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21.
Cuboid-shaped ZnO hierarchical structures constructed with quasi-single-crystalline ZnO nanosheets were fabricated through a mixed surfactants mediated hydrothermal method. The products were characterized by XRD, SEM, TEM, and ED methods. Room temperature photoluminescence spectrum of the as-obtained ZnO hierarchitectures was recorded showing multiple peaks of visible emissions in blue-green region. The synergetic effect of citrate and surfactants SDBS and OP was believed to play a key role in controlling the construction features of ZnO nanosheets. The ZnO hierarchitectures showed effective photocatalytic activity for the decomposition of methyl orange. 相似文献
22.
The nonlinear D-S equations on R^d, with general power nonlinearity and with both the focusing and defocusing signs, are proved to be ill-posed in the Sobolev space H^s whenever the exponent s is lower than that predicted by scaling or Galilean invariance, or when the regularity is too low to support distributional solutions. Authors analyze a class of solutions for which the zero-dispersion limit provides good approximations. 相似文献
23.
Xiang Ru Xianghua Zeng Zhimei Li David J. Evans Caixia Zhan Ying Tang Lianjie Wang Xiaoming Liu 《Journal of polymer science. Part A, Polymer chemistry》2010,48(11):2410-2417
A complex pendant with two ethynyl groups, [Fe2(μ‐SCH2CCH)2(CO)6] ( 2 ), as a model of the diiron subunit of [FeFe]‐hydrogenase was polymerized and the {Fe2(CO)6} core was successfully incorporated into the polymer matrix. The polymer was characterized by a variety of spectroscopic techniques, TGA, FTIR, SEM, TEM, and NMR. The resultant polymer was immobilized via “click” chemistry using its terminal C?CH bond onto the surface of a gold electrode, which was premodified with azidothiol by self‐assembled monolayer (SAM). The assembled electrode showed electrochemical responses. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2410–2417, 2010 相似文献
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Ming Zhao Yuji Wang Caixia Huo Chunyu Li Xiaoyi Zhang Li Peng Shiqi Peng 《Tetrahedron: Asymmetry》2009,20(2):247-258
In lead detoxification, the α-anomer of N-glycocyl-l-amino acid is more potent than its β-anomer. Here a six-step-reaction route for stereoselectively preparing N-(α-l-arabinose-1-yl)-l-amino acids is reported. Treating l-arabinose with acetic anhydride and sodium acetate provided 1,2,3,5-tetra-O-acetyl-l-arabinofuranose in 90% yield. After removing the 1-acetyl group, the thus formed 2,3,5-tri-O-acetyl-l-arabinofuranose and N-(2-nitrophenylsulfonyl)-l-amino acid t-butylesters were treated with triphenylphosphine to perform Mitsunobu dehydration and form 2,3,5-tri-O-acetyl-l-arabinofuranosyl-l-[N-(2-nitrophenylsulfonyl)]amino acid t-butylesters 2a–f, and the ratios of their α- to β-anomer ranged from 8/1 to 9/1. Chromatographic separation provided epimerically pure 2a–f-α and 2a–f-β. In the presence of CF3CO2H, 2a–f-α and 2a–f-β were converted to α- and β-anomers of N-(2,3,5-tri-O-acetyl-l-arabinofuranosyl)-N-(2-nitrobenzenesulfonyl)-l-amino acids, 3a–f-α and 3a–f-β, in 87–92% yields. While in the presence of NaOCH3, 3a–f-α and 3a–f-β were converted to α- and β-anomers of N-(l-arabinofuranosyl)-N-(2-nitrobenzenesulfonyl)-l-amino acids, 4a–f-α and 4a–f-β, in 90–96% yields. Treating 4a–f-α and 4a–f-β with N-ethyldiisopropylamine (DIPEA) and thiophenol, their 2-nitrophenylsulfonyl groups were removed, and the α- and β-anomers of N-(l-arabinose-1-yl)-l-amino acids were formed in 70–79% yields. The bioassay confirmed that the lead detoxification activity of the α-anomer was significantly higher than that of the β-anomer. 相似文献
27.
We found in our previous work that the high photoactivity of N-doped TiO2 for the oxidation of propylene under visible light was attributed to the photoactive center Vo•-NO-Ti and the formation of sub-band originated from a large amount of single-electron-trapped oxygen vacancies (denoted as Vo•; C. X. Feng, Y. Wang, Z. S. Jin, J. W. Zhang, S. L. Zhang, Z. S. Wu, Z. J. Zhang [2008], New J. Chem. 32 , 1038). In the present study, the structure of the sub-band within Eg of a representative sample N-NTA-400 was investigated by means of photoluminescence (PL) spectrometry and ultraviolet-visible light-near infrared diffuse reflectance spectra. The coaction of the sub-band and doped nitrogen on visible light photocatalytic activity of N-doped TiO2 was also investigated. The electron spin resonance spectra measured under laser irradiation (λ = 532 nm) indicate that the doped nitrogen may contribute to stabilize the trapping electron center, i.e. surface oxygen vacancy (Vo••), and hence suppress the PL, enhancing the photocatalytic activity. 相似文献
28.
Zhan C Wang X Wei Z Evans DJ Ru X Zeng X Liu X 《Dalton transactions (Cambridge, England : 2003)》2010,39(46):11255-11262
By using "click" chemistry between a diazide and a diiron model complex armed with two alkynyl groups, two polymeric diiron complexes (Poly-Py and Poly-Ph) were prepared. The two polymeric complexes were investigated using infrared spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), M?ssbauer spectroscopy, and cyclic voltammetry (Poly-Py only, due to the insolubility of Poly-Ph). To probe the coordinating mode of the diiron units in the two polymeric complexes, two control complexes (3 and 4) were also synthesised using a monoazide. Complexes 3 and 4 were well characterised and the latter was further crystallographically analysed. It turns out that in both complexes (3 and 4) and the two polymeric diiron complexes, one of the two iron atoms in the diiron unit coordinates with one of the triazole N atoms. Our results revealed that both morphologies and properties of Poly-Py and Poly-Ph are significantly affected by the organic moiety of the diazide. Compared to the protonating behaviour of the complexes 3 and 4, Poly-Py exhibited proton resistance. In electrochemical reduction, potentials for the reduction of the diiron units in Poly-Py and hence its catalytic reduction of proton in acetic acid-DMF shifted by over 400 mV compared to those for complexes 3 and 4. It is likely that the polymeric nature of Poly-Py offers the diiron units a "protective" environment in an acidic medium and more positive reduction potential. 相似文献
29.
A non-closed hydrothermal synthetic processing is improved to synthesize Sm3+ doped β-NaYbF4 nano-phosphors at 98 °C without any high-temperature and high-pressure treatments as a final step. Novel green, red, and near-infrared broadband (799-873 nm) upconversion emissions of Sm3+-doped β-NaYbF4 nano-phosphors under 980 nm excitation are observed. These UC emissions can be assigned to the Sm3+ transitions of 4GJ, 4F3/2 and 6F11/2→6HJ. The half-width of 873 nm emission band is broadened nearly two-fold through the annealing treatment for nano-phosphors. The upconversion process in Yb3+-Sm3+ system is discussed based on energy transfer mechanisms. 相似文献
30.
Cover Picture: Stabilizing Two Classical Antiaromatic Frameworks: Demonstration of Photoacoustic Imaging and the Photothermal Effect in Metalla‐aromatics (Angew. Chem. Int. Ed. 21/2015)
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