight passes. The impact of the ECAP process on corrosion behavior of SS samples was evaluated through performing the electrochemical polarization corrosion tests in Ringer's solution. Scanning electron microscopy was employed to study the surface morphology of common SS and ECAPed SS sample after the electrochemical polarization tests. Moreover, the biological behavior of the samples was evaluated via cell culture using fibroblast cells. The corrosion test results revealed a substantial decrease of corrosion rate from 3.12 (coarse‐grained sample) to 0.42 μA cm?2 (for nanostructured). Furthermore, the cell proliferation in the interface of nanostructured sample and cell culture medium enhanced dramatically compared with the coarse‐grained one. The much better biological behavior of nanostructured SS sample in comparison with the coarse‐grained one is mostly due to the significant decrease of corrosion rate on the surface of SS samples, and the presence of much more chrome oxide on the surface of SS sample. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
102.
A novel, cost‐effective, and simple electrocatalyst based on a Pt‐modified glassy carbon electrode (GCE), using cetyltrimethylammonium bromide (CTAB) as a cationic surfactant, is reported. Am‐phiphilic... 相似文献
103.
Zahra Shokri Behzad Zeynizadeh Seyed Ali Hosseini Behrooz Azizi 《Journal of the Iranian Chemical Society》2017,14(1):101-109
Magnetically separable nano core–shell Fe3O4@Cu(OH)x with 22 % Cu content was prepared by the addition of sodium hydroxide to a mixture of CuCl2·2H2O and nano Fe3O4 in water. Characterization of the impregnated copper hydroxide was carried out by X-ray fluorescence (XRF), X-ray diffraction (XRD) atomic absorption spectroscopy (AAS), scanning electron microscopy (SEM), value stream mapping (VSM) and Brunauer–Emmett–Teller (BET) analysis. The core–shell nanocatalyst exhibited the excellent catalytic activity toward reduction of various nitro compounds to the corresponding amines with NaBH4. All reactions were carried out in H2O (55–60 °C) within 3–15 min to afford amines in high to excellent yields. Reusability of core–shell Cu(OH)x catalyst was examined 9 times without significant loss of its catalytic activity. 相似文献
104.
Rouhollah Heydari Mohammad Hosseini Reza Rezaeepour 《Journal of the Iranian Chemical Society》2017,14(8):1691-1698
In this study, a new device for semi-automated salt-assisted liquid–liquid extraction was designed and coupled with high-performance liquid chromatography (HPLC) to determine three aromatic hydrocarbons in aqueous samples. In order to evaluate the performance of the designed device, three aromatic hydrocarbons including 2-naphthol, naphthalene and anthracene were selected as model analytes. Sample solution, extraction solvent and salt solution using separate channels were transferred to a sample holder, respectively. These three components were mixed using a magnetic stirrer. After stirrer stopping, the aqueous and organic phases were separated and organic layer transferred to the injection loop of HPLC system. Optimization process was achieved using response surface methodology by Design-Expert software. A central composite design was used to optimize the main parameters including pH (A), stirrer time (B), organic solvent volume (C) and salt concentration (D). The limit of quantitation for 2-naphthol, naphthalene and anthracene was 15.0, 25.0 and 1.0 ng mL?1, respectively. Under the optimum conditions, obtained recoveries for three analytes were in the range of 76.0–96.2% with relative standard deviation less than 8.2%. The salt-assisted liquid–liquid extraction method using the proposed device has been successfully used for the analysis of real samples containing studied analytes in various matrices. 相似文献
105.
Esmaeil Hosseini 《代数通讯》2017,45(7):3068-3074
We provide a necessary and su?cient condition which ensure that every flat quasi-coherent sheaf has finite cotorsion dimension. Also, we will show that every locally noetherian scheme with a dualizing complex has this requirement. 相似文献
106.
Akbar Ali Shabnam Shahida Muhammad Haleem Khan Muhammad Mufazzal Saeed 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(3):735-743
A very sensitive and selective flow injection on-line determination method of thorium (IV) after preconcentration in a minicolumn having XAD-4 resin impregnated with N-benzoylphenylhydroxylamine is described. Thorium (IV) was selectively adsorbed from aqueous solution of pH 4.5 in a minicolumn at a flow rate of 13.6 mL min?1, eluted with 3.6 mol dm?3 HCl (5.6 mL min?1), mixed with arsenazo-III (0.05% in 3.6 mol dm?3 HCl stabilized with 1% Triton X-100, 5.6 mL min?1) at confluence point and taken to the flow through cell of spectrophotometer where its absorbance was measured at 660 nm. Peak height was used for data analyses. The preconcentration factors obtained were 32 and 162, detection limits of 0.76 and 0.150 ??g L?1, sample throughputs of 40 and 11 h?1 for preconcentration times of 60 and 300 s, respectively. The tolerance levels for Zr(IV) and U(VI) metal ions is increased to 50-folds higher concentration to Th(IV). The proposed method was applied on different spiked tap water, sea water and biological sample and good recovery was obtained. The method was also applied on certified reference material IAEA-SL1 (Lake Sediment) for the determination of thorium and the results were in good agreement with the reported value. 相似文献
107.
Fatemeh Niroomand Hosseini Alireza Ariafard Gholamhassan Azimi 《Journal of organometallic chemistry》2011,696(21):3351-3358
Three metal square planar complexes of the type [M(CH3)2(NH3)2] (M = Ni, Pd, Pt), with a systematic variation in the metals, are chosen to investigating their SN2-type oxidative addition reactions with methyl iodide by using the B3LYP levels of theory. The oxidative addition was found to take place via a transition state with a nearly linear arrangement of the I-CH3-M moiety. Solvation effects in these oxidative addition reactions were also investigated. Considering the nature of the metal centre and solvation effects, the following conclusions emerge: (i) addition of MeI is exothermic for all three metals, and Pt is predicted to react with a much lower barrier than either Pd or Ni. The results describe that the MeI addition would be expected to be more favourable with the complex bearing the third-row metal (platinum) as compared to the other triad metals, nickel or palladium, in which case a more strongly bound MeI adduct is formed with a lower activation barriers and the reaction being more exothermic; (ii) the reaction is very difficult to occur in low polar solvents, such as benzene, due to the high barrier which is induced by dissociation of iodide anion from methyl group, but the reaction easily occurs in polar solvents, such as acetonitrile; this is attributed to the ability of polar solvents to solvate and therefore stabilize the related polar intermediate ion pair. Ethane reductive elimination from the M(VI) complexes fac-[M(CH3)3(NH3)2I] were also studied, indicating that the Ni(IV) and Pd(IV) complexes are very prone to undergo the reductive elimination while the Pt(IV) analogous is less reactive towards the reductive elimination. The results indicate that in contrast to the Me-Me reductive elimination, the SN2 oxidative addition reaction of MeI to M(II) is much less sensitive to the nature of the metal centre, suggesting that the nucleophilicity of M(II) in [M(CH3)2(NH3)2] does not change significantly as one moves from M = Ni to Pt. 相似文献
108.
Competition of methyltrioxorhenium (MTO) with osmium tetroxide (OsO4) toward L = pyridine and its derivatives, based on the equilibrium constant for the reaction OsO4·L + MTO = MTO·L + OsO4, has been measured. A successful correlation of log Keq with the Hammett σ constants of the substituents on the ligands was realized. A negative reaction constant, obtained for the reactions, shows that a more positive charge expands on the pyridine nitrogen in the complex MTO·L as compared with the complex OsO4·L. So, the rhenium center acts as a better electron acceptor than osmium center. The thermodynamic parameters have been obtained and an excellent linear relationship was observed between the enthalpy and entropy of the reactions. 相似文献
109.
An ionic liquid mediated sol-gel sorbents for hollow fiber solid-phase microextraction (HF-SPME) was developed for extraction of the pesticides: diazinon, fenitrothion, malathion, fenvalerate, phosalone and tridemorph from human hair and water samples. The analytes were subsequently analyzed with high performance liquid chromatography and diode array detection (HPLC-DAD). Preliminary experiments were carried out in order to study experimental conditions for pesticides' extraction from spiked hair and water samples with HF-SPME using hollow fiber-supported ionic liquid mediated sol-gel sorbent. The sol-gel nanocomposites were reinforced with nanoparticles such as carboxylic functionalized multi-walled carbon nanotubes (COOH-MWCNTs), amino functionalized multi-walled carbon nanotubes (NH(2)-MWCNTs), nano SiO(2), nano TiO(2) and nano MgO comparatively to promote extraction efficiency. In this device, the innovative solid sorbents were developed by the sol-gel method via the reaction of tetraethylorthosilicate (TEOS) with 2-amino-2-hydroxymethyl-propane-1,3-diol (TRIS). In the basic condition (pH 10-11), the gel growth process in the presence of ionic liquid and nanoparticles was initiated. Then, the sol was injected into a polypropylene hollow fiber segment for in situ gelation process. Parameters affecting the efficiency of HF-SPME were thoroughly investigated. Linearity was observed over a range of 0.01-25,000 ng/mL with detection limits between 0.004 and 0.095 ng/mL for the pesticides in the aqueous matrices and 0.003-0.080 ng/mL in the hair matrices. The relative recoveries in the real samples ranged from 82.0% to 94.0% for the pesticides store seller's hair and the work researchers' hair. Results are showing the great possibilities of HF-SPME-HPLC-PDA for analysis of pesticides in biological and environmental samples. 相似文献
110.
S. Hosseini M.R. Pouryayevali 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(12):3884-3895
In this paper, a notion of generalized gradient on Riemannian manifolds is considered and a subdifferential calculus related to this subdifferential is presented. A characterization of the tangent cone to a nonempty subset S of a Riemannian manifold M at a point x is obtained. Then, these results are applied to characterize epi-Lipschitz subsets of complete Riemannian manifolds. 相似文献