全文获取类型
收费全文 | 1856篇 |
免费 | 72篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 118篇 |
综合类 | 4篇 |
化学工业 | 526篇 |
金属工艺 | 47篇 |
机械仪表 | 45篇 |
建筑科学 | 29篇 |
矿业工程 | 1篇 |
能源动力 | 74篇 |
轻工业 | 138篇 |
水利工程 | 2篇 |
无线电 | 89篇 |
一般工业技术 | 331篇 |
冶金工业 | 319篇 |
原子能技术 | 57篇 |
自动化技术 | 150篇 |
出版年
2023年 | 12篇 |
2022年 | 15篇 |
2021年 | 34篇 |
2020年 | 29篇 |
2019年 | 22篇 |
2018年 | 46篇 |
2017年 | 36篇 |
2016年 | 52篇 |
2015年 | 34篇 |
2014年 | 59篇 |
2013年 | 74篇 |
2012年 | 71篇 |
2011年 | 112篇 |
2010年 | 65篇 |
2009年 | 77篇 |
2008年 | 72篇 |
2007年 | 84篇 |
2006年 | 72篇 |
2005年 | 70篇 |
2004年 | 46篇 |
2003年 | 48篇 |
2002年 | 51篇 |
2001年 | 37篇 |
2000年 | 34篇 |
1999年 | 42篇 |
1998年 | 135篇 |
1997年 | 85篇 |
1996年 | 57篇 |
1995年 | 41篇 |
1994年 | 28篇 |
1993年 | 39篇 |
1992年 | 27篇 |
1991年 | 27篇 |
1990年 | 10篇 |
1989年 | 18篇 |
1988年 | 15篇 |
1987年 | 11篇 |
1986年 | 10篇 |
1985年 | 13篇 |
1984年 | 15篇 |
1983年 | 12篇 |
1982年 | 14篇 |
1981年 | 18篇 |
1980年 | 7篇 |
1979年 | 12篇 |
1978年 | 6篇 |
1977年 | 9篇 |
1976年 | 13篇 |
1973年 | 3篇 |
1972年 | 4篇 |
排序方式: 共有1930条查询结果,搜索用时 46 毫秒
21.
This paper investigates induced voltage characteristics from an overhead transmission line by applying a method of modeling of induced voltages proposed by the authors. EMTP simulation results obtained by the modeling method agree with analytical results obtained from a well‐known formula. The induced voltages are significantly dependent on the configuration of the overhead line. A horizontal line induces the largest voltage in a gas pipeline, and the voltage induced by a vertical twin‐circuit line is about 20% smaller than that induced by a vertical single‐circuit line. The method is applied to a real pipeline system and the simulation results show reasonable agreement with field test results. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(1): 43–51, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20465 相似文献
22.
In the case of the wet coal charging process in coke oven chamber, it is known that the coking process is uneven and a local carbonization delay occurs. The reason was investigated through a laboratory-scale experiment and a quantitative estimation. A partial carbonization test in a test coke oven replicated the uneven plastic layer and local carbonization delay. It was revealed that most of the gas generated in the uncarbonized coal layer results from the evaporation of condensed water and that steam can break through the plastic layer in a test coke oven. Moreover, the order estimation implied that steam that generates in the uncarbonized coal layer and breaks through the plastic layer has sufficient heat capacity to cool the heating wall and delay the carbonization. It was also shown that the steam pressure peak measured in a commercial coke oven is much lower than the estimated steam pressure in this study assuming steam not breaking through the plastic layer. The above-mentioned results and quantitative investigation strongly support the ‘steam breaking through the plastic layer’ theory proposed by Dr. Rohde that an uneven carbonization process is caused by vaporized coal moisture breaking through the plastic layer at definite, unforeseeable points, which results in cooling of the wall by the steam flow. 相似文献
23.
Tooru Tanaka Toshiyuki Yamaguchi Akihiro Wakahara Akira Yoshida Ryoichi Taniguchi Yatsuka Matsuda Masatoshi Fujishiro 《Solar Energy Materials & Solar Cells》2003,75(1-2):115-120
Radiation damages due to 8 MeV electron irradiation in electrical properties of CuInSe2 thin films have been investigated. The n-type CuInSe2 films in which the carrier concentration was about 3×1016 cm−3, were epitaxially grown on a GaAs(0 0 1) substrate by RF diode sputtering. No significant change in the electrical properties was observed under the electron fluence <3×1016 e cm−2. As the electron fluence exceeded 1017 e cm−2, both the carrier concentration and Hall mobility slightly decreased. The carrier removal rate was estimated to be about 0.8 cm−1, which is slightly lower than that of III–V compound materials. 相似文献
24.
The continuous production of hydrogen from cyclohexanes is achieved effectively using Pt/ACF (ACF = activated carbon fiber) catalysts in a fixed-bed flow reactor. The Pt catalysts are more effective than a Pd/ACF catalyst for the reaction. Besides cyclohexane, methylcyclohexane, 1,4-dimethylcyclohexane, and p-menthane can also be employed as hydrogen source in the reaction system. 相似文献
25.
26.
27.
Transaction Oriented Prolog-Online Environment is a multi-user, mainframe implementation of the logic programming language Prolog, specially designed and developed for the data processing environment. This article describes the background, functionality, implementation and use of TOP-ONE, stressing that applications of knowledge-based systems technology to data processing environments will achieve full success only when existing systems and existing conventional data are incorporated within the applications. 相似文献
28.
R Constantinides S Xenophontos P Neophytou S Nomura A Pierides CC Deltas 《Canadian Metallurgical Quarterly》1997,99(5):644-647
The PKD1 gene, which is responsible for the most common form of autosomal dominant polycystic kidney disease, has recently been cloned and sequenced. Many disease-causing mutations have been characterized in this gene, most of them resulting in premature protein termination. However, mutation analysis not routinely implemented for family investigations in a clinical setting, because of the large size and complexity of the gene. Instead, genetic linkage analysis using highly polymorphic CA dinucleotide repeats that map around the gene is still the method of choice. Recently, a few intragenic polymorphisms have been described that are also useful for linkage studies. Here, a new diallelic polymorphism is described for amino acid residue 4058, Ala/Val4058, with allelic frequencies of 0.88 and 0.12, respectively, and a heterozygosity of 0.23, in the Greek and Greek-Cypriot populations. Interestingly, this polymorphism and Ala4091-A/G, which has previously been described in Caucasians, were not detected in DNA from 44 Japanese samples tested. This is particularly important when allelic frequencies in a particular population are used for linkage analysis of families of different ethnic origin. Also, observation of the two polymorphisms together as haplotypes suggests that the Ala/Val4058 polymorphism occurred more recently than the establishment of the Ala4091-A/G polymorphism, and specifically on the G allele. 相似文献
29.
Stability of large-scale coal-fired MHD channels is studied by (1) linearized stability analysis, and (2) time-dependent 1-D analysis. The channel length is 15 m with 600 electrode pairs, and the output power ranges from 220.6 MW through 258.7 MW. Linearized stability analyses show that the Faraday channels operated with fixed loading resistance are stable, whereas the two waves of u and u–a (u, a: gas and sound velocity) become unstable in the Faraday channel with fixed loading factor. Two waves of u and u–a are unstable in the diagonal channel with fixed loading current and the u + a wave becomes unstable in the diagonal channel with fixed electrode current. Time-dependent one-dimensional analyses indicate that the Faraday channels with fixed load resistance are smooth without growth of fluctuation. The diagonal channels with fixed electrode current are smooth with no fluctuation, though the linear theory indicates that the u + a wave is unstable. The diagonal channel with fixed load current suffers large disturbance along the latter half of the channel, being consistent with the linearized analysis which indicates that the u - a and u waves are unstable. 相似文献
30.