全文获取类型
收费全文 | 1532篇 |
免费 | 150篇 |
国内免费 | 74篇 |
专业分类
电工技术 | 165篇 |
综合类 | 111篇 |
化学工业 | 429篇 |
金属工艺 | 68篇 |
机械仪表 | 162篇 |
建筑科学 | 51篇 |
矿业工程 | 58篇 |
能源动力 | 88篇 |
轻工业 | 58篇 |
水利工程 | 50篇 |
石油天然气 | 117篇 |
武器工业 | 3篇 |
无线电 | 91篇 |
一般工业技术 | 118篇 |
冶金工业 | 53篇 |
原子能技术 | 40篇 |
自动化技术 | 94篇 |
出版年
2024年 | 4篇 |
2023年 | 19篇 |
2022年 | 43篇 |
2021年 | 45篇 |
2020年 | 39篇 |
2019年 | 49篇 |
2018年 | 48篇 |
2017年 | 49篇 |
2016年 | 60篇 |
2015年 | 61篇 |
2014年 | 91篇 |
2013年 | 103篇 |
2012年 | 111篇 |
2011年 | 108篇 |
2010年 | 97篇 |
2009年 | 89篇 |
2008年 | 70篇 |
2007年 | 104篇 |
2006年 | 99篇 |
2005年 | 60篇 |
2004年 | 68篇 |
2003年 | 58篇 |
2002年 | 45篇 |
2001年 | 21篇 |
2000年 | 46篇 |
1999年 | 32篇 |
1998年 | 31篇 |
1997年 | 19篇 |
1996年 | 19篇 |
1995年 | 14篇 |
1994年 | 15篇 |
1993年 | 2篇 |
1992年 | 7篇 |
1991年 | 5篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1951年 | 1篇 |
排序方式: 共有1756条查询结果,搜索用时 15 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(45):19718-19731
Metals and alloys forming reversible hydrides with hydrogen gas are potential building blocks for compact, solid state hydrogen storage systems. Based on the materials’ thermodynamic characteristics, their use as temperature-swing gas compression and delivery systems in the hydrogen economy is also possible. Given the wide variety of materials developed and tested at laboratory and pilot scales, a harmonized method of selecting the feasible material(s) for a particular real-life application is required. This study proposes a system selection framework based on a normalized, multi-criteria metric. Using calculated values of multi-criteria metric, multi-criteria screening and ranking of potential materials has been demonstrated for a particular use case. It is found that the alloy TiMn1.52 having value of additive metric between 0.25 and 0.35 represents the best material for a single stage system. The alloy pair CaNi5–Ti1.5CrMn represents the best alternative for a two-stage system with additive metric values between 0.63 and 0.82. Energy and economic characteristics of the metal hydride gas compression and delivery systems are evaluated and compared with an equivalent mechanical compression system producing the same final effect (i.e., delivery of a given quantity of gas at a defined pressure). 相似文献
2.
H. Yamamoto N. Heyamoto T. Matsui N. Murayama J. Shibata 《International Journal of Thermophysics》2003,24(5):1385-1394
Polyvinylalcohol (PVA) polymer gel is a temperature sensitive polymeric gel, with a critical transition temperature (with H2O) of 310 K. At higher than 310 K, this temperature sensitive polymer gel shrinks because of discharging water, whereas at lower temperatures, the gel swelled because of absorbing water. The reversibility of the gel's volume change was confirmed by temperature swing. The adsorption behavior of an organic compound onto the PVA polymer gel in water was tested at various temperatures. The amount of adsorbed organic compound increased remarkably at temperatures higher than about 310 K. Then, it was confirmed that the organic compound in PVA polymer gel could be reversibly adsorbed and desorbed by a temperature change between 293 and 323 K. The mechanism of adsorption of the organic compound onto the PVA polymer gel could be explained by hydration and dehydration of polymer gel. 相似文献
3.
4.
C Brito L Niklitschek L H Molina I Molina 《International Journal of Dairy Technology》2002,55(1):32-39
This study was performed to obtain an adequate tool for predicting the yield of Chilean Gouda cheese. The theoretical yields were calculated by applying equations derived from technical references to industrial cheese production and were compared with their own actual yields, thus selecting those equations showing the best correlation with the actual yield.
The manufacturing and ripening of the cheese were controlled through the chemical composition of milk, whey and cheese, and the weight of the product before and after ripening was recorded.
The actual and theoretical yield values derived from each formula were compared using the mean yield graphs. Furthermore, the global concordance coefficient ( W ) of Kendall and Smith was also applied, showing the lack of significant discrepancy between actual and theoretical yield values [ P > 0.01 ( W = 27; W ≥ 18.48)] for either 3- or 30-day cheeses. Out of the 11 formulae used to measure the yield of cheese, six showing a good correlation between the yields were selected through the comparison of error sums and Pearson correlation analysis. However, two formulae showed the best yield results for practical use. 相似文献
The manufacturing and ripening of the cheese were controlled through the chemical composition of milk, whey and cheese, and the weight of the product before and after ripening was recorded.
The actual and theoretical yield values derived from each formula were compared using the mean yield graphs. Furthermore, the global concordance coefficient ( W ) of Kendall and Smith was also applied, showing the lack of significant discrepancy between actual and theoretical yield values [ P > 0.01 ( W = 27; W ≥ 18.48)] for either 3- or 30-day cheeses. Out of the 11 formulae used to measure the yield of cheese, six showing a good correlation between the yields were selected through the comparison of error sums and Pearson correlation analysis. However, two formulae showed the best yield results for practical use. 相似文献
5.
详细介绍了进口的VPSA制氧装置的流程特点、工艺参数及主要设备的配置。实际运转证明 ,该制氧装置具有运行可靠、启动时间短、部分负荷性能优越、负荷转换速度快等优点 ,能满足金隆铜业有限公司的实际生产要求。 相似文献
6.
介绍了邯钢动力厂真空变压吸附制氧设备的工艺流程,从切换阀本体、电磁阀及仪表气源等方面分析和总结了真空风机入口压力低引起系统联锁停车故障原因,并介绍了相应的处理措施。 相似文献
7.
8.
重油催化裂化干气氢提纯技术的开发 总被引:3,自引:0,他引:3
石家庄炼油厂和西南化工研究设计院合作开发的中国石化系统第一套利用变压吸附技术进行RFCC干气氢提纯工业试生产装置一年的平稳运行说明:提纯后产品氢纯度达99.9%,回收率大于85%;操作简便灵活;装置负荷弹性裕度大;经济效益显著。实践证明它是一项富有吸引力的新工艺,为重油催化裂化装置的挖潜增效展示了美好的前景。 相似文献
9.
Results from long-term field experiments in south-western Australia are presented in the form of relationships between yield, expressed as a percentage of the maximum yield, and soil test for phosphorus (P) values. Maximum yields were not always indicated by well defined yield plateaux. Different methods have been used to estimate the maximum yield value which is used to calculate yield as a percentage of the maximum yield so as to remove interseasonal variation. For all of these methods and for the same site, the same P fertilizer (superphosphate), and the same plant species, the relationship between yield and soil test P differed for different years. Consequently fertilizer recommendations based on the assumption that this relationship is constant are likely to be incorrect. We therefore question the validity of the common practice in soil testing programmes of using percentage yield values to remove interseasonal variation. 相似文献
10.
新岭大桥转体施工技术 总被引:1,自引:0,他引:1
新岭大桥采用有平衡重的平面转体法施工 ,这在我省尚属首例。施工中因地制宜采用拉链葫芦滑轮组进行牵引 ,仅用 3小时就使拱肋平稳、安全地转体就位 ,牵引施工获得成功 ,为我省的桥梁施工积累了经验 ,具有推广价值 相似文献