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   743篇
  免费   32篇
  国内免费   5篇
电工技术   24篇
综合类   2篇
化学工业   151篇
金属工艺   20篇
机械仪表   21篇
建筑科学   19篇
矿业工程   1篇
能源动力   78篇
轻工业   60篇
水利工程   10篇
石油天然气   21篇
无线电   83篇
一般工业技术   115篇
冶金工业   27篇
原子能技术   23篇
自动化技术   125篇
  2023年   11篇
  2022年   15篇
  2021年   40篇
  2020年   28篇
  2019年   30篇
  2018年   51篇
  2017年   31篇
  2016年   50篇
  2015年   24篇
  2014年   35篇
  2013年   80篇
  2012年   33篇
  2011年   50篇
  2010年   33篇
  2009年   35篇
  2008年   20篇
  2007年   33篇
  2006年   25篇
  2005年   13篇
  2004年   9篇
  2003年   9篇
  2002年   7篇
  2001年   3篇
  2000年   5篇
  1999年   4篇
  1998年   9篇
  1997年   8篇
  1996年   8篇
  1995年   6篇
  1994年   6篇
  1993年   6篇
  1992年   4篇
  1991年   3篇
  1990年   3篇
  1989年   3篇
  1987年   2篇
  1986年   4篇
  1985年   3篇
  1984年   5篇
  1983年   2篇
  1981年   5篇
  1979年   2篇
  1978年   2篇
  1977年   5篇
  1976年   2篇
  1975年   6篇
  1974年   3篇
  1971年   1篇
  1970年   2篇
  1965年   1篇
排序方式: 共有780条查询结果,搜索用时 46 毫秒
1.
Clinical narratives such as progress summaries, lab reports, surgical reports, and other narrative texts contain key biomarkers about a patient's health. Evidence-based preventive medicine needs accurate semantic and sentiment analysis to extract and classify medical features as the input to appropriate machine learning classifiers. However, the traditional approach of using single classifiers is limited by the need for dimensionality reduction techniques, statistical feature correlation, a faster learning rate, and the lack of consideration of the semantic relations among features. Hence, extracting semantic and sentiment-based features from clinical text and combining multiple classifiers to create an ensemble intelligent system overcomes many limitations and provides a more robust prediction outcome. The selection of an appropriate approach and its interparameter dependency becomes key for the success of the ensemble method. This paper proposes a hybrid knowledge and ensemble learning framework for prediction of venous thromboembolism (VTE) diagnosis consisting of the following components: a VTE ontology, semantic extraction and sentiment assessment of risk factor framework, and an ensemble classifier. Therefore, a component-based analysis approach was adopted for evaluation using a data set of 250 clinical narratives where knowledge and ensemble achieved the following results with and without semantic extraction and sentiment assessment of risk factor, respectively: a precision of 81.8% and 62.9%, a recall of 81.8% and 57.6%, an F measure of 81.8% and 53.8%, and a receiving operating characteristic of 80.1% and 58.5% in identifying cases of VTE.  相似文献   
2.
Microbial fuel cell (MFC) is a promising technology for simultaneous wastewater treatment and energy harvesting. The properties of the anode material play a critical role in the performance of the MFC. In this study, graphene oxide was prepared by a modified hummer's method. A thin layer of graphene oxide was incorporated on the carbon brush using an electrophoretic technique. The deoxygenated graphene oxide formed on the surface of the carbon brush (RGO-CB) was investigated as a bio-anode in MFC operated with real wastewater. The performance of the MFC using the RGO-CB was compared with that using plain carbon brush anode (PCB). Results showed that electrophoretic deposition of graphene oxide on the surface of carbon brush significantly enhanced the performance of the MFC, where the power density increased more than 10 times (from 33 mWm?2 to 381 mWm?2). Although the COD removal was nearly similar for the two MFCs, i.e., with PCB and RGO-CB; the columbic efficiency significantly increased in the case of RGO-CB anode. The improved performance in the case of the modified electrode was related to the role of the graphene in improving the electron transfer from the microorganism to the anode surface, as confirmed from the electrochemical impedance spectroscopy measurements.  相似文献   
3.
The paper presents a family of methods with postintegration, for numerical integration of non-linear dynamic equations of motion of discrete systems. Both explicit and implicit algorithms of these methods are conditionally stable, but can give solutions of accuracy of a few orders higher than the known methods with preintegration, corresponding to them. A general analysis of stability and accuracy of single-step methods is carried out. The postintegration methods have been tested on a single-degree-of-freedom non-linear system.  相似文献   
4.
A fermentation procedure using wheys from buffalo milk, sweet rennet and salted wheys containing up to 15% NaC1, and based on the selection of salt-tolerant fungal cultures for production of microbial proteins and some economically important enzymes, is described. Certain strains of Aspergillus flavus, A. niger, A. ochraceus and A. terreus gave yields of mycelium ranging between 1.5 and 30 g on a dry weight basis. Strong proteolytic activities were exhibited by A. ochraceus, A. flavus and, to a lesser extent, by A. niger in the presence of salt up to 10% as final concentration. Powerful milk-clotting activities were also detected in culture supernatants of A. flavus and A. ochraceus. Extracellular β-galactosidases were released in to the culture fluids of these fungal strains with variable activities, depending upon the salt content of the growth medium. The application of the procedure is discussed.  相似文献   
5.
6.
7.
8.
In this paper the time-domain surface impedances of an homogeneous absorber layer, are given for the vertical and horizontal polarizations, or respectively for the electric field perpendicular or parallel to the incidence plane. It turns out that the application of the concept in finite difference time-domain (FDTD) in absorbing surface impedances boundary conditions, gives results in good agreement with analytical Fresnel reflection coefficients.  相似文献   
9.
Knowledge and Information Systems - Developing effective and efficient data stream classifiers is challenging for the machine learning community because of the dynamic nature of data streams. As a...  相似文献   
10.
Quantitative cellular in vitro nanoparticle uptake measurements are possible with a large number of different techniques, however, all have their respective restrictions. Here, we demonstrate the application of synchrotron-based X-ray fluorescence imaging (XFI) on prostate tumor cells, which have internalized differently functionalized gold nanoparticles. Total nanoparticle uptake on the order of a few hundred picograms could be conveniently observed with microsamples consisting of only a few hundreds of cells. A comparison with mass spectroscopy quantification is provided, experimental results are both supported and sensitivity limits of this XFI approach extrapolated by Monte-Carlo simulations, yielding a minimum detectable nanoparticle mass of just 5 pg. This study demonstrates the high sensitivity level of XFI, allowing non-destructive uptake measurements with very small microsamples within just seconds of irradiation time.  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