全文获取类型
收费全文 | 1137篇 |
免费 | 37篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 54篇 |
化学工业 | 357篇 |
金属工艺 | 26篇 |
机械仪表 | 23篇 |
建筑科学 | 17篇 |
能源动力 | 65篇 |
轻工业 | 94篇 |
水利工程 | 4篇 |
石油天然气 | 2篇 |
无线电 | 80篇 |
一般工业技术 | 244篇 |
冶金工业 | 98篇 |
原子能技术 | 38篇 |
自动化技术 | 75篇 |
出版年
2023年 | 11篇 |
2022年 | 38篇 |
2021年 | 37篇 |
2020年 | 18篇 |
2019年 | 29篇 |
2018年 | 33篇 |
2017年 | 29篇 |
2016年 | 36篇 |
2015年 | 21篇 |
2014年 | 50篇 |
2013年 | 84篇 |
2012年 | 75篇 |
2011年 | 67篇 |
2010年 | 64篇 |
2009年 | 61篇 |
2008年 | 67篇 |
2007年 | 48篇 |
2006年 | 41篇 |
2005年 | 36篇 |
2004年 | 30篇 |
2003年 | 36篇 |
2002年 | 21篇 |
2001年 | 19篇 |
2000年 | 20篇 |
1999年 | 10篇 |
1998年 | 24篇 |
1997年 | 14篇 |
1996年 | 17篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1987年 | 8篇 |
1986年 | 7篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1971年 | 2篇 |
排序方式: 共有1177条查询结果,搜索用时 15 毫秒
21.
Takuya Tsutsui Masahiko Natsuhara Kaoru Yamada Yoshiaki Tanizawa 《Journal of surfactants and detergents》2007,10(1):53-59
The cooking of oil-containing food products at high temperatures results in an insoluble, unsightly, greasy layer of grime
on appliance surfaces in residential and commercial kitchens. Over time, adsorbed grime becomes difficult to remove using
normal dishwashing detergents. A number of studies have focused on the deterioration and oxidation of oils and the harmful
effects that volatile compounds associated with such processes have on human health. Little attention, however, has been paid
to kitchen grime. The present study examined grime obtained from the surfaces of appliances such as sirocco fans, filters,
and range hoods in residential kitchens in Tokyo. The grime was characterized by X-ray fluorescence spectroscopy (XRF), Fourier-transform
infrared spectroscopy (FT-IR), size exclusion chromatography (SEC), thermal hydrolysis methylation–gas chromatography–mass
spectroscopy (THM–GCMS), and nuclear magnetic resonance (NMR) techniques. The chemical composition and structure of the grime
differed from those of the edible oils. The grime consisted mainly of polymerized and oxidized triacylglycerols. Bridging
between unsaturated acyl groups of triglycerols occurred through thermal oxidation and aging in air, yielding their dimers,
trimers, and highly polymerized products while also transforming unsaturated acyl groups into saturated ones. Cross-linking
reactions involving dibasic acids also caused polymerization. Those polymerized products strongly adhered to the hard surfaces
of the appliances. Small amounts of cellulose fibers from air or towel may also play a role in mechanically stabilizing the
dirt structure.
相似文献
Yoshiaki TanizawaEmail: |
22.
The demulsification of oil-in-water (O/W) emulsions under freezing conditions is connected to fat crystallization in the oil
droplet. Therefore, demulsification can be prevented by the use of oil with a low melting point, and also by lowering the
O/W ratio. However, an oil with a low melting point, such as sunflower, is rather expensive, and the O/W ratio has a significant
effect on the texture of emulsions. We searched for an oil that is suitable for the production of a freeze-stable emulsion
and found that soybean oil has unique characteristics. Normally, emulsions are more unstable at lower temperatures; soybean
oil emulsion is unstable at −10°C and stable at −20°C. This unique characteristic results from the following two reasons.
First, the solid fat content of soybean oil is almost the same at −10 and −20°C. Second, small crystals form a larger network
over a period of time, and the higher temperature promotes faster restructuring. This structure formation was microscopically
observed with the use of a thermostated stage. Structure formation was suppressed with the addition of a crystal structure
modifier, polyglycerol fatty acid full ester, which also suppressed coalescence. 相似文献
23.
Tomohiro Toigawa Yasuhiro Tsubata Takeshi Kai Takuya Furuta Yuta Kumagai Tatsuro Matsumura 《溶剂提取与离子交换》2021,39(1):74-89
ABSTRACT Absorbed-dose estimation is essential for evaluation of the radiation tolerance of minor-actinide-separation processes. We propose a dose-evaluation method based on radiation permeability, with comparisons of heterogeneous structures seen in the solvent-extraction process, such as emulsions forming in the mixture of the organic and aqueous phases. A demonstration of radiation-energy-transfer simulation is performed with a focus on the minor-actinide-recovery process from high-level liquid waste with the aid of the Monte Carlo radiation-transport code PHITS. The simulation results indicate that the dose absorbed by the extraction solvent from alpha radiation depends upon the emulsion structure, and that from beta and gamma radiation depends upon the mixer-settler-apparatus size. Non-negligible contributions of well-permeable gamma rays were indicated in terms of the plant operation of the minor-actinide-separation process. 相似文献
24.
Methylcyclohexane dehydrogenation for hydrogen production via a bimodal catalytic membrane reactor 下载免费PDF全文
Lie Meng Xin Yu Takuya Niimi Hiroki Nagasawa Masakoto Kanezashi Tomohisa Yoshioka Toshinori Tsuru 《American Institute of Chemical Engineers》2015,61(5):1628-1638
The dehydrogenation of methylcyclohexane (MCH) to toluene (TOL) for hydrogen production was theoretically and experimentally investigated in a bimodal catalytic membrane reactor (CMR), that combined Pt/Al2O3 catalysts with a hydrogen‐selective organosilica membrane prepared via sol‐gel processing using bis(triethoxysilyl) ethane (BTESE). Effects of operating conditions on the membrane reactor performance were systematically investigated, and the experimental results were in good agreement with those calculated by a simulation model with a fitted catalyst loading. With H2 extraction from the reaction stream to the permeate stream, MCH conversion at 250°C was significantly increased beyond the equilibrium conversion of 0.44–0.86. Because of the high H2 selectivity and permeance of BTESE‐derived membranes, a H2 flow with purity higher than 99.8% was obtained in the permeate stream, and the H2 recovery ratio reached 0.99 in a pressurized reactor. A system that combined the CMR with a fixed‐bed prereactor was proposed for MCH dehydrogenation. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1628–1638, 2015 相似文献
25.
Takuya Noguchi Toshihiro Shimada Takashi Chiba Masao Terada Tetsuya Hasegawa 《Diamond and Related Materials》2010,19(2-3):107-109
We have carried out very high temperature heat treatment at 1400–2700 °C of about 10 nm-thick amorphous carbon thin films deposited on refractory substrates MgO, Al2O3, and yttria-stabilized zirconia (YSZ) using pulsed laser deposition techniques. After the annealing, a few nanometer scale sp2 crystallization of the films and a large corrugation with a height of more than 1 μm were observed by Raman spectroscopy analysis and optical/atomic force microscopes, respectively. The corrugation is probably caused by the formation of gases at the film/substrate interface during the heat treatment. 相似文献
26.
We examined which isomer, the erythro or threo, of non-phenolic β-O-4-type lignin model compounds is stereo-preferentially attacked by hydroxyl radical and its conjugate base, oxyl anion radical, generated by the decomposition of hydrogen peroxide in the presence of ferric ion and its precipitates under hydrogen peroxide bleaching conditions. The intrinsic stereo-preference of oxyl anion radical was slightly toward the erythro isomer, while hydroxyl radical had a further smaller stereo-preference. These stereo-preferences can be explained by our prior knowledge that oxyl anion radical preferentially attacks the side-chain of the lignin model compounds rather than the aromatic nucleus. The amount of the degraded lignin model compounds became less great with decreasing pH, but reversely and intensively greater in the pH range below 10. This phenomenon can be attributed to the change in the decomposition mechanism of hydrogen peroxide accompanying the pH variation. 相似文献
27.
Hiroki Uehara Takuya Tamura Masaki Kakiage Takeshi Yamanobe 《Advanced functional materials》2012,22(10):2048-2057
Crystalline homopolymers, including polyethylene (PE), which has the simplest architecture, form a nanometer‐sized combination of crystalline and amorphous components, but their arrangement control, similar to self‐assembled phase‐separation of block‐copolymers, is usually difficult. However, molecular entanglements trapped between crystalline and amorphous components of homopolymers coincide with the segmental linking points on the interfaces of the microphase separation for block copolymers. Nanowrinkled PE membranes are prepared with a network of 30 nm‐thick homogeneous lamellae using a novel entanglement control technique composed of biaxial melt‐drawing and melt‐shrinking procedures, which are limited for highly entangled ultrahigh molecular weight materials. Such a network arrangement of nanowrinkling lamellae spreading on membrane surface and also across the membrane thickness improves the mechanical properties of both tensile strength and tearing strength. Subsequent cold‐drawing causes delamination of the lamellar interfaces, leading to the resultant nanoporous morphology composed of passing‐through channels that are several tens of nanometers in diameter, without any solvent processing. 相似文献
28.
29.
ZnO nanoparticles doped with up to 5 at% of Co and Mn were prepared using a co-precipitation method. The location of dopant
ions and the effect of doping on the photocatalytic activity were investigated. The crystal structure of nanoparticles and
local atomic arrangements around dopant ions were analyzed by X-ray absorption spectroscopy. The results showed that the Co
ions substituted the Zn ions in the ZnO wurtzite phase structure and induced lattice shrinkage, while Mn ions were not completely
incorporated in the crystal lattice. The photocatalytic activity under simulated sunlight was characterized by the decomposition
of Rhodamine B dye molecules. It was revealed that Co-doping strongly reduced the photocatalytic activity but Mn-doping showed
a weaker effect on the reduction of the photoactivity. 相似文献
30.