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   381篇
  免费   14篇
  国内免费   2篇
电工技术   1篇
化学工业   95篇
金属工艺   12篇
机械仪表   18篇
建筑科学   14篇
矿业工程   5篇
能源动力   60篇
轻工业   43篇
水利工程   1篇
石油天然气   2篇
无线电   20篇
一般工业技术   63篇
冶金工业   15篇
原子能技术   11篇
自动化技术   37篇
  2024年   1篇
  2023年   3篇
  2022年   5篇
  2021年   9篇
  2020年   10篇
  2019年   8篇
  2018年   16篇
  2017年   17篇
  2016年   19篇
  2015年   10篇
  2014年   13篇
  2013年   28篇
  2012年   24篇
  2011年   26篇
  2010年   46篇
  2009年   32篇
  2008年   25篇
  2007年   27篇
  2006年   16篇
  2005年   9篇
  2004年   6篇
  2003年   12篇
  2002年   5篇
  2001年   6篇
  2000年   3篇
  1999年   4篇
  1998年   3篇
  1997年   2篇
  1996年   2篇
  1995年   3篇
  1994年   3篇
  1993年   1篇
  1984年   1篇
  1977年   1篇
  1974年   1篇
排序方式: 共有397条查询结果,搜索用时 15 毫秒
391.
We introduce an image reproduction model that retargets colors for printing purposes to ensure similar luminance perception under photopic and scotopic vision. Our model is based on the physiological functioning of the rod and cone cells in the retina in varying lighting conditions, so that the human visual system exhibits responses akin to a printed output of the model for different illumination levels. Prior to retargeting, digital color images are converted to spectral representations and their photopic and scotopic luminance responses are obtained. The color retargeting is realized by optimizing our compensation function over the color space. In addition, we present a spatially varying operator to enhance the color coherence over salient regions. Reproduction results demonstrate substantially decreased difference between the two luminance responses. Further, it is validated through psychophysical evaluation that our model on average provides superior recognition rates in dark environments, while keeping the noticeable differences in aesthetic appeal acceptable in well-lit environments.  相似文献   
392.
In forest lands, the stream channels receive the highest amount of sediment during road construction activities due to removal of vegetation cover from road surface, cut-slope, fill-slope, and ditch areas. Sediment delivered from a road section to streams causes serious damages on water resources and aquatic life. Performing revegetation in cut-slope and fill-slope reduce sediment yield from a road section; however, road surface and ditch continue to deliver considerable amount of sediment to the streams. Therefore, accurate prediction of sediment yield from existing road network can be very critical. In order to estimate average sediment yield, several sediment prediction models have been developed based on empirical relationships between various road erosion factors. In this study, average annual sediment yield from a road network to streams in a forest watershed was estimated by using the methodology of a GIS-based sediment prediction model, the SEDMODL model. GIS techniques were used to provide required data layers such as topography, streams, roads, geology, and average precipitation. The results indicated that the SEDMODL model integrated with GIS techniques can assist road managers to estimate total sediment yield quickly and effectively. Besides, critical road sections with high sediment yield potential can be identified and the efficiencies of various sediment control measures can be evaluated for these sections.  相似文献   
393.
As a response to the challenge of providing high-quality healthcare services with reasonable costs while the elderly population and the associated chronic diseases increase, SAPHIRE architecture provides an intelligent healthcare monitoring architecture. The monitoring of patients is achieved through a clinical decision support system based on clinical guidelines. SAPHIRE provides the necessary interoperability layers to access the patient's vital signs from wireless medical sensors and the electronic healthcare records of the patient in order to exploit them in the decision process seamlessly. This architecture is presented through two pilot applications: one for the bedside monitoring of cardiac patients at hospitals, and the other for homecare monitoring of the cardiac patients rehabilitated after a revascularisation therapy.  相似文献   
394.
In this article we introduce a new collision free prunable random interleaver. The suggested interleaver is a joint structure involving rectangular and S-random interleaver. It comprises a general model for all kind of collision free prunable random interleavers. In addition, it can be designed for any number of parallel processors and any length of information sequence vector and can be considered also as a template for collision free prunable interleavers. The proposed interleaver can be used with all kind of turbo-like codes. The performance of the proposed interleaver is measured with parallel decodable serially concatenated convolutional codes (PDSCCCs) and compared to the PDSCCCs?? performance with collision full S-random interleaver.  相似文献   
395.
The quantification of choline-containing compounds (Cho) in breast tumors by proton MR spectroscopy (1H-MRS) has been of great interest because such compounds have been linked to malignancy. In this study, an internal reference method for the absolute quantification of Cho metabolite in malignant breast tumors was presented using a clinical 1.5 T scanner. We performed in vitro measurements to examine the accuracy of absolute quantification using four phantoms of known choline chloride concentrations. There was a high correlation between the calculated concentrations by MRS and the known concentrations (r 2 > 0.98). We applied the technique to in vivo breast study conducted on 45 patients with biopsy-confirmed breast cancer. After T 1 and T 2 relaxation times were corrected, the Cho levels in this work had a range of 0.76 – 21.20 mmol/kg from 34 MR spectra of 32 patients with malignant breast lesions. This result was rather consistent with the previously published value (i.e., 1.38 – 10 mmol/kg, Bolan et al. in Magn Reson Med 50:1134–1143, 2003). Therefore, we conclude that the internal method using the fully relaxed water as a reference could be used for quantifying Cho metabolite accurately in breast cancer patients using a clinical 1.5 T scanner.  相似文献   
396.
Pure anatase-TiO2 nanoparticles with 8 nm average crystallite size was synthesized hydrothermally at 200 degrees C in 2 h. The structural and physico-chemical properties of nano-TiO2 were determined by powder XRD, FT-IR, BET and SEM analyses. The behavior of anatase nano-TiO2 in catalytic degradation of Rhodamine B (RB) dye in transparent nano-TiO2 sol under UV-light was examined as a function of irradiation power of UV-light, irradiation time, amount of nano-TiO2 and initial RB concentration in the sol. Rhodamine B was fully degraded with the catalysis of the nano-TiO2 in a short time as low as 60 min. Photocatalytic activity of the nano-TiO2 for degradation of RB was compared with Degussa P-25 at optimum catalysis conditions determined for the nano-TiO2. It was found that, when compared to Degussa P-25, the nano-TiO2 could be repeatedly used with increasing photocatalytic activity. It was found that the photodegradation obeys the pseudo first-order reaction kinetics with the rate constant of 0.0658 min(-1), and the half period t1/2 was 10.53 min.  相似文献   
397.
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