全文获取类型
收费全文 | 6684篇 |
免费 | 393篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 98篇 |
综合类 | 5篇 |
化学工业 | 1726篇 |
金属工艺 | 161篇 |
机械仪表 | 176篇 |
建筑科学 | 191篇 |
矿业工程 | 42篇 |
能源动力 | 278篇 |
轻工业 | 1009篇 |
水利工程 | 56篇 |
石油天然气 | 27篇 |
无线电 | 492篇 |
一般工业技术 | 1069篇 |
冶金工业 | 842篇 |
原子能技术 | 58篇 |
自动化技术 | 858篇 |
出版年
2024年 | 17篇 |
2023年 | 70篇 |
2022年 | 151篇 |
2021年 | 270篇 |
2020年 | 187篇 |
2019年 | 197篇 |
2018年 | 215篇 |
2017年 | 213篇 |
2016年 | 235篇 |
2015年 | 176篇 |
2014年 | 310篇 |
2013年 | 431篇 |
2012年 | 421篇 |
2011年 | 431篇 |
2010年 | 348篇 |
2009年 | 325篇 |
2008年 | 324篇 |
2007年 | 307篇 |
2006年 | 218篇 |
2005年 | 183篇 |
2004年 | 145篇 |
2003年 | 135篇 |
2002年 | 126篇 |
2001年 | 106篇 |
2000年 | 85篇 |
1999年 | 89篇 |
1998年 | 204篇 |
1997年 | 143篇 |
1996年 | 107篇 |
1995年 | 96篇 |
1994年 | 71篇 |
1993年 | 89篇 |
1992年 | 46篇 |
1991年 | 46篇 |
1990年 | 37篇 |
1989年 | 31篇 |
1988年 | 45篇 |
1987年 | 27篇 |
1986年 | 24篇 |
1985年 | 34篇 |
1984年 | 28篇 |
1983年 | 22篇 |
1982年 | 28篇 |
1981年 | 23篇 |
1980年 | 18篇 |
1979年 | 16篇 |
1977年 | 24篇 |
1976年 | 26篇 |
1972年 | 14篇 |
1943年 | 21篇 |
排序方式: 共有7088条查询结果,搜索用时 15 毫秒
1.
2.
Gabriela Pitolli Lyra Valdemir Santos Eliria Maria de Jesus Agnolon Pallone Ruth Herta Goldschmidt Aliaga Kiminami Bruno Carlos De Santis João Adriano Rossignolo 《International Journal of Applied Ceramic Technology》2021,18(3):705-715
This work aimed to examine the performance of the hybrid sintering of clay ceramic in a microwave furnace, compared to the sintering process in a conventional furnace. The raw materials were subjected to X-ray fluorescence, loss on ignition (LOI), X-ray diffraction, particle size distribution, real specific mass, and thermogravimetric analyses. The red clay ceramic mass was prepared, extruded, pre-sintered in a conventional furnace at 600°C/60 min, and sintered at temperatures between 700 °C and 1100 °C. The sintering conventional (resistive oven) was carried out for 60 min with a heating rate of 10°C/min. In the microwave furnace, the sintering times were 5, 10, and 15 min, with a heating rate of 50°C/min, with a sintering chamber coated with silicon carbide (susceptor). The sintered specimens were characterized according to linear shrinkage, water absorption, apparent porosity, apparent specific mass, X-ray diffraction, Raman spectroscopy analysis, spectroscopy analysis in the ultraviolet and visible regions, microhardness, and scanning electron microscopy. The results showed that microwave sintering promoted an increase in the microhardness and apparent specific mass, and reduction in water absorption and apparent porosity values, due to greater densification in the microstructure. The best results occurred for specimens sintered at 1100°C. 相似文献
3.
Juliano Henrique Borges Daniel Minutti de Oliveira Sofia Helena Valente de Lemos-Marini Bruno Geloneze Ezequiel Moreira Gonçalves Gil Guerra-Júnior 《Lipids》2021,56(1):101-110
We aimed to compare detailed fat distribution and lipid profile between young adults with congenital adrenal hyperplasia due to 21-hydroxylase enzyme deficiency and a control group. We also verified independent associations of treatment duration and daily hydrocortisone dose equivalent (HDE) with lipid profile within patients. This case–control study included 23 patients (7 male and 16 female) matched by an age range of young adults (18–31 years) with 20 control subjects (8 male and 12 female). Dual energy X-ray absorptiometry was used to measure the fat distribution. Male patients demonstrated elevated indices of fat mass for total (7.7 ± 2.1 vs. 4.5 ± 1.3 kg/m2, p = 0.003), trunk (4.0 ± 1.2 vs. 2.2 ± 0.8 kg/m2, p = 0.005), android (0.63 ± 0.24 vs. 0.32 ± 0.15 kg/m2, p = 0.008), gynoid (1.34 ± 0.43 vs. 0.74 ± 0.24 kg/m2, p = 0.005), arm (0.65 ± 0.16 vs. 0.39 ± 0.10 kg/m2, p = 0.009), and leg regions (2.7 ± 0.8 vs. 1.6 ± 0.4 kg/m2, p = 0.005) than the control group, but not in females. However, female patients demonstrated elevated ratio of low-density lipoprotein cholesterol to high-density lipoprotein cholesterol (1.90 ± 0.46 vs. 1.39 ± 0.47, p = 0.009) than the control group, but not in males. Total fat mass was inversely correlated with total testosterone (r = −0.64, p = 0.014) and positively correlated with leptin in males (r = 0.75, p = 0.002). An elevated daily HDE (β = 0.43, p = 0.038 and β = 0.47, p = 0.033) and trunk to total fat mass ratio (β = 0.46, p = 0.025, and β = 0.45, p = 0.037) were independently correlated with impaired lipid profile markers. Although there is no altered lipid profile, male patients demonstrated an increased fat distribution. However, female patients presented with an impaired lipid profile marker but demonstrated close values of normal fat distribution. Interestingly, the dose of glucocorticoid therapy can have some role in the lipid mechanisms. 相似文献
4.
5.
6.
7.
8.
9.