全文获取类型
收费全文 | 1344篇 |
免费 | 28篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 119篇 |
化学工业 | 407篇 |
金属工艺 | 51篇 |
机械仪表 | 43篇 |
建筑科学 | 39篇 |
能源动力 | 64篇 |
轻工业 | 148篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 78篇 |
一般工业技术 | 220篇 |
冶金工业 | 49篇 |
原子能技术 | 39篇 |
自动化技术 | 121篇 |
出版年
2023年 | 7篇 |
2022年 | 16篇 |
2021年 | 26篇 |
2020年 | 9篇 |
2019年 | 15篇 |
2018年 | 24篇 |
2017年 | 22篇 |
2016年 | 22篇 |
2015年 | 18篇 |
2014年 | 35篇 |
2013年 | 82篇 |
2012年 | 58篇 |
2011年 | 90篇 |
2010年 | 48篇 |
2009年 | 86篇 |
2008年 | 88篇 |
2007年 | 54篇 |
2006年 | 54篇 |
2005年 | 49篇 |
2004年 | 53篇 |
2003年 | 56篇 |
2002年 | 43篇 |
2001年 | 19篇 |
2000年 | 26篇 |
1999年 | 26篇 |
1998年 | 35篇 |
1997年 | 30篇 |
1996年 | 26篇 |
1995年 | 25篇 |
1994年 | 19篇 |
1993年 | 18篇 |
1992年 | 13篇 |
1991年 | 19篇 |
1990年 | 10篇 |
1989年 | 18篇 |
1988年 | 11篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 18篇 |
1978年 | 8篇 |
1976年 | 6篇 |
1975年 | 5篇 |
1970年 | 5篇 |
1969年 | 3篇 |
排序方式: 共有1382条查询结果,搜索用时 14 毫秒
81.
ABSTRACT The interfacial adsorption of 2-hydroxy-5-nonylbenzo-phenone oxime (LIX65N) at a n-heptane/water interphase was examined under static and vigorously stirred conditions, varying the aqueous pH from 2 to 12. In static systems, the pH and the concentration dependences of the interfacial tension were analysed on the basis of the Gibbs equation. The acid dissociation equilibrium at the interface was evaluated. In vigorously stirred systems, the interfacial adsorption was observed as a reversible, reproducible decrease of the organic phase concentration in response to stirring. A Langmuir isotherm was applicable for the adsorption of neutral LIX65N in acidic condition. The greater adsorption of the anionic form of LIX65N occurring in alkaline condition required an alternative isotherm. 相似文献
82.
Super environment-friendly electrodeposition paint 总被引:1,自引:0,他引:1
Toshitaka Kawanami Ichiro Kawakami Hiroyuki Sakamoto Hitoshi Hori 《Progress in Organic Coatings》2000,40(1-4):61-62
Super low VOC due to new composition/reaction mechanism can minimize the environmental risk as it does not contain lead and tin, hazardous air pollutants (HAPs) and endocrine disrupters (EPA/67 items, SPEED’98/JEA/67 items) currently specified as contaminants. New EAD (electrolyzed activate deposition paint) is not the only conventional cure agent or solvent, but also the super low VOC, HAPs materials and endocrine disrupters. The electric energy used by EAD is utilized for the reaction but not for the deposition. EAD consists of two technologies. One is propargyl group change to the allene by using electrodeposition. Propargyl group is stable, but allene group is highly polymerizing. As a result, EAD had high bath stability. The other is sulfonium change to sulfide by using electrodeposition. This sulfonium salt is lost as a result of the electrolytic reduction, and hence can be irreversibly rendered non-conductive. As a result, EAD showed high throwing power. 相似文献
83.
Yutaka Tokuda Youichi Nagae Hitoshi Sakane Jyoji Ito 《Journal of Electronic Materials》2010,39(6):719-722
Defect production behavior in hydrogen-implanted n-type silicon has been studied by varying the implantation temperature from 88 K to 303 K. Deep-level transient spectroscopy
has been used to reveal electron trap spectra for Schottky diodes fabricated at room temperature after implantation. Metastable
defects are observed in addition to vacancy- and hydrogen-related defects. It is found that the production rates of these
defects are greatly enhanced by hydrogen implantation near 270 K. It is suggested that hydrogen plays an important role in
enhancement of defect production rates, since such defect production behavior is not observed in He-implanted samples. 相似文献
84.
Hitoshi Takamura Hiroshi Sugai Masato Watanabe Takehiro Kasahara Atsunori Kamegawa Masuo Okada 《Journal of Electroceramics》2006,17(2-4):741-748
The preparation and oxygen permeation properties of the (Ce0.8Pr0.2)O2−δ − x vol% MnFe2O4 composites, where x = 0 to 35, have been investigated. The samples were prepared by the Pechini method. In the case of Ce0.8Pr0.2O2−δ, an oxygen flux density of 6 μmol⋅cm−2⋅s−1 (L = 0.0247 cm) and the maximum methane conversion of 50% were attained at 1000∘C. Unlike composites consisting of Gd-doped CeO2 and MnFe2O4, the oxygen permeability of the (Ce0.8Pr0.2)O2−δ – x vol% MnFe2O4 composites was almost constant regardless of the volume fraction of MnFe2O4; however, the optimum volume fraction of MnFe2O4 was determined to be 5 to 25 in the context of the chemical and mechanical stabilities under methane conversion atmosphere.
In addition, the surface modification of the (Ce0.8Gd0.2)O2−δ – 15 vol% MnFe2O4 composite was performed by using the FePt nanoparticles. The catalyst loading of 2.8 mg/cm2 on the both side of the 0.3 mm-thick (Ce0.8Gd0.2)O2−δ – 15vol% MnFe2O4 composite increased the oxygen flux density from 0.30 to 0.76 μmol⋅cm−2⋅s−1 in the case of He/air gradients; however, the effect seems to be reduced in the case of high oxygen flux density caused by
a large pO2 gradient. Moreover, the Langmuir-Blodgett film of the FePt nanoparticles were successfully prepared on the tape-cast (Ce0.8Gd0.2)O2−δ – 15vol% MnFe2O4 composite. Hydrophobic treatments for the surface of the composite were crucial to achieve high transfer ratio for the deposition
of the LB film. 相似文献
85.
Norihiko Shinomiya Toshio Koide Hitoshi Watanabe 《International Journal of Circuit Theory and Applications》2001,29(4):367-379
This paper presents a new circuit theoretical concept based on the principal partition theorem for distributed network management focusing on loops of an information network. To realize a simple network management with the minimum number of local agents, namely the topological degrees of freedom of a graph, a reduced loop agent graph generated by contracting the minimal principal minor is proposed. To investigate the optimal distribution of the loop agents, a theory of tie‐set graph is proposed. Considering the total processing load of loop agents, a complexity of a tie‐set graph is introduced to obtain the simplest tie‐set graph with the minimum complexity. As for the simplest tie‐set graph search, an experimental result shows that the computational time depends heavily on the nullity of the original graph. Therefore, a tie‐set graph with the smallest nullity is essential for network management. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
86.
Masanobu Yoshida Toshihiro Takahashi Masayuki Hikita Hiroyuki Watanabe Naomi Hashimoto Hitoshi Okubo 《Electrical Engineering in Japan》1999,129(4):58-65
We observed current pulse waveforms of partial discharge (PD) in SF6 gas so as to investigate the PD mechanism. We also measured light intensity and light emission image of PD simultaneously under different conditions of applies voltage and SF6 gas pressure. From these experiments, we found that the “double-peak current waveform” appeared at high pressure and high voltage conditions. We also analyzed the mutual correlation of waveforms between a single current and the light emission. Moreover, we obtained experimental evidence of filmentlike light image appearing at the PD tip under the same condition with double-peak current waveform. From the electric field analysis around the needle electrode tip, we believe that the filamentlike light image expands beyond the critical electric field of SF6 gas. Thus, we concluded that these current waveforms with double peaks showed evidence of leader-type PD, leading to breakdown. Finally, we could point out that leader-type PD should be distinguished and measured for the diagnosis of GIS insulation performance. © 1999 Scripta Technica, Electr Eng Jpn, 129(4): 58–65, 1999 相似文献
87.
Toshihisa Shimizu Keisuke Kakazu Koushi Takano Hitoshi Ishii 《Electrical Engineering in Japan》2015,192(4):51-63
Because of the improved performance of power devices, the volume of the ac filter inductors used in high‐frequency PWM inverters has been reduced. However, the temperature rise in the filter inductor due to this miniaturization has become more pronounced. Therefore, we have proposed an iron loss calculation method for the ac filter inductor. However, the accuracy of the value calculated via the loss map method cannot be verified, because the iron loss arising during each switching period cannot be measured with conventional power measuring instruments. In order to resolve this problem, we developed an inductor loss analyzer (ILA), which allows precise measurement of the iron loss in the inductor during each switching period. The accuracy of the calculation of iron loss in the filter inductor by the loss map method was verified with the ILA. We found that the value calculated by the loss map method differed slightly from the value measured with the ILA. However, these differences can be reduced if we take into account the accurate flux density calculation and the effect of the duty ratio of PWM pulses on the loss. Finally, we verified that the loss map method can provide accurate iron loss calculations. 相似文献
88.
Takashi Ikegami Hitoshi Yano Koji Kudo Kazuhiko Ogimoto 《Electrical Engineering in Japan》2015,193(2):42-57
The high penetration of variable sources of renewable power generation will lead to operational difficulties in supply/demand balancing in the entire power system. The mass deployment of electric vehicles (EVs) and plug‐in hybrid vehicles (PHEVs) will also cause significant changes in electricity demand. Therefore, controlling and managing the charging time of EVs/PHEVs are effective approaches that are imperative for improving balancing in power system operation. We assumed travel patterns for EVs in a model of the future Tokyo power system and analyzed the power system loads, including the charging load of the EVs, under several charging control scenarios. We verified that charging time controls are substantially effective for reducing the fuel costs in the power system. Further, we found that load leveling under a multicar charging management scenario gave the best results in terms of the fuel costs in all cases. 相似文献
89.
Hiroaki Matsumori Toshihisa Shimizu Koushi Takano Hitoshi Ishii 《Electrical Engineering in Japan》2015,190(2):57-71
In recent years, remarkable advancement of new power semiconductor devices, such as SiC and GaN, enables the increase of switching frequency of power converters, and hence the volume of passive components, such as ac filters and transformers, can be reduced. However, temperature rise caused by the inductor loss is increasing, and hence iron loss evaluation of the inductor is one of the most important issues to realize high power density converters. Conventionally, an improved generalized Steinmetz equation (iGSE) has proposed in order to calculate the iron loss under a pulse voltage magnetizing condition. However, accurate iron loss calculation of the ac filter inductor used in a PWM inverter cannot be realized. The authors have proposed two methods of iron loss evaluation of ac filter inductors. The first one is a loss map method which can calculate the iron loss without using a real PWM inverter. Another one is an ILA (Inductor Loss Analyzer) which can measure the iron loss in every switching period in a real PWM inverter. In this paper, comparisons of the iron loss between the ILA and the loss map method on both the single‐phase and three‐phase inverters are studied. It is found that iron loss of the ac filter inductor in the three‐phase PWM inverter which is calculated by the loss map method cause a large error on a specific condition. In order to prevent the calculation error, the authors proposed a revised loss map method and proved the effectiveness of the method. 相似文献
90.
Hiroshi Kishi Youichi Mizuno Tomoya Hagiwara Hirokazu Orimo Hitoshi Ohsato 《Journal of Electroceramics》2008,21(1-4):22-28
The effect of re-oxidation treatment on the solubility of dopants and the dielectric properties of rare-earths (La, Ho) and V-substituted BaTiO3 solid solutions, assuming the shell phase of X7R dielectrics, was investigated. Ho-V-substituted samples showed larger increase of the lattice parameter and T c by re-oxidation treatment compared with La-V-substituted samples. Electron spin resonance measurements revealed that the oxidation of V3+ to V4+ or V5+ appeared in the range in which the increase of lattice parameter by re-oxidation treatment was observed. This suggests that the increase of T c is due to the change of preferential occupational site of Ho ion from A-site to B-site, being accompanied with the oxidation of V3+. We also investigated the effect of re-oxidation treatment on the electrical properties and microstructure in Ni-MLCC samples, using rare-earths (La, Ho, Yb) and acceptors (Mn, V) doped BaTiO3 based X7R dielectrics. The change in temperature characteristic of the dielectric constant by re-oxidation treatment was observed for the MLCC samples containing V with smaller content. In the case of Ho-V- and Yb-V-doped samples showed larger increase of the dielectric constant at around 120 °C compared with La-V-doped samples. The relationship between the microstructure and electrical properties of the MLCC sample was investigated by impedance measurement at elevated temperature. 相似文献