全文获取类型
收费全文 | 7500篇 |
免费 | 336篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 81篇 |
综合类 | 10篇 |
化学工业 | 1846篇 |
金属工艺 | 173篇 |
机械仪表 | 203篇 |
建筑科学 | 269篇 |
矿业工程 | 13篇 |
能源动力 | 444篇 |
轻工业 | 925篇 |
水利工程 | 42篇 |
石油天然气 | 20篇 |
武器工业 | 1篇 |
无线电 | 362篇 |
一般工业技术 | 1199篇 |
冶金工业 | 965篇 |
原子能技术 | 134篇 |
自动化技术 | 1155篇 |
出版年
2024年 | 22篇 |
2023年 | 74篇 |
2022年 | 182篇 |
2021年 | 275篇 |
2020年 | 186篇 |
2019年 | 160篇 |
2018年 | 337篇 |
2017年 | 323篇 |
2016年 | 351篇 |
2015年 | 232篇 |
2014年 | 314篇 |
2013年 | 692篇 |
2012年 | 444篇 |
2011年 | 490篇 |
2010年 | 423篇 |
2009年 | 416篇 |
2008年 | 311篇 |
2007年 | 301篇 |
2006年 | 221篇 |
2005年 | 153篇 |
2004年 | 115篇 |
2003年 | 119篇 |
2002年 | 105篇 |
2001年 | 72篇 |
2000年 | 71篇 |
1999年 | 61篇 |
1998年 | 254篇 |
1997年 | 178篇 |
1996年 | 114篇 |
1995年 | 71篇 |
1994年 | 78篇 |
1993年 | 81篇 |
1992年 | 36篇 |
1991年 | 22篇 |
1990年 | 28篇 |
1989年 | 28篇 |
1988年 | 26篇 |
1987年 | 19篇 |
1986年 | 18篇 |
1985年 | 28篇 |
1984年 | 32篇 |
1983年 | 16篇 |
1982年 | 18篇 |
1981年 | 35篇 |
1980年 | 17篇 |
1979年 | 24篇 |
1977年 | 42篇 |
1976年 | 55篇 |
1975年 | 17篇 |
1973年 | 20篇 |
排序方式: 共有7842条查询结果,搜索用时 15 毫秒
11.
Holmér AK 《Applied optics》1996,35(15):2614-2618
A kinoform is used to split the beam of a Nd:YAG laser into six beams. The laser beams are, by means of optical fibers and collimating-focusing optics, transferred to the surface to be machined. Thus multiple grooves can be machined simultaneously. For demonstration, 100-μm-wide grooves are simultaneously machined into a SnO(2) thin film deposited on a glass substrate. The resulting grooves are well isolated. This result shows that the technique could be used, for example, in solar cell manufacturing to increase the efficiency of laser scribing. 相似文献
12.
E Huidovici M Artino R Carmaciu A B?d?r?u A Iancu 《Canadian Metallurgical Quarterly》1996,100(3-4):135-137
Our previous experimental studies on rats motionless for 7 to 60 days in special devices limiting their movements revealed a significantly increased activity of the fibrinolytic system (Groza, Artino) due to the "detention stress" rather then to the immobilization. Starting from these studies we have tried to observe the behaviour of the fibrinolytic system during long-term orthopedic immobilization (7-28 days) on patients having different injuries of the lower limb and submitted to orthopedic therapy (with or without osteosynthesis) to which an anticoagulant preventive treatment was added (heparin or low-molecular-weight substitutes such as Clivarine, Fraxiparine). We studied on 23 patients (11 male and 12 female) motionless for 14, 21, 28 days the plasma fibrinolytic activity (PFA) through euglobulin lysis time (ELT). Clinical investigation revealed that PFA did not change significantly during long-term orthopedic immobilization regardless of the duration of immobilization (14,21,28 days). Rosenfeld et al. (1994) described in healthy volunteers on bedrest for 36 hours an increase of PFA beginning at 24 hours of immobilization, this variation being capable of preventing stasis effects. Our results suggest that preventive anticoagulant therapy properly given during immobilization prevents thromboembolic events. 相似文献
13.
Yılmaz Yılmaz 《Computers & Mathematics with Applications》2010,59(6):1957-1964
Our aim in this article is to introduce and study the notion of weak and strong Schauder bases in fuzzy normed spaces. Further, we introduce strong and weak fuzzy approximation properties and set a relationship between these two new notions which may provide an acceleration to the structural analysis of fuzzy normed spaces. 相似文献
14.
15.
Fatih Çalışır Muhammet Baştan Özgür Ulusoy Uğur Güdükbay 《Multimedia Tools and Applications》2017,76(10):12433-12456
High user interaction capability of mobile devices can help improve the accuracy of mobile visual search systems. At query time, it is possible to capture multiple views of an object from different viewing angles and at different scales with the mobile device camera to obtain richer information about the object compared to a single view and hence return more accurate results. Motivated by this, we propose a new multi-view visual query model on multi-view object image databases for mobile visual search. Multi-view images of objects acquired by the mobile clients are processed and local features are sent to a server, which combines the query image representations with early/late fusion methods and returns the query results. We performed a comprehensive analysis of early and late fusion approaches using various similarity functions, on an existing single view and a new multi-view object image database. The experimental results show that multi-view search provides significantly better retrieval accuracy compared to traditional single view search. 相似文献
16.
Attempts to carry out the hydroformylation of allyldiethylamine homogeneously catalyzed by rhodium complexes led to unexpected formation of N,N,N,N-tetraethyl-1,4-diaminobutane and 4-(diethylamino)-1-butanole as final products. The role of the catalyst on the product formation and the reaction mechanism are briefly discussed. 相似文献
17.
18.
19.
Slag samples, hot‐metal samples and hot‐metal temperatures were obtained during tapping of two blast furnaces. Sampling was carried out at different time points during tapping of three separate heats. The size distribution and composition of metal droplets found in the slag were determined using scanning electron microscopy. Only metal droplets above 0.75 μm could be counted and analysed. All droplets were below 8 μm in diameter and the great majority of these droplets were found to be between 0.75 and 2 μm. The size distribution did not differ significantly for different slag samples. Iron was the main droplet component. Electron probe microanalysis showed that the droplets contained small amounts of carbon. The percentage of the area in a studied cross‐section that was covered with metal droplets varied between 0.01 and 0.07%. Calculations based on Stoke's law showed that the distance droplets travel in the slag is in the micron range. Slag samples taken in the beginning of slag tapping contained more droplets than those taken in the middle of slag tapping, an indication that most droplets can be found in the area near the furnace wall. Some droplets were determined to have magnesium enrichment at the external surface. 相似文献
20.