全文获取类型
收费全文 | 301199篇 |
免费 | 40426篇 |
国内免费 | 16218篇 |
专业分类
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 |
出版年
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.
Lü 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.
Nazir Kizzie‐Hayford Doris Jaros Yvonne Schneider Harald Rohm 《International Journal of Food Science & Technology》2015,50(2):381-388
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.
Zhijiang Li Yingping Zheng Liqin Cao Lei Jiao Yanfei Zhong Caiyi Zhang 《Color research and application》2020,45(4):656-670
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.
Muntasir Hashim Farnoosh Farhad David Smyth‐Boyle Robert Akid Xiang Zhang Philip J. Withers 《工业材料与腐蚀》2019,70(11):2009-2019
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