全文获取类型
收费全文 | 754篇 |
免费 | 29篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 210篇 |
金属工艺 | 37篇 |
机械仪表 | 8篇 |
建筑科学 | 25篇 |
能源动力 | 39篇 |
轻工业 | 75篇 |
水利工程 | 4篇 |
石油天然气 | 4篇 |
无线电 | 87篇 |
一般工业技术 | 117篇 |
冶金工业 | 63篇 |
原子能技术 | 7篇 |
自动化技术 | 102篇 |
出版年
2023年 | 10篇 |
2022年 | 29篇 |
2021年 | 29篇 |
2020年 | 21篇 |
2019年 | 24篇 |
2018年 | 26篇 |
2017年 | 22篇 |
2016年 | 22篇 |
2015年 | 14篇 |
2014年 | 23篇 |
2013年 | 54篇 |
2012年 | 30篇 |
2011年 | 35篇 |
2010年 | 29篇 |
2009年 | 46篇 |
2008年 | 39篇 |
2007年 | 29篇 |
2006年 | 14篇 |
2005年 | 18篇 |
2004年 | 13篇 |
2003年 | 22篇 |
2002年 | 19篇 |
2001年 | 11篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 25篇 |
1997年 | 23篇 |
1996年 | 15篇 |
1995年 | 12篇 |
1994年 | 6篇 |
1993年 | 13篇 |
1992年 | 4篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 14篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1969年 | 2篇 |
排序方式: 共有788条查询结果,搜索用时 0 毫秒
11.
Youssef Bokhabrine Ralph Seulin Lew F. C. Lew Yan Voon Patrick Gorria Gouenou Girardin Miguel Gomez Daniel Jobard 《Machine Vision and Applications》2012,23(3):417-425
During industrial forging of hot metallic shells, it is necessary to regularly measure the dimensions of the parts, especially
the inner and outer diameters and the thickness of the walls. A forging sequence lasts 2 h or more during which the diameter
of the shell is regularly measured in order to decide when to stop the forging process. For better working conditions, for
the safety of the blacksmiths, and for a faster and more accurate measurement, we have developed a novel system based on two
commercially available time of flight laser scanners for the measurement of the diameters of hot cylindrical metallic shells
during the forging process. The advantages of using laser scanners are that they can be placed very far from the hot shell,
more than 15 m, while at the same time giving an accurate point cloud from which three-dimensional views of the shell can
be reconstructed and diameter measurements done. Moreover, more accurate measurement is achieved in less time with the laser
system than with the conventional method using a large ruler. The system has been successfully used to measure the diameters
of hot cylindrical metallic shells. 相似文献
12.
Raouf Boutaba Wojciech Golab Youssef Iraqi Tianshu Li Bill St. Arnaud 《Journal of Grid Computing》2003,1(4):387-394
Grid applications call for high performance networking support. One attractive solution is to deploy Grids over optical networks. However, resource management in optical domains is traditionally very rigid and cannot successfully meet the requirements of Grid applications, such as flexible provisioning and configuration. In this paper, we present a customizable resource management solution for optical networks where users can create lightpaths on demand and manage their own network resources. Thanks to a Grid-centric system architecture, lightpath resources can be shared among users and easily integrated with data and computation Grids. 相似文献
13.
Hierarchial Zeolites: Beyond Creation of Mesoporosity: The Advantages of Polymer‐Based Dual‐Function Templates for Fabricating Hierarchical Zeolites (Adv. Funct. Mater. 12/2016) 下载免费PDF全文
14.
15.
The explosive increase in data demand coupled with the rapid deployment of various wireless access technologies have led to the increase of number of multi-homed or multi-interface enabled devices. Fully exploiting these interfaces has motivated researchers to propose numerous solutions that aggregate their available bandwidths to increase overall throughput and satisfy the end-user’s growing data demand. These solutions, however, do not utilize their interfaces to the maximum without network support, and more importantly, have faced a steep deployment barrier. In this paper, we propose an optimal deployable bandwidth aggregation system (DBAS) for multi-interface enabled devices. We present the DBAS architecture that does not introduce any intermediate hardware, modify current operating systems, modify socket implementations, nor require changes to current applications or legacy servers. The DBAS architecture is designed to automatically estimate the characteristics of applications and dynamically schedule various connections and/or packets to different interfaces. We also formulate our optimal scheduler as a mixed integer programming problem yielding an efficient solution. We evaluate DBAS via implementation on the Windows OS and further verify our results with simulations on NS2. Our evaluation shows that, with current Internet characteristics, DBAS reaches the throughput upper bound with no modifications to legacy servers. It also highlights the significant enhancements in the response time introduced by DBAS, which directly enhances the user experience. 相似文献
16.
The cell formation is the first step in the design of Cellular Manufacturing systems. It consists of grouping parts with similar processing needs into cells and identifying the set of machines needed to process these parts. The aim is to minimize the material handling costs and maximize the use of the machines. In this paper, the machine reliability and the alternative process routings are taken into account to form the production cells. The presence of these factors in addition to the production volume, operation sequence and production time makes the problem more realistic but also more complex. Most authors solve this kind of problems by mathematical programming approaches that require large amounts of computational efforts. Therefore, a modified version of the Clonal Selection Algorithm is introduced and a local search mechanism is adopted in this paper. The obtained results are compared with those of the Branch and Bound (B&B) method using LINGO software. The comparison reveals the effectiveness and the efficiency of the proposed method in terms of both solution quality and computation time required. 相似文献
17.
Ahmed M. Youssef Norbert H. Maerz 《Bulletin of Engineering Geology and the Environment》2012,71(1):171-186
The Missouri Rock Fall Hazard Rating System (MORFH RS) was recently developed for the State of Missouri. It is a system that
separates the risk of failure from the consequences of failure factors, thus allowing better assessment of the hazards of
rock falls. Efficiency is gained by video logging of highway rock cuts from vehicles moving at highway speeds, pre-screening
of rock cuts from video images, making some of the measurements needed for the rating system on digital images, and using
GPS receivers to collect field data and GIS to organize all the data. This paper describes the rationale behind the parameters
selected for the system using factor analysis and other methods and the verification of the system through sensitivity studies
and multiple rater tests. Simulations of remediation techniques were applied to recognize the most effective methods for remediation. 相似文献
18.
19.
Giuseppe Colla Youssef Rouphael Mariateresa Cardarelli Eva Svecova Elvira Rea Luigi Lucini 《Journal of the science of food and agriculture》2013,93(5):1119-1127
BACKGROUND: Cynara cardunculus is a species native to the Mediterranean basin. It includes globe artichoke and cultivated cardoon as well as their progenitor wild cardoon. The species is a source of biophenols, and its leaf extracts have been widely used in herbal medicine as hepatoprotectors and choleretics since ancient times. The aim of this study was to determine the effect of increasing the level of salinity in the nutrient solution (1 or 30 mmol L?1 NaCl) on biomass production, mineral composition, radical‐scavenging activity, caffeoylquinic acids and flavonoids in three artichoke (‘Romolo’, ‘Violetto di Provenza’ and ‘Violetto di Romagna’) and three cultivated cardoon (‘Bianco Avorio’, ‘Bianco Gigante Inerme’ and ‘Gigante di Romagna’) cultivars grown in a floating system. RESULTS: Increased salinity in the nutrient solution decreased the leaf dry biomass and leaf number of artichoke and cultivated cardoon cultivars. Salinity reduced macro‐ and microelement accumulation in leaves (e.g. N, K, Ca, Mg, Fe, Mn and B) but improved their antioxidant activity, total polyphenols, chlorogenic acid, cynarin and luteolin. The cultivated cardoons, especially ‘Bianco Avorio’ and ‘Gigante di Romagna’, showed higher biomass and leaf number than those observed in artichoke genotypes. ‘Violetto di Provenza’ exhibited the highest content of chlorogenic acid, closely followed by ‘Violetto di Romagna’, whereas for cynarin content the highest values were recorded in ‘Violetto di Provenza’, ‘Bianco Avorio’ and ‘Gigante di Romagna’. The highest content of luteolin was recorded in ‘Gigante di Romagna’ and ‘Bianco Avorio’, while the highest content of apigenin was observed in ‘Gigante di Romagna’. CONCLUSION: The results showed that the floating system could be considered an effective tool to improve quality aspects through proper management of the salt concentration in the nutrient solution. They also suggest that specific cultivars should be selected to obtain the desired profile of bioactive compounds. © 2012 Society of Chemical Industry 相似文献
20.
Investigation of Heat‐Induced Degradation of Virgin Olive Oil Using Front Face Fluorescence Spectroscopy and Chemometric Analysis 下载免费PDF全文
Yvon Mbesse Kongbonga Hassen Ghalila Youssef Majdi William Mbogning Feudjio Zohra Ben Lakhdar 《Journal of the American Oil Chemists' Society》2015,92(10):1399-1404
A simple setup using a 365‐nm light‐emitting diode coupled to a USB spectrometer through an optical fiber, in a front‐face fluorescence configuration, was used to investigate the heat‐induced deterioration of virgin olive oil at different heating temperatures and times. The samples were heated for 30, 60, 120 and 180 min for every temperature setting of 140, 160 and 180 °C, respectively. Two important results are reported in this article. First, a neo‐formed compound around 665 nm due to the degradation of chlorophyll was observed. This new peak was attributed to pyropheophytins. The second result showed an important rise of the peak around 489 nm, which corresponded to the oxidation products. The correlation obtained between the peroxide value and the 489 nm peak using principal component analysis revealed the mechanism of the oxidation process. It further showed that the peak around 489 nm is a direct consequence of the degradation of hydroperoxide. 相似文献