全文获取类型
收费全文 | 517篇 |
免费 | 23篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 148篇 |
金属工艺 | 5篇 |
机械仪表 | 8篇 |
建筑科学 | 13篇 |
能源动力 | 12篇 |
轻工业 | 45篇 |
水利工程 | 2篇 |
石油天然气 | 4篇 |
无线电 | 52篇 |
一般工业技术 | 91篇 |
冶金工业 | 25篇 |
原子能技术 | 3篇 |
自动化技术 | 129篇 |
出版年
2024年 | 2篇 |
2023年 | 3篇 |
2022年 | 12篇 |
2021年 | 23篇 |
2020年 | 7篇 |
2019年 | 23篇 |
2018年 | 25篇 |
2017年 | 21篇 |
2016年 | 25篇 |
2015年 | 9篇 |
2014年 | 20篇 |
2013年 | 50篇 |
2012年 | 18篇 |
2011年 | 35篇 |
2010年 | 29篇 |
2009年 | 26篇 |
2008年 | 24篇 |
2007年 | 20篇 |
2006年 | 30篇 |
2005年 | 19篇 |
2004年 | 15篇 |
2003年 | 9篇 |
2002年 | 10篇 |
2001年 | 5篇 |
2000年 | 2篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 3篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有540条查询结果,搜索用时 15 毫秒
61.
A new multilayer incremental neural network (MINN) architecture and its performance in classification of biomedical images
is discussed. The MINN consists of an input layer, two hidden layers and an output layer. The first stage between the input
and first hidden layer consists of perceptrons. The number of perceptrons and their weights are determined by defining a fitness
function which is maximized by the genetic algorithm (GA). The second stage involves feature vectors which are the codewords
obtained automaticaly after learning the first stage. The last stage consists of OR gates which combine the nodes of the second
hidden layer representing the same class. The comparative performance results of the MINN and the backpropagation (BP) network
indicates that the MINN results in faster learning, much simpler network and equal or better classification performance. 相似文献
62.
Ahmed El Shafie Tamer Khattab Amr El‐Keyi Mohamed Nafie 《Wireless Communications and Mobile Computing》2016,16(2):166-176
In this paper, we consider a cognitive scenario where an energy harvesting secondary user shares the spectrum with a primary user. The secondary source helps the primary source in delivering its undelivered packets during periods of silence of the primary source. The primary source has a queue for storing its data packets, whereas the secondary source has two data queues: a queue for storing its own packets and the other for storing the fraction of the undelivered primary packets accepted for relaying. The secondary source is assumed to be a battery‐based node, which harvests energy packets from the environment. In addition to its data queues, the secondary user has an energy queue to store the harvested energy packets. The secondary energy packets are used for primary packets decoding and data packets transmission. More specifically, if the secondary energy queue is empty, the secondary source can neither help the primary source nor transmit a packet from the data queues. The energy queue is modeled as a discrete‐time queue with Markov arrival and service processes. Because of the interaction of the queues, we provide inner and outer bounds on the stability region of the proposed system. We investigate the impact of the energy arrival rate on the stability region. Numerical results show the significant gain of cooperation.Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
63.
This paper presents the results of an experimental study designed to investigate the effect of fiber-reinforced polymer (FRP) wraps on corrosion activity and concrete cracking in chloride-contaminated concrete cylinders. Thirty-five concrete cylinders, each having 102?mm diameter and 204?mm height, concentrically reinforced with one steel reinforcing bar, were subjected to accelerated corrosion exposure for 80?days. Test parameters included level of applied potential, presence of FRP wraps, and bar diameter. The corresponding current and concrete expansion were continuously monitored throughout the corrosion exposure. At the end of the test, the steel bars were extracted, cleaned of rust, and weighed to determine the actual steel mass loss. The results showed that, for the same applied fixed potential, FRP wraps effectively reduced the corresponding current, the concrete expansion, and the steel mass loss. For the same applied potential, the current density increased as the bar diameter decreased. For the same corrosion depth, the circumferential expansion of the cylinder caused by corrosion decreased as the concrete cover-to-bar diameter ratio (c/d) increased. 相似文献
64.
Multimedia Tools and Applications - 相似文献
65.
66.
In this paper, we study optimal nonlinear pricing policy design for a monopolistic network service provider in the face of a large population of users of different types described by a given probability distribution. In an earlier work (Shen and Ba?ar in IEEE J. Sel. Areas Commun. 25(6):1216?C1223, 2007), we had considered games with symmetric information, in the sense that either users?? true types are public information available to all parties, or each user??s true type is private information known only to that user. In this paper, we study the intermediate case with information asymmetry; that is, users?? true types are shared information among the users themselves, but are not disclosed to the service provider. The problem can be formulated as an incentive-design problem, for which an ??-team optimal incentive (pricing) policy has been obtained, which almost achieves Pareto optimality for the service provider. A comparative study between games with information symmetry and asymmetry are conducted as well to evaluate the service provider??s game preferences. 相似文献
67.
68.
The aim of this study was to obtain prolonged action by preparing semi-solid matrices (SSM) into hard gelatin capsules using Oxprenolol as a model drug.
SSM formulations were prepared by using different lipophilic and hydrophilic pharmaceutical excipients, polyethylene glycols as channeling agent in the semi solid mass and Gelucires. The release kinetic of drug from these formulations was determined and compared with the commercial preparation in the form of polymeric matrix of this drug.
Among the generally used excipients, we have found that Gelucires were the most appropriate excipients for preparation of SSMs and drug release from these dosage forms can be improved by the method mentioned above depending on quantity and type of channeling agent which was used. 相似文献
SSM formulations were prepared by using different lipophilic and hydrophilic pharmaceutical excipients, polyethylene glycols as channeling agent in the semi solid mass and Gelucires. The release kinetic of drug from these formulations was determined and compared with the commercial preparation in the form of polymeric matrix of this drug.
Among the generally used excipients, we have found that Gelucires were the most appropriate excipients for preparation of SSMs and drug release from these dosage forms can be improved by the method mentioned above depending on quantity and type of channeling agent which was used. 相似文献
69.
T Essam E Tamer M A Amin O El Tayeb B Mattiasson B Guieysse E T Ossama M Bo G Benoit 《Water science and technology》2006,53(11):117-125
An algal-bacterial consortium was tested for the treatment from a coke factory. A Chlorella vulgaris strain and a phenol-degrading Alcaligenes sp. were first isolated from the wastewater treatment plant to serve as inocula in the subsequent biodegradation tests. Batch tests were then conducted with samples from the real wastewater or using a synthetic wastewater containing 325 mg phenol/l and 500 mg NH4+/l as target pollutants. Direct biological treatment of the real wastewater was not possible due to the toxicity of organic compounds. Activated carbon adsorption and UV(A-B)-irradiation were efficient in detoxifying the effluent for subsequent biological treatment as inoculation of pretreated samples with the algal-bacterial consortium was followed by complete phenol removal and NH4+ removal of 45%. Complete phenol removal and 33% NH4+ removal were achieved during the fed-batch treatment of artificial wastewater at 6 d hydraulic retention time (HRT). Under continuous feeding at 3.6 d HRT, phenol and NH4+ removal dropped to 58 and 18%, respectively. However, complete phenol removal and 29% NH4+ removal were achieved when 8 g NaHCO3/l was added to the artificial wastewater to enhance algal growth. This study confirms the potential of solar-based industrial wastewater treatment based on solar-based UV pretreatment followed by algal-bacterial biodegradation. 相似文献
70.
A project is described that has two goals: to explore the use of expert systems techniques for developing advanced operation support systems and to build a useful tool to assist the operators of the Canadian National Datapac network to cope with the rapid growth and evolution. Progress in developing and evaluating an advanced prototype system, DAD (Datapac Advisor), is reported. The prototype's environment and each of its functional components are described. The knowledge based design techniques used are highlighted, and the testing methodology and the results of a technical trial are described. Key findings are summarized, and their significance for the development of future network operation support systems is discussed 相似文献