全文获取类型
收费全文 | 72526篇 |
免费 | 5826篇 |
国内免费 | 3032篇 |
专业分类
电工技术 | 3798篇 |
技术理论 | 10篇 |
综合类 | 4296篇 |
化学工业 | 12445篇 |
金属工艺 | 4095篇 |
机械仪表 | 4588篇 |
建筑科学 | 6170篇 |
矿业工程 | 2099篇 |
能源动力 | 2162篇 |
轻工业 | 4508篇 |
水利工程 | 1193篇 |
石油天然气 | 4622篇 |
武器工业 | 586篇 |
无线电 | 8486篇 |
一般工业技术 | 9274篇 |
冶金工业 | 3578篇 |
原子能技术 | 838篇 |
自动化技术 | 8636篇 |
出版年
2024年 | 99篇 |
2023年 | 1147篇 |
2022年 | 1658篇 |
2021年 | 2644篇 |
2020年 | 2125篇 |
2019年 | 1864篇 |
2018年 | 2021篇 |
2017年 | 2346篇 |
2016年 | 2081篇 |
2015年 | 2795篇 |
2014年 | 3428篇 |
2013年 | 4116篇 |
2012年 | 4557篇 |
2011年 | 4795篇 |
2010年 | 4145篇 |
2009年 | 3917篇 |
2008年 | 3895篇 |
2007年 | 3840篇 |
2006年 | 4049篇 |
2005年 | 3485篇 |
2004年 | 2414篇 |
2003年 | 2108篇 |
2002年 | 2010篇 |
2001年 | 1834篇 |
2000年 | 1829篇 |
1999年 | 2082篇 |
1998年 | 1857篇 |
1997年 | 1512篇 |
1996年 | 1465篇 |
1995年 | 1138篇 |
1994年 | 1063篇 |
1993年 | 738篇 |
1992年 | 574篇 |
1991年 | 450篇 |
1990年 | 334篇 |
1989年 | 272篇 |
1988年 | 234篇 |
1987年 | 141篇 |
1986年 | 101篇 |
1985年 | 70篇 |
1984年 | 35篇 |
1983年 | 32篇 |
1982年 | 40篇 |
1981年 | 21篇 |
1980年 | 13篇 |
1979年 | 6篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1959年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Fangjun Zhu You Shi Guorong Hu Zhongdong Peng Yanbing Cao Qian Sun Zhichen Xue Yinjia Zhang Ke Du 《Ceramics International》2021,47(3):3070-3078
Titanium and boron are simultaneously introduced into LiNi0.8Co0.1Mn0.1O2 to improve the structural stability and electrochemical performance of the material. X-ray diffraction studies reveal that Ti4+ ion replaces Li+ ion and reduces the cation mixing; B3+ ion enters the tetrahedron of the transition metal layers and enlarges the distance of the [LiO6] layers. The co-doped sample has spherical secondary particles with elongated and enlarged primary particles, in which Ti and B elements distribute uniformly. Electrochemical studies reveal the co-doped sample has improved rate performance (183.1 mAh·g-1 at 1 C and 155.5 mAh·g-1 at 10 C) and cycle stability (capacity retention of 94.7% after 100 cycles at 1 C). EIS and CV disclose that Ti and B co-doping reduces charge transfer impedance and suppresses phase change of LiNi0.8Co0.1Mn0.1O2. 相似文献
22.
23.
24.
Ai Li Wang Zhenyan Zhao Jianfu Zhu Pengfei Jiang Hechun Duan Xiulan 《Journal of Materials Science: Materials in Electronics》2022,33(13):10360-10367
Journal of Materials Science: Materials in Electronics - Co-doped LaMgAl11O19 microcrystals were synthesized by a facile sol–gel method. The as-synthesized microcrystals were near hexagonal... 相似文献
25.
Cuiping Yi Lan Xie Zhongfu Cao Ke Quan Hong Zhu Jieyao Yuan 《International Journal of Food Science & Technology》2022,57(8):5048-5056
Brown rice noodles (RN) are typical whole-grain products with health benefits. This study investigated the effects of rice bran fermented with Lactobacillus plantarum on palatability, volatile profiles, and antioxidant activity of brown RN. Three kinds of RN, including RN, brown RN (BRN), and bran fermented RN (BFRN), were involved in this study. The results indicated that bran fermentation reduced the cooking loss of BFRN and improved the elongation and the sensory attributes of brown RN. After fermentation, aldehydes were significantly decreased while alcohols increased, and more pleasant flavours were shown in BFRN. Fermentation increased the content of free phenolics and decreased the content of bound phenolics. Among the four major phenolics detected in this study, ferulic acid was the most abundant one in all three RN samples. The DPPH radical scavenging activity and the ferric reducing antioxidant power of free phenolics in BFRN increased significantly compared to BRN. This study proved that rice bran fermentation is an effective approach to improve palatability, enrich the flavour as well as enhance the antioxidant activity of brown RN, which may facilitate the development of processing technology for brown RN. 相似文献
26.
Linhui Lu Qingli Shu Guiru Zhang Qi Zhang Ping Du Xuedong Zhu 《American Institute of Chemical Engineers》2022,68(10):e17787
Palladium-based catalysts have been widely employed in the electro-Fenton process for in situ generation of H2O2. However, the process is still far from being practical on a large scale. In this work, a series of ClxFePd/γ-Al2O3/Al catalysts were prepared by a three-step-impregnation method. They exhibited excellent activity in H2O2 in situ synthesis and high efficiency in phenol degradation. The characterization results showed that Cl could assist in increasing the content of Pd0 and reducing the isoelectric point of catalysts, which led to the drastic promotion in the synthesis of H2O2. Theoretical calculations further demonstrated that Cl doping could facilitate the main reaction in H2O2 synthesis, as well as inhibit side reactions such as dissociation of the O O bond. Furthermore, kinetic models were proposed and fitted. A plausible reaction mechanism as well as degradation pathways were elaborated based on electron spin resonance and gas chromatography–mass spectrometry results. These findings illustrate the value of palladium-based ClxFePd/γ-Al2O3/Al catalysts for their application in the electro-Fenton process. 相似文献
27.
Yao Qin Yajing You Guangzheng Jin Wei Zhu Yudan Zhu Qiutian Wang Xiaohua Lu Yijun Shi 《American Institute of Chemical Engineers》2022,68(4):e17581
Molecular dynamics simulations are performed to investigate the solid surface-induced microstructure and friction coefficient of glycerol aqueous solutions with different water contents confined in graphene and FeO nanoslits. Results show that the friction coefficient of glycerol aqueous solutions confined in both nanoslits presents similar nonlinear variation tendencies with increasing water content, but their lowest value and the corresponding water contents differ. Distinctive microstructures of the near-surface liquid layer induced by surfaces with different hydrophilicity are responsible for their difference in lubrication. The sliding primarily occurs at the solid–liquid interface for the hydrophobic graphene nanoslit owing to almost the same velocity difference in fluid molecules. By contrast, the sliding mainly occurs at the liquid–liquid interface for the hydrophilic FeO nanoslit because of the large velocity difference in fluid molecules. The weaker the interaction force at the sliding position, the lower the friction coefficient. 相似文献
28.
Aqueous film-forming foams (AFFFs) are an important for fire extinguishing, and their key ingredient is fluorinated surfactant. In recent years, traditional long-chain fluorinated surfactants have been banned by most countries because of their persistence, bio-accumulation and toxicity. Therefore, increased attention has been paid to the research and development of short-chain fluorinated surfactants. As is well known, the introduction of hydrophilic or hydrophobic groups in a surfactant affects its surface activity, and therefore, the fire extinguishing performance of AFFFs. In this work, a series of short-chain fluorosurfactant-based AFFFs with different hydrophobic chain lengths were prepared. The physicochemical performance of mixed systems (fluorinated surfactant plus sodium hexanesulfonate), including surface activity, spreading ability, foam expansion, drainage time, and the fire extinguishing and burn-back performance of AFFFs were studied. The results show that the critical micelle concentration (CMC) and the surface tension (γCMC) at the CMC of mixed systems at 25°C are lower than 7.68 mmol/L and 16.51 mN/m, respectively. For mixed systems, the average spreading rate is more than 1.09 cm/s, the foam expansion is over 7.1, and the drainage time is greater than 3.28 min. The fire extinguishing time of AFFFs on fuels is less than 51 s while the burn-back time is more than 15.18 min. The results imply a potential application prospect of the short-chain fluorinated surfactants in AFFFs. 相似文献
29.
Ding Haomiao Zhang Yuzhe Zha Yue Zhou Sijia Cao Chaoqing Zhu Huajian Xu Feng Zhang Xiuqiang Wang Caisheng 《Food science and biotechnology》2022,31(13):1741-1751
Food Science and Biotechnology - The cytoprotective and potential molecular mechanisms of Hylocereus polyrhizus protein (RFPP) were investigated on the hydrogen peroxide (H2O2)-triggered damage in... 相似文献
30.
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