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71.
X.Z. Yu M. Uchida Y. Onose J.P. He Y. Kaneko T. Asaka K. Kimoto Y. Matsui T. Arima Y. Tokura 《Journal of magnetism and magnetic materials》2006
The effect of Ru substitution for Mn in bilayered oxides La1.2Sr1.8(Mn1−yRuy)2O7 (0?y?0.2) was investigated by magnetization measurements and low-temperature Lorentz transmission electron microscopy. It was found that the magnetic anisotropy is controlled by the Ru content y and temperature T. The easy axis changes from 〈1 1 0〉 for the y=0 crystal to the c -axis for y=0.2, and it rotates away from the c- axis for the y=0.05 and y=0.07 crystals with decreasing temperature. Furthermore, maze-shaped magnetic domain structures were observed in the (0 0 1) thin crystals with 0.05?y?0.2. Changes in domain size and structure indicate that the uniaxial magnetic anisotropy becomes stronger as Ru content y increases. 相似文献
72.
Asaka T Anan Y Nagai T Tsutsumi S Kuwahara H Kimoto K Tokura Y Matsui Y 《Physical review letters》2002,89(20):207203
Magnetic domain structures of Nd(1/2)Sr(1/2)MnO3 were investigated by means of low-temperature Lorentz electron microscopy. On cooling, magnetic domain walls started to appear at 250 K, and they were oriented straight along the [100] and [110] directions. With a further decrease in temperature, the volume of each magnetic domain increased with discontinuous domain-wall jumps. A characteristic granular image was observed at around 140 K, near the charge-ordering transition temperature. We consider that this originated from ferromagnetic nanoclusters that appeared in the antiferromagnetic matrix. 相似文献
73.
The title compound (C8H6F3N3O) crystallizes as colorless plates, triclinic, a = 10.916(2) Å, b = 11.140(1) Å, c = 8.368(1) Å, α = 95.938(9)o, β = 105.24(1)o, γ = 64.843(9)o, V = 888.6(2) Å3, Z = 4, Dcalc = 1.623g/cm3, space group P . The structure was solved by direct methods and refined by the full‐matrix least‐squares method (Rw = 0.047). 相似文献
74.
75.
Homoepitaxial growth of 4H–SiC{0001} by hot-wall chemical vapor deposition (CVD) and characterization of deep levels in both n- and p-type epilayers have been investigated. On 4 off-axis 4H–SiC(0001), formation of macrosteps can be reduced by decreasing the C/Si ratio during CVD, though the growth condition leads to the increase in nitrogen incorporation. The 4H–SiC() face is promising, owing to its very smooth surface morphology even on 4 off-axis substrates and to its superior quality of the oxide/SiC interface. Deep level transient spectroscopy measurements in the wide temperature range from 100 K to 820 K on both n- and p-type 4H–SiC epilayers have revealed almost all the deep levels located in the whole energy range of the bandgap. Thermal annealing at 1350–1700 C of epilayers has resulted in reduction of deep level concentrations by one order of magnitude. 相似文献
76.
ZrB2(0 0 0 1) crystals grown by the rf-floating zone technique were characterized by X-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and atomic force microscopy. These characteristics were investigated as a function of thermal cleaning temperature up to 1000 °C in vacuum for as-received substrates as well as substrates treated ex situ in HF aqueous solution. The HF treatment process removed the ZrO2 native oxide layer present on as-received substrates and resulted in ZrB2(0 0 0 1) surfaces exhibiting long-range order. Upon annealing the HF-treated surface in high vacuum, two types of reconstructions were observed: an incommensurate reconstruction from 650 to 900 °C related to residual H2 gas, and n × n reconstructions at 1000 °C, possibly related to oxygen. 相似文献
77.
Watanabe T Kawasaki H Kimoto T Arakawa R 《Rapid communications in mass spectrometry : RCM》2007,21(5):787-791
Thin-layer chromatography (TLC) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) were combined to achieve characterization of polyether mixtures. Three polyethers, polyethylene glycol (PEG), polypropylene glycol (PPG) and polytetramethylene glycol (PTMG), or mixtures of these compounds, were studied. One shortcoming of mixture analysis of synthetic polymers using MALDI-MS is that individual polymers in the mixture may display different detection sensitivities. For example, the MALDI mass spectrum of an equimolar mixture of PEG, PPG and PTMG displayed a high intensity of PPG ions, while no PTMG ions were detectable; however, PTMG ions were detected after the mixture had been separated by TLC. This combined TLC and MALDI-MS analysis of a PPG polymer bearing reactive epoxy groups showed that the polymer contained byproducts with different end-groups. These byproducts were identified as chloro-substituted polymers formed during polymer synthesis. Our study shows TLC to be a rapid and low-cost separation technique, and that it can be combined with MALDI-MS to achieve effective analysis of synthetic polymers. 相似文献
78.
Belik AA Iikubo S Yokosawa T Kodama K Igawa N Shamoto S Azuma M Takano M Kimoto K Matsui Y Takayama-Muromachi E 《Journal of the American Chemical Society》2007,129(4):971-977
Structural properties of polycrystalline single-phased BiMnO3 samples prepared at 6 GPa and 1383 K have been studied by selected area electron diffraction (SAED), convergent beam electron diffraction (CBED), and the Rietveld method using neutron diffraction data measured at 300 and 550 K. The SAED and CBED data showed that BiMnO3 crystallizes in the centrosymmetric space group C2/c at 300 K. The crystallographic data are a = 9.5415(2) A, b = 5.61263(8) A, c = 9.8632(2) A, beta = 110.6584(12) degrees at 300 K and a = 9.5866(3) A, b = 5.59903(15) A, c = 9.7427(3) A, beta = 108.601(2) degrees at 550 K, Z = 8, space group C2/c. The analysis of Mn-O bond lengths suggested that the orbital order present in BiMnO3 at 300 K melts above TOO = 474 K. The phase transition at 474 K is of the first order and accompanied by a jump of magnetization and small changes of the effective magnetic moment and Weiss temperature, mueff = 4.69 microB and theta = 138.0 K at 300-450 K and mueff = 4.79 microB and theta = 132.6 K at 480-600 K. 相似文献
79.
Keiji Yoshimura Ryoei Kikuchi Takashi Kimoto Toru Ozeki Kazuhiko Imano Masahiro Kajikawa Nobuaki Ogawa 《Analytical sciences》2006,22(6):845-848
Fog droplets in the atmosphere are first produced by the activation of cloud condensation nuclei (CCN), which are originally some ionic compound. Subsequently, the nuclei grow by vapor diffusion. Fog droplets are polluted through the activation process and successive diffusion growth and residence (post activation). We cannot distinguish the effects of the two pollution processes of natural fog water samples. We found that fog droplets can be produced artificially without CCN using an ultrasonic humidifier. Because the artificial fog droplets are not polluted by CCN, the movement of the fog droplets in natural air will take up some pollutants in the air. Consequently, the two pollution processes of fog (the activation of CCN and the post activation process) can be discriminated using data from field experiments. This sampling analytical method is extremely important for further research regarding fog, clouds and environmental chemistry. 相似文献
80.