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   301199篇
  免费   40426篇
  国内免费   16218篇
电工技术   21749篇
技术理论   9篇
综合类   21840篇
化学工业   54343篇
金属工艺   16560篇
机械仪表   18418篇
建筑科学   23967篇
矿业工程   8167篇
能源动力   8524篇
轻工业   27587篇
水利工程   6568篇
石油天然气   12932篇
武器工业   2924篇
无线电   38142篇
一般工业技术   37995篇
冶金工业   11061篇
原子能技术   3190篇
自动化技术   43867篇
  2024年   1162篇
  2023年   4199篇
  2022年   8506篇
  2021年   11855篇
  2020年   9816篇
  2019年   9491篇
  2018年   10333篇
  2017年   11735篇
  2016年   11142篇
  2015年   15037篇
  2014年   17963篇
  2013年   21984篇
  2012年   22596篇
  2011年   23488篇
  2010年   22051篇
  2009年   20876篇
  2008年   20319篇
  2007年   19263篇
  2006年   17735篇
  2005年   14289篇
  2004年   10402篇
  2003年   8938篇
  2002年   8710篇
  2001年   7662篇
  2000年   6360篇
  1999年   5009篇
  1998年   3080篇
  1997年   2601篇
  1996年   2419篇
  1995年   2005篇
  1994年   1645篇
  1993年   1134篇
  1992年   947篇
  1991年   716篇
  1990年   520篇
  1989年   439篇
  1988年   336篇
  1987年   225篇
  1986年   178篇
  1985年   103篇
  1984年   80篇
  1983年   52篇
  1982年   75篇
  1981年   57篇
  1980年   63篇
  1979年   44篇
  1978年   21篇
  1977年   20篇
  1976年   23篇
  1951年   21篇
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
91.
  Qing  Xu  Bin  Yu  Yang  Zhan  Wei  Zhao  Yu  Zheng  Jun  Ji  Jian 《Bulletin of Engineering Geology and the Environment》2021,80(8):6513-6525
Bulletin of Engineering Geology and the Environment - Many uncertainties exist in pile-stabilized slopes which make their design substantially complicated. In this paper, a first-order reliability...  相似文献   
92.
93.
94.
A standard method for the extraction of tiger nut milk has been introduced. It has been shown that, although milling duration improves the yield of tiger nut milk solids and its nutrient composition, there is a quantifiable loss of nutrient in the pressing residue during milk extraction. Milling duration improved the colloidal stability of the milk against creaming during 16 h of storage. A higher milling intensity resulted in the aggregation of biological polymers which resulted in colloidal destabilisation. Milling improved the lightness and stability and reduced browning rate of the tiger nut milk during storage. This report is important for the production of tiger nut milk of consistent and comparable characteristics. Milling has been introduced as a processing method for the qualitative and quantitative modulation of the properties of tiger nut milk. It is recommended to develop further strategies to improve the colloidal stability of tiger nut milk as a beverage.  相似文献   
95.
Image color clustering is a basic technique in image processing and computer vision, which is often applied in image segmentation, color transfer, contrast enhancement, object detection, skin color capture, and so forth. Various clustering algorithms have been employed for image color clustering in recent years. However, most of the algorithms require a large amount of memory or a predetermined number of clusters. In addition, some of the existing algorithms are sensitive to the parameter configurations. In order to tackle the above problems, we propose an image color clustering method named Student's t-based density peaks clustering with superpixel segmentation (tDPCSS), which can automatically obtain clustering results, without requiring a large amount of memory, and is not dependent on the parameters of the algorithm or the number of clusters. In tDPCSS, superpixels are obtained based on automatic and constrained simple non-iterative clustering, to automatically decrease the image data volume. A Student's t kernel function and a cluster center selection method are adopted to eliminate the dependence of the density peak clustering on parameters and the number of clusters, respectively. The experiments undertaken in this study confirmed that the proposed approach outperforms k-means, fuzzy c-means, mean-shift clustering, and density peak clustering with superpixel segmentation in the accuracy of the cluster centers and the validity of the clustering results.  相似文献   
96.
为了避免回收单一钕铁硼废料中有价元素带来的操作复杂和资源浪费等问题,本研究采用共沉淀法共沉淀出钕铁硼废料中的有价元素Me(Nd,Pr,Co,Fe),制备可用于生产再生钕铁硼的原料;根据质量守恒和同时平衡原理,采用MATLAB软件建立Me(Nd,Pr,Co,Fe)-OH--NH3热力学模型,绘制lg[Me]-p H曲线模拟共沉淀工艺,并根据模拟结果确立了共沉淀工艺;模拟和实验的结果表明:根据lg[Me]-p H模拟结果可以确立一步共沉淀法的p H:6~10,Fe3+比Fe2+更易于沉淀完全;在上述条件下获得的共沉淀粉末主相均为Nd,Pr,Co,Fe的化合物,且有价元素的百分比含量均大于99.4%;其中,当p H值在8左右时回收率最高,在该条件下金属元素Me(Nd,Pr,Co,Fe)的沉淀效率分别为:98.7%,99.9%,93.6%,99.9%。该结果也表明共沉淀法工艺不仅高效,而且所制备的共沉淀粉末可以满足制备二次钕铁硼的需要。  相似文献   
97.
98.
99.
100.
The environmental performance of 316L grade stainless steel, in the form of tensile specimens containing a single corrosion pit with various aspect ratios, under cyclic loading in aerated chloride solutions is investigated in this study. Results from environmental tests were compared and contrasted with those obtained using finite element analysis (FEA). Fractography of the failed specimens obtained from experiments revealed that fatigue crack initiation took place at the base of the shallow pit. The crack initiation shifted towards the shoulder and the mouth of the pit for pits of increasing depth. This process is well predicted by FEA, as the strain contour maps show that strain is the highest around the centric strip of the pit. However, for shallow pits, local strain is uniformly distributed around that strip but begins to concentrate more towards the shoulder and the mouth region for increasingly deep pits.  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