全文获取类型
收费全文 | 81964篇 |
免费 | 15033篇 |
国内免费 | 9883篇 |
专业分类
电工技术 | 9597篇 |
技术理论 | 2篇 |
综合类 | 10045篇 |
化学工业 | 2950篇 |
金属工艺 | 1784篇 |
机械仪表 | 5885篇 |
建筑科学 | 2249篇 |
矿业工程 | 1410篇 |
能源动力 | 1660篇 |
轻工业 | 3703篇 |
水利工程 | 1596篇 |
石油天然气 | 2996篇 |
武器工业 | 1282篇 |
无线电 | 13327篇 |
一般工业技术 | 5156篇 |
冶金工业 | 753篇 |
原子能技术 | 487篇 |
自动化技术 | 41998篇 |
出版年
2024年 | 242篇 |
2023年 | 1502篇 |
2022年 | 2933篇 |
2021年 | 3213篇 |
2020年 | 3462篇 |
2019年 | 2855篇 |
2018年 | 2694篇 |
2017年 | 2947篇 |
2016年 | 3386篇 |
2015年 | 4210篇 |
2014年 | 5692篇 |
2013年 | 5484篇 |
2012年 | 7109篇 |
2011年 | 7342篇 |
2010年 | 5908篇 |
2009年 | 5985篇 |
2008年 | 6404篇 |
2007年 | 7033篇 |
2006年 | 5740篇 |
2005年 | 4721篇 |
2004年 | 3871篇 |
2003年 | 3109篇 |
2002年 | 2310篇 |
2001年 | 1807篇 |
2000年 | 1539篇 |
1999年 | 1148篇 |
1998年 | 885篇 |
1997年 | 712篇 |
1996年 | 541篇 |
1995年 | 404篇 |
1994年 | 360篇 |
1993年 | 269篇 |
1992年 | 260篇 |
1991年 | 130篇 |
1990年 | 161篇 |
1989年 | 117篇 |
1988年 | 81篇 |
1987年 | 31篇 |
1986年 | 39篇 |
1985年 | 40篇 |
1984年 | 30篇 |
1983年 | 23篇 |
1982年 | 27篇 |
1981年 | 16篇 |
1980年 | 26篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1975年 | 9篇 |
1959年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
1.
2.
介绍了用AC8612气相色谱仪对六个汽油组分馏程分析的应用情况,结果表明:该方法的重复性和准确性都较好,与D86相比,结果满足方法的再现性要求,但对于差值大于3℃的点,应定期进行修正,以使结果更准确,该方法用于炼油厂各装置汽油组分馏出口的日常质量监测分析,可以提高分析效率并减少劳动强度。 相似文献
3.
4.
Liudmila Zakharova Viktoria Sharova Marina Izvolskaia 《International journal of molecular sciences》2021,22(1)
Different aspects of the reciprocal regulatory influence on the development of gonadotropin-releasing hormone (GnRH)-producing- and immune systems in the perinatal ontogenesis and their functioning in adults in normal and pathological conditions are discussed. The influence of GnRH on the development of the immune system, on the one hand, and the influence of proinflammatory cytokines on the development of the hypothalamic-pituitary-gonadal system, on the other hand, and their functioning in adult offspring are analyzed. We have focused on the effects of GnRH on the formation and functional activity of the thymus, as the central organ of the immune system, in the perinatal period. The main mechanisms of reciprocal regulation of these systems are discussed. The reproductive health of an individual is programmed by the establishment and development of physiological systems during critical periods. Regulatory epigenetic mechanisms of development are not strictly genetically controlled. These processes are characterized by a high sensitivity to various regulatory factors, which provides possible corrections for disorders. 相似文献
5.
6.
7.
8.
9.
10.
Matthew Thomas Ferreira Juliano Andreoli Miyake Renata Nascimento Gomes Fbio Feitoza Pollyana Bulgarelli Stevannato Andrew Silva da Cunha Fernanda de Oliveira Serachi Alexandros Theodoros Panagopoulos Alison Colquhoun 《International journal of molecular sciences》2021,22(9)
Prostaglandin E2 (PGE2) is known to increase glioblastoma (GBM) cell proliferation and migration while cyclooxygenase (COX) inhibition decreases proliferation and migration. The present study investigated the effects of COX inhibitors and PGE2 receptor antagonists on GBM cell biology. Cells were grown with inhibitors and dose response, viable cell counting, flow cytometry, cell migration, gene expression, Western blotting, and gelatin zymography studies were performed. The stimulatory effects of PGE2 and the inhibitory effects of ibuprofen (IBP) were confirmed in GBM cells. The EP2 and EP4 receptors were identified as important mediators of the actions of PGE2 in GBM cells. The concomitant inhibition of EP2 and EP4 caused a significant decrease in cell migration which was not reverted by exogenous PGE2. In T98G cells exogenous PGE2 increased latent MMP2 gelatinolytic activity. The inhibition of COX1 or COX2 caused significant alterations in MMP2 expression and gelatinolytic activity in GBM cells. These findings provide further evidence for the importance of PGE2 signalling through the EP2 and the EP4 receptor in the control of GBM cell biology. They also support the hypothesis that a relationship exists between COX1 and MMP2 in GBM cells which merits further investigation as a novel therapeutic target for drug development. 相似文献