全文获取类型
收费全文 | 2218篇 |
免费 | 72篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 112篇 |
综合类 | 2篇 |
化学工业 | 732篇 |
金属工艺 | 86篇 |
机械仪表 | 56篇 |
建筑科学 | 45篇 |
矿业工程 | 3篇 |
能源动力 | 96篇 |
轻工业 | 235篇 |
水利工程 | 8篇 |
石油天然气 | 3篇 |
无线电 | 111篇 |
一般工业技术 | 457篇 |
冶金工业 | 77篇 |
原子能技术 | 69篇 |
自动化技术 | 206篇 |
出版年
2023年 | 9篇 |
2022年 | 23篇 |
2021年 | 44篇 |
2020年 | 26篇 |
2019年 | 39篇 |
2018年 | 42篇 |
2017年 | 35篇 |
2016年 | 52篇 |
2015年 | 43篇 |
2014年 | 63篇 |
2013年 | 124篇 |
2012年 | 103篇 |
2011年 | 134篇 |
2010年 | 120篇 |
2009年 | 126篇 |
2008年 | 126篇 |
2007年 | 124篇 |
2006年 | 98篇 |
2005年 | 78篇 |
2004年 | 90篇 |
2003年 | 74篇 |
2002年 | 58篇 |
2001年 | 43篇 |
2000年 | 45篇 |
1999年 | 43篇 |
1998年 | 71篇 |
1997年 | 45篇 |
1996年 | 38篇 |
1995年 | 27篇 |
1994年 | 32篇 |
1993年 | 25篇 |
1992年 | 27篇 |
1991年 | 29篇 |
1990年 | 17篇 |
1989年 | 17篇 |
1988年 | 9篇 |
1987年 | 23篇 |
1986年 | 17篇 |
1985年 | 18篇 |
1984年 | 14篇 |
1983年 | 11篇 |
1982年 | 20篇 |
1981年 | 16篇 |
1980年 | 16篇 |
1979年 | 18篇 |
1978年 | 7篇 |
1977年 | 9篇 |
1976年 | 9篇 |
1975年 | 4篇 |
1974年 | 5篇 |
排序方式: 共有2298条查询结果,搜索用时 31 毫秒
71.
Toshiaki Kikuma Tadao Ishikawa Masahiro Takasaki Hiroshi Mochikawa Atsuhiko Kuzumaki Kazuya Kodani Takeru Murao 《Electrical Engineering in Japan》2015,192(3):54-64
The recent years have seen an increasing trend in the cumulative installed capacity of distributed generators. As a result, voltage management may become difficult in existing power distribution systems in the future. A STATCOM (STAtic synchronous COMpensator) is a promising option for solving this problem because it can control reactive power rapidly and continuously. For a distribution system, STATCOM needs to be pole‐mounted to realize its low cost. However, a transformer for a STATCOM is large and heavy, and hence it is difficult to install a STATCOM on a distribution pole. We adopt a transformerless STATCOM to reduce STATCOM size and use SiC devices with low‐loss performance to obtain a more compact and efficient STATCOM. There are a large number of circuits available for a STATCOM, and there has been considerable research on performance comparisons among these circuits. However, these comparisons were drawn under different conditions, including switching frequency and level number for the circuits. In addition, these comparisons do not include the use of SiC devices. We made an equitable comparison for a 100 kVa pole‐mounted STATCOM using SiC devices. We discuss the performance and characteristics of each circuit in terms of efficiency and volume. 相似文献
72.
73.
A Method for Reducing the Dead‐Time Voltage and Impedance Voltage in a Series Voltage Compensator
下载免费PDF全文
![点击此处可从《Electrical Engineering in Japan》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Atsushi Nakata Masahiro Nozaki Akihiro Torii Akiteru Ueda 《Electrical Engineering in Japan》2014,186(3):85-93
Many research groups are developing series voltage compensators. In a series converter, since a transformer is used in series in the power system, the power system current flows into the voltage source inverter through the transformer. The inverter current, which is determined by the transformation ratio, gives rise to an error voltage that consists of a dead‐time voltage and an impedance voltage. The error voltage is generated even when the reference voltage is zero. This paper describes the mechanism by which the error voltage occurs and proposes a method for reducing the error voltage. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(3): 85–93, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22333 相似文献
74.
75.
Susumu Fujii Masato Yoshiya Akuto Yumura Yohei Miyauchi Masahiro Tada Hideyuki Yasuda 《Journal of Electronic Materials》2014,43(6):1905-1915
The phonon thermal conductivity of misfit-layered Ca3Co4O9 has been calculated by perturbed molecular dynamics using a classical force field. Detailed numerical analyses reveal that, in spite of its smaller cross-sectional area, the CoO2 layer transports more heat than the thicker rock salt (RS) layer, although its local thermal conduction is more suppressed than in another layered cobaltite, Na x CoO2. The origins of these differences have been elucidated through careful examination of the atomic arrangements in each layer. Since thermal conduction in the RS layer can be reduced without deteriorating electronic properties for which the CoO2 layer is responsible, it is suggested that the RS layer should be modified to further suppress the overall in-plane thermal conductivity. Computational experiments with increasing number of Ca–O planes in the RS layer showed the opposite trend to what can be predicted based on the misfit between two dissimilar layers. Further analyses to reveal the origin of these unexpected results provide yet another strategy to further decrease the thermal conductivity, namely to control the dynamic interference between atoms across the interface between two layers. 相似文献
76.
Toshio Shimoo Masahiro Ito Kiyohito Okamura Michio Takeda 《Journal of the American Ceramic Society》2001,84(1):111-116
Electron-beam-cured polycarbosilane fibers were heat-treated at 673–1773 K in a tube evacuated to 1.3 × 10−1 Pa and then exposed at 1873 K in argon. The effect of vacuum heat treatment on improving the high-temperature stability of low-oxygen SiC fibers was investigated by examining gas evolution, grain growth, surface composition, tensile strength, and morphology. The fibers heat-treated at <1173 K lost strength, because of the vigorous generation of residual hydrogen. A minute amount of oxygen in the atmosphere caused the active oxidation of SiC during heat treatment at >1673 K, resulting in severe strength degradation for the as-heat-treated fibers. Vacuum heat treatment at 1573 K provided the best characteristics in low-oxygen SiC fibers. 相似文献
77.
The prevalence of Campylobacter (>90%) and Salmonella (33%) in turkeys at slaughter has been estimated. This report describes studies to estimate the time of entry of Campylobacter and Salmonella into the brooder house, which is the first stage of commercial turkey production. In trial 1, birds (∼100 per time point)
were monitored by conventional culture at three intervals (0, 9, and 16 days of age). Campylobacter spp. were not detected in poults at the day of hatch; Salmonella was isolated from the ceca (3.9%) and yolk sac (0.1%). By day 9, Salmonella were frequently isolated from the ceca (55%) and small intestine (45%) while Campylobacter was not cultured. By day 16, the prevalence of Salmonella in the ceca (21%) and small intestine (5.1%) had declined; Campylobacter was infrequently isolated from either the ceca (2%) or small intestine (3%). In trial 2, poults (50 per time point at 5,
20, and 33 days of age) were monitored for Campylobacter and Salmonella by real-time polymerase chain reaction (PCR); Salmonella was also monitored by conventional culture. Whereas Campylobacter was not detected by real-time PCR in the ceca of 5-day-old birds, it was detected on days 20 (92%) and 33 (90%). In contrast,
Salmonella was isolated from young birds at days 5 (98%), 20 (98%), and 33 (98%), after which time the turkeys were moved to the finisher
house. At slaughter at 138 days, Salmonella prevalence in the ceca had declined (4.5%) in contrast to the prevalence of Campylobacter (92%). Antimicrobial sensitivity profiles of the Salmonella isolates indicated an increase of sulfonamide-resistant isolates throughout the brooder stage. Genotyping by pulsed-field
gel electrophoresis analysis of Salmonella (45 isolates per sampling time) indicated fluctuating populations as the birds matured. 相似文献
78.
Mohammed Shahien Motohiro Yamada Masahiro Fukumoto 《Journal of Thermal Spray Technology》2016,25(5):851-873
Reactive plasma spraying (RPS) is a promising technology for the in situ formation of several ceramic coatings. The focus of this paper is to summarize the state of our current knowledge about the RPS process and using the nitriding of Al particles and the fabrication of aluminum nitride coatings, as a case study. The aspects and challenges in this process such as the influence of the plasma power, in-flight time, particle size, nitriding mechanism, splat morphology, in-flight particle diagnostics, N2 plasma gas, and the feeding rate on the RPS process are analyzed and discussed. 相似文献
79.
Toshiaki Ozawa Koji Endo Takashi Masui Masahiro Miyaki Keiko Matsuo Shinji Yamada 《Journal of surfactants and detergents》2016,19(4):785-794
Five anionic surfactants widely used in commercial skin cleansers were studied: sodium polyoxyethylene lauryl ether carboxylate (EC), sodium polyoxyethylene alkyl ether sulfate (ES), sodium dodecyl sulfate, potassium laurate, and N-cocoyl-l-glutamic acid monosodium salt. The amount of surfactant from aqueous solution adsorbed into the stratum corneum (SC), the degree of SC swelling, the change of the secondary structure of SC proteins (denaturation). The surface tension of surfactant–zein mixed solutions, and the solubilization behavior of zein were measured. Results showed that EC had the lowest adsorption into SC, the lowest SC swelling, and lowest denaturation of SC proteins. Low interactions between surfactants and SC proteins were also observed for EC/ES mixture solutions as well as. Mixing EC with ES good foaming performance. The EC/ES mixture, at about 1:1 ratio, is an excellent surfactant system for skin cleanser applications having cleansing characteristics and mildness to the skin. 相似文献
80.