首页 | 官方网站   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   636篇
  免费   42篇
  国内免费   2篇
工业技术   680篇
  2024年   2篇
  2023年   8篇
  2022年   35篇
  2021年   47篇
  2020年   33篇
  2019年   35篇
  2018年   46篇
  2017年   44篇
  2016年   30篇
  2015年   32篇
  2014年   26篇
  2013年   44篇
  2012年   44篇
  2011年   41篇
  2010年   25篇
  2009年   28篇
  2008年   24篇
  2007年   18篇
  2006年   15篇
  2005年   14篇
  2004年   9篇
  2003年   6篇
  2002年   11篇
  2001年   1篇
  2000年   7篇
  1999年   2篇
  1998年   9篇
  1997年   8篇
  1996年   3篇
  1995年   3篇
  1994年   4篇
  1991年   1篇
  1990年   1篇
  1988年   1篇
  1987年   2篇
  1985年   7篇
  1984年   2篇
  1983年   5篇
  1982年   1篇
  1981年   3篇
  1980年   1篇
  1976年   1篇
  1968年   1篇
排序方式: 共有680条查询结果,搜索用时 0 毫秒
1.
Enrique  Sant   《Electric Power Systems Research》2008,78(11):1946-1952
Since demand for power exhibits great variability the amount of firm energy to be purchased to meet real time demand based on forecasts is usually different from the realized demand for that period. The role of generation reserves is to meet the real time fluctuations of power demand. The predictable part of the demand is met through purchases of firm energy. In this paper a model is presented to determine optimal quantities of firm energy and generation reserves to meet random demands. The model is then parameterized introducing a set of factors to perform a sensitivity study. A full factorial experiment is designed to study the impact of five factors on the response variable (i.e., proportion of generation reserves on the total purchased quantity). An example consisting of 640 simulations corresponding to 25 treatment combinations evaluated over 20 randomly generated mean demands is used to identify significant factors on the response variable. Results from the experiment suggest that generation reserve requirements should be adjusted considering changes in significant factors and in the mean demand over the dispatch interval.  相似文献   
2.
3.
The impact of digital technology in biometrics is much more efficient at interpreting data than humans, which results in completely replacement of manual identification procedures in forensic science. Because the single modality‐based biometric frameworks limit performance in terms of accuracy and anti‐spoofing capabilities due to the presence of low quality data, therefore, information fusion of more than one biometric characteristic in pursuit of high recognition results can be beneficial. In this article, we present a multimodal biometric system based on information fusion of palm print and finger knuckle traits, which are least associated to any criminal investigation as evidence yet. The proposed multimodal biometric system might be useful to identify the suspects in case of physical beating or kidnapping and establish supportive scientific evidences, when no fingerprint or face information is present in photographs. The first step in our work is data preprocessing, in which region of interest of palm and finger knuckle images have been extracted. To minimize nonuniform illumination effects, we first normalize the detected circular palm or finger knuckle and then apply line ordinal pattern (LOP)‐based encoding scheme for texture enrichment. The nondecimated quaternion wavelet provides denser feature representation at multiple scales and orientations when extracted over proposed LOP encoding and increases the discrimination power of line and ridge features. To best of our knowledge, this first attempt is a combination of backtracking search algorithm and 2D2LDA has been employed to select the dominant palm and knuckle features for classification. The classifiers output for two modalities are combined at unsupervised rank level fusion rule through Borda count method, which shows an increase in performance in terms of recognition and verification, that is, 100% (correct recognition rate), 0.26% (equal error rate), 3.52 (discriminative index), and 1,262 m (speed).  相似文献   
4.
Silicon - In the present report, a photonic crystal based micro-ring resonator (MRR) structure is proposed which is very compact in size and has very fast response and is employed for temperature...  相似文献   
5.
An air-water experimental system consisting of two inlets and one outlet is constructed and characterised. It reaches the state of sliding mode, or equivalently, two phase slug flow. The linear hydraulic model proposed in the literature is adequate to describe it. Experimental data are used to tune this model. The resistance to the flow of air through the outlet valve during the two phase flow is much larger than that when air alone flows out. At the operating range, the resistance to water flow is not affected by the presence of air.  相似文献   
6.
Identification of particulate matter is important in assessing an individual’s exposure to potentially harmful particles, such as aeroallergens, toxins, and emissions from combustion sources, which can contribute to cardio-pulmonary diseases. Efficient collection of aerosols is essential for aerosol exposure studies such as analysis of chemical and biological components. We present the design and evaluation of a capillary collector that collects PM2.5 onto the outer surface of a capillary for in-situ spectroscopic analysis. The capillary collector uses a needle-to-ring corona generator to charge particles; the electric field between a cylinder and a wire inserted into the bore of a capillary is used to collect the charged particles. Corona and repelling voltages are optimized for maximum collection of ambient PM2.5 particles and fluorescent polystyrene latex microspheres in the PM2.5 size range, on the capillary. The capillary collection efficiency of ambient PM2.5 at 3 slpm operating flow rate and optimal operating voltages is 63%. Fluorescence spectroscopy is used to quantify the collection of polystyrene latex microspheres. The fluorescence-based capillary collection efficiency is in close agreement with the capillary collection efficiency of ambient PM2.5. The collection and analysis methodology can be used to develop a compact, low-cost sensor for in-situ spectroscopic analysis of aerosols to determine their chemical composition for source apportionment.

Copyright © 2019 American Association for Aerosol Research  相似文献   

7.
Multifocus image fusion is the process of obtaining a single image from multiple partially focused images such that the newly formed image consists of the well-defined information extracted from each source image. This paper proposes the use of saliency of the source images based on Mutual Spectral Residual. Spectral Residual brings out the unique/salient features of an image in frequency domain. The idea of proposed mutual spectral residual is to emphasize the relative unique features of a source image with respect to the other source images. The relative unique features are utilized to form saliency maps for each source image. These saliency maps can clearly indicate the focused and defocused parts of an image. Based on the saliency maps obtained, the image fusion takes place in spatial domain. Visual inspection and quantitative evaluation of the fused images obtained by the proposed method, using different evaluation metrics, demonstrate its effectiveness over several existing image fusion methods.  相似文献   
8.
Wireless Personal Communications - Wireless Sensor Networks (WSNs) are used to collect and transmitted the data in various applications from normal to those which requires significant security...  相似文献   
9.
Delay and cost overrun are common phenomena in projects worldwide. However, these are especially severe in developing countries. In India as per MOSPI report, 235 projects out of 410 were severely affected cost overrun due to certain factors. A short questionnaire was conducted with 15 prominent factors responsible for cost overrun and forwarded to 190 constructional professionals across India. Total 85 responses were received and it was analyzed using various statistical tools such as analysis of variance (ANOVA) and factor analysis tool using SPSS. In this study, top three factors affecting cost overruns were identified such as price escalation of raw material, delay in planned activity and lack of co-ordination between construction parties which could be significantly responsible for cost overnun of construction project in India. Factor analysis method was also carried out to group the factors into three components of overall questionnaire. These components, such as client control component, project management component, and contractor control component, would be useful to the various parties involved in the construction activities. This paper also provides suggestive frameworks which have been framed after discussing with large number of construction professionals or expert.  相似文献   
10.
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-23

京公网安备 11010802026262号