全文获取类型
收费全文 | 201篇 |
免费 | 4篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 83篇 |
金属工艺 | 8篇 |
机械仪表 | 4篇 |
建筑科学 | 1篇 |
能源动力 | 2篇 |
轻工业 | 37篇 |
无线电 | 6篇 |
一般工业技术 | 40篇 |
冶金工业 | 12篇 |
原子能技术 | 3篇 |
自动化技术 | 3篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 8篇 |
2021年 | 7篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 5篇 |
2013年 | 17篇 |
2012年 | 13篇 |
2011年 | 14篇 |
2010年 | 12篇 |
2009年 | 13篇 |
2008年 | 6篇 |
2007年 | 7篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 3篇 |
2001年 | 7篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 1篇 |
1997年 | 8篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有205条查询结果,搜索用时 15 毫秒
51.
Yosuke Matsuo Yusuke Fujita Sachiko Ohnishi Takashi Tanaka Hideaki Hirabaru Takanori Kai Hiroshi Sakaida Shoko Nishizono Isao Kouno 《Food chemistry》2010
Chemical constituents of the leaves of rabbiteye blueberry (Vaccinium ashei READE) were investigated in detail. The major phenolic components were caffeoyl quinic acids, flavonol glycosides, flavan-3-ols and proanthocyanidins. Catechins and proanthocyanidins having additional phenylpropanoid units, such as cinchonains, kandelins and mururins, characterised the polyphenols of this plant. Among them, vaccinin A, an isomer of mururin A, was found to be a new compound, and the structure was characterised by spectroscopic methods. The most abundant polyphenols (11.3% of freeze-dried leaves) were oligomeric proanthocyanidins. Thiol degradation with mercaptoethanol indicated that the polymer was constituted of (+)-catechin and (−)-epicatechin as the terminal units and (−)-epicatechin, procyanidin A-2, and cinchonains Ia and Ib as the extension units. Mass spectral analysis suggested the presence of at least dodecamers with A-type linkages and phenylpropanoid moieties. 相似文献
52.
Hidetaka Kawakita Sachiko Nakano Kohshi Hamamoto Yumi Matsunaga Yuko Yoshimura Keisuke Ohto Katsutoshi Inoue 《应用聚合物科学杂志》2010,118(1):247-252
Polyphenols were synthesized via a horseradish peroxidase reaction from phenol, catechol, and pyrogallol for use as copper‐ion adsorbents. The molecular weights of the polyphenols ranged from about 1000 to 3000 g/mol. The hydroxyl group contents in the polyphenols from phenol, catechol, and pyrogallol were 5.9, 4.0, and 0.94 mol/kg, respectively, as determined by titration. The saturation binding capacity for copper ions of the polyphenols from phenol, catechol, and pyrogallol were calculated to be 1.44, 0.88, and 0.22 mol/kg, respectively, at pH 4.5. Copper ions were efficiently adsorbed via an ion‐exchange interaction by the synthesized polyphenols with vicinal hydroxyl groups, and those polyphenols could be applied to metal adsorption. Gold ions were selectively reduced by the phenol group in polypyrogallol in acid media to form gold particles. The reduced gold particles were eluted with a solution of 1.0M thiourea plus 0.5M HCl. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
53.
Yuichi Sawai Yuji Iwamoto Sachiko Okuzaki Yoshiyuki Yasutomi Koichi Kikuta Shin-ichi Hirano 《Journal of the American Ceramic Society》1999,82(8):2121-2125
A chemically modified polycarbosilane (PC) containing organofluoric groups (PCOCF) has been synthesized from PC and fluoroalkylmethyldimethoxysilane. PCOCF acts as an efficient compaction binder for SiC powders and as a coating material with excellent oxidation resistance in wet air. PCOCF-coated SiC powders also show excellent packing properties because of the organofluoric side chains, which give highly dense green compacts. PCOCF provides a high ceramic yield of 75% and highly dense SiC ceramics. Four-point bending strength increases and the scatter in strength values decreases significantly by PCOCF coating. 相似文献
54.
High corrosion resistance of magnesium coated with hydroxyapatite directly synthesized in an aqueous solution 总被引:1,自引:0,他引:1
Anticorrosion coatings are crucial for practical applications of magnesium alloys, which are used to reduce the weight of vehicles, aircraft, electronics enclosures etc. Hydroxyapatite (HAp) potentially offers high corrosion resistance and no environmental toxicity because its thermodynamic structural stability is high and it is a basic component of bone. However, direct synthesis of HAp on magnesium in aqueous solutions has been a scientific challenge because Mg ions prevent HAp crystallization. A new method of direct synthesis of HAp on magnesium was developed using a Ca chelate compound, which can maintain a sufficiently high concentration of Ca ions on the magnesium surface to overcome prevention of HAp crystallization with Mg ions. Highly crystallized HAp coatings were successfully formed on pure magnesium and AZ series alloys. Corrosion behavior of HAp-coated pure magnesium was examined by cyclic dry and wet tests with 1 g m−2 NaCl on the surface and polarization tests in a 3.5 wt% NaCl solution. A HAp-coated pure magnesium showed no noticeable corrosion pits after the dry and wet test. HAp-coated specimens showed 103-104 times lower anodic current density than as-polished specimen in the polarization test. The results demonstrate the remarkable anticorrosion performance of HAp coatings on magnesium for the first time. 相似文献
55.
Hidenobu Sumitani Sachiko Suekane Aya Nakatani Kiyoaki Tatsuka 《Journal of the science of food and agriculture》1997,75(1):73-79
White peach (Prunus persica L cv Yamane) homogenates with sugar (20%), or with sugar (20%) and/or L -ascorbic acid (0·1%) and/or sodium chloride (0·5%), were packed in plastic bottles, pressurised (400 MPa, 20°C, 10 min), and then stored at 0 and 25°C for various periods. The headspace volatiles which were absorbed on Tenax TA using dynamic headspace sampling were heat desorbed and analysed by capillary gas chromatography mass spectrometry. Enzymatic formation of benzaldehyde during storage was observed in all samples. The homogenate with L -ascorbic acid showed the highest level of benzaldehyde formation. The flavour quality and colour of the pressurised homogenates with ascorbic acid stored at lower temperature were excellent. © 1997 SCI. 相似文献
56.
Tomoyuki Murakami Tetsuya Suekane Kiyoshi Tsuji Yoshihiro Okuno Yasuo Hasegawa Shigeharu Kabashima 《Electrical Engineering in Japan》1997,120(1):16-22
Electron temperatures of nonequilibrium cesium seeded argon plasmas in a disk MHD generator installed in a blow-down facility are measured spectroscopically, and the generator performance is discussed in relation to the electron temperature. The temperature is decreased from ∼9000 K to ∼3000 K when the seed fraction is increased from 1 × 10−4 to 3 × 10−4. For the seed fraction of about 2 × 10−4 corresponding to the maximum power output, the temperature is found to be 4000–5000 K and the temperature fluctuation becomes minimal. For the seed fraction around 2 × 10−4, the electrical conductivity evaluated from the temperature is almost independent of the temperature. These facts suggest that the plasma is almost in the full seed ionization regime. Partially ionized argon and cesium plasmas are dominant at seed fractions below 1.3 × 10−4 and over 2.3 × 10−4, respectively, which degrades generator performance. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(1): 16–22, 1997 相似文献
57.
Sugita-Konsihi Y Tanaka T Sugiura Y Tabata S Nakajima M Sakurai H Nakaie Y Sato K Kitani Y Fujita K Hayashi S Iizuka T Hirakawa Y Mochizuki N Hoshino M Sato Y Takahashi N Takatori K 《Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan》2005,46(5):224-227
To validate a modified version of AOAC official method of analysis 995.10 as an official standard in Japan for determination of patulin in apple juice, an inter-laboratory study was performed in 11 laboratories using a non-contaminated sample, 2 naturally contaminated samples and 2 spiked samples of apple juice. For naturally contaminated apple juices, the relative standard deviations for repeatability and reproducibility were 3.2, 7.1% and 10.0, 21.7%, respectively. HORRAT values were 0.4, 0.9. The average recovery of patulin from spiked sample was 83.7%. The limit of quantification was calculated as 10 microg/kg. From these results, the method was thought to be suitable as an official standard for determination of patulin in apple juice in Japan. 相似文献
58.
A microwave-hydrothermal treatment with 1 and 5N-NaOH solution was used at 150°C and 190°C to dissolve excess silica glass and thus make porous mullite ceramics from a fired New Zealand kaolin honeycomb. The effect of microwave-hydrothermal (M-H) treatment time on the dissolution of the glass was examined and compared to the result of conventional-hydrothermal (C-H) treatment. As expected, the rate of the dissolution of glass was faster with M-H treatment compared to C-H treatment. The dissolution of 40–43% glass was almost complete after M-H treatment in 1N-NaOH for 6 hrs at 150°C, in1N-NaOH for 3 hrs at 190°C, in5N-NaOH for 1.5 hrs at 150°C, and in 5N-NaOH for 35 minutes at 190°C. When the M-H treatment in 5N-NaOH solution at 190°C was more than 45 minutes, nonporous prismatic crystals were formed on the honeycomb and these crystals decreased the specific surface area. There were no changes in the morphology of mullite whiskers or in the structure of porous mullite body after M-H treatments in NaOH solutions compared to that of C-H treatment. The M-H treatment has been shown to be a rapid technique to prepare porous mullite ceramics from fired kaolin honey comb. 相似文献
59.
ABSTRACT: The morphological change of silicon macropore arrays formed by metal-assisted chemical etching using shape-controlled Au thin film arrays was investigated during anisotropic chemical etching in tetramethylammonium hydroxide (TMAH) aqueous solution. After the deposition of Au as the etching catalyst on (111) silicon through a honeycomb mask prepared by sphere lithography, the specimens were etched in a mixed solution of HF and H2O2 at room temperature, resulting in the formation of ordered macropores in silicon along the [111] direction, which is not achievable by conventional chemical etching without a catalyst. In the anisotropic etching in TMAH, the macropores changed from being circular to being hexagonal and finally to being triangular owing to the difference in etching rate between the crystal planes. 相似文献
60.
To improve absorption chiller performance, an aqueous solution of lithium bromide and lithium iodide mixture at the ratio of 1:0.7 was proposed for an absorbing medium since it has a higher solution limit than conventional lithium bromide solution. But the component lithium iodide solution has a higher equilibrium pressure than the lithium bromide solution. To investigate the absorption performance of the mixture liquid, experiments were carried out using a horizontal pipe column. Experimental range of the mass concentration was 62–66% for the mixture solution and 62–63% for the lithium bromide solution. The absorption rate of lithium bromide solution at 62% and 63% is almost equal to the mixture solution at 63% and 64%, respectively. Compared at the same concentrations, the mixture solution is inferior to the lithium bromide solution; at the maximum concentration, the mixture solution has about 20 to 50% higher absorption rates than the lithium bromide solution. Surface temperature of the falling films was measured by thermal video and used to determine the heat transfer coefficient and mass transfer coefficient, which becomes larger for the mixture solution than for the lithium bromide solution. This is due to the decreased viscosity of the mixture solution. © 2008 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(7): 431–444, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20213 相似文献