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71.
Yujiro Watanabe Yusuke Moriyoshi Yasushi Suetsugu Toshiyuki Ikoma Takeshi Kasama Tadashi Hashimoto Hirohisa Yamada Junzo Tanaka 《Journal of the American Ceramic Society》2004,87(7):1395-1397
Type-A zeolite evenly covered with hydroxyapatite thin layers was prepared using hydrothermal treatment at 120°C for 8 h under autogenous pressure. The hydroxyapatite needlelike nanocrystals, 100–200 nm in diameter and 30 nm in thickness, were grown under the reaction between discharged Ca2+ ions from type-A zeolite and PO4 3− ions in (NH4 )3 PO4 solution. The preferential orientations of the c -axis of hydroxyapatite crystals perpendicular to a zeolite surface were observed using transmission electron microscopy. The crystal structure of type-A zeolite was not destroyed under the reaction, but the surface morphology was changed only with complete covering of scaly hydroxyapatite particles. 相似文献
72.
Maeda Yoshitake; Koga Hiroshi; Yamada Hidenori; Ueda Tadashi; Imoto Taiji 《Protein engineering, design & selection : PEDS》1995,8(2):201-205
To increase the folding yield of concentrated reduced lysozyme,we developed a renaturation method by means of dialysis fromconcentrated urea with redox agents. After lysozyme was incubatedin the reducing buffer (8 M urea solution) with oxidized glutathione,renaturation of reduced lysozyme was started by dialysis againstthe dialyzing buffer containing 8 M urea with redox agents.The urea concentration of the dialyzing bottle was graduallydiluted with dialyzing buffer without urea at a flow rate of0.1 ml/min by high pressure pump. Using this systematic dialysis,a concentration as high as 5 mg/ml of reduced lysozyme couldbe renaturated in 80% yield, while the folding yield was <5%even at a concentration of 1 mg/ml using a conventional rapiddilution method [Goldberg et al. (1991) Biochemistry, 30, 27902797].Therefore, it was concluded that gentle removal of urea fromdenatured proteins, dissolved in concentrated urea solution,by means of dialysis should be useful to renature denaturedproteins effectively. 相似文献
73.
Yasushi Murakami Taki Matsumoto Kiyochika Yahikozawa Yoshio Takasu 《Catalysis Today》1995,23(4):383-389
The sol-gel process for the hydrolysis and polycondensation of tin tetra-n-butoxide in butanol was followed by viscosity measurements. The precipitation of tin-containing ultrafine particles was observed without any variation in the solution viscosity in the absence of diethylene glycols, while the viscosity increase was made without any precipitation by the addition of diethylene glycol. The induction period and the rate of the viscosity increase after the induction period was independent of the diethylene glycol content but depended upon the water content. The Monte Carlo simulation data were consistent with data for the viscosity experiment. The simulation was based on a kinetic model of the slow hydrolysis of tin tetra-n-butoxide, the reverse reaction of hydrolysis, and the polycondensation of the hydroxy derivatives. 相似文献
74.
T. Sato T. Murakami T. Endo M. Shimada K. Komeya T. Kameda M. Komatsu 《Journal of Materials Science》1991,26(7):1749-1754
Corrosion behaviour of Si3N4 ceramics containing Y2O3, Al2O3 and AIN as sintering aids was investigated under hydrothermal conditions at 200–300 C and saturated vapour pressures of water for 1–10 days. Hydrothermal corrosion resulted in the dissolution of the Si3N4 matrix and the formation of a product layer consisting of the original grain-boundary phases and hydrated silica. The dissolution rate of Si3N4 ceramics decreased with decreasing crystallinity of the grain-boundary phase. The dissolution rate could be adequately described by a parabolic plot in the initial stage of the reaction. The apparent activation energies were 83.5–108 kJ mol–1, and the bending strength of the corroded samples decreased from 600 to 400 MPa in the initial stage of the reaction upto a weight loss of 0.004 g cm–2, and then was almost constant up to a weight loss of 0.012 g cm–2. 相似文献
75.
Hiroki Matsuo Tatsuya Murakami Junichiro Otomo 《Journal of the American Ceramic Society》2021,104(11):5740-5749
In proton-conducting oxides, analyses for their electronic structure contribute to the understanding of interactions between defects in them. In this study, electronic band alignment of (1−x)BaZr0.8Y0.2O3−δ(BZY)–xSrZr0.95Y0.05O3−δ(SZY) proton-conducting solid-solution system (BSZY) which has high defect concentration and the deep valence band is experimentally investigated. By using thin-film specimens for optical absorption measurements, absorption edges derived from electron transition from the valence band to the conduction band which was insensitive to the proton incorporation were clearly observed in spite of the high defect concentration. The obtained optical band gap energy increased from 5.61 to 5.89 eV with increasing x, which was consistent with a composition dependence of Zr(Y)O6 octahedral tilting. Ultraviolet photon-yield spectroscopy (UV-PYS) measurements under vacuum condition revealed that BZY and SZY had ionization energy of 6.98 and 7.31 eV, respectively, and thus the absolute energy levels of the valence band maximum and the conduction band minimum of BSZY were experimentally clarified. We propose that the combination of the optical absorption measurements using thin-film specimens and the UV-PYS measurements under vacuum condition is effective in evaluating fundamental electronic structures of proton-conducting oxides. 相似文献
76.
An iron electrode was modified by electrolytic reduction in deaerated acetonitrile solution of p-toluenediazonium tetrafluoroborate CH3C6H4N2BF4 (TDFB) or p-hydroxymethylbenzenediazonium tetrafluoroborate HOCH2C6H4N2BF4 (HOTDFB) below 10 °C to form a self-assembled monolayer (SAM) of toluene CH3C6H4- or hydroxymethylbenzene HOCH2C6H4- (HOMB) moiety, probably adsorbed on the electrode by the formation of a covalent bond between carbon and iron atoms, as shown in references. The protective ability of the layer was examined by polarization measurement of the electrode in an aerated 0.5 M NaCl solution. The protective efficiencies of these two SAMs were not high, around 30%, a little higher than that of the toluenethiol CH3C6H4SH SAM which was anchored on iron via a coordinate bond between sulfur and iron atoms. The iron surfaces modified with TDFB and HOTDFB were characterized by contact angle measurement, FTIR reflection spectroscopy and X-ray photoelectron spectroscopy. The persistence in protection of iron against corrosion by coverage with the HOMB SAM was confirmed by polarization measurements after immersion in 0.5 M NaCl for a long period of the time. 相似文献
77.
78.
HiroyukiHoshino HiromitsuMurakami HideoYokota SatoshiSuda HidekiTsuge KoichiTerasaka ToshiakiWakabayashi 《材料热处理学报》2004,25(5):475-479
In quenching, the cooling uniformity is most important to diminish distortion occurring on work pieces. As a trial to accomplish uniform cooling, therefore, there exist various mixing methods of a quenchant and the quenchant circulation with an external pump has so far been the well accepted mixing method. However, this study proposes an advanced oscillation mixing method that can improve more the cooling uniformity in quenching. The proposed method includes a stirrer in oscillating motion, so that the simultaneous oscillating and mixing movements of the stirrer are considered to provide efecfively the uniform cooling characteristics for the quenchant. In comparison with the case of the circulation pump mixing, the investigation using the oscillation mixing method has demonstrated the following two experimental facts:(1) the short vapor blanket stage caused by the quick breakage of the oil vapor blanket and (2) the reduced variation of the quenching distortion. 相似文献
79.
Gallium activity in the B2 phase regions of both binary Co–Ga and ternary Co–Ga–Sb systems was measured by EMF method with stabilized zirconia solid electrolyte The temperature range was 1073–1273 K and Sb concentrations were 1, 2 and 3 mol fractions. Ga activity at 1173 and 1273 K increases sharply in Ga rich region and the addition of Sb to the CoGa phase increases Ga activity. Activity change corresponds to the lattice parameter change with Sb addition to the CoGa phase. 相似文献
80.