全文获取类型
收费全文 | 328991篇 |
免费 | 6160篇 |
国内免费 | 1470篇 |
专业分类
电工技术 | 5564篇 |
综合类 | 605篇 |
化学工业 | 49009篇 |
金属工艺 | 13095篇 |
机械仪表 | 11338篇 |
建筑科学 | 7521篇 |
矿业工程 | 1625篇 |
能源动力 | 9053篇 |
轻工业 | 26079篇 |
水利工程 | 3268篇 |
石油天然气 | 5961篇 |
武器工业 | 44篇 |
无线电 | 42756篇 |
一般工业技术 | 66953篇 |
冶金工业 | 56321篇 |
原子能技术 | 8073篇 |
自动化技术 | 29356篇 |
出版年
2021年 | 3501篇 |
2020年 | 2592篇 |
2019年 | 3043篇 |
2018年 | 4874篇 |
2017年 | 4965篇 |
2016年 | 5513篇 |
2015年 | 3752篇 |
2014年 | 6326篇 |
2013年 | 15325篇 |
2012年 | 10150篇 |
2011年 | 13498篇 |
2010年 | 10425篇 |
2009年 | 11801篇 |
2008年 | 11871篇 |
2007年 | 11457篇 |
2006年 | 9924篇 |
2005年 | 9062篇 |
2004年 | 8929篇 |
2003年 | 8553篇 |
2002年 | 8266篇 |
2001年 | 8038篇 |
2000年 | 7593篇 |
1999年 | 7875篇 |
1998年 | 18354篇 |
1997年 | 12907篇 |
1996年 | 9615篇 |
1995年 | 7674篇 |
1994年 | 6622篇 |
1993年 | 6630篇 |
1992年 | 4799篇 |
1991年 | 4586篇 |
1990年 | 4409篇 |
1989年 | 4355篇 |
1988年 | 3988篇 |
1987年 | 3595篇 |
1986年 | 3578篇 |
1985年 | 3905篇 |
1984年 | 3608篇 |
1983年 | 3314篇 |
1982年 | 3137篇 |
1981年 | 3122篇 |
1980年 | 3108篇 |
1979年 | 2896篇 |
1978年 | 2927篇 |
1977年 | 3236篇 |
1976年 | 4224篇 |
1975年 | 2480篇 |
1974年 | 2436篇 |
1973年 | 2435篇 |
1972年 | 2054篇 |
排序方式: 共有10000条查询结果,搜索用时 187 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
2.
Wireless Personal Communications - Chronic kidney disease (CKD) is a gradual loss of kidney function over the period of time and it is irrevocable once functionality reaches the critical state.... 相似文献
3.
4.
5.
Muniyandi Kasipandi Jagadeesan Gayathri George Blassan P. Manoharan Ashwini Lydia Nataraj Gayathri Abrahamse Heidi Thangaraj Parimelazhagan 《Food science and biotechnology》2022,31(13):1717-1728
Food Science and Biotechnology - A rich source of nutrients, figs have a number of clinically validated benefits. This study aimed to evaluate the in vitro simulated gastrointestinal digestion, and... 相似文献
6.
Multimedia Tools and Applications - In this work, a new fuzzy logic-based algorithm is proposed for the enhancement of low light color images. A generalization of a fuzzy set known as an... 相似文献
7.
Shin Hansub Sim Sungyong Kwon Hyukyoon Hwang Sangheum Lee Younho 《International Journal of Information Security》2022,21(1):25-36
International Journal of Information Security - This paper deals with a well-known problem in the area of the smudge attacks: when a user draws a pattern to unlock the pattern lock on a smartphone... 相似文献
8.
Karimi Bayan Chang Yu-Cheng Pekola Jukka P. 《Journal of Low Temperature Physics》2022,207(3-4):220-225
We discuss the temperature dependence of a common low temperature local thermometer, a tunnel junction between a superconductor and a normal metal (NIS junction). Towards the lowest temperatures its characteristics tend to saturate, which is usually attributed to selfheating effects. In this technical note, we reanalyze this saturation and show that the temperature independent subgap current of the junction alone explains in some cases the low temperature behavior quantitatively.
相似文献9.
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
10.