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21.
Ali Khalafi‐Nezhad Mohammad Navid Soltani Rad A. A. Moosavi‐Movahedi M. Kosari 《Helvetica chimica acta》2007,90(4):730-737
The syntheses of the novel acyclic nucleosides 5a – 5m , carrying different N‐[(benzyloxy)(aryl)methyl] substituents, are described (Scheme). These compounds could be prepared in medium‐to‐good yields by either direct or silyl‐assisted coupling of the electrophiles 6 with either purine or pyrimidine nucleobases, or with different imidazole derivatives. The reactivity of the positively charged electrophilic intermediates derived from 6 upon Cl? abstraction was rationalized by ab initio HF/6‐311G quantum‐mechanic calculations. The positive charge was found to be dispersed differently, depending on the electronic properties of the aryl substituents. 相似文献
22.
Khodabakhsh Niknam Abdollah Deris Farhad Panahi M. Reza Hormozi Nezhad 《Journal of the Iranian Chemical Society》2013,10(6):1291-1296
An efficient heterogeneous palladium catalyst system has been developed based on immobilization of Pd nanoparticles on silica-bonded N-propylpiperazine sodium N-propionate (SBPPSP) substrate. SBPPSP substrate can stabilize the Pd nanoparticles effectively so that it can improve their stability against aggregation. In addition, grafted piperazine species on to the silica backbone prevent the removing of Pd nanoparticles from the substrate surface. Transmission electron microscopy (TEM) of catalyst is shown the size of Pd nanoparticles, also it confirmed by particle size analyzer which shown the average size of 21 nm for Pd. The catalytic activity of these catalysts was investigated in the Sonogashira reaction. The catalyst could be recycled several times without appreciable loss in catalytic activity. 相似文献
23.
Rezayati Sobhan Jafroudi Mogharab Torabi Nezhad Eshagh Rezaee Hajinasiri Rahimeh Abbaspour Sima 《Research on Chemical Intermediates》2016,42(6):5887-5898
Research on Chemical Intermediates - An efficient and cost-effective procedure for preparation of Fe3O4 nanoparticles and supported Brønsted acidic ionic liquid... 相似文献
24.
25.
M Pattabiraman G Rangarajan Kwang-Yong Choi P Lemmens G Guentherodt G Balakrishnan DMcK Paul MR Lees 《Pramana》2002,58(5-6):1013-1017
We report polarized Raman scattering in single crystals of Nd0.7Sr0.3MnO3. The temperature dependence of the MnO6 octahedral bending and stretching modes observed in the XX spectra points to the existence of local lattice distortions,
possibly polarons. The XY spectra have been analyzed using a collision-dominated model, which allows the extraction of the
carrier scattering rate. 相似文献
26.
Molecular dynamics simulations of transport and separation of carbon dioxide-alkane mixtures in carbon nanopores 总被引:2,自引:0,他引:2
The configurational-bias Monte Carlo method, which is used for efficient generation of molecular models of n-alkane chains, is combined for the first time with the dual control-volume grand-canonical molecular-dynamics simulation, which has been developed for studying transport of molecules in pores under an external potential gradient, to investigate transport and separation of binary mixtures of n-alkanes, as well as mixtures of CO2 and n-alkanes, in carbon nanopores. The effect of various factors, such as the temperature of the system, the composition of the mixture, and the pore size, on the separation of the mixtures is investigated. We also report the preliminary results of an experimental study of transport and separation of some of the same mixtures in a carbon molecular-sieve membrane with comparable pore sizes. The results indicate that, for the mixtures considered in this paper, even in very small carbon nanopores the energetic effects still play a dominant role in the transport and separation properties of the mixtures, whereas in a real membrane they are dominated by the membrane's morphological characteristics. As a result, for the mixtures considered, a single pore may be a grossly inadequate model of a real membrane, and hence one must resort to three-dimensional molecular pore network models of the membrane. 相似文献
27.
Cerium oxide nanoparticle (CeO-NP) was synthesized using Origanum majorana L. leaf extract and characterized using particle size analyzer, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR). The antioxidant properties and cytotoxic effects of CeO-NP in human breast carcinoma cells (MDA-MB-231 cell line) and human umbilical vein endothelial cells (HUVEC) as normal cells were evaluated. To determine the probable molecular mechanism of action of CeO-NP on cellular redox and anti-inflammatory potential, the expressions of antioxidant-related genes catalase (CAT), superoxide dismutase (SOD) in HUVEC cell line were also analyzed. The results indicated that spherically shaped nanoparticles with a size of 10–70 nm bound to functional phenolic and flavonoids from O. majorana L. leaf extract. The green synthesized CeO-NP showed antioxidant activity by free radical scavenging activity against DPPH and ABTS free radicals. The antioxidant activity was significantly (p < 0.001) lower than that of Butylated hydroxyanisole (BHA) as a reference antioxidant. The obtained results elucidated that CeO-NP possessed cytotoxicity. The cytotoxic effects of CeO-NP were higher against MDA-MB-231 cancer cells compared to HUVEC normal cells. In addition, this NP was capable to enhance the expression of CAT and SOD as main antioxidant-related genes. Consequently, the higher cytotoxic effects of CeO-NP against breast cancer compared to normal cells indicated the potential use of this NP as anti-cancer agent. However, more research on its cytotoxicity against other cancer cells and mechanisms in which this NP exert its anti-cancer properties should be performed. 相似文献
28.
Zare Abdolkarim Kohzadian Alireza Filian Hossein Nezhad Mariam Sadat Ghoreishi Karami Amirali 《Research on Chemical Intermediates》2022,48(4):1631-1644
Research on Chemical Intermediates - In this research, highly efficient protocols for the production of pyrido[2,3-d:6,5-d′]dipyrimidine and bis(pyrazolyl)methane derivatives using an acid... 相似文献
29.
A method for simultaneous analysis of V(IV) and Co(II) has been developed by using artificial neural network (ANN). This method is based on the difference of the chemical reaction rate of V(IV) and Co(II) with Fe(III) in the presence of chromogenic reagent, 1,10-phenanthroline. The reduced product of the reaction, Fe(II), can form a colored complex with 1,10-phenanthroline and make a visible spectrophotometric signal for indirect monitoring of the V(IV) and Co(II) concentrations. Feed forward neural networks have been trained to quantify considered metal ions in mixtures under optimum conditions. The networks were shown to be capable of correlating reduced spectral kinetic data using principal component analysis (PCA) of mixtures with individual metal ion. In this way an ANN containing three layers of nodes was trained. Sigmoidal and linear transfer functions were used in the hidden and output layers, respectively, to facilitate nonlinear calibration. Both V(IV) and Co(II) were analyzed in the concentration range of 0.1-4.0 μg ml−1. The proposed method was also applied satisfactorily to the determination of considered metal ions in several synthetic and water samples. 相似文献
30.
Beulen MW Bugler J de Jong MR Lammerink B Huskens J Schonherr H Vancso GJ Boukamp BA Wieder H Offenhauser A Knoll W van Veggel FC Reinhoudt DN 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(7):1176-1183
We have developed synthesis routes for the introduction of short and long dialkylsulfides onto the primary side of alpha-, beta-, and gamma-cyclodextrins. Monolayers of these cyclodextrin adsorbates were characterized by electrochemistry, wettability studies, X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and atomic force microscopy (AFM). The differences in thickness and polarity of the outerface of the monolayers were measured by electro-chemistry and wettability studies. On average about 70% of the sulfide moieties were used for binding to the gold, as measured by XPS. Tof-SIMS measurements showed that the cyclodextrin adsorbates adsorb without any bond breakage. AFM measurements revealed for beta-cyclodextrin monolayers a quasi-hexagonal lattice with a lattice constant of 20.6 A, which matches the geometrical size of the adsorbate. The alpha-cyclodextrin and gamma-cyclodextrin monolayers are less ordered. Interactions of the anionic guests 1-anilinonaphthalene-8-sulfonic acid (1,8-ANS) and 2-(p-toluidinyl)naphthalene-6-sulfonic acid (2,6-TNS) and the highly ordered monolayers of heptapodant beta-cyclodextrin adsorbates were studied by surface plasmon resonance (SPR) and electrochemical impedance spectroscopy. The SPR measurements clearly showed interactions between a beta-cyclodextrin monolayer and 1,8-ANS. Electrochemical impedance spectroscopy measurements gave high responses even at low guest concentrations (< or = 5 microM). The association constant for the binding of 1,8-ANS (K = 289,000 +/- 13,000M-1) is considerably higher than the corresponding value in solution. (Partial) methylation of the secondary side of the beta-cyclodextrin strongly decreases the binding. 相似文献