全文获取类型
收费全文 | 4448篇 |
免费 | 240篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 55篇 |
综合类 | 4篇 |
化学工业 | 1162篇 |
金属工艺 | 64篇 |
机械仪表 | 79篇 |
建筑科学 | 159篇 |
矿业工程 | 18篇 |
能源动力 | 177篇 |
轻工业 | 791篇 |
水利工程 | 24篇 |
石油天然气 | 16篇 |
无线电 | 212篇 |
一般工业技术 | 717篇 |
冶金工业 | 204篇 |
原子能技术 | 21篇 |
自动化技术 | 987篇 |
出版年
2024年 | 14篇 |
2023年 | 49篇 |
2022年 | 201篇 |
2021年 | 199篇 |
2020年 | 124篇 |
2019年 | 147篇 |
2018年 | 186篇 |
2017年 | 176篇 |
2016年 | 179篇 |
2015年 | 154篇 |
2014年 | 193篇 |
2013年 | 339篇 |
2012年 | 329篇 |
2011年 | 361篇 |
2010年 | 283篇 |
2009年 | 240篇 |
2008年 | 253篇 |
2007年 | 211篇 |
2006年 | 163篇 |
2005年 | 147篇 |
2004年 | 105篇 |
2003年 | 95篇 |
2002年 | 93篇 |
2001年 | 44篇 |
2000年 | 39篇 |
1999年 | 34篇 |
1998年 | 46篇 |
1997年 | 33篇 |
1996年 | 26篇 |
1995年 | 43篇 |
1994年 | 18篇 |
1993年 | 17篇 |
1992年 | 12篇 |
1991年 | 17篇 |
1990年 | 13篇 |
1989年 | 13篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 5篇 |
1985年 | 7篇 |
1984年 | 11篇 |
1983年 | 8篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1975年 | 8篇 |
1974年 | 3篇 |
排序方式: 共有4690条查询结果,搜索用时 15 毫秒
81.
Stefan Weinschenk Carsten Weiss Justus Benrath Volker von Baehr Thomas Strowitzki Manuel Feißt 《International journal of molecular sciences》2022,23(6)
Background. Local anesthetics (LAs) have potent anti-inflammatory properties. Inflammatory down-regulation is crucial in diseases with overactive immune reactions, such as acute respiratory distress syndrome (ARDS) and chronic inflammation. We investigated the influence of four LAs, procaine, lidocaine, mepivacaine, and bupivacaine, on the reduction of tumor necrosis factor-alpha (TNF-α) secretion in lipopolysaccharide (LPS)-activated human leucocytes. Methods. Blood samples of 28 individuals were stimulated with LPS. The reduction of TNF-α production by each of the four LAs added (0.5 mg/mL) was measured and correlated with biometric variables. A response was defined as reduction to <85% of initial levels. Results. All four LAs down-regulated the TNF-α secretion in 44–61%: Bupivacaine (44.4%), lidocaine (61.5%), mepivacaine (44.4%), and procaine (50% of the individuals, “responders”). The TNF-α secretion was reduced to 67.4, 68.0, 63.6, and 67.1% of the initial values in responders. The effects in both patients and healthy persons were the same. Interindividual responses to LAs were not correlated with the duration or type of complaints, basal TNF-α serum level, sex, BMI, or age of responders. Conclusions. Four clinically relevant LAs (amid-LA and ester-LA) attenuate the inflammatory response provoked by LPS. They are potential candidates for drug repositioning in treating overactive immune reactions and chronic inflammation. 相似文献
82.
83.
The combined effect of resistance spot welding and precipitation hardening on the localised corrosion of A286 superalloy is studied. The specimens tested by double loop electrochemical potentiokinetic reactivation were welded in the solution treated condition, and then subjected to different precipitation hardening treatments. For both base metal and weld nugget, the maximum localised corrosion is reached when η phase is clearly observable. The fact that the localised corrosion resistance of weld nugget is different from that shown by base metal may be explained by the segregation of Ni and Ti towards the interdendritic region of weld nugget (studied by using scanning electron microscope/energy dispersive X-ray analysis). 相似文献
84.
Dolz Manuel F. Alventosa Fran J. Alonso-Jordá Pedro Vidal Antonio M. 《The Journal of supercomputing》2019,75(3):1470-1482
The Journal of Supercomputing - There exist problems in the field of digital signal processing, such as filtering of acoustic signals that require processing a large amount of data in real time.... 相似文献
85.
86.
87.
88.
89.
Antonio C. Fuentes-Fayos Miguel E. G-García Jesús M. Prez-Gmez Annabel Peel Cristbal Blanco-Acevedo Juan Solivera Alejandro Ibez-Costa Manuel D. Gahete Justo P. Castao Raúl M. Luque 《International journal of molecular sciences》2022,23(3)
Glioblastoma (GBM) is the most malignant and lethal brain tumor. Current standard treatment consists of surgery followed by radiotherapy/chemotherapy; however, this is only a palliative approach with a mean post-operative survival of scarcely ~12–15 months. Thus, the identification of novel therapeutic targets to treat this devastating pathology is urgently needed. In this context, the truncated splicing variant of the somatostatin receptor subtype 5 (sst5TMD4), which is produced by aberrant alternative splicing, has been demonstrated to be overexpressed and associated with increased aggressiveness features in several tumors. However, the presence, functional role, and associated molecular mechanisms of sst5TMD4 in GBM have not been yet explored. Therefore, we performed a comprehensive analysis to characterize the expression and pathophysiological role of sst5TMD4 in human GBM. sst5TMD4 was significantly overexpressed (at mRNA and protein levels) in human GBM tissue compared to non-tumor (control) brain tissue. Remarkably, sst5TMD4 expression was significantly associated with poor overall survival and recurrent tumors in GBM patients. Moreover, in vitro sst5TMD4 overexpression (by specific plasmid) increased, whereas sst5TMD4 silencing (by specific siRNA) decreased, key malignant features (i.e., proliferation and migration capacity) of GBM cells (U-87 MG/U-118 MG models). Furthermore, sst5TMD4 overexpression in GBM cells altered the activity of multiple key signaling pathways associated with tumor aggressiveness/progression (AKT/JAK-STAT/NF-κB/TGF-β), and its silencing sensitized GBM cells to the antitumor effect of pasireotide (a somatostatin analog). Altogether, these results demonstrate that sst5TMD4 is overexpressed and associated with enhanced malignancy features in human GBMs and reveal its potential utility as a novel diagnostic/prognostic biomarker and putative therapeutic target in GBMs. 相似文献
90.
Summary Acenaphthylene was polymerized in methylenedichloride at 273, 291 and 308 K by sulphuric acid. The initiation step takes place by addition of the proton of sulphuric acid to the monomer. The propagation step is through ion-pairs, and the propagation constants are first-order with respect to the monomer and initiator(kp = 0.22 M–1. s–1(273K), kp=0.88 M–1. s–1(291K), kp = 2.81 M–1. s–1 (308K)). There is not appreciable loss of active centres, being this confirmed by experiments carried out with succesive additions of monomer. The molecular weights obtained confirm the importance of processes to monomer in this polymerization. 相似文献