全文获取类型
收费全文 | 232739篇 |
免费 | 32884篇 |
国内免费 | 11960篇 |
专业分类
电工技术 | 16309篇 |
技术理论 | 10篇 |
综合类 | 16420篇 |
化学工业 | 44047篇 |
金属工艺 | 12522篇 |
机械仪表 | 13964篇 |
建筑科学 | 18222篇 |
矿业工程 | 6515篇 |
能源动力 | 6667篇 |
轻工业 | 21358篇 |
水利工程 | 5048篇 |
石油天然气 | 10291篇 |
武器工业 | 2179篇 |
无线电 | 29886篇 |
一般工业技术 | 30540篇 |
冶金工业 | 8825篇 |
原子能技术 | 2325篇 |
自动化技术 | 32455篇 |
出版年
2024年 | 963篇 |
2023年 | 3189篇 |
2022年 | 6262篇 |
2021年 | 8759篇 |
2020年 | 7748篇 |
2019年 | 7889篇 |
2018年 | 8409篇 |
2017年 | 9770篇 |
2016年 | 9390篇 |
2015年 | 12216篇 |
2014年 | 14468篇 |
2013年 | 17466篇 |
2012年 | 17294篇 |
2011年 | 17692篇 |
2010年 | 16887篇 |
2009年 | 15927篇 |
2008年 | 15265篇 |
2007年 | 14407篇 |
2006年 | 13134篇 |
2005年 | 10513篇 |
2004年 | 7848篇 |
2003年 | 7193篇 |
2002年 | 7203篇 |
2001年 | 6422篇 |
2000年 | 5101篇 |
1999年 | 3843篇 |
1998年 | 2331篇 |
1997年 | 1900篇 |
1996年 | 1729篇 |
1995年 | 1463篇 |
1994年 | 1224篇 |
1993年 | 791篇 |
1992年 | 634篇 |
1991年 | 467篇 |
1990年 | 370篇 |
1989年 | 316篇 |
1988年 | 223篇 |
1987年 | 151篇 |
1986年 | 148篇 |
1985年 | 65篇 |
1984年 | 67篇 |
1983年 | 53篇 |
1982年 | 52篇 |
1981年 | 57篇 |
1980年 | 50篇 |
1979年 | 37篇 |
1978年 | 15篇 |
1977年 | 14篇 |
1976年 | 23篇 |
1951年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 0 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.
4.
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
5.
开展智慧化阅读推广,紧跟时代步伐,有效提升读者多重阅读体验和满意度,增强智慧化阅读推广的价值,促进智慧化阅读推广服务的有效化、规范化、科学化、常态化、长期化发展,已成为当前阅读推广研究中一个重要的切入点。文章基于智慧化阅读研究,结合"新媒体"高新技术环境,提出智慧化阅读推广的内容分析、具体实施、环境构建、推广评估与效果、推广改进等几个方面组成的以读者为中心的核心服务体系。本文分析了智慧化阅读基本方面,以我校图书馆实际运用推广效果,智慧化阅读存在的优、劣势及相应的对策。 相似文献
6.
Yuhang Xing Ruyi Li Lu Xue Mianhong Chen Xuli Lu Zhihao Duan Wei Zhou Jihua Li 《International Journal of Food Science & Technology》2022,57(8):5268-5279
Mangiferin (MGF) is a phenolic compound isolated from mango, but its poor solubility significantly limits its use. In this study, MGF was embedded into the inner aqueous phase of W1/O/W2 emulsions. Firstly, the dissolution method of MGF was determined. MGF remained stable in solution with pH 13 at 30 min, and its solubility reached 10 mg mL−1. When the pH of MGF solutions was adjusted from pH 13 to pH 6, MGF did not immediately crystallise, providing sufficient time to construct the MGF-loaded W1/O/W2 emulsions. Subsequently, the MGF-loaded W1/O/W2 emulsions were constructed using polyglycerol polyricinoleate (PGPR) and calcium caseinate (CAS). The formation and stability of the W1/O/W2 emulsions were investigated. The MGF-loaded W1/O/W2 emulsions stabilised with 1% PGPR and 1% – 3% CAS exhibited a low viscosity, limited loading capacity, and poor stability. Conversely, the MGF-loaded W1/O/W2 emulsions stabilised by 3%PGPR–3%CAS exhibited optimal loading capacity (encapsulation efficiency = 95.31% and loading efficiency = 0.91%) and stability, which was attributed to the fact that high viscosity and gel state retarded the migration of inner aqueous phase. These results indicated that the W1/O/W2 emulsions stabilised by PGPR and CAS may be a potential alternative for encapsulating mangiferin. 相似文献
7.
8.
有机-无机压电材料是一种分子铁电体,具有柔性、结构灵活、易成膜、全液相合成及环保节能等优点,可满足新一代薄膜器件及可穿戴设备的需求。该文以三甲基卤代甲基铵(TMXM, X=F, Cl, Br)为有机部分,MnCl2为无机部分,通过溶液蒸发法制备了具有钙钛矿分子结构的有机-无机压电材料三甲基氯三氯化锰(TMCM-MnCl3),并对其分子结构组成、压电、热学、声学及铁电性进行表征。结果表明,TMCM-MnCl3的压电常数为106 pC/N,居里温度为130 ℃,声阻抗值约为16.5 MRayl,低于压电陶瓷PZT-4(大于33 MRayl),具有广阔的应用前景。 相似文献
10.
Jinfeng Zeng Zhiting Liu Hanbo Zou Wei Yang Haosen Fan Haijun Yu Shengzhou Chen 《金属学报(英文版)》2021,34(8):1153-1162
A appropriate size with three-dimension(3 D) channels for lithium diffusion plays an important role in constructing highperforming LiNi_(0.5)Mn_(1.5)O_4(LNMO) cathode materials, as it can not only reduce the transport path of lithium ions and electrons, but also reduce the side effects and withstand the structural strain in the process of repetitive Li~+ intercalation/deintercalation. In this work, an e fficient method for designing the hollow LNMO microsphere with 3 D channels structure by using polyethylene oxide(PEO) as soft template agent assisted solvothermal method is proposed. Experimental results indicate that PEO can make the reagents mingle evenly and nucleate slowly in the solvothermal process, thus obtaining a homogeneous distribution of carbonate precursors. In the final LNMO products, the hollow 3 D channels structure obtained by the decomposition of PEO and carbonate precursor in the calcination can provide abundant electroactive zones and electron/ion transport paths during the charge/discharge process, which benefits to improve the cycling performance and rate capability. The LNMO prepared by adding 1 g PEO possesses the most outstanding electrochemical performance, which presented an excellent discharge capacity of 143.1 mAh g~(-1) at 0.1 C and with a capacity retention of 92.2% after 100 cycles at 1 C. The superior performance attributed to the 3 D channels structure of hollow microspheres, which provide uninterrupted conductive systems and therefore achieve the stable transfer for electron/ion. 相似文献