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91.
Sima Sedighi Mohammad T. Baei Masoud Javan Joshua Charles Ince Alireza Soltani Mohammad Hassan Jokar Samaneh Tavassoli 《Surface and interface analysis : SIA》2020,52(11):725-734
This study provides details of the electronic and optical structures and binding energies of sarin (SF) and chlorosarin (SC) with Al–N and Al–P surfaces of Al12N12 and Al12P12 nanoclusters in the gas phase. The adsorption mechanism of SF and SC on these nanoclusters containing the Al3+ central cation was studied. Optimized geometries and thermodynamic parameters of SF and SC adsorption complexes were calculated. SF and SC are chemisorbed on these nanoclusters because of the formation of PO···Al bonds. The chemical bond is formed between an oxygen atom of SF and SC and an aluminum atom of fullerene-likes (chemisorption). However, the binding energies of the complexes with the Al12N12 nanocluster are larger than these values for the Al12P12 nanocluster. The interaction enthalpy and Gibbs free energy of all studied systems were found to be negative. We can conclude that SF and SC will be adsorbed preferably on Al12N12 nanocluster. 相似文献
92.
Thin‐layer chromatography—an image‐processing method for the determination of acidic catecholamine metabolites 下载免费PDF全文
A sensitive and convenient method for acidic catecholamine metabolites (including homovanillic acid, vanillylmandelic acid, 3,4‐dihydroxymandelic acid, and 3,4‐dihydroxyphenylacetic acid) determination was developed based on thin‐layer chromatography and image‐processing analysis. The metabolites were separated without a prederivatization step using reversed phase RP‐18W high‐performance plates. The mobile phase composition, detection, and quantification conditions were systematically investigated through several trials. The reaction with 2,2‐diphenyl‐1‐picrylhydrazyl radical allowed specific detection of acidic catecholamine metabolites with a high sensitivity and a wide linear range. The limit of detection and the limit of quantification were in the range of 13–103 and 18–120 ng/spot, respectively, in all cases. Mean recoveries determined were in the range 95–106% for all of the investigated compounds. The proposed method allowed rapid simultaneous determination of acidic catecholamine metabolites from spiked human urine sample. 相似文献
93.
94.
Recent results have shown that size-effects in nanostructured materials may enable much more efficient thermoelectric devices. In this paper, the electrochemical preparation of Bi1.95Te2.7Se0.35 and Bi2.15Te2.55Se0.3 submicron wires arrays with nanosized grain structure is reported. X-ray diffraction (XRD) analysis has indicated the presence of nanosized crystallites in the structure of the wires; high resolution transmission electron microscopy (HRTEM) investigations have confirmed the formation of crystallites with geometrical dimensions of 5–14 nm and random orientations in the structure of these wires. These wires were further analyzed by field emission scanning electron microscopy (FESEM). The measurement of the transport properties showed that a highly degenerate semiconductor with a large thermopower (−125 μV K−1 at 300 K) and a low resistivity was obtained. 相似文献
95.
Hikmat H.Asadov Islam M.Mirzabalayev Davud Z.Aliyev Javid A.Agayev Sima R.Azimova Nabi A.Nabiyev Sevinj N.Abdullayeva 《中国光学快报(英文版)》2009,7(5):361-363
The method for synthesis of corrected three-wavelengths spectrometers for trace gas components of atmo- sphere on the basis of development of mathematical model has been suggested. The classification table for possible structures of corrected spectrometers is considered. The synthesis allows to reveal some new variants for development of three-wavelength spectrometers for trace gas components of atmosphere. For experimental checkup of achieved theoretical results, a laboratory pattern of three-wavelength spectrome- ter is developed and tested. 相似文献
96.
Sima Sedghiniya Janet Soleimannejad Jan Janczak 《Acta Crystallographica. Section C, Structural Chemistry》2019,75(4):412-421
At one extreme of the proton‐transfer spectrum in cocrystals, proton transfer is absent, whilst at the opposite extreme, in salts, the proton‐transfer process is complete. However, for acid–base pairs with a small ΔpKa (pKa of base ? pKa of acid), prediction of the extent of proton transfer is not possible as there is a continuum between the salt and cocrystal ends. In this context, we attempt to illustrate that in these systems, in addition to ΔpKa, the crystalline environment could change the extent of proton transfer. To this end, two compounds of salicylic acid (SaH) and adenine (Ad) have been prepared. Despite the same small ΔpKa value (≈1.2), different ionization states are found. Both crystals, namely adeninium salicylate monohydrate, C5H6N5+·C7H5O3?·H2O, I , and adeninium salicylate–adenine–salicylic acid–water (1/2/1/2), C5H6N5+·C7H5O3?·2C5H5N5·C7H6O3·2H2O, II , have been characterized by single‐crystal X‐ray diffraction, IR spectroscopy and elemental analysis (C, H and N) techniques. In addition, the intermolecular hydrogen‐bonding interactions of compounds I and II have been investigated and quantified in detail on the basis of Hirshfeld surface analysis and fingerprint plots. Throughout the study, we use crystal engineering, which is based on modifications of the intermolecular interactions, thus offering a more comprehensive screening of the salt–cocrystal continuum in comparison with pure pKa analysis. 相似文献
97.
Poullet JB Sima DM Van Huffel S 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,195(2):134-144
In this paper an overview of time-domain and frequency-domain quantitation methods is given. Advantages and drawbacks of these two families of quantitation methods are discussed. An overview of preprocessing methods, such as lineshape correction methods or unwanted component removal methods, is also given. The choice of the quantitation method depends on the data under investigation and the pursued objectives. 相似文献
98.
The extension of pulsed laser deposition to the synthesis on Ti substrates of β-tricalcium phosphate (β-TCP) coatings doped with manganese is reported. Targets sintered from two crystalline Mn-doped β-TCP powders (with the composition Ca2.9Mn0.1(PO4)2 and Ca2.8Mn0.2(PO4)2) were ablated with an UV KrF* (λ = 248 nm, τ ∼ 7 ns) laser source. X-ray diffraction and energy dispersive X-ray spectroscopy investigations showed that the films, while prevalently amorphous, had a Ca/P ratio of about 1.50-1.52. Scanning electron microscopy analyses revealed a rather homogeneous aspect of the coatings which were molded to the relief of the chemically etched Ti substrate. Fluorescence microscopy was applied to test the proliferation of mesenchymal stem cells grown on the obtained biostructures. Our investigations found that, even 14 days after cultivation, the synthesized films were not cytotoxic. On the contrary, they showed excellent bioactivity, as demonstrated by the neat spread of the cells over the entire surface of Mn-doped β-TCP. When tested in osteoprogenitor cell culture, the Ca2.8Mn0.2(PO4)2 samples revealed a higher potential for proliferation and better viability compared with Ca2.9Mn0.1(PO4)2. 相似文献
99.
O. Sima 《Journal of Radioanalytical and Nuclear Chemistry》2000,244(3):669-673
The GESPECOR software, initially developed for the computation of efficiency of HPGe detectors in environmental -ray spectrometry, was applied to NAA. The software is useful for the computation of efficiency and of self-attenuation and coincidence-summing corrections for common experimental conditions. A new source subroutine was implemented in GESPECOR for solving the more complex case of non-uniform sources. In this way neutron self-shielding in the activation of samples of large volume is taken into account. The dependence of the detection efficiency on the flux distribution is discussed. 相似文献
100.
Distribution and Valence of the Cations in Spinel Systems with Iron and Chromium. III. Lattice Constants, Mössbauer Spectra, and Seebeck Coefficients of the Solid Solution ZnFeCrO4? Fe2CrO4 For the spinel system Zn1–x2+Fex–λ2+Feλ3+(Feλ2+ · Fe1?λ3+ Cr3+)O4 λ has been determined by lattice constants and ionic distances: λ = 0 in the region 0 ? x ? 0.3; in the region 0.3 < x ? 1 λ increases linearly to 0.44. Mössbauer spectra between x = 0 and x = 0.6 confirm this distribution. All spinels are n-type hopping conductors mainly conducting on the octahedral sites. 相似文献