全文获取类型
收费全文 | 1050篇 |
免费 | 18篇 |
专业分类
电工技术 | 11篇 |
综合类 | 5篇 |
化学工业 | 151篇 |
金属工艺 | 13篇 |
机械仪表 | 31篇 |
建筑科学 | 18篇 |
能源动力 | 14篇 |
轻工业 | 107篇 |
水利工程 | 7篇 |
石油天然气 | 7篇 |
无线电 | 63篇 |
一般工业技术 | 148篇 |
冶金工业 | 388篇 |
原子能技术 | 8篇 |
自动化技术 | 97篇 |
出版年
2023年 | 5篇 |
2021年 | 7篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 17篇 |
2017年 | 14篇 |
2016年 | 10篇 |
2015年 | 9篇 |
2014年 | 23篇 |
2013年 | 48篇 |
2012年 | 21篇 |
2011年 | 29篇 |
2010年 | 18篇 |
2009年 | 25篇 |
2008年 | 23篇 |
2007年 | 22篇 |
2006年 | 26篇 |
2005年 | 18篇 |
2004年 | 23篇 |
2003年 | 27篇 |
2002年 | 21篇 |
2001年 | 29篇 |
2000年 | 20篇 |
1999年 | 31篇 |
1998年 | 104篇 |
1997年 | 67篇 |
1996年 | 50篇 |
1995年 | 27篇 |
1994年 | 39篇 |
1993年 | 28篇 |
1992年 | 21篇 |
1991年 | 13篇 |
1990年 | 22篇 |
1989年 | 19篇 |
1988年 | 15篇 |
1987年 | 12篇 |
1986年 | 16篇 |
1985年 | 14篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1982年 | 14篇 |
1981年 | 8篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1977年 | 10篇 |
1976年 | 16篇 |
1975年 | 8篇 |
1974年 | 9篇 |
1973年 | 5篇 |
1969年 | 4篇 |
排序方式: 共有1068条查询结果,搜索用时 0 毫秒
1.
2.
3.
BJ Carr 《Canadian Metallurgical Quarterly》1994,14(4):217-223
Many facilities in Australia have taken the Total Quality Management (TQM) step. The objective of this study was to examine progress of adopted formal quality systems in health. Sixty per cent of organizations surveyed have adopted formal systems. Of these, Deming adherents are the most common, followed by eclectic choices. Only 35% considered the quality transition as reasonably easy. There was no relationship between accreditation and formal quality systems identified. The most common improvement techniques were: flow charts, histograms, and cause and effect diagrams. Quality practitioners are happy to use several tools exceptionally well rather than have many tools at their disposal. The greatest impediment to the adoption of quality was the lack of top management support. This study did not support the view that clinicians are not readily actively supporting quality initiatives. Total Quality Management is not a mature concept; however, Chief Executive Officers are assured that rewards will be realized over time. 相似文献
4.
There is little information on the possible value of screening children who are liable to haemoglobinopathies as part of pre-operative assessment for dental treatment under general anaesthesia. The present retrospective investigation examined, first, the number of patients having low haemoglobin levels among 1000 patients who had undergone haematological investigation prior to general anaesthesia in a dental outpatient unit, and, secondly, the subsequent clinical management of these patients. Haemoglobin levels of 10.0 g/dl or less were found in 31 children: 13 Asian, 7 Afro-Caribbean, 5 Mediterranean, 3 Arabic, 1 white Caucasian and 2 Oriental children. In addition, 17 patients had sickle-cell trait and 2 had beta-thalassaemia trait, but there was no relationship between the presence of haemoglobinopathy and low levels of haemoglobin. The planned general anaesthesia was undertaken for 22 of the 31 children who had low levels of haemoglobin and for the 19 children with haemoglobinopathy. Only 6 children ultimately did not undergo general anaesthesia, all failing to return. It is concluded that pre-anaesthetic haematological assessment of children needing minor dental surgery is rarely of any significant clinical value. 相似文献
5.
6.
A near-field preconditioner and its performance in conjunction with the BiCGstab(ell) solver 总被引:6,自引:0,他引:6
This paper describes a simple physically-motivated "near-field" preconditioning scheme that is effective in accelerating convergence of surface, volume, and combined surface/volume integral equations for a broad variety of electromagnetic scattering problems. It can be easily implemented numerically in method of moment (MoM) solvers (both conventional and those employing matrix-compression techniques), irrespective of the analytical form of the integral-equation kernel. It has low memory and CPU requirements, both of which scale linearly with the number of unknowns, and is easily amenable to efficient parallelization. We demonstrate the preconditioner's performance (in conjunction with the BiCGstab(ell) iterative solver) on two representative geometries, and observe a significant reduction in the number of iterations required for convergence. 相似文献
7.
8.
In rats, the phosphorothionate insecticide parathion exhibits greater toxicity than chlorpyrifos, while in catfish the toxicities are reversed. The in vitro inhibition of brain acetylcholinesterase (AChE) by the active metabolites of the insecticides and the rates at which these inhibitor-enzyme complexes undergo reactivation/ aging were investigated in both species. Rat AChE was more sensitive to inhibition than catfish AChE as demonstrated by greater bimolecular rate constants (ki) in rats than in catfish. In both species, chlorpyrifos-oxon yielded higher ki's than paraoxon. The higher association constant (KA) of chlorpyrifos-oxon than paraoxon in both species and the lack of significant differences in the phosphorylation constants (kp) suggest that association of the inhibitor with AChE is the principal factor in the different potencies between these two inhibitors. In catfish, the ki of chlorpyrifos-oxon was 22-fold greater than that of paraoxon, while in rats it was 9-fold greater, suggesting that target site sensitivity is an important factor in the higher toxicity of chlorpyrifos to catfish but not in the higher toxicity of parathion to rats. No spontaneous reactivation of phosphorylated catfish AChE occurred and there were no differences in the first oder aging constants (ka) between compounds. For phosphorylated rat AChE, there were no differences in the first order reactivation constants (kr) but the ka for chlorpyrifos-oxon was significantly greater than that for paraoxon. This difference suggests that the steric positioning of the diethyl phosphate in the esteratic site is not the same between the two compounds, leading to differences in aging. 相似文献
9.
Gordonia amarae is a right-angled branching filament belonging to the mycolic acid-containing Actinobacteria which is commonly found in many foaming activated sludge wastewater treatment plants. Although studies on different substrates as sole carbon sources by pure cultures of G. amarae have been carried out, none have examined substrate uptake by this organism in situ. Uptake of several hydrophilic and hydrophobic substrates by G. amarae was evaluated in situ using a combination of fluorescence in situ hybridization and microautoradiography. G. amarae could assimilate a range of both hydrophilic and hydrophobic substrates. From the data, G. amarae appears to be physiologically active under aerobic, anaerobic and anoxic condition (NO2 and NO3) for some substrates. This might explain why attempts to control foaming caused by G. amarae using anoxic and anaerobic selectors have been unsuccessful. This study emphasizes that bacteria can behave differently in situ to pure cultures and that it is important to evaluate the in situ physiology of these bacteria if we are to better understand their role in the wastewater treatment process. 相似文献
10.