全文获取类型
收费全文 | 437962篇 |
免费 | 6204篇 |
国内免费 | 1520篇 |
专业分类
电工技术 | 8023篇 |
综合类 | 930篇 |
化学工业 | 62638篇 |
金属工艺 | 16930篇 |
机械仪表 | 14245篇 |
建筑科学 | 9098篇 |
矿业工程 | 2535篇 |
能源动力 | 11891篇 |
轻工业 | 29871篇 |
水利工程 | 4764篇 |
石油天然气 | 7946篇 |
武器工业 | 21篇 |
无线电 | 50864篇 |
一般工业技术 | 85918篇 |
冶金工业 | 92302篇 |
原子能技术 | 9349篇 |
自动化技术 | 38361篇 |
出版年
2021年 | 3897篇 |
2020年 | 2948篇 |
2019年 | 3840篇 |
2018年 | 6910篇 |
2017年 | 7100篇 |
2016年 | 7897篇 |
2015年 | 5052篇 |
2014年 | 7520篇 |
2013年 | 20375篇 |
2012年 | 13320篇 |
2011年 | 17466篇 |
2010年 | 12743篇 |
2009年 | 14396篇 |
2008年 | 14591篇 |
2007年 | 14359篇 |
2006年 | 12919篇 |
2005年 | 14216篇 |
2004年 | 12910篇 |
2003年 | 12346篇 |
2002年 | 10625篇 |
2001年 | 10430篇 |
2000年 | 9395篇 |
1999年 | 10003篇 |
1998年 | 29037篇 |
1997年 | 19654篇 |
1996年 | 14820篇 |
1995年 | 10677篇 |
1994年 | 9148篇 |
1993年 | 9197篇 |
1992年 | 6206篇 |
1991年 | 5885篇 |
1990年 | 5877篇 |
1989年 | 5484篇 |
1988年 | 5220篇 |
1987年 | 4561篇 |
1986年 | 4413篇 |
1985年 | 4918篇 |
1984年 | 4434篇 |
1983年 | 4016篇 |
1982年 | 3713篇 |
1981年 | 3842篇 |
1980年 | 3561篇 |
1979年 | 3357篇 |
1978年 | 3390篇 |
1977年 | 4271篇 |
1976年 | 6023篇 |
1975年 | 2925篇 |
1974年 | 2671篇 |
1973年 | 2748篇 |
1972年 | 2305篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
High Temperature - The influence of heating from 260 to 400 K on the structure and mechanism of the formation of a molecular water film adsorbed on the walls of a plane fracture with the width of... 相似文献
92.
93.
94.
Bochkareva N. I. Ivanov A. M. Klochkov A. V. Kogotkov V. S. Rebane Yu. T. Virko M. V. Shreter Y. G. 《Semiconductors》2015,49(6):827-835
Semiconductors - It is shown that the emission efficiency and the 1/f noise level in light-emitting diodes with InGaN/GaN quantum wells correlate with how the differential resistance of a diode... 相似文献
95.
Angelico Mendy Nervana Metwali Sarah S. Perry Elizabeth A. Chrischilles Kai Wang Peter S. Thorne 《Indoor air》2020,30(1):88-97
Endotoxin exacerbates asthma. We designed the Louisa Environmental Intervention Project (LEIP) and assessed its effectiveness in reducing household endotoxin and improving asthma symptoms in rural Iowa children. Asthmatic school children (N = 104 from 89 homes) of Louisa and Keokuk counties in Iowa (aged 5-14 years) were recruited and block-randomized to receive extensive (education + professional cleaning) or educational interventions. Environmental sampling collection and respiratory survey administration were done at baseline and during three follow-up visits. Mixed-model analyses were used to assess the effect of the intervention on endotoxin levels and asthma symptoms in the main analysis and of endotoxin reduction on asthma symptoms in exploratory analysis. In the extensive intervention group, dust endotoxin load was significantly reduced in post-intervention visits. The extensive compared with the educational intervention was associated with significantly decreased dust endotoxin load in farm homes and less frequent nighttime asthma symptoms. In exploratory analysis, dust endotoxin load reduction from baseline was associated with lower total asthma symptoms score (Odds ratio: 0.52, 95% confidence interval: 0.29-0.92). In conclusion, the LEIP intervention reduced household dust endotoxin and improved asthma symptoms. However, endotoxin reductions were not sustained post-intervention by residents. 相似文献
96.
Rafaelle Spear Ludovic Boytard Renaud Blervaque Maggy Chwastyniak David Hot Jonathan Vanhoutte Bart Staels Yves Lemoine Nicolas Lamblin Fran?ois-René Pruvot Stephan Haulon Philippe Amouyel Florence Pinet 《International journal of molecular sciences》2015,16(5):11276-11293
Abdominal aortic aneurysm (AAA) is an inflammatory disease associated with marked changes in the cellular composition of the aortic wall. This study aims to identify microRNA (miRNA) expression in aneurysmal inflammatory cells isolated by laser microdissection from human tissue samples. The distribution of inflammatory cells (neutrophils, B and T lymphocytes, mast cells) was evaluated in human AAA biopsies. We observed in half of the samples that adventitial tertiary lymphoid organs (ATLOs) with a thickness from 0.5 to 2 mm were located exclusively in the adventitia. Out of the 850 miRNA that were screened by microarray in isolated ATLOs (n = 2), 164 miRNAs were detected in ATLOs. The three miRNAs (miR-15a-3p, miR-30a-5p and miR-489-3p) with the highest expression levels were chosen and their expression quantified by RT-PCR in isolated ATLOs (n = 4), M1 (n = 2) and M2 macrophages (n = 2) and entire aneurysmal biopsies (n = 3). Except for the miR-30a-5p, a similar modulation was found in ATLOs and the two subtypes of macrophages. The modulated miRNAs were then evaluated in the plasma of AAA patients for their potential as AAA biomarkers. Our data emphasize the potential of miR-15a-3p and miR-30a-5p as biomarkers of AAA but also as triggers of ATLO evolution. Further investigations will be required to evaluate their targets in order to better understand AAA pathophysiology. 相似文献
97.
98.
99.
100.