全文获取类型
收费全文 | 2066篇 |
免费 | 195篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 42篇 |
综合类 | 10篇 |
化学工业 | 634篇 |
金属工艺 | 67篇 |
机械仪表 | 120篇 |
建筑科学 | 82篇 |
矿业工程 | 6篇 |
能源动力 | 134篇 |
轻工业 | 269篇 |
水利工程 | 38篇 |
石油天然气 | 24篇 |
无线电 | 172篇 |
一般工业技术 | 331篇 |
冶金工业 | 53篇 |
原子能技术 | 18篇 |
自动化技术 | 276篇 |
出版年
2024年 | 11篇 |
2023年 | 53篇 |
2022年 | 77篇 |
2021年 | 170篇 |
2020年 | 149篇 |
2019年 | 172篇 |
2018年 | 193篇 |
2017年 | 181篇 |
2016年 | 191篇 |
2015年 | 103篇 |
2014年 | 164篇 |
2013年 | 229篇 |
2012年 | 150篇 |
2011年 | 131篇 |
2010年 | 91篇 |
2009年 | 73篇 |
2008年 | 35篇 |
2007年 | 22篇 |
2006年 | 16篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 6篇 |
2002年 | 7篇 |
2000年 | 4篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有2276条查询结果,搜索用时 9 毫秒
21.
In this study,we initially performed interfacial tension(IFT)tests to investigate the potential of using the Persian Gulf sea-water(PGSW)as smart water with dif... 相似文献
22.
New Approaches in Monitoring Multivariate Categorical Processes based on Contingency Tables in Phase II 下载免费PDF全文
Reza Kamranrad Amirhossein Amiri Seyed Taghi Akhavan Niaki 《Quality and Reliability Engineering International》2017,33(5):1105-1129
In some statistical process control (SPC) applications, quality of a process or product is characterized by contingency table. Contingency tables describe the relation between two or more categorical quality characteristics. In this paper, two new control charts based on the WALD and Stuart score test statistics are designed for monitoring of contingency table‐based processes in Phase‐II. The performances of the proposed control charts are compared with the generalized linear test (GLT) control chart proposed in the literature. The results show the better performance of the proposed control charts under small and moderate shifts. Moreover, new schemes are proposed to diagnose which cell corresponding to different levels of categorical variables is responsible for out‐of‐control signal. In addition, we propose EWMA–WALD and EWMA–Stuart score test control charts to improve the performance of Shewhart‐based control charts in detecting small and moderate shifts in contingency table parameters. Meanwhile, we compare the performances of two proposed EWMA‐based control charts with the ones of three existing control charts called EWMA–GLT, EWMA–GLRT and an EWMA‐type control chart for multivariate binomial/multinomial processes along with the ones of the corresponding Shewhart‐based control charts. A numerical example is given to show the efficiency of the proposed methods. Finally, the effect of parameter estimation in Phase I based on m historical contingency table on the performance of the Shewhart‐based control charts is studied. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
23.
Passive Three Dimensional Face Recognition Using Iso-Geodesic Contours and Procrustes Analysis 总被引:1,自引:0,他引:1
Sina Jahanbin Rana Jahanbin Alan C. Bovik 《International Journal of Computer Vision》2013,105(1):87-108
We introduce a new model for personal recognition based on the 3-D geometry of the face. The model is designed for application scenarios where the acquisition conditions constrain the facial position. The 3-D structure of a facial surface is compactly represented by sets of contours (facial contours) extracted around automatically pinpointed nose tip and inner eye corners. The metric used to decide whether a point on the face belongs to a facial contour is its geodesic distance from a given landmark. Iso-geodesic contours are inherently robust to head pose variations, including in-depth rotations of the face. Since these contours are extracted from rigid parts of the face, the resulting recognition algorithms are insensitive to changes in facial expressions. The facial contours are encoded using innovative pose invariant features, including Procrustean distances defined on pose-invariant curves. The extracted features are combined in a hierarchical manner to create three parallel face recognizers. Inspired by the effectiveness of region ensembles approaches, the three recognizers constructed around the nose tip and inner corners of the eyes are fused both at the feature-level and the match score-level to create a unified face recognition algorithm with boosted performance. The performances of the proposed algorithms are evaluated and compared with other algorithms from the literature on a large public database appropriate for the assumed constrained application scenario. 相似文献
24.
25.
Seyed Saeid Masoumzadeh Kourosh Meshgi Saeid Shiry Ghidari Gelareh Taghizadeh 《International Journal of Network Management》2011,21(2):147-167
In a potentially congested network, random early detection (RED) active queue management (AQM) proved effective in improving throughput and average queuing delay. The main disadvantage of RED is its sensitive parameters that are impossible to estimate perfectly and adjust manually because of the dynamic nature of the network. For this reason, RED performs differently during different phases of a scenario and there is no guarantee that it will have optimal performance. Giving adaptability to RED has been the subject of broad research studies ever since RED was proposed. After a substantial study of AQM schemes and presenting a novel categorization for so‐called modern approaches utilizing artificial intelligence tools to improve AQM, this paper proposes an algorithm enhancing RED as an add‐on patch that makes minimal changes to the original RED. Being built on the basis of AQM schemes like ARED and Fuzzy‐RED, this algorithm inherits adaptability and is able to adjust RED inaccurate parameters regarding network traffic status, trying to optimize throughput and average queuing delay in a scenario. This algorithm is a Q‐learning method enhanced with a fuzzy inference system to provide RED with self‐adaptation and improved performance as a result. Given the name of FQL‐RED, this algorithm outperformed RED, ARED, and Fuzzy‐RED, as the OPNET simulations show. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
26.
27.
28.
Seyed A. Shojaosadati Hamid R. Sanaei Seyed M. Fatemi 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1996,67(4):362-366
Modifications of the conventional ethanol fermentation process using biomass and stillage recycle were investigated and the advantages of the technique were studied. The biomass recycle method resulted in a reduction in the use of approximately 8% raw material (molasses). The recycle of 15–70% of stillage (dealcoholised) from a previous fermentation was also tested successfully. Generally the results of these experiments revealed 13–47% less water consumption and consequently about 13–47% reduction of stillage volume, which was more economical for further treatments. 相似文献
29.
Thermal,mechanical, and corrosion resistance properties of vinyl ester/clay nanocomposites for the matrix of carbon fiber‐reinforced composites exposed to electron beam 下载免费PDF全文
Seyed Mohammad Razavi Negar Dehghanpour Seyed Javad Ahmadi Mahdi Rajabi Hamaneh 《应用聚合物科学杂志》2015,132(33)
Vinyl ester/clay nanocomposites with 1, 3, and 5% nanoclay contents were prepared. X‐ray diffractography patterns and Scanning Electron micrographs showed that nanocomposites with the exfoliated structure were formed. Thermogravimetric analysis, water absorption test, and Tafel polarization method, respectively, revealed the improvements in thermal resistance, water barrier properties, and corrosion resistance properties of the samples with an increase in the amount of the incorporated nanoclay. Tensile tests showed that nanoclay also enhanced the mechanical properties of the polymer, so that the tensile strength of the samples with 5% nanoclay was more than 3 times higher than tensile strength of pure vinyl ester samples. Overall, the best properties were observed for the samples containing 5% nanoclay. Pure vinyl ester and nanocomposite with 5% nanoclay content were exposed to the electron beam radiation and their mechanical properties improved up to 500 kGy irradiation dose. Finally, pure vinyl ester and vinyl ester/nanoclay (5%) matrixes were reinforced with carbon fiber and the effect of electron beam irradiation on their mechanical properties was examined. The tensile strength and the modulus of the samples initially increased after exposure to the radiation doses up to 500 kGy and then a decrease was observed as the irradiation dose rose to 1000 kGy. Moreover, nanoclay moderated the effect of the irradiation. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42393. 相似文献
30.
Due to their non-polluting nature and environment friendliness, Renewable Energies have gained great deal of attention and deserve a substantial body of both theoretical and empirical research. Amongst other factors, the low operational cost and simple maintenance procedures attributed the Oscillating Water Column (OWC) are perhaps the main reasons why this system is the most used concept for the ocean wave energy capture.In this paper, through extensive experimental research various geometrical designs of an OWC system is investigated and the optimized set up for the maximum energy harness is obtained.The initial chamber dimensions were 10 × 50 × 53 cm with the chamber being placed in an open channel with wave-simulating equipment with dimensions of 16 × 0.7 × .05 m. For various chamber geometries, with the aid of a air rotameter and a Pitot tube equipped with a digital manometer, the outlet air flow and velocity from the chamber was measured and registered.The measurements were then interpreted to provide design data for the optimal geometry of the chamber that may yield the maximum conversion of wave energy to useful energy. 相似文献