全文获取类型
收费全文 | 566篇 |
免费 | 9篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 92篇 |
化学工业 | 144篇 |
金属工艺 | 23篇 |
机械仪表 | 20篇 |
建筑科学 | 18篇 |
能源动力 | 22篇 |
轻工业 | 40篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 28篇 |
一般工业技术 | 81篇 |
冶金工业 | 30篇 |
原子能技术 | 21篇 |
自动化技术 | 55篇 |
出版年
2022年 | 3篇 |
2021年 | 10篇 |
2020年 | 6篇 |
2019年 | 9篇 |
2018年 | 10篇 |
2017年 | 5篇 |
2016年 | 10篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 28篇 |
2012年 | 30篇 |
2011年 | 36篇 |
2010年 | 13篇 |
2009年 | 25篇 |
2008年 | 25篇 |
2007年 | 21篇 |
2006年 | 33篇 |
2005年 | 16篇 |
2004年 | 35篇 |
2003年 | 27篇 |
2002年 | 20篇 |
2001年 | 15篇 |
2000年 | 10篇 |
1999年 | 10篇 |
1998年 | 16篇 |
1997年 | 16篇 |
1996年 | 14篇 |
1995年 | 14篇 |
1994年 | 5篇 |
1993年 | 15篇 |
1992年 | 8篇 |
1991年 | 2篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有580条查询结果,搜索用时 62 毫秒
21.
22.
23.
We demonstrated an intrinsic conversion efficiency of 56% from the input fundamental power to the generated second-harmonic power. The second-harmonic power of 581 mW was obtained from the external cavity with a LiB3O5 crystal through the frequency doubling of a 1.17-W Ti:sapphire laser at 746 nm, when the finesse of the robust external cavity was 260. 相似文献
24.
Meta-level abduction is a method to abduce missing rules in explaining observations. By representing rule structures of a problem in a form of causal networks, meta-level abduction infers missing links and unknown nodes from incomplete networks to complete paths for observations. We examine applicability of meta-level abduction on networks containing both positive and negative causal effects. Such networks appear in many domains including biology, in which inhibitory effects are important in several biological pathways. Reasoning in networks with inhibition involves nonmonotonic inference, which can be realized by making default assumptions in abduction. We show that meta-level abduction can consistently produce both positive and negative causal relations as well as invented nodes. Case studies of meta-level abduction are presented in p53 signaling networks, in which causal relations are abduced to suppress a tumor with a new protein and to stop DNA synthesis when damage has occurred. Effects of our method are also analyzed through experiments of completing networks randomly generated with both positive and negative links. 相似文献
25.
Small eddies observed in Lake Superior using SAR and sea surface temperature imagery 总被引:1,自引:0,他引:1
Making use of the fine resolution of satellite SAR imagery, we observe small eddies during the spring and summer months in several locations in Lake Superior. During these months there is a thermal gradient between warmer nearshore waters and colder offshore waters which enhances cyclonic coastal currents. Using spaceborne SAR imagery from the European Space Agency's ERS-1 and ERS-2 missions from 1992 to 1998, we observe small eddies, identifying and mapping basic eddy characteristics including diameter, location, and rotational sense. In total, 45 eddies were located, of which 41 were cyclonic and 4 anticyclonic. Average diameter was 9.8 km and average distance to shore was 8.1 km. Based on sea surface temperature data from AVHRR, the eddies are located within the region of sharp thermal gradients of order 3–5 °C per 3 km. Spatial and temporal coverage was uneven, however, more eddies were seen in SAR images taken in late summer along the southern and eastern shores as well as areas where the boundary current interacts with topographic features including islands and promontories. 相似文献
26.
THE REFINERY MAINTENANCE ACTIVITIES WHILE TREATING MIDDLE EAST CRUDE TO RUN THE PLANT DURING 4 YEARS
KatsumiMASUDA 《石油学报(石油加工)》2001,17(1):63-69
Middle East crude oil is known to be a higher sulfur and metal containing crude than Far East etude. To treat higher sulfur crude requires appropriate procedures on refinery maintenance since corrosion environment of equipment can be affected by sulfur content. This paper introduces our experiences and measures in running the plant while facing corrosion and degradation by Middle East crude. 相似文献
27.
28.
The arrangement of permanent magnets in double‐layer interior permanent‐magnet motors is optimized for variable‐speed applications. First, the arrangement of magnets is decided by automatic optimization. Next, the superiority of the optimized motor is discussed by considering d‐ and q‐axis equivalent circuits that take into account the magnetic saturation of the rotor core. Finally, experimental veri?cation is carried out with a prototype motor. It is con?rmed that the maximum torque of the optimized motor under both low‐speed and high‐speed conditions is higher than that of conventional motors because of the relatively large q‐axis inductance and small d‐axis inductance. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(4): 54–63, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22348 相似文献
29.
30.
Bis-(monoacylglyceryl) phosphate and acyl phosphatidylglycerol were isolated from the liver of two patients with lipidosis
induced by 4,4′-diethylaminoethoxyhexesterol. Identification was based upon the results of alkaline hydrolysis, acetolysis,
IR spectrometry, and upon the determination of molar ratio of phosphorus-glycerol-ester. The contents of the bis-(monoacylglyceryl)
phosphate were 10 and 16% total phospholipid phosphorus in them. The bis-(monoacylglyceryl) phosphate contained mainly docosahexaenoic
(42%), oleic (29%), and linoleic acid (14%) and had the hemolytic activity of ca. one-eighth lysolecithin from egg yolk. Acidic
lipids from the liver also were found to contain a lipid which is less polar than bis-(monoacylglyceryl) phosphate. The results
of lipid analysis showed that the lipid possessed the structure of an acyl phosphatidylglycerol, and its content was ca. 2%
total phospholipid phosphorus. Accumulation of 4,4′-diethylaminoethoxyhexesterol and its derivatives was found in clinical
cases by thin layer chromatography and IR spectrometry. This fact suggested that human liver has an ability to metabolize
the drug. 相似文献