全文获取类型
收费全文 | 98745篇 |
免费 | 8228篇 |
国内免费 | 4250篇 |
专业分类
电工技术 | 5608篇 |
技术理论 | 6篇 |
综合类 | 6272篇 |
化学工业 | 16279篇 |
金属工艺 | 6206篇 |
机械仪表 | 7009篇 |
建筑科学 | 8009篇 |
矿业工程 | 3364篇 |
能源动力 | 2908篇 |
轻工业 | 6316篇 |
水利工程 | 1647篇 |
石油天然气 | 7281篇 |
武器工业 | 812篇 |
无线电 | 10669篇 |
一般工业技术 | 11491篇 |
冶金工业 | 4802篇 |
原子能技术 | 1019篇 |
自动化技术 | 11525篇 |
出版年
2024年 | 350篇 |
2023年 | 1666篇 |
2022年 | 2769篇 |
2021年 | 4172篇 |
2020年 | 3248篇 |
2019年 | 2629篇 |
2018年 | 2870篇 |
2017年 | 3244篇 |
2016年 | 3020篇 |
2015年 | 4116篇 |
2014年 | 4913篇 |
2013年 | 5843篇 |
2012年 | 6359篇 |
2011年 | 6787篇 |
2010年 | 5812篇 |
2009年 | 5546篇 |
2008年 | 5405篇 |
2007年 | 5112篇 |
2006年 | 5455篇 |
2005年 | 4731篇 |
2004年 | 3001篇 |
2003年 | 2854篇 |
2002年 | 2677篇 |
2001年 | 2427篇 |
2000年 | 2340篇 |
1999年 | 2628篇 |
1998年 | 2081篇 |
1997年 | 1731篇 |
1996年 | 1698篇 |
1995年 | 1400篇 |
1994年 | 1151篇 |
1993年 | 732篇 |
1992年 | 641篇 |
1991年 | 437篇 |
1990年 | 348篇 |
1989年 | 294篇 |
1988年 | 219篇 |
1987年 | 140篇 |
1986年 | 112篇 |
1985年 | 68篇 |
1984年 | 45篇 |
1983年 | 40篇 |
1982年 | 41篇 |
1981年 | 26篇 |
1980年 | 23篇 |
1979年 | 16篇 |
1978年 | 1篇 |
1965年 | 1篇 |
1959年 | 3篇 |
1951年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Zhao Jiandong Lei Wei Li Zijian Zhao Dongfeng Han Mingmin Hou Xiaoqing 《Multimedia Tools and Applications》2022,81(4):4753-4780
Multimedia Tools and Applications - The crowding in bus is an important factor affecting passenger satisfaction and bus dispatching level. However, how to use video images to detect crowding... 相似文献
2.
Wireless Networks - Geolocation is important for many emerging applications such as disaster management and recommendation system. In this paper, we propose a multilayer recognition model (MRM) to... 相似文献
3.
了解我国儿童家长的家庭食品安全知识知晓情况及其影响因素,对开展精准食品安全宣教,减少家庭食源性疾病具有积极意义。本研究在7个城市的13 923名3~12岁儿童家长中开展问卷调查,收集基本信息、家庭食品安全知识知晓情况及需求。家长家庭食品安全知识平均得分为18.6分(总分29分),及格率为68.7%。易错知识点包括熟食室温存储时间、食品保质期、易引起中毒的食物以及食品贮存环境等。多因素logistics回归分析显示:家长家庭食品安全知识及格率受地区、文化程度、职业、家长类型、是否关注食品安全、孩子是否讲过食品安全知识以及是否阅读孩子带回来资料的影响。家长最关心的前三位内容为滥用食品添加剂(84.9%)、卫生状况不合格(82.9%)、农药/药物残留(82.7%)。受家长信任的信息来源主要为电视/广播/广告(76.1%)、书籍/报纸/期刊(70.4%)、微博/微信等新媒体(57.7%)。家长的家庭食品安全知识仍存在短板,需利用传统媒体和新媒体结合的方式以及小手牵大手形式开展精准专题宣传,并特别关注文化程度低,从事食品行业的家长以及孩子父亲和保姆。 相似文献
4.
Sinan Zhang Yadonga Zhao Xueshuang Yao Zhenhong Zheng Chuyao Zheng Zhuo Jiang 《International Journal of Food Science & Technology》2022,57(7):4245-4253
Ripe carambolas are hard to store and transport, while freeze-dried ones are easy to store. However, its long production time leads to higher costs. This study shows that high hydrostatic pressure (HHP) treatment could shorten the freeze-drying time of carambola slices. After HHP treatment (25–250 MPa), the drying time of the fresh sample can be shortened by 33.3–44.4% and the distribution of water and pigment in tissues is much uniform. With the increment of the pressure, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical scavenging rate are increased. At 250 MPa, the total phenolic content (TPC) increased from 11.34 to 13.36 mg GAE g−1, and the total flavonoid content (TFC) of the control sample was increased from 10.77 to 12.73 mg RE g−1. Compared with the untreated sample, HHP treatment can enhance the flavour and shorten the freeze-drying time. This work guides the application of HHP technology for drying food processing. 相似文献
5.
Peiying Wang Juanli Zhao Yun Fan Wei Zhang Yuanyuan Cui Liangmiao Zhang Bin Liu Hongqiang Nian Yiran Li 《Ceramics International》2021,47(11):15023-15029
In this work, the composition-dependent point defect types and formation energies of RE2Hf2O7 (RE = La, Ce, Pr, Nd, Pm, Sm, Eu and Gd) as well as the oxygen diffusion behavior are systematically investigated by first-principles calculations. The possible defect reactions and dominant defect complexes under stoichiometric and non-stoichiometric conditions are revealed. It is found that O Frenkel pairs are the predominant defect in stoichiometric pyrochlore hafnates. Hf-RE cation anti-site defects, accompanied by RE vacancies and/or oxygen interstitials, are stable in the non-stoichiometric case of HfO2 excess. On the other hand, RE-Hf anti-site defects together with oxygen vacancies and/or RE interstitials are preferable in the case of RE2O3 excess. The energy barriers for the migration along the VO48f - VO48f pathway of pyrochlore hafnates were calculated to be between 0.81 eV and 0.89 eV. Based on these results, a defect engineering strategy is proposed and the pyrochlore hafnates investigated here are predicted to exhibit potential oxygen ionic conductivity. 相似文献
6.
Applied Composite Materials - In this paper, the low-velocity impact deformation behavior of biaxial warp-knitted flexible composite was investigated. A simplified finite element model (FEM) of the... 相似文献
7.
8.
Zhang Nan Zhao Man Liu Guangfa Wang Jiaoyang Chen Yunzhi Zhang Zhengjian 《Journal of Materials Science》2022,57(19):8687-8700
Journal of Materials Science - A green modification method for effectively enhancing toughness of PLA was established. Herein, alkaline lignin (LG) was firstly alkylated with dodecane, and then... 相似文献
9.
Wang Chen Bao Chun-Hui Wu Wan-Yu Hsu Chia-Hsun Zhao Ming-Jie Zhang Xiao-Ying Lien Shui-Yang Zhu Wen-Zhang 《Journal of Materials Science》2022,57(26):12341-12355
Journal of Materials Science - Molybdenum oxide (MoOx) films had been grown by using plasma-enhanced atomic layer deposition (PEALD) with Mo(CO)6 precursor and O2 plasma reactant in a substrate... 相似文献
10.
Journal of Porous Materials - Co3O4 has been widely investigated as a promising candidate anode material for lithium-ion batteries. We report on the porous Co3O4 column synthesized via a simple... 相似文献