全文获取类型
收费全文 | 498624篇 |
免费 | 37126篇 |
国内免费 | 20705篇 |
专业分类
电工技术 | 27795篇 |
技术理论 | 47篇 |
综合类 | 33365篇 |
化学工业 | 78346篇 |
金属工艺 | 29007篇 |
机械仪表 | 30000篇 |
建筑科学 | 35873篇 |
矿业工程 | 14228篇 |
能源动力 | 12668篇 |
轻工业 | 32995篇 |
水利工程 | 9807篇 |
石油天然气 | 26385篇 |
武器工业 | 3674篇 |
无线电 | 54902篇 |
一般工业技术 | 59869篇 |
冶金工业 | 23400篇 |
原子能技术 | 4689篇 |
自动化技术 | 79405篇 |
出版年
2024年 | 1777篇 |
2023年 | 6487篇 |
2022年 | 11852篇 |
2021年 | 16327篇 |
2020年 | 12435篇 |
2019年 | 10022篇 |
2018年 | 24371篇 |
2017年 | 24971篇 |
2016年 | 20873篇 |
2015年 | 17104篇 |
2014年 | 21264篇 |
2013年 | 25020篇 |
2012年 | 30402篇 |
2011年 | 38879篇 |
2010年 | 34640篇 |
2009年 | 30832篇 |
2008年 | 31768篇 |
2007年 | 31447篇 |
2006年 | 24463篇 |
2005年 | 22213篇 |
2004年 | 15822篇 |
2003年 | 14427篇 |
2002年 | 13717篇 |
2001年 | 11708篇 |
2000年 | 10557篇 |
1999年 | 10460篇 |
1998年 | 7771篇 |
1997年 | 6584篇 |
1996年 | 6211篇 |
1995年 | 5102篇 |
1994年 | 4156篇 |
1993年 | 2803篇 |
1992年 | 2220篇 |
1991年 | 1707篇 |
1990年 | 1313篇 |
1989年 | 1062篇 |
1988年 | 876篇 |
1987年 | 557篇 |
1986年 | 439篇 |
1985年 | 266篇 |
1984年 | 217篇 |
1983年 | 167篇 |
1982年 | 138篇 |
1981年 | 93篇 |
1980年 | 107篇 |
1979年 | 56篇 |
1966年 | 46篇 |
1959年 | 55篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Feng Wenran Li Zhen Chen Yingying Chen Jinyang Lang Haoze Wan Jianghong Gao Yan Dong Haitao 《Journal of Materials Science》2022,57(3):1881-1889
Journal of Materials Science - Although chalcogenide materials continue to generate considerable interest due to great potentials for various optoelectronic devices, annealing for a long time in... 相似文献
2.
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
3.
油液监测是判断设备健康状况和提供设备故障隐患预警的有效方法。综述了用于监测润滑油中磨损颗粒的最新各类在线传感器的基本原理,包括批量磁吸附式传感器、微流体电容传感器、金属扫描传感器、双层平面线圈传感器、超声波传感器和光学传感器等,并讨论各种传感方法的优缺点以及未来发展面临的挑战;指出了高通量、高灵敏度、能区别金属与非金属磨粒、可采集磨粒图像信息的集成式传感器是未来研究的重点,集成式、智能化、无线传输的传感器是未来研发方向。 相似文献
4.
8.
Shanshan Zhuang Wenxiong Zheng Yunong Na Naiyi Chen Fan Gong Bingxuan Huang Stephen Brennan Charles Congyi Liu Jian Cheng Lukai Ma Huifan Liu 《International Journal of Food Science & Technology》2022,57(2):1093-1103
The β-Carotene (BC), an important precursor of vitamin A (VA), possesses antioxidant activity but is fat-soluble and has low bioavailability. In previous in-vitro assays evaluating antioxidant and 2,2′-azobis(2-amidinopropane) dihydrochloride (AAPH) free radical scavenging, both BC and VA showed a strong ability to scavenge radicals and protected cells from oxidative stress. Here, we used artificially simulated gastrointestinal digestion and Caco-2 cell absorption models to evaluate the bioavailability of the BC during gastrointestinal digestion and absorption using high-performance liquid chromatography (HPLC) analysis. We observed high absorptive and transfer rates of BC and detected retinol metabolites (Vitamin A). Therefore, BC can be detected in the acidic gastrointestinal environment using HPLC. Optimised method provided better separation of BC and VA in the column, improving the accuracy of the test results. 相似文献
9.
Peng Wang Yan Li Yujiao Qu Baowei Wang Jingxin Sun Chunwei Miao Ming Huang He Huang Congxiang Zhang 《International Journal of Food Science & Technology》2022,57(6):3428-3439
The effects of cellulose microfibres (CMFs, Average size: 100 ± 5 μm) and cellulose nanofibres (CNFs, Average size: 60 ± 3 nm) on the properties of myofibrillar protein (MP) gels from duck breast meat were studied. The results demonstrated that CMFs and CNFs were mostly connected to MP by non-covalent bonds, the diffusion and cross-linking of MP molecules was promoted, and a denser and more complete gel network was formed. With the increases of CMFs and CNFs concentration (0–10%), the hardness was increased by 13.15% and 19.78% for CMFs10% and CNFs10% gels, respectively, and the elasticity was increased by 40% and 80%, respectively. At the same concentration (0–10%), the increase in gel hardness, viscoelasticity and immobilised water content was greater in the CNFs-MP group than in the CMFs-MP group. The CNFs-MP group had a tighter gel network, and CNFs had a better potential to improve the gelation performance of MP. 相似文献
10.
Xin Li Yurui Wang Minxuan Xu Yueqin Shi Hemiao Wang Xin Yang Haoting Ying Qi Zhang 《应用聚合物科学杂志》2021,138(19):50406
Polymer electrets have revealed great potential application in electromechanical devices because of the low weight, large quasi-piezoelectric sensitivity, and excellent flexibility. For an electret, a permanent and macroscopic electric field exists on the surface, principally led by a macroscopic electrostatic charge on the surface or a net orientation of polar groups inside the object. Here, progress in the development of polymer electrets is reviewed. After a brief retrospect of the research courses and those typical polymer electrets that are classified into fluorine polymer and nonfluorine polymer, we present a survey on the charging methods, including corona, soft X-ray, contact, thermal and monoenergetic particle beams. The latest representative applications (i.e., power harvesting, sensors, field effect transistors, and biomedicine) based on polymer electrets are also summarized. Finally, we complete this review with a discussion on perspectives and challenges in this field. 相似文献