全文获取类型
收费全文 | 29518篇 |
免费 | 2222篇 |
国内免费 | 1056篇 |
学科分类
工业技术 | 32796篇 |
出版年
2024年 | 55篇 |
2023年 | 512篇 |
2022年 | 703篇 |
2021年 | 1165篇 |
2020年 | 997篇 |
2019年 | 745篇 |
2018年 | 942篇 |
2017年 | 943篇 |
2016年 | 902篇 |
2015年 | 1126篇 |
2014年 | 1420篇 |
2013年 | 1769篇 |
2012年 | 1872篇 |
2011年 | 1900篇 |
2010年 | 1712篇 |
2009年 | 1677篇 |
2008年 | 1566篇 |
2007年 | 1544篇 |
2006年 | 1650篇 |
2005年 | 1366篇 |
2004年 | 882篇 |
2003年 | 838篇 |
2002年 | 745篇 |
2001年 | 617篇 |
2000年 | 655篇 |
1999年 | 784篇 |
1998年 | 677篇 |
1997年 | 608篇 |
1996年 | 541篇 |
1995年 | 454篇 |
1994年 | 348篇 |
1993年 | 261篇 |
1992年 | 196篇 |
1991年 | 152篇 |
1990年 | 113篇 |
1989年 | 96篇 |
1988年 | 78篇 |
1987年 | 48篇 |
1986年 | 49篇 |
1985年 | 22篇 |
1984年 | 18篇 |
1983年 | 14篇 |
1982年 | 16篇 |
1981年 | 9篇 |
1980年 | 7篇 |
1979年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
高寒地区矿山边坡岩体会经历冻融循环作用,引起岩体结构损伤和强度弱化,对矿山边坡的稳定性构成危害。水泥砂浆作为模拟裂隙边坡岩体常用的类岩石材料,其配合比对该类岩石材料抗冻性影响较大。为探究冻融作用下水灰比对类岩石材料物理力学特性的影响机制,制作了7种不同水灰比的类岩石——水泥砂浆标准试样,进行了不同次数的冻融循环试验及0~50次冻融后的单轴压缩试验。结果表明:①冻融前,随着水灰比的增大,试样初始孔隙率增大、密度降低,进而导致其波速下降;冻融过程中,波速随着冻融次数的增加而减小,且水灰比越大,波速损失率越高。②随着水灰比增大,类岩石材料的单轴抗压强度、弹性模量均出现了先增大后减小的现象;当水灰比为0.325~0.35时,类岩石试样的单轴抗压强度最高且抗冻性能最好。③随着冻融循环次数增加,应力应变曲线趋于扁平化,试样由脆性逐渐向延性转化,且水灰比越大,试样孔隙压密阶段变形越大。研究成果可为寒区矿山边坡及相关岩体工程类裂隙岩体冻融试验中的配比设计提供借鉴。 相似文献
102.
Yanli Cao 《The International Journal of Advanced Manufacturing Technology》2020,107(3):1061-1070
In 2015, the State Council issued “Made in China 2025,” stating that the deep integration of information technology and manufacturing should be 相似文献
103.
Mechanically Robust,Ultraelastic Hierarchical Foam with Tunable Properties via 3D Printing 下载免费PDF全文
A mechanically robust, ultraelastic foam with controlled multiscale architectures and tunable mechanical/conductive performance is fabricated via 3D printing. Hierarchical porosity, including both macro‐ and microscaled pores, are produced by the combination of direct ink writing (DIW), acid etching, and phase inversion. The thixotropic inks in DIW are formulated by a simple one‐pot process to disperse duo nanoparticles (nanoclay and silica nanoparticles) in a polyurethane suspension. The resulting lightweight foam exhibits tailorable mechanical strength, unprecedented elasticity (standing over 1000 compression cycles), and remarkable robustness (rapidly and fully recover after a load more than 20 000 times of its own weight). Surface coating of carbon nanotubes yields a conductive elastic foam that can be used as piezoresistivity sensor with high sensitivity. For the first time, this strategy achieves 3D printing of elastic foam with controlled multilevel 3D structures and mechanical/conductive properties. Moreover, the facile ink preparation method can be utilized to fabricate foams of various materials with desirable performance via 3D printing. 相似文献
104.
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
105.
为了提高铝颜料在水性涂料中的耐腐蚀性能,以正硅酸乙酯( TEOS)为前驱物,通过溶胶-凝胶反应在铝颜料表面形成了一层致密的二氧化硅包覆薄膜,通过优化固含量、溶剂种类及 TEOS的用量,提高铝颜料的耐碱性。利用扫描电镜、刮板试验、接触角测试、析氢实验进行表征,结果表明:以无水乙醇为溶剂,铝金属颜料固含量为 10%,升温至 50 ℃后,逐滴加入 6 g TEOS,再升温至 80 ℃,该条件下制备的 SiO2膜包覆后的铝颜料具有优异的耐碱性,同时表面性能由疏水性转变成亲水性,对铝颜料起到了很好的保护作用。 相似文献
106.
107.
Cao Bing-wei Liu Xin-hui Chen Wei Yang Kuo Liu Dan 《Journal of Mechanical Science and Technology》2020,34(3):1081-1090
Journal of Mechanical Science and Technology - This study applies image recognition technology to the shovel loading operation of a wheel loader for the first time. In the proposed method, the... 相似文献
108.
Cao Jinfeng Lai Jianzhong Zhou Jiehang Kang Ningyu Du Longyu Miao Yiqiu 《Journal of Mechanical Science and Technology》2020,34(7):2783-2793
Journal of Mechanical Science and Technology - A lightweight multilayer ceramic composite armor with a sandwich structure back plate was proposed by studying the penetration process, damage... 相似文献
109.
He Gang Cao Zhaoyuan Li Qian Zhu Denglin Aimin Ji 《Journal of Mechanical Science and Technology》2020,34(9):3823-3831
Journal of Mechanical Science and Technology - Hexapod robots have attracted attention for their excellent terrain adaptabilities. When a robot walks on soft soil, dynamic subsidence and slippage... 相似文献
110.
Hui Liu Shuang Dai Jun Li Rui Ma Yan Cao Gang Wang Sridhar Komarneni Jianhong Luo 《化学工程与技术》2020,43(5):974-982
The very good extraction selectivity of Cu2+ from water was demonstrated with a new microchannel equipment, by employing di-(2-ethylhexyl)phosphoric acid (D2EHPA) as an extractant and kerosene as a solvent. The effects of different experimental parameters on the extraction efficiency E, the volumetric mass transfer coefficient KLa, and the entrainment were experimentally investigated. The results showed that the extraction efficiency increased with increasing temperature, extractant concentration, phase ratio (organic/aqueous), and pH. The total flow rate, phase ratio, and pH were found to have a great effect on the mass transfer, whereas the temperature and the extractant concentration showed little effect. 相似文献