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排序方式: 共有111条查询结果,搜索用时 15 毫秒
1.
Mohammad Navid Soltani Rad Somayeh Behrouz Abdollah Movahedian Mohammad Mahdi Doroodmand Younes Ghasemi Sara Rasoul‐Amini Abdol‐Rasoul Ahmadi Gandomani Ramin Rezaie 《Helvetica chimica acta》2013,96(4):688-701
A facile and simple protocol for the 1,3‐dipolar cycloaddition of organic azides with terminal alkynes catalyzed by doped nano‐sized Cu2O on melamine? formaldehyde resin (nano‐Cu2O? MFR) as a new and convenient heterogeneous catalyst is described. In this method, ‘click’ cycloaddition of various structurally diverse β‐azido alcohols and alkynes in the presence of nano‐Cu2O? MFR in H2O/THF 1 : 2 furnished the corresponding 1,4‐disubstituted 1H‐1,2,3‐triazole adducts 1a – 1o in good to excellent yields at room temperature (Scheme and Table 3). The nano‐Cu2O? MFR was characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), inductively coupled plasma (ICP) analysis, and FT‐IR. The nano‐Cu2O? MFR could be easily recovered and recycled from the reaction mixture and reused for many consecutive trials without significant decrease in activity (Table 4). The in vitro antibacterial activities of all synthesized compounds were tested on several Gram‐positive and/or Gram‐negative bacteria (Table 5). The results demonstrate the promising antibacterial activity for some of the synthesized compounds. 相似文献
2.
Vahideh Masoumi Ali Mohammadi Mohsen Amini Mohammad Reza Khoshayand Rasoul Dinarvand 《Journal of Solid State Electrochemistry》2014,18(6):1763-1771
In this work, polyaniline, polypyrrole, and polyaniline/polypyrrole composite fibers were synthesized in the absence and presence of oxidized multiwalled carbon nanotubes using electrochemical cyclic voltammetry with CF3COOH as dopant. Thermal stability of these fibers was studied by differential scanning calorimetry. Then, headspace solid-phase microextraction process coupled with gas chromatography and flame ionization detector was used for comparing extraction capability of benzaldehyde from aqueous solution. Since polyaniline fiber showed better extraction efficiency than the other fibers, its preparation conditions including acid concentration, aniline concentration, scan rate, and amount of multiwalled carbon nanotubes were studied by means of the “one-factor-at-a-time method”. The analytical performance of polyaniline fibers were investigated to determine benzaldehyde from the aqueous solution. The morphology and texture of polyaniline fibers were examined by field emission scanning electron microscopy and Fourier transform infrared spectroscopy analyses. The attained results revealed that the perfect conditions for acid concentration, aniline concentration, scan rate, and multiwalled carbon nanotubes content were 0.5 M, 0.2 M, 25 mV s?1, and 0.02 wt%, respectively. The limit of detection for the proposed polyaniline fiber was 15 ng ml?1. 相似文献
3.
Surface complexation of carbonate on goethite: IR spectroscopy, structure and charge distribution 总被引:1,自引:0,他引:1
Hiemstra T Rahnemaie R van Riemsdijk WH 《Journal of colloid and interface science》2004,278(2):282-290
The adsorption of carbonate on goethite has been evaluated, focussing on the relation between the structure of the surface complex and corresponding adsorption characteristics, like pH dependency and proton co-adsorption. The surface structure of adsorbed CO3(-2) has been assessed with (1) a reinterpretation of IR spectroscopy data, (2) determination of the charge distribution within the carbonate complex using surface complexation modeling, and (3) evaluation of the proton co-adsorption of various oxyanions, including carbonate, in relation with structural differences. Carbonate adsorption leads to a degeneration of the nu3 IR vibration. Currently, the magnitude of the Deltanu3 band splitting is used as a criterion for metal coordination. However, the interpretation is not unambiguous, since the magnitude of Deltanu3 is influenced by polarization and additional field effects, due to, e.g., H bonding. Our evaluation shows that for goethite the magnitude of band splitting Deltanu3 falls within the range of values that is representative for bidentate complex formation, despite contrarily assignments made in literature. Determination of the charge distribution (CD), derived by modeling available carbonate adsorption data, shows that a very large part (2/3) of the carbonate charge resides in the surface. Interpretation of this result with a bond valence and a ligand charge analysis strongly favors the bidentate surface complexation option for adsorbed carbonate. This option is also supported by the proton co-adsorption of carbonate. The H co-adsorption is very high, which corresponds closely to an oxyanion surface complex in which 2/3 of the ligands are common with the surface. The high H co-adsorption is in conflict with the monodentate option for adsorbed CO3(-2). The study shows that the H co-adsorption of CO3(-2) is almost equal to the experimental H co-adsorption obtained for SeO3(-2) adsorption, which can be rationalized supposing for both XO3(-2) complexes the same ligand distribution in the interface, i.e., bidentate complex formation. 相似文献
4.
Rasoul Ahangari Maleki 《代数通讯》2017,45(2):514-520
5.
NOROUZI Parviz GANJALI Mohammad Reza SHAHTAHERI Sayed Jamaleddin DINARVAND Rasoul HAMZEHPOOR Ali 《中国化学》2009,27(4):732-738
A continuous cyclic voltammetric study of methyldopa at gold micro electrode was carried out. The drug in phosphate buffer (pH 2.0) is adsorpted at 400 mV, giving rise to change in the current of well-defined oxidation peak of gold in the flow injection system. The proposed detection method has some of advantages, the greatest one of which are as follows: first, it is no more necessary to remove oxygen from the analyte solution and second, this is a very fast and appropriate technique for determination of the drug compound in a wide variety of chromatographic analysis methods. Signal-to-noise ratio has significantly increased by application of discrete Fast Fourier transform (FFT) method, background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window. Also in this work some parameters such as sweep rate, eluent pH, and accumulation time and potential were optimized. The linear concentration range was of 1.0×10-7—1.0×10-11 mol•L-1 (r=0.9975) with a limit of detection and quantitation 0.004 nmol•L-1 and 0.03 nmol•L-1, respectively. The method has the requisite accuracy, sensitivity, precision and selectivity to assay methyldopa in tablets. The influences of pH of eluent, accumulation potential, sweep rate, and accumulation time on the determination of the methyldopa were considered. 相似文献
6.
Seyyed Hossein Asadpour Mostafa Sahrai Rasoul Sadighi-Bonabi Amir Soltani Hamed Mahrami 《Physica E: Low-dimensional Systems and Nanostructures》2011,43(10):1759-1762
The giant Kerr nonlinearity with reduced linear and nonlinear absorption in a four-level quantum dot by employing the tunnel coupling is investigated. It is shown that by enhancement of tunnel coupling value the Kerr nonlinearity increases and at the same time linear and nonlinear absorption reduces at the long wavelength which is very important for communicational applications. Enhanced of Kerr nonlinearity in a double quantum dots is investigated. It is found that the electron tunneling has an essential role to reducing the linear absorption and increasing the Kerr nonlinearity at long wavelength. 相似文献
7.
Zhi Ping Xu Zi Gu Xiaoxi Cheng Firas Rasoul Andrew K. Whittaker Gao Qing Max Lu 《Journal of nanoparticle research》2011,13(3):1253-1264
A novel nanocomposite film for sustained release of anionic ophthalmic drugs through a double-control process has been examined
in this study. The film, made as a drug-loaded contact lens, consists principally of a polymer hydrogel of 2-hydroxyethyl
methacrylate (HEMA), in whose matrix MgAl-layered double hydroxide (MgAl-LDH) nanoparticles intercalated with the anionic
drug are well dispersed. Such nanocomposite films (hydrogel-LDH-drug) contained 0.6–0.8 mg of MgAl-LDH and 0.08–0.09 mg of
the ophthalmic drug (ketorolac) in 1.0 g of hydrogel. MgAl-drug-LDH nanoparticles were prepared with the hydrodynamic particle
size of 40–200 nm. TEM images show that these nanoparticles are evenly dispersed in the hydrogel matrix. In vitro release
tests of hydrogel-LDH-drug in pH 7.4 PBS solution at 32 °C indicate a sustained release profile of the loaded drug for 1 week.
The drug release undergoes a rapid initial burst and then a monotonically decreasing rate up to 168 h. The initial burst release
is determined by the film thickness and the polymerization conditions, but the following release rate is very similar, with
the effective diffusion coefficient being nearly constant (3.0 × 10−12 m2/s). The drug release from the films is mechanistically attributed to anionic exchange and the subsequent diffusion in the
hydrogel matrix. 相似文献
8.
Investigation of a mutual interaction force at different pressure amplitudes in sulfuric acid 下载免费PDF全文
This paper investigates the secondary Bjerknes force for two oscillating bubbles in various pressure amplitudes in a concentration of 95% sulfuric acid.The equilibrium radii of the bubbles are assumed to be smaller than 10 μm at a frequency of 37 kHz in various strong driving acoustical fields around 2.0 bars (1 bar=10 5 Pa).The secondary Bjerknes force is investigated in uncoupled and coupled states between the bubbles,with regard to the quasi-adiabatic model for the bubble interior.It finds that the value of the secondary Bjerknes force depends on the driven pressure of sulfuric acid and its amount would be increased by liquid pressure amplitude enhancement.The results show that the repulsion area of the interaction force would be increased by increasing the driven pressure because of nonlinear oscillation of bubbles. 相似文献
9.
Let \(\mathcal{{A}}\) be a Banach algebra and let \(\mathcal{{X}}\) be an introverted closed subspace of \(\mathcal{{A}}^*\) . Here, we give necessary and sufficient conditions for that the dual algebra \(\mathcal{{X}}^*\) of \(\mathcal{{X}}\) or the topological centers \({\mathfrak {Z}}_t^{(1)}(\mathcal{{X}}^{*})\) and \({\mathfrak {Z}}_t^{(2)}(\mathcal{{X}}^{*})\) of \(\mathcal{{X}}^*\) are Banach \(*\) -algebras. We finally apply these results to the Banach space \(L_0^\infty (G)\) of all equivalence classes of essentially bounded functions vanishing at infinity on a locally compact group \(G\) . 相似文献
10.
Hydrolytic degradation of POSS-PEG-lactide hybrid hydrogels 总被引:2,自引:0,他引:2
A polyhedral oligomeric silsesquioxane (POSS), functionalized with eight arms of poly(ethylene glycol) (PEG; MW 400) and then acrylated, was incorporated into a hydrogel network based on triblock copolymers of poly(lactide-b-ethylene glycol-b-lactide) diacrylates using a redox-initiated polymerization. The organic-inorganic hybrid hydrogels so prepared contained the inorganic crosslinker POSS from 1 to 28 wt.%. The degradation properties of the hydrogels in a pH 7.4 phosphate-buffered saline solution at 37 °C were studied using measurements of mass loss, cryogenic SEM, and ATR-FTIR spectroscopy. It was found that copolymerization of acrylated 1kPEG-lactide with increasing amounts of POSS created a more porous network which was more resistant to hydrolysis. The ATR-FTIR technique was used to monitor the progress of degradation with exposure time through the changes in the carbonyl and C-H deformation bands of the lactide and the Si-C stretching band of the POSS. Increasing POSS incorporation resulted in decreased rate of degradation due to its hydrophobic nature and inertness to hydrolysis. Conversely, an increase in lactide content increased the degradation rate due to the increased number of hydrolytically-sensitive ester groups in the network. 相似文献