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   515篇
  免费   24篇
  国内免费   4篇
电工技术   51篇
化学工业   187篇
金属工艺   19篇
机械仪表   11篇
建筑科学   10篇
矿业工程   2篇
能源动力   21篇
轻工业   32篇
无线电   26篇
一般工业技术   87篇
冶金工业   16篇
原子能技术   17篇
自动化技术   64篇
  2023年   6篇
  2022年   21篇
  2021年   30篇
  2020年   14篇
  2019年   6篇
  2018年   12篇
  2017年   6篇
  2016年   20篇
  2015年   18篇
  2014年   29篇
  2013年   37篇
  2012年   28篇
  2011年   47篇
  2010年   26篇
  2009年   36篇
  2008年   25篇
  2007年   25篇
  2006年   15篇
  2005年   15篇
  2004年   16篇
  2003年   10篇
  2002年   13篇
  2001年   6篇
  2000年   6篇
  1999年   7篇
  1998年   6篇
  1997年   3篇
  1996年   7篇
  1995年   7篇
  1994年   6篇
  1993年   9篇
  1992年   2篇
  1991年   1篇
  1990年   3篇
  1989年   3篇
  1988年   2篇
  1987年   1篇
  1986年   2篇
  1985年   3篇
  1983年   1篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1977年   1篇
  1976年   3篇
  1975年   1篇
  1974年   2篇
  1973年   1篇
排序方式: 共有543条查询结果,搜索用时 0 毫秒
61.
Many methods have been studied for mining association rules efficiently. However, because these methods usually generate a large number of rules, it is still a heavy burden for the users to find the most interesting ones. In this paper, we propose a novel method for finding what the user is interested in by assigning several keywords, like searching documents on the Web using search engines. By considering both the semantic similarity between the rules and keywords, and the statistical information like support, confidence, chi-squared value, etc. we could rank the rules by a new method named RuleRank, where evolutionary methods are applied to find the optimal ranking model. Experiments show that our approach is effective for the users to find what they want. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.  相似文献   
62.
Elevator Group Supervisory Control System (EGSCS) is a traffic system, which provides the transportation services for passengers in modern buildings. As the elevator systems include uncertainty due to the future arrival of the passengers, it difficult to model, analyze, and optimize the elevator group supervisory control system. Recently, artificial intelligence technology has been used in such complex systems. Genetic Network Programming(GNP), a graph‐based evolutionary method extended from genetic algorithm and genetic programming, has been already applied to EGSCS. On the other hand, since energy consumption is becoming one of the greatest challenges in the society, it should be taken as one of the criteria of the elevator operations. The elevators with maximum energy efficiency are therefore required. In this paper, the GNP is used to solve EGSCS with energy consumption (EC). Moreover, the idle car assignment has been embedded in the proposed method. Finally, the simulations show that some factors should be introduced into GNP in order to deal with the higher EC in the light traffic of the elevator systems. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.  相似文献   
63.
Recently, pulse coupled neural network (PCNN) attracts much attention in image denoising as a nonlinear filtering technique. The PCNN‐based anisotropic diffusion (PCNN‐AD) method has been proposed previously for flicker noise reduction and its effectiveness has been demonstrated. Using the visual characteristics of PCNN, PCNN‐AD has also solved the problem of AD that AD is not able to suppress the isolate noise. However, there are still two drawbacks in PCNN‐AD, that is, time consuming and PCNN parameters' estimation. In order to improve the efficiency and the denoising performance of PCNN‐AD, a PCNN‐based method with an adaptive Pareto genetic algorithm (GA‐PCNN) has been proposed to restrain from additive white Gaussian noise (AWGN) in this paper. GA‐PCNN firstly integrates the PCNN and AD as a parallel system, then, optimizes the parameters of a simplified PCNN by the adaptive Pareto GA. Experimental results indicate that GA‐PCNN has better performances than the previous denoising techniques, i.e. median filter, Wiener filter, AD filter, and PCNN‐AD. The effectiveness of GA‐PCNN on AWGN reduction and edge preservation are shown finally. The results will also contribute to denoising in CMOS image sensors in the future. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.  相似文献   
64.
A new simulation model, namely, ADEM Ductile Fracture model (ADF model) is developed to represent elastoplastic deformation and fracture behaviors of solid fats. Experimental measurement of the coefficient of plastic starting distance and the yield point affecting the deformation behavior has been obtained by compression test. The fracture distance affecting the fracture behavior has been measured by cutting test. The ADF model shows a good match with the experimentally determined compression and cutting behaviors of the solid fats, and load–strain curves as a function of plate thickness. This confirms that the ADF model could represent the elastoplastic deformation and fracture behaviors of the solid fats.  相似文献   
65.
Pore structure of carbons coated on ceramic particles   总被引:1,自引:0,他引:1  
Pore structure of carbon coated on ceramic particles by carbonization of precursor in a powder mixture at 900 °C was studied by focusing on the effects of substrate ceramics (MgO, TiO2 and various phases of Al2O3) and of carbon precursor (poly(vinyl alcohol) (PVA), poly(ethylene terephthalate) (PET) and hydroxyl propyl cellulose (HPC)). By dissolving substrate MgO particles, carbon coated was found to have a high BET surface area, more than 1000 m2/g, which was almost the same as the value estimated from apparent surface area measured on carbon-coated MgO particles under the assumption of zero surface area of the substrate. The carbon separated was found to be rich in micropores from the analyses by DFT method and αs plot. The dependence of the BET surface area on the amount of carbon coated on TiO2 with a high surface area was the same for three carbon precursors, although the carbon yields from the precursors were slightly different. Porous Al2O3 substrates, γ-Al2O3as-received and that formed from Al(OH)3 during carbonization, gave a high BET surface area, but dense Al2O3, α-Al2O3, gave a low surface area.  相似文献   
66.
Accumulation of nitrous oxide in aerobic groundwaters   总被引:1,自引:0,他引:1  
N2O concentrations in the groundwaters collected in the Kanto District and Nagano Prefecture in Japan and five counties in New York State were determined. These N2O data were obtained from the water samples from wells, springs and seepages from soils in forests and cropping fields. The N2O concentrations in all samples greatly exceeded those of atmospheric equilibration. The average concentration of 690 nM N2O is one order of magnitude larger than that in deep ocean. All groundwaters of the present study were aerobic with a high level of NO3, but with the absence of NO2 and NH4+, and with a very low level of dissolved organic carbon. These characteristics suggest that the nitrate respiration in the aquifers is of little significance for the production of N2O.

ΔN2O/NO3 molar ratios in the groundwaters were between 10−4 and 10−2 (Δ indicates the excess gas over that which would be in equilibrium). This supports the above view since the observed N2O yield agrees with that reported for the production during an ammonia oxidation. If nitrification was indeed a major mechanism for the production of groundwater N2O, subsequent release of N2O from the aquifers that are polluted with nitrogen may deserve more close attention as a potential source of atmospheric N2O via diffusion and discharge.  相似文献   

67.
Novel sulfonated ester types of cleavable surfactants were easily prepared by acid-catalyzed esterification of 1-O-alkylglycerols with bromocarboxylic acids, followed by the Strecker reaction. These surfactants have good solubility in water. Though this series of cleavable surfactants are divalent in type, they show good micelle formation and the ability to lower surface tension. The solubility of these surfactants in hard water was more than 10 times higher than sodium 1-dodecanesulfonate. They decompose quickly and completely in 0.5 M NaOD. Their biodegradabilities were higher or almost the same as that of sodium 1-dodecanesulfonate.  相似文献   
68.
Endothelial cells acquire different phenotypes to establish functional vascular networks. Vascular endothelial growth factor (VEGF) signaling induces endothelial proliferation, migration, and survival to regulate vascular development, which leads to the construction of a vascular plexuses with a regular morphology. The spatiotemporal localization of angiogenic factors and the extracellular matrix play fundamental roles in ensuring the proper regulation of angiogenesis. This review article highlights how and what kinds of extracellular environmental molecules regulate angiogenesis. Close interactions between the vascular and neural systems involve shared molecular mechanisms to coordinate developmental and regenerative processes. This review article focuses on current knowledge about the roles of angiogenesis in peripheral nerve regeneration and the latest therapeutic strategies for the treatment of peripheral nerve injury.  相似文献   
69.
In this paper we propose an analytical method of DCBLM with polar anisotropic plastic rotor magnets. The orientation of the polar anisotropic plastic magnet is different for each part. In our method, the magnetic flux distribution of the injection mold for polar anisotropic plastic magnets is analyzed by FEM first. Next, the orientation is determined from the magnetic flux distribution. Finally, based on the latter, the nonlinear dynamic magnetic field of DCBLM is analyzed. The analytical value was in good agreement with the experimental value of magnetic flux distribution in the magnet unit and the characteristic of DCBLM. © 1999 Scripta Technica, Electr Eng Jpn, 127(3): 53–61, 1999  相似文献   
70.
β-Casomorphin-7 (BCM) is a degradation product of β-casein, a milk component, and has been suggested to affect the immune system. However, its effect on mucosal immunity, especially anti-tumor immunity, in cancer-bearing individuals is not clear. We investigated the effects of BCM on lymphocytes using an in vitro system comprising mouse splenocytes, a mouse colorectal carcinogenesis model, and a mouse orthotopic colorectal cancer model. Treatment of mouse splenocytes with BCM in vitro reduced numbers of cluster of differentiation (CD) 20+ B cells, CD4+ T cells, and regulatory T cells (Tregs), and increased CD8+ T cells. Administration of BCM and the CD10 inhibitor thiorphan (TOP) to mice resulted in similar alterations in the lymphocyte subsets in the spleen and intestinal mucosa. BCM was degraded in a concentration- and time-dependent manner by the neutral endopeptidase CD10, and the formed BCM degradation product did not affect the lymphocyte counts. Furthermore, degradation was completely suppressed by TOP. In the azoxymethane mouse colorectal carcinogenesis model, the incidence of aberrant crypt foci, adenoma, and adenocarcinoma was reduced by co-treatment with BCM and TOP. Furthermore, when CT26 mouse colon cancer cells were inoculated into the cecum of syngeneic BALB/c mice and concurrently treated with BCM and TOP, infiltration of CD8+ T cells was promoted, and tumor growth and liver metastasis were suppressed. These results suggest that by suppressing the BCM degradation system, the anti-tumor effect of BCM is enhanced and it can suppress the development and progression of colorectal cancer.  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