全文获取类型
收费全文 | 243篇 |
免费 | 15篇 |
专业分类
电工技术 | 7篇 |
综合类 | 2篇 |
化学工业 | 88篇 |
金属工艺 | 7篇 |
机械仪表 | 12篇 |
建筑科学 | 5篇 |
能源动力 | 9篇 |
轻工业 | 31篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 19篇 |
一般工业技术 | 42篇 |
冶金工业 | 7篇 |
原子能技术 | 4篇 |
自动化技术 | 22篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 4篇 |
2013年 | 29篇 |
2012年 | 12篇 |
2011年 | 15篇 |
2010年 | 13篇 |
2009年 | 9篇 |
2008年 | 10篇 |
2007年 | 11篇 |
2006年 | 10篇 |
2005年 | 12篇 |
2004年 | 8篇 |
2003年 | 18篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 2篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1987年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1977年 | 3篇 |
1976年 | 1篇 |
排序方式: 共有258条查询结果,搜索用时 15 毫秒
1.
Tadashi Hano Michiaki Matsumoto Takahisa Kawazu Takaaki Ohtake 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,62(1):60-63
The extraction equilibria of various di- and tripeptides with di-2-ethylhexylphosphoric acid (D2EHPA) were studied at low pH values. The complex extracted to organic phase consisted of one molecule of peptide and two molecules of D2EHPA dimer. The extraction constants of the peptides correlated well with the distribution coefficients of peptides between 1-octanol and water, which is a measure of hydrophobicity. The permeation rates of peptides through an emulsion liquid membrane were examined by using D2EHPA as a carrier, Span 80 as an emulsifier and kerosene as a diluent. The rates varied considerably with peptide type, depending upon the hydrophobicity. 相似文献
2.
N,N'- Unsymmetrical dialkyl-3,4:9,10-perylenebis(dicarboximide)s (in which alkyl = methyl, ethyl, propyl, butyl, isobutyl, pentyl, hexyl and octyl) were prepared by the condensation of N-alkyl-3,4:9,10-perylene-tetracarboxylic monoanhydride monoimide with the appropriate alkyl-amines. The properties of these derivatives as pigments were tested and their thermal stability measured. 相似文献
3.
N′-Alkyl-N′-aryl-3,4:9,10-perylenebis(dicarboximide) (alkyl = isobutyl, pentyl, hexyl, octyl, etc.; aryl = phenyl, p-tolyl, p-methoxyphenyl, etc.) were prepared by the condensation of N-alkyl-3,4:9,10-perylene-tetracarboxylic monoanhydride monoimide with arylamines (aniline, p-toluidine, p-anisidine, o-phenylenediamine, etc.). The properties of these derivatives as pigments were tested, and also the thermal stability of 3,4:9,10-perylenebis(dicarboximide) derivatives was measured. 相似文献
4.
An ozone generator using a rotating electrode to improve ozone generation efficiency is proposed. The ozone generator electrode unit consists of a rotating electrode and fixed electrode. The rotating electrode has the grounded 36 pieces of tungsten wires fixed in parallel to the rotation axis on the rotating cylinder surface. A dielectric electrode is used as a fixed electrode located on the inside of the tube of the electrode unit. The width of the apparent discharge gap is 1mm. Alternating current with a frequency of 50 Hz is applied to the electrode unit. The rotation speed can be adjusted from 0 rpm to 1200 rpm by a variable speed motor. Oxygen gas is used as the material gas. Higher ozone concentration and higher ozone generation efficiency are obtained compared with that when the rotation speed is 0 rpm. The gas temperature is measured at the inlet and outlet of the ozone generator, and the rotation speed for the cooling effect is most effective at about 500 rpm. The maximum generation efficiency is estimated to be 61 g/kWh at 800 rpm, and this value is twice as large as in the case of 0 rpm. 相似文献
5.
Electrocodeposition of Sm and Co on a Cu substrate was investigated in a molten LiCl-KCl-SmCl3 (0.5 mol.%)-CoCl2 (0.1 mol.%) system at 723 K. Phase of the deposited Sm-Co alloys could be controlled by electrolysis potential. SmCo3 was formed on a Cu substrate by potentiostatic electrolysis in the potential range of 0.20-0.90 V (vs. Li+/Li). Sm2Co17 was obtained in the potential range of 0.90-1.50 V. 相似文献
6.
Tetsuro Kobayashi Jeffrey Boase Tsutomu Suzuki Takahisa Suzuki 《Journal of Computer-Mediated Communication》2015,20(3):330-345
The tele‐cocooning hypothesis posits that mobile communication increases interaction with communication rich ties, while simultaneously weakening interaction with communication weak ties. In this study, we demonstrate how smartphones can be used to mitigate tele‐cocooning behavior by stimulating interaction with communication weak ties. Using a smartphone application to collect non‐identifying mobile communication log data, we conducted a field experiment with 193 Japanese participants. The treatment consisted of onscreen reminders designed to stimulate interaction with communication weak ties. The results indicate that the treatment promoted the activation of communication weak ties and the acquisition of information through those ties, suggesting that smartphones can be utilized to promote access to social capital. 相似文献
7.
Ferroelectric and Magnetic Properties in Room‐Temperature Multiferroic GaxFe2−xO3 Epitaxial Thin Films 下载免费PDF全文
Tsukasa Katayama Shintaro Yasui Yosuke Hamasaki Takahisa Shiraishi Akihiro Akama Takenori Kiguchi Mitsuru Itoh 《Advanced functional materials》2018,28(2)
GaFeO3‐type iron oxide is a promising room‐temperature multiferroic material due to its large magnetization. To expand its usability, controlling the ferroelectric and magnetic properties is crucial. In this study, high‐quality GaxFe2–xO3 (x = 0–1) epitaxial films are fabricated and their properties are systematically investigated. All films exhibit room‐temperature out‐of‐plane ferroelectricity, showing that the coercive electric field (Ec) decreases monotonically with x. Additionally, the films show in‐plane ferrimagnetism with a Curie temperature (TC) >350 K at x = 0–0.6. The coercive magnetic field (Hc) decreases with x at x ≤ 0.6, but shows a constant value at x > 0.6, whereas the saturated magnetization (Ms) increases with x at x ≤ 0.6, but decreases with x at x > 0.6. X‐ray magnetic circular dichroism reveals that the large magnetization at x = 0.6 is derived from Fe3+ (3d5) at octahedral sites. The controllable range of the Ec, Hc, and Ms values at room temperature (400–800 kV cm?1, 1–8 kOe, and 0.2–0.6 µB/f.u.) is very wide and differs from those of well‐known multiferroic BiFeO3. Furthermore, the GaxFe2?xO3 films exhibit room‐temperature magnetocapacitance effects, indicating that adjusting TC near room temperature is useful to achieve large room‐temperature magnetocapacitance behavior. 相似文献
8.
Lianqi Zhang Hideyuki Noguchi Decheng Li Takahisa Muta Xiaoqing Wang Masaki Yoshio Izumi Taniguchi 《Journal of power sources》2008
On the basis of extreme similarity between the triangle phase diagrams of LiNiO2–LiTiO2–Li[Li1/3Ti2/3]O2 and LiNiO2–LiMnO2–Li[Li1/3Mn2/3]O2, new Li–Ni–Ti–O series with a nominal composition of Li1+z/3Ni1/2−z/2Ti1/2+z/6O2 (0 ≤ z ≤ 0.5) was designed and attempted to prepare via a spray-drying method. XRD identified that new Li–Ni–Ti–O compounds had cubic rocksalt structure, in which Li, Ni and Ti were evenly distributed on the octahedral sites in cubic closely packed lattice of oxygen ions. They can be considered as the solid solution between cubic LiNi1/2Ti1/2O2 and Li[Li1/3Ti2/3]O2 (high temperature form). Charge–discharge tests showed that Li–Ni–Ti–O compounds with appropriate compositions could display a considerable capacity (more than 80 mAh g−1 for 0.2 ≤ z ≤ 0.27) at room temperature in the voltage range of 4.5–2.5 V and good electrochemical properties within respect to capacity (more than 150 mAh g−1 for 0 ≤ z ≤ 0.27), cycleability and rate capability at an elevated temperature of 50 °C. These suggest that the disordered cubic structure in some cases may function as a good host structure for intercalation/deintercalation of Li+. A preliminary electrochemical comparison between Li1+z/3Ni1/2−z/2Ti1/2+z/6O2 (0 ≤ z ≤ 0.5) and Li6/5Ni2/5Ti2/5O2 indicated that charge–discharge mechanism based on Ni redox at the voltage of >3.0 V behaved somewhat differently, that is, Ni could be reduced to +2 in Li1+z/3Ni1/2−z/2Ti1/2+z/6O2 while +3 in Li6/5Ni2/5Ti2/5O2. Reduction of Ti4+ at a plateau of around 2.3 V could be clearly detected in Li1+z/3Ni1/2−z/2Ti1/2+z/6O2 with 0.27 ≤ z ≤ 0.5 at 50 °C after a deep charge associated with charge compensation from oxygen ion during initial cycle. 相似文献
9.
Noriya Izu Haruo Kishimoto Takahisa Omata Kousuke One 《Science and Technology of Advanced Materials》2013,14(2):397-404
Tetragonal CaF2-related-type t′-/Ce0.5Zr0.5)O2 phase was reduced at 773 K ≤ Tred. ≤ 1073 K to prepare precursors with various oxygen compositions: Ce2Zr2O712d /0.111 < δ < 0.379). Metastable tetragonal t′meta-(Ce0.5Zr0.5)O2 phases were prepared by oxidizing in O2 at 873 K the precursors, and subjected to evolved oxygen gas analysis by heating the samples at a constant rate. When the precursor was prepared at Tred: ? 773 K; i.e. δ ? 0:379; the oxygen release behavior of the tetragonal phase agreed approximately with that of the t′. For δ < 0.29, distinct features of the t′meta-(Ce0.5Zr0.5)O2 appeared in the XRD results and Raman spectra. The temperature exhibiting the maximum release rate of oxygen from the t′meta became lower with decreasing the d value. It could be concluded that the thermodynamic behavior of the t′meta is related closely to the precursor composition and becomes more unstable with decrease in the δ value. The t′ and t′meta phases with disordered arrangement of Ce and Zr ions may belong to the same space group; nevertheless, difference in the random arrays of the Ce and Zr ions was suggested on the basis of the present experimental results. 相似文献
10.
Osteoclast differentiation and characteristic trabecular bone formation during growth plate destruction in osteoprotegerin-deficient mice 总被引:3,自引:0,他引:3
Osteoprotegerin (OPG) is an osteoblast-derived secreted member of the tumour necrosis factor receptor superfamily that inhibits osteoclastogenesis. Mice that are OPG-deficient have severe bone loss, including growth plate cartilage destruction. Using OPG-deficient mice as a useful animal model, we attempted to clarify differentiation and ultrastructural features of osteoclasts located on destructed growth plate cartilage and trabecular bone matrix. In the humerus and femur of OPG homozygous (-/-) mice, adjacent to the growth plate cartilage, bone trabeculae without a calcified cartilage core were characteristically formed at the metaphyseal side of the medullary cavity, which resulted in an irregular chondrocyte distribution and arrangement in growth plate cartilage. During growth plate cartilage destruction, osteoclasts positive for tartrate-resistant acid phosphatase showed unusual localization on both type-II collagen-positive cartilage and type-I collagen-positive trabecular bone matrix at the ossification centre of the epiphyseal/metaphyseal border. Although multinucleated osteoclasts were distributed within open lacunar canals in the growth plate, those on uncalcified cartilage matrix lacked a ruffled border. Facing the calcified cartilage matrix within lacunar canals, osteoclasts showed irregularly formed ruffled borders. After growth plate destruction, a thin bone layer was deposited on the remaining cartilage surfaces by invading osteoblasts. Osteoclasts formed prominent ruffled border structures on bone matrix, deposited on the remaining growth plate cartilage. These results suggest that, in OPG (-/-) mice, terminal osteoclast differentiation requires the presence of newly produced bone matrix, as the coupled phenomenon of bone formation and resorption, as well as osteoblast-derived cytokines. 相似文献