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   7189篇
  免费   525篇
  国内免费   17篇
电工技术   84篇
综合类   4篇
化学工业   1942篇
金属工艺   88篇
机械仪表   188篇
建筑科学   354篇
矿业工程   12篇
能源动力   318篇
轻工业   990篇
水利工程   82篇
石油天然气   33篇
无线电   518篇
一般工业技术   1202篇
冶金工业   390篇
原子能技术   38篇
自动化技术   1488篇
  2024年   16篇
  2023年   81篇
  2022年   257篇
  2021年   330篇
  2020年   213篇
  2019年   244篇
  2018年   288篇
  2017年   250篇
  2016年   322篇
  2015年   257篇
  2014年   330篇
  2013年   594篇
  2012年   463篇
  2011年   579篇
  2010年   372篇
  2009年   407篇
  2008年   385篇
  2007年   344篇
  2006年   296篇
  2005年   241篇
  2004年   190篇
  2003年   174篇
  2002年   163篇
  2001年   74篇
  2000年   64篇
  1999年   64篇
  1998年   101篇
  1997年   57篇
  1996年   61篇
  1995年   55篇
  1994年   64篇
  1993年   40篇
  1992年   36篇
  1991年   33篇
  1990年   27篇
  1989年   28篇
  1988年   19篇
  1987年   25篇
  1986年   17篇
  1985年   29篇
  1984年   26篇
  1983年   18篇
  1982年   16篇
  1981年   8篇
  1980年   20篇
  1979年   7篇
  1978年   6篇
  1976年   9篇
  1975年   7篇
  1974年   6篇
排序方式: 共有7731条查询结果,搜索用时 15 毫秒
1.
A recent development in tactile technology enables an improvement in the appreciation of the visual arts for people with visual impairment (PVI). The tactile sense, in conjunction with, or a possibly as an alternative to, the auditory sense, would allow PVIs to approach artwork in a more self‐driven and engaging way that would be difficult to achieve with just an auditory stimulus. Tactile colour pictograms (TCPs), which are raised geometric patterns, are ideographic characters that are designed to enable PVIs to identify colours and interpret information by touch. In this article, three TCPs are introduced to code colours in the Munsell colour system. Each colour pattern consists of a basic cell size of 10 mm × 10 mm to represent the patterns consistently in terms of regular shape. Each TCP consists of basic geometric patterns that are combined to create primary, secondary, and tertiary colour pictograms of shapes indicating colour hue, intensity and lightness. Each TCP represents 29 colours including six hues; they were then further expanded to represent 53 colours. Two of them did not increase the cell size, the other increased the cell size 1.5 times for some colours, such as yellow‐orange, yellow, blue, and blue‐purple. Our proposed TCPs use a slightly larger cell size compared to most tactile patterns currently used to indicate colour, but code for more colours. With user experience and identification tests, conducted with 23 visually impaired adults, the effectiveness of the TCPs suggests that they were helpful for the participants.  相似文献   
2.

Romanian policy makers have to perceive that human intervention on river basins land cover is influencing rainfall-runoff relation and the used methodology cannot accurately estimate watershed surface flow transformations. Global water cycles and energy fluxes understanding is leading to better predictions of land atmosphere interaction and local hydro-climates evolution. The water transfer time determination from rainfall to runoff needs accurate measurements of river basins hydrological parameters. Here, we analyzed and compared the lag time value results of two different methodologies (curve number and rational methodology) used for 54 Romanian small catchment areas study. The focus of this paper is the lag time evaluation and interpretation for an effective implementation of the best methodology approach in the Romanian geographical space. Our research in small river basins was developed using remote sensing technology maps, GIS and environmental datasets in combination with field work on every drainage basin in order to assess the specific morphological features and validate the land cover typology. We found that Soil Conservation Service - Curve Number (SCS-CN) method is widely used according to USA landscape features classification, but not necessarily applicable to Romanian river basins characteristics. Our results show how the official Romanian rational methodology national standard (RNS) can be improved and the limits of SCS-CN method.

  相似文献   
3.
An alternative for reducing emissions from marine fuel is to blend bio-oil from lignocellulose non-edible feedstocks to diesel fossil fuels. Phase diagrams of the ternary systems were built to represent the transition from heterogeneous regions to homogeneous regions. Four homogeneous blends of bio-oil of eucalyptus-bioethanol-marine gasoil were experimentally characterized with respect to the most important fuel parameters for marine engines: water content, flash point, low heating value, viscosity, and acidity. Blends with closer properties to marine gasoil replacement, lower costs, and environmental impacts should be tested for large engines.  相似文献   
4.
5.
Food Analytical Methods - The habanero pepper (Capsicum chinense Jacq.) is very aromatic and is the hottest pepper in the world. In this study, a headspace solid-phase microextraction/gas...  相似文献   
6.
7.
8.
9.
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