全文获取类型
收费全文 | 98407篇 |
免费 | 7312篇 |
国内免费 | 3509篇 |
专业分类
电工技术 | 5070篇 |
技术理论 | 10篇 |
综合类 | 5827篇 |
化学工业 | 17285篇 |
金属工艺 | 5041篇 |
机械仪表 | 5947篇 |
建筑科学 | 7791篇 |
矿业工程 | 2256篇 |
能源动力 | 2849篇 |
轻工业 | 6904篇 |
水利工程 | 1704篇 |
石油天然气 | 4888篇 |
武器工业 | 583篇 |
无线电 | 11545篇 |
一般工业技术 | 12566篇 |
冶金工业 | 5065篇 |
原子能技术 | 926篇 |
自动化技术 | 12971篇 |
出版年
2024年 | 184篇 |
2023年 | 1425篇 |
2022年 | 2173篇 |
2021年 | 3628篇 |
2020年 | 2788篇 |
2019年 | 2348篇 |
2018年 | 2645篇 |
2017年 | 2956篇 |
2016年 | 2721篇 |
2015年 | 3615篇 |
2014年 | 4896篇 |
2013年 | 6129篇 |
2012年 | 6460篇 |
2011年 | 6800篇 |
2010年 | 6008篇 |
2009年 | 5829篇 |
2008年 | 5474篇 |
2007年 | 5285篇 |
2006年 | 5359篇 |
2005年 | 4548篇 |
2004年 | 3030篇 |
2003年 | 2652篇 |
2002年 | 2314篇 |
2001年 | 2095篇 |
2000年 | 2354篇 |
1999年 | 2612篇 |
1998年 | 2428篇 |
1997年 | 1922篇 |
1996年 | 1732篇 |
1995年 | 1466篇 |
1994年 | 1226篇 |
1993年 | 890篇 |
1992年 | 664篇 |
1991年 | 547篇 |
1990年 | 412篇 |
1989年 | 369篇 |
1988年 | 316篇 |
1987年 | 169篇 |
1986年 | 161篇 |
1985年 | 106篇 |
1984年 | 93篇 |
1983年 | 62篇 |
1982年 | 59篇 |
1981年 | 55篇 |
1980年 | 43篇 |
1979年 | 33篇 |
1978年 | 13篇 |
1977年 | 36篇 |
1976年 | 17篇 |
1975年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 218 毫秒
1.
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
3.
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
4.
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
5.
6.
Fan Deng-Ping Huang Ziling Zheng Peng Liu Hong Qin Xuebin Van Gool Luc 《国际自动化与计算杂志》2022,19(4):257-287
Machine Intelligence Research - This paper aims to conduct a comprehensive study on facial-sketch synthesis (FSS). However, due to the high cost of obtaining hand-drawn sketch datasets, there is a... 相似文献
7.
Multimedia Tools and Applications - The study presents a new approach to automate segmentation of clinically significant brain tumor and, to a certain extent, addresses two major issues associated... 相似文献
8.
Ping-Chi Hsu Jia-Ying Jhong Li-Ping Huang Kuo-Hsin Lee Hsin-Pao Chen Yue-Leon Guo 《International journal of molecular sciences》2021,22(8)
Di(2-ethylhexyl) phthalate (DEHP) is widely used as a plasticizer in the manufacture of polyvinylchloride plastics and has been associated with concerns regarding male reproductive toxicity. In this study, we hypothesized that maternal exposure to DEHP induces transgenerational inheritance of adult-onset adverse reproductive outcomes through the male germline in the F1, F2, and F3 generations of male offspring. Pregnant rats were treated with 5 or 500 mg of DEHP/kg/day through gavage from gestation day 0 to birth. The offspring body weight, anogenital distance (AGD), anogenital index (AGI), sperm count, motility, and DNA fragmentation index (DFI) were measured for all generations. Methyl-CpG binding domain sequencing was performed to analyze sperm DNA methylation status in the F3. DEHP exposure at 500 mg/kg affected AGD, AGI, sperm count, mean DFI, and %DFI in the F1; AGD, sperm count, and mean DFI in the F2; and AGD, AGI, mean DFI, and %DFI in the F3. DEHP exposure at 5 mg/kg affected AGD, AGI, sperm count, and %DFI in the F1; sperm count in the F2; and AGD and AGI in F3. Compared with the control group, 15 and 45 differentially hypermethylated genes were identified in the groups administered 5 mg/kg and 500 mg/kg DEHP, respectively. Moreover, 130 and 6 differentially hypomethylated genes were observed in the groups administered 5 mg/kg and 500 mg/kg DEHP. Overall, these results demonstrated that prenatal exposure to DEHP caused transgenerational epigenetic effects, which may explain the observed phenotypic changes in the male reproductive system. 相似文献
9.
通过对EBZ-260型掘进机截割头的截割性能进行分析和研究,深入了解和掌握了相关截割头的数据参数、设计结构及载荷等情况,进一步研究了截割头的受力情况、形状结构及其截齿运行轨迹及安装分布等特性,可为截割工作提供必要的数据参考及理论基础,有利于重要部件的有限元分析,对研究掘进机整机受力的情况、截割的性能、所具备的可靠性及稳定性等方面具有重要作用. 相似文献
10.
分析研究目前通信工程网络安全问题,提出几点解决问题的对策,旨在为提升通信工程网络安全性提供一定的帮助,以此来促使通信工程网络系统安全性的提升。 相似文献