首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2066篇
  免费   195篇
  国内免费   15篇
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
  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.
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.
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.
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.
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.
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   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号