全文获取类型
收费全文 | 2682篇 |
免费 | 118篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 23篇 |
化学工业 | 340篇 |
金属工艺 | 26篇 |
机械仪表 | 28篇 |
建筑科学 | 58篇 |
矿业工程 | 2篇 |
能源动力 | 62篇 |
轻工业 | 333篇 |
水利工程 | 13篇 |
石油天然气 | 9篇 |
无线电 | 129篇 |
一般工业技术 | 248篇 |
冶金工业 | 1265篇 |
原子能技术 | 16篇 |
自动化技术 | 251篇 |
出版年
2023年 | 7篇 |
2022年 | 7篇 |
2021年 | 40篇 |
2020年 | 24篇 |
2019年 | 45篇 |
2018年 | 44篇 |
2017年 | 56篇 |
2016年 | 56篇 |
2015年 | 45篇 |
2014年 | 69篇 |
2013年 | 121篇 |
2012年 | 101篇 |
2011年 | 94篇 |
2010年 | 89篇 |
2009年 | 95篇 |
2008年 | 74篇 |
2007年 | 85篇 |
2006年 | 53篇 |
2005年 | 62篇 |
2004年 | 58篇 |
2003年 | 50篇 |
2002年 | 38篇 |
2001年 | 37篇 |
2000年 | 36篇 |
1999年 | 50篇 |
1998年 | 406篇 |
1997年 | 203篇 |
1996年 | 177篇 |
1995年 | 104篇 |
1994年 | 82篇 |
1993年 | 81篇 |
1992年 | 12篇 |
1991年 | 30篇 |
1990年 | 18篇 |
1989年 | 29篇 |
1988年 | 20篇 |
1987年 | 18篇 |
1986年 | 18篇 |
1985年 | 21篇 |
1984年 | 4篇 |
1982年 | 10篇 |
1981年 | 8篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 29篇 |
1976年 | 66篇 |
1975年 | 2篇 |
1959年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有2803条查询结果,搜索用时 656 毫秒
1.
2.
D.R. Santos‐Peñate C.M. Campos‐Rodríguez J.A. Moreno‐Pérez 《International Transactions in Operational Research》2019,26(1):340-363
The ‐centroid problem or leader–follower problem is generalized considering different customer choice rules where a customer may use facilities belonging to different firms, if the difference in travel distance (or time) is small enough. Assuming essential goods, some particular customer choice rules are analyzed. Linear programming formulations for the generalized ‐medianoid and ‐centroid problems are presented and an exact solution approach is applied. Some computational examples are included. 相似文献
3.
4.
Ana M. García José M. Villora Diego A. Moreno Carlos Ranninger Pío Callejas M. Flora Barba 《Journal of the American Ceramic Society》2003,86(12):2200-2202
The objective of this research was to study the removal of cadmium and lead from an aqueous solution through a biological treatment. For this purpose a glass-ceramic material was manufactured from industrial and urban wastes. Biofilms of microorganisms found in wastewater were developed on its surface, and continuous tests were conducted in the presence and absence of the biofilm to analyze the glass-ceramic's ability to remove the heavy metals from an aqueous environment. The results suggest that this bioremediation process, developed on an industrial scale, could represent an alternative to the chemical processes currently used. 相似文献
5.
6.
7.
Effect of thapsigargin on calcium homeostasis in Trypanosoma cruzi trypomastigotes and epimastigotes
By using the fluorescent calcium indicator fura-2, it was found that the concentration of free Ca2+ in the cytoplasm of Trypanosoma cruzi trypomastigotes incubated in the presence or absence of external calcium was maintained at very low levels (10-20 nM). When trypomastigotes were incubated in the presence of succinate and ATP and permeabilized with digitonin, they lowered the medium calcium concentration to a submicromolar level. In the presence of 1 microM FCCP the initial rate of Ca2+ sequestration by these permeabilized cells was very slow. When succinate alone was present, the initial rate of Ca2+ accumulation was slower than with ATP plus succinate, and the calcium set point was about 0.6 microM. The succinate dependence and FCCP sensitivity of the later Ca2+ uptake indicate that it may be exerted by the mitochondria. High concentrations of the tumor promoter thapsigargin slightly increased cytosolic Ca2+ in the presence of extracellular Ca2+ but had no effect on the FCCP- and oligomycin/antimycin A-insensitive Ca2+ pool. In addition, when used at those concentrations (4-20 microM), thapsigargin was shown to release Ca2+ from the mitochondria and to decrease the inner mitochondrial membrane potential of trypomastigotes and epimastigotes as measured using safranine O. Despite the presence of inositol phosphates as determined by [3H]inositol incorporation, no IP3-sensitive Ca2+ release could be detected in trypomastigotes. 相似文献
8.
We performed simultaneous fasting and fed antroduodenal manometry and EGG in 25 children with functional bowel disorders. Three patients (12%) had an uninterpretable EGG. The manometric studies showed severe neuropathy in six patients; milder neuropathic changes in five patients; postprandial hypomotility in one patient; myopathy in four patients, and normal motility in the remaining six patients. The percentage of tachygastria time (frequency > 3.5 cycles/min) was higher in the patiens with mild (44.1 +/- 15.8%) and severe (48 +/- 19.1%) neuropathy than in the patients with myopathy (20 +/- 16.2%, P < 0.05) or with normal motility (23 +/- 13.3%, P < 0.05). There was a considerable overlap in the percentage of tachygastria and total arrhythmia time among the different study groups. The ratio of post- to preprandial power was significantly higher (2.5 +/- 0.07) in children with normal motility than in the other patients groups. Every child with total arrhythmia time < 35% and a ratio of post- to preprandial power > 2.4 had normal manometry. In summary, EGG differentiated groups of children with normal manometry from others with neuropathic or myopathic changes, but in a minority of patients the study was not interpretable and there was overlap in EGG results between children with normal and abnormal manometry. 相似文献
9.
SV Filippov MD Rekhter RS Polishchuk SV Gurkin SN Voronov VI Cherviakov AA Mironov 《Canadian Metallurgical Quarterly》1993,35(9):62-65
It has been shown that changes in the orientation of arterial smooth muscle cells during a constant longitudinal stretching of the artery in vivo are not similar in different sections of the stretching zone. Cells in the proximal and distal sections keep their orientation but this orientation differs from that of smooth muscle cells in the control arteries. Cells in the central part of the stretching region lose their definite orientation to settle randomly. 相似文献
10.