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41.
The objective of the present study was to investigate the changes in the degree of dispersion in a negative AgI sol under the influence of organic components introduced into the medium only after nucleation. It was found that the polar molecules of those components can stimulate the process of formation of individual colloidal particles from unstable metaphase clusters emerging as a result of embryo aggregation. 相似文献
42.
Chin‐San Wu 《Journal of polymer science. Part A, Polymer chemistry》2005,43(8):1690-1701
In this study, a silicic acid and tetra isopropyl ortho titanate ceramic precursor and a metallocene polyethylene‐octene elastomer (POE) or acrylic acid grafted metallocene polyethylene‐octene elastomer (POE‐g‐AA) were used in the preparation of hybrids (POE/SiO2? TiO2 and POE‐g‐AA/SiO2? TiO2) using an in situ sol‐gel process, with a view to identifying a hybrid with improved thermal and mechanical properties. Hybrids were characterized using Fourier transform infrared spectroscopy, 29Si solid‐state nuclear magnetic resonance (NMR), X‐ray diffraction, differential scanning calorimetry, thermogravimetry analysis, dynamic mechanical thermal analysis, and Instron mechanical testing. Properties of the POE‐g‐AA/SiO2? TiO2 hybrid were superior to those of the POE/SiO2? TiO2 hybrid. This was because the carboxylic acid groups of acrylic acid acted as coordination sites for the silica‐titania phase to allow the formation of stronger chemical bonds. 29Si solid‐state NMR showed that Si atoms coordinated around SiO4 units were predominantly Q3 and Q4. The 10 wt % SiO2? TiO2 hybrids gave the maximum values of tensile strength and glass transition temperature in both POE/SiO2? TiO2 and POE‐g‐AA/SiO2? TiO2. It is proposed that above this wt %, excess SiO2? TiO2 particles caused separation between the organic and inorganic phases. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1690–1701, 2005 相似文献
43.
有机染料TMQ掺杂的SiO2薄膜的光谱特性 总被引:4,自引:1,他引:4
采用溶胶 -凝胶法合成了紫外波段有机染料 TMQ掺杂的 Si O2 薄膜和块体材料。薄膜中掺杂的染料浓度高达 1.2 4× 10 -2 mol/ L,块体材料中染料浓度可掺至 1.5× 10 -3 mol/ L。由于Si O2 “笼”的束缚作用 ,在吸收光谱中未观察到二聚体的特征谱带 ,在荧光光谱中未观察到荧光猝灭现象 ;同时由于 Si O2 “笼”的极化作用 ,其吸收峰和发射峰的位置相对于其在环己烷溶液中的吸收峰和发射峰位置发生了 10 nm左右的红移。 相似文献
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45.
F. P. Yu D. R. Yuan S. Y. Guo X. L. Duan X. Q. Wang L. M. Kong X. Q. Zhang X. Zhao 《Crystal Research and Technology》2008,43(5):522-525
The effects of Er3+ doping concentration and calcination were examined on the fluorescence properties of La3Ga5.5Nb0.5O14 (Er:LGN) nanoparticles for the first time. High quality Er:LGN nanoparticles were synthesized by sol‐gel method. The room temperature fluorescence spectra showed a green emission, which can be attributed to 2H11/2‐4I15/2 and 4S3/2‐4I15/2 transition. The relationship between the relative emission intensity and the doping concentration was investigated. The maximum of the Er3+ doping concentration in LGN nanopowders is 2.0%. The fluorescent lifetime of 2.0% Er:LGN nanoparticles is 1.45ns. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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48.
Ying Li Gaoyang Zhao Yang Ren Dichun Chen 《Surface and interface analysis : SIA》2011,43(9):1199-1202
The technique for ITO (Tin‐doped indium oxide) thin films by sol‐gel process is presented in this paper. After annealing at 500° for 15 min, ITO gel films get transformed into nanocrystallined indium tin oxide films. We studied the microstructure of ITO thin film which is closely related to optical and electrical properties. The microstructure of ITO thin film can be observed through high‐resolution transmission electronic spectroscopy (HRTEM) and the Fast Fourier Transform (FFT) technique. The film is nanocrystallite with grain sizes about 20 nm. Also, the surface chemical components were studied by XPS spectra. The transmission and the resistivity of ITO films is 97.0% and 3.5 × 10?3 Ω?cm, respectively. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
49.
Ming Zhang Yi Li Lifeng Bi Wei Zhuang Sibing Wang Yuanli Chen Baozong Li Yonggang Yang 《中国化学》2011,29(5):933-941
The morphologies and pore architectures of mesoporous ethenylene‐silica were controlled using cetyltrimethylammonium bromide (CTAB) as template and (S)‐β‐citronellol as a co‐structure‐directing agent under basic conditions. When the (S)‐β‐citronellol/CTAB molar ratios are in the range of 0.75–2.0, helical nanofibers were obtained. With increasing the (S)‐β‐citronellol/CTAB molar ratio, the lengths of the nanofibers increases. Lamellar mesopores were identified on the surfaces of the nanofibers prepared in the (S)‐β‐citronellol/CTAB molar ratio range of 1.5–2.0. At the (S)‐β‐citronellol/CTAB molar ratio of 2.5:1, nanoparticles with nanoflakes on the surfaces were obtained. The field emission scanning electron microscopy images taken after different reaction times indicated that the helical pitches of the nanofibers decreased with increasing the reaction time. Helical 1,4‐phenylene‐silica and methylene‐silica nanofibers were also prepared. The results indicated that the morphologies and pore architectures of the obtained organic‐inorganic hybrid silicas are also sensitive to the hybrid silica precursors. Helical ethenylene‐silica nanofibers with lamellar mesopores on their surfaces can be also prepared using the mixtures of CTAB and racemic citronellol within a narrower citronellol/CTAB molar ratio range. 相似文献
50.