全文获取类型
收费全文 | 532篇 |
免费 | 14篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 24篇 |
化学工业 | 166篇 |
金属工艺 | 6篇 |
机械仪表 | 6篇 |
建筑科学 | 8篇 |
能源动力 | 54篇 |
轻工业 | 57篇 |
水利工程 | 2篇 |
无线电 | 26篇 |
一般工业技术 | 108篇 |
冶金工业 | 11篇 |
原子能技术 | 27篇 |
自动化技术 | 55篇 |
出版年
2023年 | 3篇 |
2021年 | 5篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 8篇 |
2013年 | 19篇 |
2012年 | 19篇 |
2011年 | 27篇 |
2010年 | 28篇 |
2009年 | 31篇 |
2008年 | 31篇 |
2007年 | 32篇 |
2006年 | 24篇 |
2005年 | 15篇 |
2004年 | 24篇 |
2003年 | 18篇 |
2002年 | 18篇 |
2001年 | 12篇 |
2000年 | 14篇 |
1999年 | 12篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 11篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 5篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 3篇 |
排序方式: 共有550条查询结果,搜索用时 15 毫秒
51.
Hiroyuki Fujiwara Tetsuya Kaneko Michio Kondo 《Solar Energy Materials & Solar Cells》2009,93(6-7):725-728
In heterojunction solar cells consisting of hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si), suppression of epitaxial growth at the heterointerface is found to be crucial to achieve high solar cell efficiencies. In order to avoid the epitaxial growth, wide-gap hydrogenated amorphous silicon oxide (a-SiO:H) has been applied to the heterojunction solar cells. We have fabricated a-SiO:H/c-Si solar cells using n-type and p-type c-Si substrates and demonstrated that incorporation of the a-SiO:H i layer prevents the harmful epitaxial growth at the heterointerface completely. 相似文献
52.
Vladimir Švrček Hiroyuki Fujiwara Michio Kondo 《Solar Energy Materials & Solar Cells》2009,93(6-7):774-778
We demonstrate that the electrochemical etching and pulverization of porous silicon films allow the fabrication of boron- and phosphorous-doped freestanding silicon nanocrystals (Si-ncs). The presence of boron in freestanding Si-ncs was confirmed from low-temperature photoluminescence (PL) analysis. The temperature dependence of PL for both types of doped Si-ncs reveals two PL bands due to the quantum confinement effect and surface state defects. Blending of Si-ncs into poly[methoxy-ethylexyloxy-phenylenevinilene] polymer leads to suppression of the PL band originated from surface states. More importantly, those blends showed a photoconductivity response under illumination AM1.5 at room temperature. 相似文献
53.
Hitoshi Sai Hiroyuki Fujiwara Michio Kondo 《Solar Energy Materials & Solar Cells》2009,93(6-7):1087-1090
Back surface reflectors (BSRs) with grating structures have been developed to enhance light trapping in thin-film hydrogenated microcrystalline Si (μc-Si:H) solar cells. As a grating structure, a periodic honeycomb-like dimple pattern with a period of ~450 nm has been fabricated on Al substrates by a self-ordering process using anodic oxidation of Al. The clear diffraction effect has been confirmed on the patterned Al from the angle-dependent reflection. From quantum efficiency measurements, we found that the periodically patterned BSR can confine the incident light more effectively than the random textured BSR, especially at longer wavelengths. 相似文献
54.
55.
Fumi Kojin Masanobu Mori Yumiko Noda Michio Inagaki 《Applied catalysis. B, Environmental》2008,78(3-4):202-209
Carbon-coated W18O49 powders were prepared from the mixture of para-ammonium tungstate with poly(vinyl alcohol) by heat treatment in inert atmosphere at a temperature between 750 and 900 °C for 1 h. The synthesized W18O49 crystals had prismatic morphology in small size, less than 0.5 μm in diameter and about 1 μm in length. Carbon-coated W18O49 was shown to have photoactivity under visible light irradiation by comparing the concentration changes of methylene blue, phenol and dimethylsulfoxide with time under the irradiation of visible light to that in the dark. Photoactivity of W18O49 was supposed to be due to the formation of OH radicals on the basis of the degradation of dimethylsulfoxide, its quantitative transformation to methanesulfonic acid. Carbon coating seemed to have various roles: to reduce WO3 to W18O49, to inhibit the sintering and crystal growth of W18O49 to keep them small size, and also to concentrate pollutants around W18O49 crystal by adsorption. 相似文献
56.
Zhengxin Liu Atsushi Masuda Takehiko Nagai Takashi Miyazaki Miwako Takano Masahiro Takano Haruyuki Yoshigahara Kazutoshi Sakai Koichi Asai Michio Kondo 《Solar Energy Materials & Solar Cells》2007,91(19):1805-1810
Spherical Si solar cell, which is made up of Si spheres with a diameter of approximately 1.0 mm, is expected to be a promising candidate for low consumption of Si feedstock and simple process technology. This paper describes the formation process and the structure of a concentrator module in detail. The concentrator lens was formed by casting with ultraviolet light hardening resin. The concentration ratio was 4.4 times and the pitch between the spheres was 2.0 mm. By this module design, it was possible to realize a consumption of the Si feedstock of about 3.0 g/W. Conversion efficiencies of 11.3% from single-sphere cell, 8.5% from a 23-spheres module and 5.2% from a 105-spheres module under AM1.5, 100 mW/cm2 illumination were achieved. 相似文献
57.
Michio Yamada Konomi Tokutomi Ayaka Takehara Yusuke Sakai Yutaka Maeda Tadashi Hasegawa 《Fullerenes, Nanotubes and Carbon Nanostructures》2014,22(1-3):66-74
Tröger's base (TB, 1) and its analogues were synthesized and were subject to the titration experiments to evaluate their ability of supramolecular complexation with C60. Results demonstrate clearly that the fluorene-based TB analogue (2) and the bioctylfluorene-based TB analogue (3) show 1:1 binding with C60 to form the corresponding complexes while TB 1 does not. Titration experiments exhibited that the association constant (Kass) of 3/C60 (48.1 ± 7.9 M ?1) was larger than that of 2/C60 (13.7 ± 1.4 M ?1). The formation of the 1:1 binding complexes 2/C60 and 3/C60 was also confirmed by MALDI-TOF mass spectrometry. Theoretical calculations suggest that 2 and 3 have appropriate cavities to embrace C60. These findings indicate that not only the π/π interaction between the fluorene moieties and the C60 surface but also the CH/π interaction between the octyl groups and the C60 surface serve efficiently in the supramolecular complexation with C60. 相似文献
58.
Photocarrier generation in organic thin-film solar cells with an organic heterojunction 总被引:1,自引:0,他引:1
Takahiro Osasa Shuhei Yamamoto Yohei Iwasaki Michio Matsumura 《Solar Energy Materials & Solar Cells》2006,90(10):1519-1526
Photocurrent–voltage characteristics for organic solar cells with a heterojunction formed between copper phthalocyanine and a perylene derivative (or C60) were studied. The photocurrent was observed under both reverse and forward biases. From the analysis of the photocurrent action spectra, the origin of the reverse photocurrent was attributed to the excitons formed in both the organic layers, whereas that of the forward photocurrent was attributed to the excitons formed in the perylene derivative (or C60) layer. The photocurrent density under reverse bias increased at higher temperatures, suggesting that the charge recombination possibility was lowered at higher temperatures. On the basis of the time responses of the photocurrents observed after pulsed photoirradiation, the charge separation and transport processes are discussed. 相似文献
59.
Michio Yamawaki Tetsuo Nishihara Yoshiyuki Inagaki Kazuo Minato Hiroyuki Oigawa Kaoru Onuki Ryutaro Hino Masuro Ogawa 《International Journal of Hydrogen Energy》2007
It is universally admitted that hydrogen is one of the best energy media and its demand will increase greatly in the near future. However, little hydrogen exists naturally, so that how to generate hydrogen without bringing forth much CO2 will be very important research subject. Hydrogen generation from water using nuclear energy is one of the solutions for this problem. Especially, the high temperature gas cooled reactor (HTGR) has a possibility to generate hydrogen economically compared with other types of nuclear reactors. As for long-lived radioactive waste to be generated by nuclear reactors, it is expected to significantly reduce its burden to the human environment by applying transmutation technologies. This report describes the feature of the hydrogen generation with HTGR and the development of the accelerator-driven subcritical system to reduce radioactive waste ongoing at JAEA. 相似文献
60.
Occurrence and formation potential of N-nitrosodimethylamine in ground water and river water in Tokyo 总被引:1,自引:0,他引:1
N-nitrosodimethylamine (NDMA), a disinfection byproduct of water and wastewater treatment processes, is a potent carcinogen. We investigated its occurrence and the potential for its formation by chlorination (NDMA-FP2Cl) and by chloramination (NDMA-FP2NHCl) in ground water and river water in Tokyo. To characterize NDMA precursors, we revealed their molecular weight distributions in ground water and river water. We collected 23 ground water and 18 river water samples and analyzed NDMA by liquid chromatography-tandem mass spectrometry. NDMA-FP2Cl was evaluated by chlorinating water samples with free chlorine for 24 h at pH 7.0 while residual free chlorine was kept at 1.0-2.0 mgCl2/L. NDMA-FP2NHCl was evaluated by dosing water samples with monochloramine at 140 mgCl2/L for 10 days at pH 6.8. NDMA precursors and dissolved organic carbon (DOC) were fractionated by filtration through 30-, 3-, and 0.5 kDa membranes. NDMA concentrations were <0.5-5.2 ng/L (median: 0.9 ng/L) in ground water and <0.5-3.4 ng/L (2.2 ng/L) in river water. NDMA concentrations in ground water were slightly lower than or comparable to those in river water. Concentrations of NDMA-FP2Cl were not much higher than concentrations of NDMA except in samples containing high concentrations of NH3 and NDMA precursors. The increased NDMA was possibly caused by reactions between NDMA precursors and monochloramine unintentionally formed by the reaction between free chlorine and NH3 in the samples. NDMA precursors ranged from 4 to 84 ng-NDMA eq./L in ground water and from 11 to 185 ng-NDMA eq./L in river water. Those in ground water were significantly lower than those in river water, suggesting that NDMA precursors were biodegraded, adsorbed, or volatilized during infiltration. The molecular weight of NDMA precursors in river water was dominant in the <0.5 kDa fraction, followed by 0.5-3 kDa. However, their distribution was inconsistent in ground water: one was dominant in the <0.5 kDa fraction, and the other in 0.5-3 kDa. Molecular weight distributions of NDMA precursors were very different from those of DOC. This is the first study to reveal the widespread occurrence and characterization of NDMA precursors in ground water. 相似文献