全文获取类型
收费全文 | 1171篇 |
免费 | 32篇 |
国内免费 | 59篇 |
专业分类
电工技术 | 30篇 |
综合类 | 23篇 |
化学工业 | 248篇 |
金属工艺 | 145篇 |
机械仪表 | 37篇 |
建筑科学 | 75篇 |
矿业工程 | 6篇 |
能源动力 | 49篇 |
轻工业 | 120篇 |
水利工程 | 4篇 |
石油天然气 | 49篇 |
武器工业 | 3篇 |
无线电 | 44篇 |
一般工业技术 | 238篇 |
冶金工业 | 66篇 |
原子能技术 | 26篇 |
自动化技术 | 99篇 |
出版年
2024年 | 1篇 |
2023年 | 12篇 |
2022年 | 17篇 |
2021年 | 36篇 |
2020年 | 33篇 |
2019年 | 21篇 |
2018年 | 29篇 |
2017年 | 32篇 |
2016年 | 40篇 |
2015年 | 40篇 |
2014年 | 83篇 |
2013年 | 118篇 |
2012年 | 70篇 |
2011年 | 99篇 |
2010年 | 50篇 |
2009年 | 70篇 |
2008年 | 70篇 |
2007年 | 66篇 |
2006年 | 56篇 |
2005年 | 60篇 |
2004年 | 50篇 |
2003年 | 45篇 |
2002年 | 30篇 |
2001年 | 17篇 |
2000年 | 27篇 |
1999年 | 19篇 |
1998年 | 22篇 |
1997年 | 6篇 |
1996年 | 7篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有1262条查询结果,搜索用时 15 毫秒
111.
冰淇淋生产中老化条件的确定 总被引:6,自引:0,他引:6
冰淇淋生产中老化条件的确定是冰淇淋质量好坏的重要因素之一。根据冰淇淋的实际生产配方、加工工艺与条件,测定料液在老化时粘度的增长情况。通过凝冻操作鉴定冰淇淋质量,最终确定料液所需老化时间。 相似文献
112.
Several different types of commercially available greases, aged in a roll stability tester, have been tested in a ball-on-disc machine where the film thickness was measured using the interferometry method. The grease film thickness at very low speed is thicker than the base oil film thickness due to the contribution of the thickener in this regime, which practically vanishes at higher speeds. The (mechanical) aging process reduces the thickener material, decreasing the grease film thickness at very low speeds (entrainment speed less than 0.01 m/s) with aging time, whereas no significant difference was found at higher speeds where the grease film thickness still approached the calculated base oil film thickness. 相似文献
113.
In lithium-ion batteries, several electrical and physical parameters are responsible for the degradation of the electrode materials. Here the application of Kelvin probe microscopy (KPM) is demonstrated to measure the charge sustaining capability of the LiFePO4 cathode under aged and unaged conditions. The aged sample shows lower surface potential than the unaged sample, which can be attributed to changes in physical and chemical properties including particle size, phase of the surface layer and nanocrystalline deposits. 相似文献
114.
《Petroleum Science and Technology》2013,31(5-6):641-650
In this paper the aging processes of two penetration-grade paving asphalt which conform to the standard of Esson Company have been studied by rotation thin film oven (RTFO). The first order aging kinetic model has been established and some kinetics parameters were calculated. The relationship between pavement properties of asphalt and aging course was revealed. The intervention of oxygen in high temperature caused oxidation reactions, which changed the composition and structure of asphalt, the aging resistant performance of asphalt was weak, and the service performance went to bad. 相似文献
115.
Korea is experiencing an extraordinarily rapid demographic transition. We investigated the short-term association between air pollution and mortality and assessed the impact of improved air quality on mortality in a rapidly aging city, Seoul, Korea.The generalized additive model (GAM) was used to estimate the relative risks (RR) of mortality associated with changes in air pollution. The time trends, seasonal variations, day of the week effects, and weather effects were controlled in the models. To estimate the health benefits, we used the US Environmental Protection Agency's BenMAP.For people 0–64 years of age, elderly people (65+ years), and all age groups, an increase of 10 μg/m3 in PM10 was associated with increases in daily death counts of 0.27% (95% CI: 0.04–0.50), 0.45% (95% CI: 0.27–0.64), and 0.37% (95% CI: 0.23–0.52), respectively. For ages 0–64 years, elderly people, and all age groups, a 10 ppb increase in 1-hour maximum ozone concentration resulted in an increased risk of daily death counts of 0.28% (95% CI: − 0.19–0.74), 0.96% (95% CI: 0.46–1.47), and 0.81% (95% CI: 0.35–1.26), respectively.For elderly people, it was estimated that the health benefits of attaining the World Health Organization's (WHO) air quality guidelines (AQGs) for PM10 (24-hour average 50 μg/m3) would suggest an annual reduction of 964 (95% CI: 564–1366) premature deaths, and 329 (95% CI: 159–500) premature deaths could be prevented annually in 2015 from attaining the WHO's guidelines for ozone (8-hour average 100 μg/m3).The rapid increase of the elderly population has major consequences and implications for society and public health. This study showed that elderly people are at higher risk for the acute mortality effects of air pollution. Therefore, cleaner air will substantially contribute to improved public health in Seoul, given the growing concern about the adverse effects of air pollution for elderly people. 相似文献
116.
Miriam Ortega-Heras M Luisa González-Sanjosé Carlos González-Huerta 《Food chemistry》2007,103(4):1434-1448
The contents of the volatile compounds extracted from wood: cis- and trans-whiskylactones, vanillin, syringaldehyde, furfural, 5-methylfurfural, eugenol, guaiacol, p-ethyl-phenol and p-ethylguaicol have been studied in 12 single-variety wines aged in new American oak barrels. The concentration of these compounds were determined after the following combinations of time in wood and time in bottle: 0 months in wood plus 18 months in bottle, 4 months in wood + 14 months in bottle, 9 months in wood + 9 moths in bottle and 12 months in wood + 6 months in bottle. According to the composition of the wines, it is possible to conclude in general, that, the extraction of these compounds was faster during the first four or 9 months of aging in wood, depending on the wines. After 12 months of oak maturation, the extraction of these compounds slowed down. Furthermore, the final concentrations of these volatile compounds were different among studied wines. These differences could be related to some of the values of some of their oenological parameters, such as the contents of tartaric acid and sulphur dioxide of each wine. 相似文献
117.
118.
用透射电镜和X-射线能谱仪对经自然和人工时效的18Cr2Ni4WA钢的微观组织、析出相及其分布进行了研究。结果表明,在应力作用下,组织的回复趋于不均,沿晶界析出的脱溶物增多。回复较充分的铁素体板条中析出粗大的(Fe、Cr)3C,局部均匀分布;回复不充分处,沿晶界还析出长杆状的(Fe、Cr)3C和更细小的杆状W2C。时效后组织中元素C、Cr和W趋于沿晶界偏聚,其中W几乎全部以碳化物的形式存在于晶界附近。析出相(Fe、Cr)3C的[001]晶带轴与α铁素体的[121]晶带轴近似平行。晶界脆性相的增多是该材料的螺栓在服役期间变脆和在腐蚀环境下失效的内在原因。 相似文献
119.
120.
《Propellants, Explosives, Pyrotechnics》2017,42(8):953-959
Aluminum‐lithium alloys are widely studied to improve performance in energetic materials. However, their high reactivity causes severe surface oxidation over micro‐Al particles in storage, resulting in significant deterioration in the overall performance. This study deals with the effect of iron coating on thermal properties and aging stability of aluminum‐lithium alloy powder. Gas atomized Al‐3Li (3 wt. %) alloy powder was prepared and then successfully coated with nano‐sized iron film by modified chemical liquid deposition method. The morphology, thermal properties and combustion enthalpies were characterized by SEM/EDX, TG/DTA and oxygen bomb calorimeter. The results showed that Fe/Al‐3Li composite powder presented obvious core‐shell structure and the outer iron film was very uniform and compact. Significantly enhanced thermal reactivities of Al‐3Li alloy powder and Fe/Al‐3Li composite powder were achieved compared with pure Al. In addition, aging studies indicated that, after coating, the reactivity decay rates of alloy powder decreased significantly, and the mass combustion enthalpies remained basically stable, which demonstrated that iron coating indeed prevented pre‐oxidation of the alloy powder and improved its aging stability. 相似文献