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   134篇
  免费   10篇
电工技术   2篇
化学工业   38篇
金属工艺   1篇
机械仪表   4篇
建筑科学   2篇
能源动力   16篇
轻工业   2篇
无线电   15篇
一般工业技术   34篇
冶金工业   5篇
自动化技术   25篇
  2023年   1篇
  2021年   4篇
  2019年   5篇
  2018年   4篇
  2017年   8篇
  2016年   7篇
  2015年   3篇
  2014年   5篇
  2013年   11篇
  2012年   12篇
  2011年   20篇
  2010年   7篇
  2009年   6篇
  2008年   4篇
  2007年   2篇
  2006年   5篇
  2005年   2篇
  2004年   4篇
  2002年   4篇
  2000年   1篇
  1999年   1篇
  1998年   4篇
  1996年   1篇
  1993年   2篇
  1992年   1篇
  1990年   2篇
  1984年   1篇
  1983年   1篇
  1982年   4篇
  1981年   1篇
  1980年   2篇
  1979年   3篇
  1978年   2篇
  1976年   2篇
  1974年   1篇
  1973年   1篇
排序方式: 共有144条查询结果,搜索用时 15 毫秒
71.
The amount of opinionated data on the web has exponentially increased especially after the emergence of online social networks. To deal with these huge deluge of data, we need to have robust mechanisms that can help identify all aspects of opinion segment and support the automatic processing of opinion data. Recently, there have been a few developments made in this direction, and different sentiment annotation schemes have been proposed such as the SentiML, OpinionMiningML, and EmotionML. In this work, we propose SentiML++, an extension of SentiML with a focus on annotating opinions, and further answering aspects of the general question “who has what opinion about whom in which context?”. A detailed comparison with SentiML and other existing annotation schemes is also presented. The data collection annotated with SentiML has been annotated with SentiML++ and is available for download for further research purposes. Experiments with data collections annotated with SentiML and SentiML++ proves that SentiML++ is a significant and valuable addition to SentiML.  相似文献   
72.
Plastic bonded cadmium electrodes of outstanding electrochemical properties, capable of replacing the commercial pocket-type electrodes of vented NiCd batteries, were produced by rolling the active mass, blended with powdered plastic polymer, onto a metallic current collector at normal temperature.  相似文献   
73.
BACKGROUND: Non-steroidal anti-inflammatory drugs can reduce the risk of colorectal cancer. Reportedly, mRNA expression of cyclooxygenase-2 (COX-2) is elevated in human colorectal cancers compared with accompanying normal mucosa. The present study was undertaken to establish a simple analytical procedure to quantify COX-2 expression levels and to characterize COX-2 expression levels in human colorectal cancers, adenomas and hyperplastic polyps. METHODS: The combination of PCR using common primers designed in the highly conserved regions and fluorescence-based single-strand conformation polymorphism (F-SSCP) analysis of the products is used for quantitative determination of the proportions of COX-2 mRNA in human colorectal cancers, adenomas, hyperplastic polyps and accompanying normal mucosa. RESULTS: The present F-SSCP analysis was a simple and powerful method for quantitative determination of the proportions of COX-2 mRNA. The proportion of COX-2 mRNA was higher in cancer tissues than in accompanying normal mucosa in 46 of the 50 cancers. There was no significant correlation between the increase of the COX-2 proportion and tumor location or stages. The enhanced COX-2 expression was also observed in colorectal adenomas. On the other hand, the proportion of COX-2 mRNA in hyperplastic polyps was not significantly different from that in normal mucosa. CONCLUSIONS: The proportion of COX-2 to COX-1 expression was elevated in most human colorectal cancers and adenomas, but not in hyperplastic polyps. Therefore, the increased proportion of COX-2 expression might be an early event in the carcinogenesis of colorectal cancer.  相似文献   
74.
The theory of the porous nickel hydroxide electrode presented in the preceeding communication was corrected by considering the dependence of the anodic and cathodic reaction rates on the concentration of current carriers in the solid phase. The influence of this correction on the calculated E-t discharge curves is not sufficient to account for the obseerved discrepancies between these curves and the measured ones, which are probably due to phenomena on the contact between the current collector and the active material and among the particles of the electrode mix.  相似文献   
75.
An equation for the impedance of a macrohomogeneous porous electrode is derived for the general case (finite electrode thickness and resistivities of the solid and liquid phases), and it is shown how to obtain from it the general solution for the transient state. The electrode model is represented by a transmission line equivalent circuit, and the theory is further generalized by including an arbitrary time delay (a hindrance) of the charge transfer process at the pore surface. A reformulation leads to the definition of an appropriate dielectric function. Two hindrance processes are considered, namely control of the charge transfer by finite diffusion and control by both diffusion and formation of a pseudocapacity (ie charge storage) on a molecular scale. The resulting impedance characteristics for selected parameter values are discussed and preliminary results of fitting experimental data with the new theory are presented.  相似文献   
76.
International Journal on Document Analysis and Recognition (IJDAR) - In the recent past, complex deep neural networks have received huge interest in various document understanding tasks such as...  相似文献   
77.
In the context of task sharing between a robot companion and its human partners, the notions of safe and compliant hardware are not enough. It is necessary to guarantee ergonomic robot motions. Therefore, we have developed Human Aware Manipulation Planner (Sisbot et al., 2010), a motion planner specifically designed for human–robot object transfer by explicitly taking into account the legibility, the safety and the physical comfort of robot motions. The main objective of this research was to define precise subjective metrics to assess our planner when a human interacts with a robot in an object hand-over task. A second objective was to obtain quantitative data to evaluate the effect of this interaction. Given the short duration, the “relative ease” of the object hand-over task and its qualitative component, classical behavioral measures based on accuracy or reaction time were unsuitable to compare our gestures. In this perspective, we selected three measurements based on the galvanic skin conductance response, the deltoid muscle activity and the ocular activity. To test our assumptions and validate our planner, an experimental set-up involving Jido, a mobile manipulator robot, and a seated human was proposed. For the purpose of the experiment, we have defined three motions that combine different levels of legibility, safety and physical comfort values. After each robot gesture the participants were asked to rate them on a three dimensional subjective scale. It has appeared that the subjective data were in favor of our reference motion. Eventually the three motions elicited different physiological and ocular responses that could be used to partially discriminate them.  相似文献   
78.
Local Principal Component Analysis (LPCA) is one of the popular techniques for dimensionality reduction and data compression of large data sets encountered in computer graphics. The LPCA algorithm is a variant of k‐means clustering where the repetitive classification of high dimensional data points to their nearest cluster leads to long execution times. The focus of this paper is on improving the efficiency and accuracy of LPCA. We propose a novel SortCluster LPCA algorithm that significantly reduces the cost of the point‐cluster classification stage, achieving a speed‐up of up to 20. To improve the approximation accuracy, we investigate different initialization schemes for LPCA and find that the k‐means++ algorithm [ [AV07] ] yields best results, however at a high computation cost. We show that similar ideas that lead to the efficiency of our SortCluster LPCA algorithm can be used to accelerate k‐means++. The resulting initialization algorithm is faster than purely random seeding while producing substantially more accurate data approximation.  相似文献   
79.
In this work, a systematic first‐principles study of the quasi‐band structure of silicon nanocrystals (Si‐NCs) is provided, focusing on bandgap engineering by combining quantum confinement of the electronic states with OH surface‐functionalization. A mapping between the bandgap, Si‐NC diameter, and the degree of hydroxide coverage is provided, which can be used as a guideline for bandgap engineering. Complementary to first‐principles calculations, the photoluminescence (PL) wavelength of Si‐NCs in the quantum‐confinement regime is measured with well‐defined diameters between 1 and 4 nm. The Si‐NCs are prepared by means of a microplasma technique, which allows a surfactant‐free engineering of the Si‐NCs surface with OH groups. The microplasma treatment technique allows us to gradually change the degree of OH coverage, enabling us, in turn, to gradually shift the emitted light in the PL spectra by up to 100 nm to longer wavelengths. The first‐principles calculations are consistent with the experimentally observed dependence of the wavelengths on the OH coverage and show that the PL redshift is determined by the charge transfer between the Si‐NC and the functional groups, while on the other hand surface strain plays only a minor part.  相似文献   
80.
Essential oils with antioxidant properties are of increasing interest in West Africa where there are many antioxidant rich plants. The objective of this study was to determine the essential oil extracted from six native plants (Lippia multiflora, Lippia rugosa, Monodora tenuifolia, Ocimum gratissimum, Pimenta racemosa, Cymbopogon citratus) extracted by hydrodistillation from local plants in Benin. These samples were also evaluated for their antioxidant capacity using the conjugated autoxidizable triene (CAT) assay performed in stripped tung oil-in-water emulsion. The essential oil of P. racemosa, containing high amounts of chavicol (10.3 %) and eugenol (54.5 %), showed the strongest antioxidant activity, followed by that from O. gratissimum containing large amounts of thymol (50.2 %). The essential oil extracted from M. tenuifolia exhibited a moderate antioxidant activity. This essential oil is primarily composed of sesquiterpene alcohols such as α-cadinol (20.5 %), its isomer, α-muurolol (14.7 %), and germacrene D-4-ol (16.8 %). Essential oils from L. multiflora, L. rugosa and C. citratus oils showed poor ability to protect tung oil from oxidation. Finally, essential oils containing phenolic compounds and, in a lesser extent, sesquiterpene alcohols, exhibited the highest CAT values indicating that these compounds are the key determinants of the antioxidant activity of these essential oils in oil-in-water emulsions.  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