全文获取类型
收费全文 | 256篇 |
免费 | 7篇 |
国内免费 | 22篇 |
专业分类
电工技术 | 5篇 |
综合类 | 2篇 |
化学工业 | 12篇 |
金属工艺 | 11篇 |
机械仪表 | 3篇 |
建筑科学 | 2篇 |
矿业工程 | 2篇 |
能源动力 | 1篇 |
轻工业 | 10篇 |
石油天然气 | 4篇 |
武器工业 | 4篇 |
无线电 | 9篇 |
一般工业技术 | 2篇 |
冶金工业 | 167篇 |
原子能技术 | 11篇 |
自动化技术 | 40篇 |
出版年
2014年 | 1篇 |
2012年 | 2篇 |
2011年 | 8篇 |
2010年 | 5篇 |
2009年 | 1篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2004年 | 16篇 |
2003年 | 6篇 |
2002年 | 13篇 |
2000年 | 2篇 |
1999年 | 20篇 |
1998年 | 31篇 |
1997年 | 26篇 |
1996年 | 24篇 |
1995年 | 19篇 |
1994年 | 44篇 |
1993年 | 5篇 |
1992年 | 1篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 1篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1977年 | 7篇 |
1976年 | 11篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1960年 | 2篇 |
1959年 | 2篇 |
1958年 | 1篇 |
1943年 | 1篇 |
1882年 | 3篇 |
排序方式: 共有285条查询结果,搜索用时 31 毫秒
51.
OF Pedersen TR Rasmussen O Omland T Sigsgaard PH Quanjer MR Miller 《Canadian Metallurgical Quarterly》1996,9(4):828-833
The purpose of this study was to examine whether the resistance of the peak flow meter influences its recordings. One hundred and twelve subjects, (healthy nonsmokers and smokers and subjects with lung diseases) performed three or more peak expiratory flow (PEF) manoeuvres through a Fleisch pneumotachograph with and without a mini-Wright peak flow meter added in random order as a resistance in series. The results were as follows. In comparison with a pneumotachograph alone, peak flow measured with an added mini-Wright meter had a smaller within-test variation, defined as the difference between the highest and second highest values of PEF in a series of blows. The mean (SE) variation was 14 (1.3) L.min-1 and 19 (1.5) L.min-1 with and without meter added, respectively. In comparison with the pneumotachograph alone, the addition of the mini-Wright meter caused PEF to be underread, especially at high flows. The difference (PEF with meter minus PEF without meter) = -0.064 (average PEF) -8 L.min-1; R2 = 0.13. The mean difference was -7.8 (1.1) %, and increased numerically for a given PEF, when maximal expiratory flow when 75% forced vital capacity remains to be exhaled (MEF75%FVC) decreased. The reproducibility criteria for repeated measurements of peak flow are more appropriately set at 30 L.min-1 than the commonly used 20 L.min-1, because a within-test variation of less than 30 L.min-1 was achieved in 76% of the subjects without PEF meter inserted and in 88% with meter inserted, with no difference between healthy untrained subjects and patients. The resistance of the peak expiratory flow meter causes less variation in recordings but reduces peak expiratory flow, especially at high values and when the peak is large as compared with the rest of the maximal expiratory flow-volume curve. 相似文献
52.
53.
54.
AN Hamlyn OF James AP Douglas MI Lavelle CW Venables 《Canadian Metallurgical Quarterly》1976,52(612):656-659
At operation for small bowel intussusception, a 26-year-old man was found to have an enlarged liver and spleen. Subsequent investigations suggested bile passage infection associated with numerous intrahepatic gall-stones but symptomatic cholangitis did not present until 5 months later. Retrograde cholangiography showed cavernous ectasia of the bile ducts which contained gall-stones. 相似文献
55.
RESEARCH SECTION ON PROCEEDING SOLID FUEL PEKING INSTITUTE OF PETROLEUM TECHNOLOGY 《化工学报》1958,9(2):95-101
试验了国产的各种硬蜡及软蜡,确定了它们的氧化可能性。提出了可供工业上应用的加速氧化反应的二个方法:改善加入催化剂的方法及在泡沫状态下进行氧化。 对於简化分离氧化蜡亦提出了新方案。 文中还叙述了在氧化初期催化剂的作用,对工艺过程的控制有一定的帮助。 相似文献
56.
57.
The critical transmural pressure (Ptm) is defined as the transmural pressure of the airway at the site where and when flow is limited during a forced expiration. According to the presented theory, the maximal expiratory flow (Vmax) can be calculated from the relation between Ptm and the corresponding cross-sectional area of the airway (A). By means of a pitot-static tube, Ptm-A curves were constructed for several locations in the elastic airway of a mechanical model. From these curves local Vmax was calculated at different values of Ptm and compared with actual flow, i.e. measured Vmax for the entire airway. In the downstream part of the airway, the actual flow equalled calculated Vmax at most Ptm values. The site of flow limitation, being the most upstream point where actual flow equals calculated local Vmax could therefore be located. Theory and experiments showed positive as well as negative Ptm not influenced by change in upstream or downstream resistance. Flow limitation could therefore be initiated at distending as well as compressing pressures across the wall of the airway. V was regarded as a function of Ptm and the elastic recoil pressure of the lung (Pel). Measured and calculated iso-Pel, Ptm-V curves agreed well with one major exception: when Ptm less than Ptm measured curves were distorted due to a concomitant downstrean compression of the collapsible airway. 相似文献
58.
59.
60.
用液氨代替烧碱作钛液水解晶种的中和剂,所得TiO2产品的白度、着色力好,且经济效益好。介绍了液氨中和剂用量的计算和TiO2晶种的制法。讨论了影响产品质量的因素。 相似文献