全文获取类型
收费全文 | 6114篇 |
免费 | 330篇 |
国内免费 | 27篇 |
专业分类
电工技术 | 72篇 |
综合类 | 22篇 |
化学工业 | 1236篇 |
金属工艺 | 161篇 |
机械仪表 | 281篇 |
建筑科学 | 199篇 |
矿业工程 | 42篇 |
能源动力 | 229篇 |
轻工业 | 577篇 |
水利工程 | 46篇 |
石油天然气 | 26篇 |
武器工业 | 1篇 |
无线电 | 738篇 |
一般工业技术 | 1055篇 |
冶金工业 | 752篇 |
原子能技术 | 46篇 |
自动化技术 | 988篇 |
出版年
2023年 | 69篇 |
2022年 | 72篇 |
2021年 | 162篇 |
2020年 | 142篇 |
2019年 | 149篇 |
2018年 | 169篇 |
2017年 | 178篇 |
2016年 | 196篇 |
2015年 | 151篇 |
2014年 | 247篇 |
2013年 | 462篇 |
2012年 | 327篇 |
2011年 | 406篇 |
2010年 | 324篇 |
2009年 | 339篇 |
2008年 | 338篇 |
2007年 | 338篇 |
2006年 | 252篇 |
2005年 | 195篇 |
2004年 | 185篇 |
2003年 | 183篇 |
2002年 | 138篇 |
2001年 | 100篇 |
2000年 | 99篇 |
1999年 | 97篇 |
1998年 | 252篇 |
1997年 | 165篇 |
1996年 | 118篇 |
1995年 | 77篇 |
1994年 | 68篇 |
1993年 | 69篇 |
1992年 | 38篇 |
1991年 | 33篇 |
1990年 | 23篇 |
1989年 | 38篇 |
1988年 | 35篇 |
1987年 | 25篇 |
1986年 | 18篇 |
1985年 | 25篇 |
1984年 | 14篇 |
1983年 | 18篇 |
1982年 | 9篇 |
1981年 | 19篇 |
1980年 | 13篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 19篇 |
1976年 | 11篇 |
1975年 | 6篇 |
1973年 | 14篇 |
排序方式: 共有6471条查询结果,搜索用时 62 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.
3.
Nelaka Govinna Papatya Kaner Davette Ceasar Anita Dhungana Cody Moers Katherine Son Ayse Asatekin Peggy Cebe 《Polymer International》2019,68(2):231-239
Nonwoven super‐hydrophobic fiber membranes have potential applications in oil–water separation and membrane distillation, but fouling negatively impacts both applications. Membranes were prepared from blends comprising poly(vinylidene fluoride) (PVDF) and random zwitterionic copolymers of poly(methyl methacrylate) (PMMA) with sulfobetaine methacrylate (SBMA) or with sulfobetaine‐2‐vinylpyridine (SB2VP). PVDF imparts mechanical strength to the membrane, while the copolymers enhance fouling resistance. Blend composition was varied by controlling the PVDF‐to‐copolymer ratio. Nonwoven fiber membranes were obtained by electrospinning solutions of PVDF and the copolymers in a mixed solvent of N,N‐dimethylacetamide and acetone. The PVDF crystal phases and crystallinities of the blends were studied using wide‐angle X‐ray diffraction and differential scanning calorimetry (DSC). PVDF crystallized preferentially into its polar β‐phase, though its degree of crystallinity was reduced with increased addition of the random copolymers. Thermogravimetry (TG) showed that the degradation temperatures varied systematically with blend composition. PVDF blends with either copolymer showed significant increase of fouling resistance. Membranes prepared from blends containing 10% P(MMA‐ran‐SB2VP) had the highest fouling resistance, with a fivefold decrease in protein adsorption on the surface, compared to homopolymer PVDF. They also exhibited higher pure water flux, and better oil removal in oil–water separation experiments. © 2018 Society of Chemical Industry 相似文献
4.
5.
6.
7.
8.
Safety-critical software systems such as certain nuclear instrumentation and control (NI&C) systems should be developed with thorough verification. This study presents a method of software requirement verification with a case study for a nuclear power plant (NPP) protection system. The verification introduces colored petri net (CPN) for system modeling and prototype verification system (PVS) for mathematical verification. In order to aid flow-through from modeling by CPN to mathematical proof by PVS, an information extractor from CPN models has been developed in this paper. In order to convert the extracted information to the PVS specification language, a translator has also been developed. This combined method has been applied to the functional requirements of the Wolsong NPP Shut Down System #2 (SDS2); logical properties of the requirements were verified. Through this research, guidelines and a tool support for the use of formal methods have been developed for application to NI&C software verification. 相似文献
9.
欧盟的电信管制陷入了与国家政体冲突的泥潭中,尽管高层有一些关于改革的勇敢论调,但事实胜于雄辩。欧盟所规定的电信规则设想在这个有25个国家、超过4.5亿人口的市场,以远远超出这个范围的影响创造一个公平的竞争环境,它能奏效吗?于布鲁塞尔制定的电信政策在许多方面呈现多极化趋向,这反映了对泛欧“超级国家”实体更大的争议。根据每天问题的不同,随着观点的转移,欧洲电信规则被同等程度地喜爱和痛恨着。对一方来说很协调的东西,对另一方则成了毫无根据 相似文献
10.
JJ Jiménez-Nácher N de Alonso B Vega A del Río JL Moya V Barrios A Hurtado 《Canadian Metallurgical Quarterly》1993,193(6):290-292
Pericardial effusion (PE) as a hypothyroidism associated sign, is something that can be found with relative frequency; nevertheless, cardiac tamponade (CT) as the first sign of this disease may be considered exceptional especially in young patients. We report a 31 years old woman with clinical symptoms and signs of CT that in the forward workshop was diagnosed of primary hypothyroidism as cause of the CT. We shortly describe the case and review the literature, emphasizing the importance of the knowledge of CT trigger factors in myxedematous PE, as well as its usual benign evolution with hormonal treatment, without recurrences of the CT after pericardiocentesis is performed. This justify a conservative approach, in spite of the slow resolution of the PE what can take as long as 1.5 years. 相似文献