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   370篇
  免费   20篇
电工技术   4篇
化学工业   73篇
金属工艺   9篇
机械仪表   16篇
建筑科学   15篇
能源动力   11篇
轻工业   16篇
石油天然气   2篇
无线电   68篇
一般工业技术   74篇
冶金工业   18篇
自动化技术   84篇
  2024年   1篇
  2023年   5篇
  2022年   11篇
  2021年   9篇
  2020年   20篇
  2019年   17篇
  2018年   17篇
  2017年   17篇
  2016年   10篇
  2015年   8篇
  2014年   12篇
  2013年   37篇
  2012年   12篇
  2011年   19篇
  2010年   11篇
  2009年   16篇
  2008年   16篇
  2007年   7篇
  2006年   14篇
  2005年   10篇
  2004年   4篇
  2003年   9篇
  2002年   7篇
  2001年   7篇
  2000年   7篇
  1999年   5篇
  1998年   13篇
  1997年   8篇
  1996年   7篇
  1995年   12篇
  1994年   6篇
  1993年   6篇
  1992年   5篇
  1991年   4篇
  1990年   3篇
  1989年   4篇
  1988年   1篇
  1986年   4篇
  1985年   4篇
  1983年   2篇
  1982年   1篇
  1979年   1篇
  1977年   1篇
排序方式: 共有390条查询结果,搜索用时 46 毫秒
81.
Progressive visual analytics (PVA) has emerged in recent years to manage the latency of data analysis systems. When analysis is performed progressively, rough estimates of the results are generated quickly and are then improved over time. Analysts can therefore monitor the progression of the results, steer the analysis algorithms, and make early decisions if the estimates provide a convincing picture. In this article, we describe interface design guidelines for helping users understand progressively updating results and make early decisions based on progressive estimates. To illustrate our ideas, we present a prototype PVA tool called Insights Feed for exploring Twitter data at scale. As validation, we investigate the tradeoffs of our tool when exploring a Twitter dataset in a user study. We report the usage patterns in making early decisions using the user interface, guiding computational methods, and exploring different subsets of the dataset, compared to sequential analysis without progression.  相似文献   
82.
Pharmaceutical compounds and their derivatives are major pollutants in the environment, as their metabolites affect the terrestrial as well as aquatic organisms in one or another way. In recent times, many papers have discussed the treatment procedures for single pharmaceutical and mixture of pharmaceutical components, but only few papers have discussed the fate and the exposure of pharmaceutical contaminants in our environment. In this paper, we discuss the sources and the forms of pharmaceutical products and their resultant in the environment and their addition to the microbial and to human communities. A detailed discussion of various treatment techniques from conventional to current techniques, their advantages and disadvantages is given here. Researchers are finding the techniques in order to completely degrade the contaminants and their transformed products from the environment. Among the technique, s nanotechnology was found to be an efficient technique, and the combination of nanotechnology with other conventional technologies gives higher removal efficiency.  相似文献   
83.
Stringent emission regulations and health awareness about air pollution have led researchers to find alternative means of minimising emissions in diesel engines. In this article, the influence of oxygen enrichment is discussed to determine the effect on diesel engine performance, emission characteristics and combustion characteristics. Normal diesel and oxygen-enriched diesel are used in this experiment. The increase in oxygen concentration led to complete combustion, producing higher thermal efficiency and low harmful emissions. From the results, it is noted that oxygen-enriched diesel fuel showed reduction of CO, HC and smoke emissions, while NOx emission increased.

Abbreviations/Nomenclature DI: direct injection; NOx: oxides of nitrogen; O2: oxygen; HC: hydrocarbon; PM: particulate matters; CO: carbon monoxide; CO2: carbon dioxide  相似文献   

84.
This paper presents an on-line learning failure-tolerant neural controller capable of controlling buildings subjected to severe earthquake ground motions. In the proposed scheme the neural controller aids a conventional H∞ controller designed to reduce the response of buildings under earthquake excitations. The conventional H∞ controller is designed to reduce the structural responses for a suite of severe earthquake excitations using specially designed frequency domain weighting filters. The neural controller uses a sequential learning radial basis function neural network architecture called extended minimal resource allocating network. The parameters of the neural network are adapted on-line with no off-line training. The performance of the proposed neural-aided controller is illustrated using simulation studies for a two degree of freedom structure equipped with one actuator on each floor. Results are presented for the cases of no failure and failure of the actuator on each of the two floors under several earthquake excitations. The study indicates that the performance of the proposed neural-aided controller is superior to that of the H∞ controller under no actuator failure conditions. In the presence of actuator failures, the performance of the primary H∞ controller degrades considerably, since actuator failures have not been considered for the design. Under these circumstances, the neural-aided controller is capable of controlling the acceleration and displacement structural responses. In many cases, using the neural-aided controller, the response magnitudes under failure conditions are comparable to the performance of the H∞ controller under no-failure conditions.  相似文献   
85.
A unique investigation has been undertaken to analyze the heat transmission by convective and radiative mechanisms in a fully saturated penetrable fin of a longitudinal structure positioned on a leaning surface. This study introduces the fusion of the realms of Homotopy perturbation and Sumudu transform techniques to address a previously unexplored problem involving a moving fin with temperature-dependent thermal conductivity. In prior research papers, the Homotopy Perturbation Sumudu Transform Method (HPSTM) was utilized to obtain analytical solutions for fins featuring temperature-dependent thermal conductivity. However, in our current study, we employ the HPSTM to tackle a novel problem involving a moving porous fin. This fin exhibits temperature-dependent thermal conductivity and is subjected to convection and radiation effects. Through a comparison with numerical results, the present study has validated the dependability of its findings. The dimensionless temperature profile has been investigated by studying its relationship with several parameters. Here we observed that when the Peclet number is augmented by 400%, there is a corresponding 1.11% increase in thermal outline at the fin's extremity. Enhancing the value of radiation parameter by 400% declines the temperature of the fin tip by 14.079%. This study encourages the application of the Homotopy perturbation Sumudu transform technique in more complex fin problems.  相似文献   
86.
Elevated concentrations of hazardous metals in aquatic systems are known to threaten human health. Mobility, bioavailability, and toxicity of metals are controlled by chemical speciation, a dynamic process. Understanding metal behavior is limited by the lack of analytical methods that can provide rapid, sensitive, in situ measurements. While electrochemistry shows promise, it is limited by its temporal resolution and the necessity for Hg modified electrodes. In this letter, we apply fast-scan deposition-stripping voltammetry at carbon-fiber microelectrodes for in situ measurements of Cu(II). We present a novel, Hg-free technique that can measure Cu(II) with ppb sensitivity at 100 ms temporal resolution.  相似文献   
87.
The vulcanization behavior and mechanical properties of clay/fluoroelastomer nanocomposites produced by melt‐mixing of Dyneon FPO 3741 (a terpolymer of vinylidene fluoride, hexafluoropropylene, and tetrafluoroethylene) with 10 phr of unmodified montmorillonite (CloisiteNA) or di(hydrogenated tallow‐alkyl) dimethyl ammonium‐modified montmorillonites (Cloisite15A and Cloisite20A) were studied. The properties of clay/FKM nanocomposites were compared with composites prepared using 10 and 30 phr of carbon black. The effects of clay surfactant and surfactant concentration on the vulcanization behavior, mechanical, and dynamical properties of peroxide cured composites were studied. XRD results of cured composites showed a decrease in d‐spacing and indicated deintercalation of the clays after the vulcanization process. It was also found that organoclays retard the FKM peroxide vulcanization process. Significantly, higher maximum torque on vulcanization was obtained with organoclays versus unmodified clay and carbon black. Although the morphologies of organoclay/FKM nanocomposites studied by XRD and TEM suggest similar intercalated/exfoliated structures, the organoclay with the lowest concentration of surfactant (95 meq/100 g clay) resulted in the highest increase in torque, modulus, hardness, and tear strength in the clay/FKM nanocomposites. It was also found that organoclays can increase both the hydrodynamic reinforcement and hysteresis loss of FKM nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   
88.
89.
Salicylic acid (SA) generally is thought to suppress jasmonic acid (JA) related signaling events. However, when we treated the roots of corn seedlings overnight with low physiological concentrations of SA (50 μM), we found a priming effect of this pretreatment on typical insect elicitor (IE)-induced responses in the leaves of these plants. IE-induced JA was more than 2-fold up regulated in SA-pretreated plants. Consequently, IE-induced volatile organic compounds (VOC) release also was significantly increased. In contrast, when corn seedlings were treated with SA overnight and then mechanically damaged, we found no significant differences in JA accumulation. We also found that the application of even lower concentrations of SA (5 μM) had no significant effect on IE-induced responses, while higher concentrations (500 μM) inhibited IE-induced JA accumulation. Likewise, shorter exposure to SA did not affect subsequent JA accumulation induced by IE or mechanical wounding. These results provide evidence for the existence of non-compatible defense priming by signaling molecules that usually are involved in a conflictive defense signaling pathway and suggests common elements in the regulation of priming plant defense responses.  相似文献   
90.
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