全文获取类型
收费全文 | 8014篇 |
免费 | 658篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 171篇 |
综合类 | 30篇 |
化学工业 | 1911篇 |
金属工艺 | 214篇 |
机械仪表 | 217篇 |
建筑科学 | 304篇 |
矿业工程 | 37篇 |
能源动力 | 281篇 |
轻工业 | 1211篇 |
水利工程 | 63篇 |
石油天然气 | 60篇 |
武器工业 | 1篇 |
无线电 | 614篇 |
一般工业技术 | 1788篇 |
冶金工业 | 234篇 |
原子能技术 | 79篇 |
自动化技术 | 1472篇 |
出版年
2024年 | 33篇 |
2023年 | 87篇 |
2022年 | 102篇 |
2021年 | 235篇 |
2020年 | 238篇 |
2019年 | 200篇 |
2018年 | 389篇 |
2017年 | 408篇 |
2016年 | 448篇 |
2015年 | 293篇 |
2014年 | 405篇 |
2013年 | 829篇 |
2012年 | 521篇 |
2011年 | 647篇 |
2010年 | 454篇 |
2009年 | 445篇 |
2008年 | 367篇 |
2007年 | 368篇 |
2006年 | 236篇 |
2005年 | 258篇 |
2004年 | 186篇 |
2003年 | 170篇 |
2002年 | 205篇 |
2001年 | 108篇 |
2000年 | 86篇 |
1999年 | 68篇 |
1998年 | 94篇 |
1997年 | 86篇 |
1996年 | 71篇 |
1995年 | 54篇 |
1994年 | 47篇 |
1993年 | 37篇 |
1992年 | 29篇 |
1991年 | 32篇 |
1990年 | 19篇 |
1989年 | 25篇 |
1988年 | 20篇 |
1986年 | 16篇 |
1985年 | 34篇 |
1984年 | 28篇 |
1983年 | 21篇 |
1982年 | 23篇 |
1981年 | 23篇 |
1980年 | 22篇 |
1979年 | 28篇 |
1978年 | 23篇 |
1977年 | 18篇 |
1976年 | 20篇 |
1974年 | 18篇 |
1973年 | 19篇 |
排序方式: 共有8687条查询结果,搜索用时 15 毫秒
1.
2.
Aleksandar Miletić Peter Panjan Miha Čekada Lazar Kovačević Pal Terek Janez Kovač Goran Dražič Branko Škorić 《Ceramics International》2021,47(2):2022-2033
With the goal to produce a hard and tough coating intended for tribological applications, CrAlN/TiSiN nanolayer coating was prepared by alternative deposition of CrAlN and TiSiN layers. In the first part of the article, a detailed study of phase composition, microstructure, and layer structure of CrAlN/TiSiN coating is presented. In the second part, its mechanical properties, fracture and tribological behavior are compared to the nanocomposite TiSiN coating. An industrial magnetron sputtering unit was used for coating deposition. X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used for compositional and microstructural analysis. Mechanical properties and fracture behavior were studied by instrumented indentation and focused ion beam techniques. Tribological properties were evaluated by ball-on-disk test in a linear reciprocal mode. A complex layer structure was found in the nanolayer coating. The TiSiN layers were epitaxially stabilized inside the coating which led to formation of dislocations at interfaces, to introduction of disturbances in the coating growth, and as a result, to development of fine-grained columnar microstructure. Indentation load required for the onset of fracture was twice lower for the nanolayer CrAlN/TiSiN, compared to the nanocomposite TiSiN coating. This agrees very well with their mechanical properties, with H3/E2 being twice higher for the TiSiN coating. However, the nanolayer coating experienced less severe damage, which had a strong impact on tribological behavior. A magnitude of order lower wear rate and four times lower steady state friction coefficient were found for the nanolayer coating. 相似文献
3.
Journal of Low Temperature Physics - This study modeled and investigated the magnetocaloric effect in Ni2MnGa Heusler alloy characterized by its magnetic entropy change (ΔSm) and its... 相似文献
4.
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
5.
6.
7.
8.
9.
Thin Film Thermoelectric Metal–Organic Framework with High Seebeck Coefficient and Low Thermal Conductivity 下载免费PDF全文
10.
Pierre Santucci Christina Dedaki Alexandros Athanasoulis Laura Gallorini Anaïs Munoz Dr. Stéphane Canaan Dr. Jean-François Cavalier Dr. Victoria Magrioti 《ChemMedChem》2019,14(3):349-358
In the quest for new antibacterial agents, a series of novel long- and medium-chain mono- and disubstituted β-lactones was developed. Their activity against three pathogenic mycobacteria—M. abscessus, M. marinum, and M. tuberculosis—was assessed by the resazurin microtiter assay (REMA). Among the 16 β-lactones synthesized, only 3-hexadecyloxetan-2-one (VM005) exhibited promising activity against M. abscessus, whereas most of the β-lactones showed interesting activities against M. marinum, similar to that of the classical antibiotic, isoniazid. Regarding M. tuberculosis, six compounds were found to be active against this mycobacterium, with β-lactone VM008 [trans-(Z)-3-(hexadec-7-en-1-yl)-4-propyloxetan-2-one] being the best growth inhibitor. The promising antibacterial activities of the best compounds in this series suggest that these molecules may serve as leads for the development of much more efficient antimycobacterial agents. 相似文献