全文获取类型
收费全文 | 642585篇 |
免费 | 49234篇 |
国内免费 | 31021篇 |
专业分类
电工技术 | 38220篇 |
技术理论 | 60篇 |
综合类 | 45280篇 |
化学工业 | 103007篇 |
金属工艺 | 39779篇 |
机械仪表 | 41742篇 |
建筑科学 | 50704篇 |
矿业工程 | 20743篇 |
能源动力 | 17531篇 |
轻工业 | 40818篇 |
水利工程 | 11818篇 |
石油天然气 | 42642篇 |
武器工业 | 5214篇 |
无线电 | 70140篇 |
一般工业技术 | 71718篇 |
冶金工业 | 32181篇 |
原子能技术 | 7512篇 |
自动化技术 | 83731篇 |
出版年
2024年 | 2051篇 |
2023年 | 8561篇 |
2022年 | 15500篇 |
2021年 | 23290篇 |
2020年 | 17487篇 |
2019年 | 14485篇 |
2018年 | 16557篇 |
2017年 | 18941篇 |
2016年 | 16939篇 |
2015年 | 23542篇 |
2014年 | 30240篇 |
2013年 | 36253篇 |
2012年 | 39733篇 |
2011年 | 46369篇 |
2010年 | 39829篇 |
2009年 | 37338篇 |
2008年 | 36613篇 |
2007年 | 34978篇 |
2006年 | 35954篇 |
2005年 | 31721篇 |
2004年 | 23769篇 |
2003年 | 19857篇 |
2002年 | 18545篇 |
2001年 | 16012篇 |
2000年 | 15967篇 |
1999年 | 18205篇 |
1998年 | 14674篇 |
1997年 | 12418篇 |
1996年 | 11258篇 |
1995年 | 9359篇 |
1994年 | 7640篇 |
1993年 | 6725篇 |
1992年 | 5353篇 |
1991年 | 4068篇 |
1990年 | 3223篇 |
1989年 | 2566篇 |
1988年 | 1926篇 |
1987年 | 1192篇 |
1986年 | 897篇 |
1985年 | 604篇 |
1984年 | 420篇 |
1983年 | 281篇 |
1982年 | 320篇 |
1981年 | 231篇 |
1980年 | 229篇 |
1979年 | 129篇 |
1978年 | 51篇 |
1977年 | 55篇 |
1976年 | 60篇 |
1965年 | 67篇 |
排序方式: 共有10000条查询结果,搜索用时 578 毫秒
2.
Xiao Zhu Chen Yanxun Jiang Hongbo Hu Zhenzhen Lui John C. S. Min Geyong Dustdar Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of... 相似文献
3.
采用直流磁控溅射和后退火氧化工艺在p型GaAs单晶衬底上成功制备了n-VO_2/pGaAs异质结,研究了不同退火温度和退火时间对VO_2/GaAs异质结性能的影响,并分析其结晶取向、化学组分、膜层质量以及光电特性。结果表明,在退火时间2 h和退火温度693 K下能得到相变性能最佳的VO_2薄膜,相变前后电阻变化约2个数量级。VO_2/GaAs异质结在308 K、318 K和328 K温度下具有较好的整流特性,对应温度下的阈值跳变电压分别为6.9 V、6.6 V和6.2 V,该结果为基于VO_2相变特性的异质结光电器件的设计与应用提供了可行性。 相似文献
5.
6.
Kelin Hu Feipeng Wang Yuyang Yan Hongcheng Liu Zijia Shen 《Ceramics International》2021,47(11):15228-15236
In this paper, a novel hybrid structure of Pd doped ZnO/SnO2 heterojunction nanofibers with hexagonal ZnO columns was one step synthesized from electrospun precursor nanofibers. Due to the synergistic effect of hexagonal ZnO, SnO2 and Pd, the structure exhibited excellent hydrogen (H2) gas sensing properties. At low-temperature of 120 °C, the response (Ra/Rg) to 100 ppm H2 gas exceeded 160, the response/recovery time was only 20 s and 6 s respectively and the limit of detection was only 0.5 ppm. Meanwhile, it also had good selectivity for H2 gas and excellent linearity. In addition, the materials were characterized by XRD, FESEM, HRTEM, XPS, and the synthesis mechanism and gas sensing mechanism were proposed. 相似文献
7.
9.
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
10.
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