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排序方式: 共有941条查询结果,搜索用时 15 毫秒
911.
Satoshi Watanabe Hiroshi Hyodo Hirohisa Taguchi Kohei Soga Yoshifumi Takanashi Mutsuyoshi Matsumoto 《Advanced functional materials》2011,21(22):4264-4269
It is demonstrated that patterned inorganic phosphor films consisting of rare earth ion doped nanoparticles (RE‐NPs) can be fabricated on plastic sheets using calcination‐ and etching‐free photolithography. Green up‐conversion luminescence and near‐infrared (NIR) fluorescence appears from the RE‐NPs that are prepared from Y2O3 doped with 1 mol% Er3+ and 0.85 mol% Yb3+. The diameter of the RE‐NPs is estimated to be about 300 nm using dynamic light scattering. Visible transmittance of the RE‐NP film fabricated by dip‐coating is more than 90%. Patterned RE‐NP films are obtained by dip‐coating the RE‐NPs on patterned photoresist films fabricated by UV exposure through a photomask, followed by selective removal of the photoresist. Optical, fluorescence, scanning electron, atomic force, and Kelvin probe force microscopies are used for the characterization of the patterned RE‐NP films. The present methodology enables fabrication of patterned RE‐NP films, not only on inorganic substrates but also on plastic sheets, with low cost and material consumption. 相似文献
912.
Yeast-based reporter assays are useful for detecting various genotoxic chemicals. We established a genotoxicity assay using recombinant strains of Saccharomyces cerevisiae, each containing a reporter plasmid with the secretory luciferase gene from Cypridina noctiluca, driven by a DNA damage-responsive promoter of the yeast RNR3 gene. This system detected the genotoxicity of methyl methanesulphonate (MMS) as sensitively as conventional yeast-based reporter assays, using the β-galactosidase gene in a concentration-dependent manner; it also detects four other genotoxic chemicals, allowing us to monitor DNA damage easily by skipping the cell extraction process for the assay. We examined Cypridina luciferase levels induced by MMS and three antitumour agents using a set of BY4741-derived deletion mutants, each defective in a DNA repair pathway or DNA damage checkpoint. Luciferase activities were particularly enhanced in mutant strains with mms2 Δ and mag1 Δ by exposure to MMS, rad59 Δ and mlh1 Δ to camptothecin and mms2 Δ and mlh1 Δ to mitomycin C, respectively, compared with their parent strains. Enhanced reporter activities were also found in some DNA repair mutants with cisplatin. These observations suggest that this Cypridina secretory luciferase reporter assay using yeast DNA repair mutants offers convenient and sensitive detection of the potential genotoxicity of numerous compounds, including antitumour drugs and studying the mechanisms of DNA damage response in yeast. 相似文献
913.
914.
Wang XY Huang CH Tsukamoto R Mortemousque PA Itoh KM Ohno Y Samukawa S 《Nanotechnology》2011,22(36):365301
The first damage-free top-down fabrication processes for a two-dimensional array of 7 nm GaAs nanodiscs was developed by using ferritin (a protein which includes a 7 nm diameter iron core) bio-templates and neutral beam etching. The photoluminescence of GaAs etched with a neutral beam clearly revealed that the processes could accomplish defect-free etching for GaAs. In the bio-template process, to remove the ferritin protein shell without thermal damage to the GaAs, we firstly developed an oxygen-radical treatment method with a low temperature of 280?°C. Then, the neutral beam etched the defect-free nanodisc structure of the GaAs using the iron core as an etching mask. As a result, a two-dimensional array of GaAs quantum dots with a diameter of ~ 7 nm, a height of ~ 10 nm, a high taper angle of 88° and a quantum dot density of more than 7 × 10(11) cm(-2) was successfully fabricated without causing any damage to the GaAs. 相似文献
915.
Andrey Lyalin Akira Nakayama Kohei Uosaki Tetsuya Taketsugu 《Topics in Catalysis》2014,57(10-13):1032-1041
Adsorption and catalytic activation of the molecular oxygen on the hexagonal boron nitride (h-BN) monolayer supported on Ni(111) and Cu(111) surfaces have been studied theoretically using density functional theory. It is demonstrated that an inert h-BN monolayer can be functionalized and become catalytically active on the transition metal support as a result of mixing of the metal d and h-BN π bands. 相似文献
916.
Kazuma Higashisaka Yasuo Yoshioka Kohei Yamashita Yuki Morishita Huiyan Pan Toshinobu Ogura Takashi Nagano Akiyoshi Kunieda Kazuya Nagano Yasuhiro Abe Haruhiko Kamada Shin-ichi Tsunoda Hiromi Nabeshi Tomoaki Yoshikawa Yasuo Tsutsumi 《Nanoscale research letters》2012,7(1):555
Practical uses of nanomaterials are rapidly spreading to a wide variety of fields. However, potential harmful effects of nanomaterials are raising concerns about their safety. Therefore, it is important that a risk assessment system is developed so that the safety of nanomaterials can be evaluated or predicted. Here, we attempted to identify novel biomarkers of nanomaterial-induced health effects by a comprehensive screen of plasma proteins using two-dimensional differential in gel electrophoresis (2D-DIGE) analysis. Initially, we used 2D-DIGE to analyze changes in the level of plasma proteins in mice after intravenous injection via tail veins of 0.8 mg/mouse silica nanoparticles with diameters of 70 nm (nSP70) or saline as controls. By quantitative image analysis, protein spots representing >2.0-fold alteration in expression were found and identified by mass spectrometry. Among these proteins, we focused on hemopexin as a potential biomarker. The levels of hemopexin in the plasma increased as the silica particle size decreased. In addition, the production of hemopexin depended on the characteristics of the nanomaterials. These results suggested that hemopexin could be an additional biomarker for analyzing the biological responses associated with exposure to silica nanoparticles. We believe that this study will contribute to the development of biomarkers to ensure the safety of silica nanoparticles. 相似文献
917.
Kohei KuboHajime Iida Seitaro NambaAkira Igarashi 《Microporous and mesoporous materials》2012,149(1):126-133
The catalytic cracking of n-heptane has been performed over HZSM-5 catalysts with various Si/Al ratios at 723-923 K to form light olefins selectively. The HZSM-5 zeolites with various acid site densities exhibited almost the same selectivity at the same conversion. The ethylene + propylene selectivity increased, while the propylene/ethylene ratio decreased with an increase in reaction temperatures. It is found that a high temperature is required to obtain a high ethylene + propylene yield. The highest ethylene + propylene yield obtained in this study was 59.7 C-% with a propylene/ethylene ratio of ca. 0.72 at 99.6% conversion over HZSM-5 (Si/Al = 31) at 923 K. Moreover, it is concluded from the selectivities and activation energies that the monomolecular cracking is predominant at a high temperature as 923 K. 相似文献
918.
919.
Conditions for direct analyses of various aromatic compounds in water by steam carrier gas chromatography (SCGC) were studied by using a hydrogen flame ionization detector and acid washed Chromosorb P modified with 3.5 ± 0.3 wt% of phosphoric acid as a stationary solid in 2 mm i.d. × 2 m glass column. A flowrate of approx. 60 ml min−1 of carrier steam and a column temperature of 150–180°C were considered to be the optimum conditions for analyses of water samples containing several groups of aromatic compounds. Under constant conditions, aromatic compounds were generally eluted in order of their boiling points. The relationship between the retention time and the boiling point was obtained for two groups of substitutes of benzene and naphthalene. The retention time of a substitute of benzene or naphthalene can, therefore, be predicted from its boiling point, and conversely, the aromatic compounds in an unknown water sample can be characterized for identification from their retention times. By SCGC, various aromatic compounds in water at concentrations higher than approx. 30 μg l−1 can be analysed directly without complicated pre-treatment. 相似文献
920.