全文获取类型
收费全文 | 367582篇 |
免费 | 30137篇 |
国内免费 | 16241篇 |
专业分类
电工技术 | 21550篇 |
技术理论 | 46篇 |
综合类 | 26491篇 |
化学工业 | 61617篇 |
金属工艺 | 21307篇 |
机械仪表 | 23115篇 |
建筑科学 | 28342篇 |
矿业工程 | 11949篇 |
能源动力 | 10024篇 |
轻工业 | 25953篇 |
水利工程 | 6986篇 |
石油天然气 | 23747篇 |
武器工业 | 2887篇 |
无线电 | 39821篇 |
一般工业技术 | 40495篇 |
冶金工业 | 18910篇 |
原子能技术 | 3722篇 |
自动化技术 | 46998篇 |
出版年
2024年 | 1496篇 |
2023年 | 5712篇 |
2022年 | 10279篇 |
2021年 | 14353篇 |
2020年 | 10855篇 |
2019年 | 8822篇 |
2018年 | 10221篇 |
2017年 | 11491篇 |
2016年 | 10509篇 |
2015年 | 14472篇 |
2014年 | 18248篇 |
2013年 | 21859篇 |
2012年 | 23785篇 |
2011年 | 26301篇 |
2010年 | 23228篇 |
2009年 | 22070篇 |
2008年 | 21559篇 |
2007年 | 20487篇 |
2006年 | 20685篇 |
2005年 | 18008篇 |
2004年 | 12165篇 |
2003年 | 10825篇 |
2002年 | 10008篇 |
2001年 | 8872篇 |
2000年 | 8814篇 |
1999年 | 9435篇 |
1998年 | 7214篇 |
1997年 | 6174篇 |
1996年 | 5834篇 |
1995年 | 4812篇 |
1994年 | 3905篇 |
1993年 | 2637篇 |
1992年 | 2085篇 |
1991年 | 1578篇 |
1990年 | 1243篇 |
1989年 | 1001篇 |
1988年 | 835篇 |
1987年 | 525篇 |
1986年 | 415篇 |
1985年 | 261篇 |
1984年 | 208篇 |
1983年 | 167篇 |
1982年 | 129篇 |
1981年 | 81篇 |
1980年 | 102篇 |
1979年 | 44篇 |
1978年 | 17篇 |
1977年 | 26篇 |
1976年 | 29篇 |
1973年 | 9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.
Ji Hye Yang Sae Kwang Ku IL Je Cho Je Hyeon Lee Chang-Su Na Sung Hwan Ki 《International journal of molecular sciences》2021,22(4)
Hepatic fibrosis occurs when liver tissue becomes scarred from repetitive liver injury and inflammatory responses; it can progress to cirrhosis and eventually to hepatocellular carcinoma. Previously, we reported that neoagarooligosaccharides (NAOs), produced by the hydrolysis of agar by β-agarases, have hepatoprotective effects against acetaminophen overdose-induced acute liver injury. However, the effect of NAOs on chronic liver injury, including hepatic fibrosis, has not yet been elucidated. Therefore, we examined whether NAOs protect against fibrogenesis in vitro and in vivo. NAOs ameliorated PAI-1, α-SMA, CTGF and fibronectin protein expression and decreased mRNA levels of fibrogenic genes in TGF-β-treated LX-2 cells. Furthermore, downstream of TGF-β, the Smad signaling pathway was inhibited by NAOs in LX-2 cells. Treatment with NAOs diminished the severity of hepatic injury, as evidenced by reduction in serum alanine aminotransferase and aspartate aminotransferase levels, in carbon tetrachloride (CCl4)-induced liver fibrosis mouse models. Moreover, NAOs markedly blocked histopathological changes and collagen accumulation, as shown by H&E and Sirius red staining, respectively. Finally, NAOs antagonized the CCl4-induced upregulation of the protein and mRNA levels of fibrogenic genes in the liver. In conclusion, our findings suggest that NAOs may be a promising candidate for the prevention and treatment of chronic liver injury via inhibition of the TGF-β/Smad signaling pathway. 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