全文获取类型
收费全文 | 1288篇 |
免费 | 26篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 85篇 |
化学工业 | 384篇 |
金属工艺 | 43篇 |
机械仪表 | 46篇 |
建筑科学 | 24篇 |
能源动力 | 54篇 |
轻工业 | 128篇 |
水利工程 | 3篇 |
石油天然气 | 2篇 |
无线电 | 80篇 |
一般工业技术 | 239篇 |
冶金工业 | 65篇 |
原子能技术 | 77篇 |
自动化技术 | 88篇 |
出版年
2023年 | 9篇 |
2022年 | 7篇 |
2021年 | 15篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 19篇 |
2017年 | 15篇 |
2016年 | 24篇 |
2015年 | 14篇 |
2014年 | 21篇 |
2013年 | 66篇 |
2012年 | 47篇 |
2011年 | 71篇 |
2010年 | 52篇 |
2009年 | 50篇 |
2008年 | 53篇 |
2007年 | 55篇 |
2006年 | 42篇 |
2005年 | 52篇 |
2004年 | 46篇 |
2003年 | 63篇 |
2002年 | 45篇 |
2001年 | 27篇 |
2000年 | 34篇 |
1999年 | 41篇 |
1998年 | 50篇 |
1997年 | 37篇 |
1996年 | 35篇 |
1995年 | 27篇 |
1994年 | 27篇 |
1993年 | 29篇 |
1992年 | 18篇 |
1991年 | 20篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 12篇 |
1987年 | 15篇 |
1986年 | 15篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 12篇 |
1982年 | 13篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 10篇 |
1978年 | 6篇 |
1977年 | 11篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 3篇 |
排序方式: 共有1318条查询结果,搜索用时 15 毫秒
41.
Tomah Sogabe Akio Ogura Mitsuyoshi Ohba Yoshitaka Okada 《Progress in Photovoltaics: Research and Applications》2015,23(1):37-48
Spectral response of multi‐junction solar cell is complicated because of the interplay between external measurement conditions such as bias light intensity, monochromatic light intensity, bias voltage, and intrinsic electrical properties of series interconnected subcells. In this paper, we report an experimental study on the bias voltage‐dependent spectral response (SR) for multi‐junction solar cell. A self‐consistent iteration loop was developed from a nonlinear least square Powell hybrid algorithm that was used for curve fitting the experimental SR versus bias voltage data of each subcell. We demonstrated for the first time that this approach enabled us to derive the electrical parameters such as dark saturation currents (J0), shunt resistance (Rsh), series resistance (Rs), and spectra response (Jphoto) for each subcell of a Ga0.99In0.01As/Ge dual junction solar cell with stable convergence. The accuracies of the fitting results were confirmed by the agreement between the J–V curves calculated on the basis of these parameters and the experimental J–V curve of multi‐junction solar cell measured under AM1.5 and 1 sun condition. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
42.
Makoto Tanaka Mikio Taguchi Tsuysohi Takahama Toru Sawada Shigeru Kuroda Takao Matsuyama Shinya Tsuda Akio Takeoka Shoichi Nakano Hiroshi Hanafusa Yukinori Kuwano 《Progress in Photovoltaics: Research and Applications》1993,1(2):85-92
A new solar cell structure named HIT (Heterojunction with Intrinsic Thin layer) has been developed based on new artificially constructed junction (ACJ) technology. In this structure a non-doped a-Si thin layer was inserted between the p(a-Si)/n(c-Si) heterojunction, improving the output characteristics and achieving a conversion efficiency of 18.1%. This structure was applied to cast polycrystalline silicon solar cells of a practical size. A high conversion efficeincy of 13.6% was obtained with a cell size of 10 cm × 10 cm using various technologies, including hydrogen plasma passivation. 相似文献
43.
Masato Nishikuni Tsuyoshi Takahama Shingo Okamoto Kunimoto Ninomiya Hidenori Nishiwaki Shinya Tsuda Akio Takeoka Michotoshi Ohnishi Shoichi Nakano Yukinori Kuwano 《Progress in Photovoltaics: Research and Applications》1994,2(3):211-219
A new approach to high-performance a-Si solar cells was studied. a-Si films prepared at a high substrate temperature (> 250°C) have a higher absorption coefficient and a low Si H2 bond density. the effect of deposition temperature on the open-circuit voltage (Voc) has been investigated systematically for glass/SnO2 Ipin/metal and glass/metal/nip/indium tin oxide (ITO) structure a-Si solar cells. The Voc is found to depend strongly on the thermal history of the p/i interface. A short-circuit current of 19.5 mA/cm−−2 was achieved for an a-Si solar cell using an a-Si i-layer with a thickness of 4000 Å, which was prepared at a substrate temperature of 270°C. 相似文献
44.
Shuqi Guo Yutaka Kagawa Toshiyuki Nishimura Hidehiko Tanaka 《Journal of the American Ceramic Society》2007,90(7):2255-2258
The thermal and electrical properties of MoSi2 and/or SiC-containing ZrB2 -based composites and the effects of MoSi2 and SiC contents were examined in hot-pressed ZrB2 –MoSi2 –SiC composites. The thermal conductivity and electrical conductivity of the ZrB2 –MoSi2 –SiC composites were measured at room temperature by a nanoflash technique and a current–voltage method, respectively. The results indicate that the thermal and electrical conductivities of ZrB2 –MoSi2 –SiC composites are dependent on the amount of MoSi2 and SiC. The thermal conductivities observed for all of the compositions were more than 75 W·(m·K)−1 . A maximum conductivity of 97.55 W·(m·K)−1 was measured for the 20 vol% MoSi2 -30 vol% SiC-containing ZrB2 composite. On the other hand, the electrical conductivities observed for all of the compositions were in the range from 4.07 × 10–8.11 × 10 Ω−1 ·cm−1 . 相似文献
45.
Accuracy and reliability of pin-by-pin fission rate distribution in large geometries calculated by the multi-group Monte-Carlo method is examined through comparison with a deterministic transport code based on the method of characteristics. Various calculation geometries from a single assembly to a PWR full core are used for comparison of pin-by-pin fission rate distribution. An integral parameter, i.e., k-effective, can be accurately calculated by the Monte-Carlo method with a practical number of neutron histories (106–107) regardless of the size of the calculation geometry. On the other hand, comparison with the deterministic calculation shows that the estimated statistical errors for pin-by-pin fission rate distribution obtained by a Monte-Carlo calculation are somewhat underestimated in a large geometry, e.g., a PWR full core, under the present calculation conditions. Such underestimation of the statistical uncertainty of a local parameter should be carefully considered when the Monte-Carlo method is used as a reference tool for verification of a deterministic code, especially in large geometries. 相似文献
46.
Corrosion characteristics of reduced activation ferritic steel, JLF-1 (8.92Cr–2W) in molten salts Flibe and Flinak 总被引:1,自引:0,他引:1
Masatoshi Kondo Takuya Nagasaka Qi Xu Takeo Muroga Akio Sagara Nobuaki Noda Daisuke Ninomiya Masaru Nagura Akihiro Suzuki Takayuki Terai Naoki Fujii 《Fusion Engineering and Design》2009,84(7-11):1081-1085
Static corrosion tests were performed in molten salts, LiF–BeF2 (Flibe) and LiF–NaF–KF (Flinak), at 500 °C and 600 °C for 1000 h. The purpose is to investigate the corrosion characteristics of reduced activation ferritic steels, JLF-1 (8.92Cr–2W) in the fluids. The concentration of hydrogen fluoride (HF) in the fluids was measured by slurry pH titration method before and after the exposure. The HF concentration determined the fluoridation potential. The corrosion was mainly caused by dissolution of Fe and Cr into the fluids due to fluoridation and/or electrochemical corrosion. Carbon on the surface might be dissolved into the fluids due to the corrosion, and this resulted to the decrease of carbide on the surface. The corrosion depth of the JLF-1 specimen, which was obtained from the weight losses, was 0.637 μm in Flibe at 600 °C and 6.73 μm in Flinak at 600 °C. 相似文献
47.
Nongluk Sriwilaijaroen Akio Kadowaki Yuriko Onishi Nobuki Gato Makoto Ujike Takato Odagiri Masato Tashiro Yasuo Suzuki 《Food chemistry》2011
Fruit-juice concentrate of Japanese apricot (Prunus mume Sieb. et Zucc.) has been shown to be effective against influenza A infection in MDCK cells. In this study, we isolated five components from the fruit-juice concentrate of Japanese apricot, 5-(hydroxymethyl)-2-formylfuran (HMF), 1-[5-(2-formylfuryl)methyl]dihydrogen 2-hydroxypropane-1,2,3-tricarboxylate (mumefural, MF), 2-[5-(2-formylfuryl)methyl]dihydrogen 2-hydroxypropane-1,2,3-tricarboxylate (MF‘), 1-[5-(2-formylfuryl)methyl]hydrogen 1-hydroxyethane-1,2-dicarboxylate (MA1) and 2-[5-(2-formylfuryl)methyl]hydrogen 1-hydroxyethane-1,2-dicarboxylate (MA2), and investigated their inhibitory activities against the novel influenza A/Narita/1/2009 (H1N1) pandemic virus hemagglutinin and neuraminidase functions, which are essential for viral attachment and budding, respectively. An hemagglutination inhibition assay indicated that MF and MF‘ were effective at minimum hemagglutination concentrations of 3.1 and 6.3 mM, respectively. An inhibition study for sialidase activity of the neuraminidase spike showed that MF was the most active anti-sialidase compound with an IC50 value of 0.21 ± 0.01 mM, followed by MA2 (IC50, 0.71 ± 0.09 mM), MA1 (IC50, 1.64 ± 0.31 mM) and MF‘(IC50, 1.62 ± 0.22 mM). Furthermore, MF was shown to inhibit the growth of the pandemic virus in a dose-dependent manner (62 ± 3% inhibition at 5 mM). The results suggest that MF, a citric acid ester linked to HMF at the 1-position of the propane backbone, might be a lead compound for the development of anti-influenza A inhibitors. 相似文献
48.
Image blurring of MeV transmission electrons for gold nanoparticles on the top surface of micrometer-thick specimens has been investigated using the Monte Carlo simulation. Both the simulated line density profile and therefore image blurring were in good agreement with the experimental ones in the ultrahigh voltage electron microscope. Quantitative effects of specimen thickness and electron energy on image blurring were presented, in which the specimen thickness had a greater influence. Image blurring was demonstrated to be caused mainly by multiple elastic scattering, but it could be reduced to several nanometers for a 5?μm thick epoxy-resin specimen at the electron energy of 2?MeV. 相似文献
49.
Electronic energy calculations of (1) Li-intercalated Mg2Si assuming 4b sites occupancy by Li and (2) the formation of MgSiLi2 with the assumed structures by Wengert et al. and Herbst and Meyer have been performed by a density-functional theory. The calculated energy changes for intercalation reactions of Mg8Si4 + nLi → Mg8Si4Lin are +0.349 eV, +0.822 eV, +1.178 eV, and +1.741 eV for n = 1-4, respectively, and the energy change for Mg8Si4 + 8Li → Mg4Si4Li8 + 4Mg is −1.95 eV when Mg is in the metallic state, while +4.12 eV when Mg is in the state of an isolated atom. If we can retard the growth of metallic Mg from Mg2Si by some methods, undesirable structural change of the Mg2Si into MgSiLi2 during charge-discharge cycles would be prevented and intercalation/disintercalation reaction of Li into/from Mg2SiLin (n = 0-1.0) would proceed reversibly by applied electric field. 相似文献
50.
Kimiyoshi Naito Yutaka Kagawa Seishi Utsuno Tamaki Naganuma Kanshi Kurihara 《Composites Science and Technology》2009,69(11-12):2027-2029
Electromagnetic wave transmittances of plain woven fabric glass fiber reinforced epoxy matrix composite (PW-GFRP) and eight-harness-stain fabric glass fiber reinforced polyimide matrix composite (8H-GFRP) with 1.0 mm thickness were measured in a terahertz (THz) frequency range. The transmittance values for both composites are nearly zero at a frequency of 1.0 THz. The real parts of the complex dielectric constant, ε′(ω) are 4.45 and 3.87 for PW-GFRP and 8H-GFRP, respectively, in the frequency range from 0.2 to 1.0 THz, and they are almost frequency independent. Conversely, the imaginary parts of the dielectric constant, ε′′(ω) for both composites linearly increases with increase of the frequency from 0.13 to 0.37 for PW-GFRP, and from 0.12 to 0.33 for 8H-GFRP. 相似文献