全文获取类型
收费全文 | 1047篇 |
免费 | 20篇 |
专业分类
电工技术 | 17篇 |
化学工业 | 117篇 |
金属工艺 | 11篇 |
机械仪表 | 22篇 |
建筑科学 | 33篇 |
能源动力 | 10篇 |
轻工业 | 79篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 116篇 |
一般工业技术 | 176篇 |
冶金工业 | 365篇 |
原子能技术 | 6篇 |
自动化技术 | 112篇 |
出版年
2022年 | 12篇 |
2021年 | 6篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 15篇 |
2017年 | 12篇 |
2016年 | 21篇 |
2015年 | 5篇 |
2014年 | 17篇 |
2013年 | 33篇 |
2012年 | 20篇 |
2011年 | 41篇 |
2010年 | 30篇 |
2009年 | 24篇 |
2008年 | 28篇 |
2007年 | 26篇 |
2006年 | 38篇 |
2005年 | 31篇 |
2004年 | 28篇 |
2003年 | 23篇 |
2002年 | 31篇 |
2001年 | 30篇 |
2000年 | 16篇 |
1999年 | 32篇 |
1998年 | 115篇 |
1997年 | 48篇 |
1996年 | 48篇 |
1995年 | 38篇 |
1994年 | 23篇 |
1993年 | 14篇 |
1992年 | 12篇 |
1991年 | 6篇 |
1990年 | 13篇 |
1989年 | 12篇 |
1988年 | 18篇 |
1987年 | 24篇 |
1986年 | 14篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 7篇 |
1982年 | 12篇 |
1981年 | 6篇 |
1980年 | 9篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 19篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1971年 | 7篇 |
排序方式: 共有1067条查询结果,搜索用时 9 毫秒
11.
12.
E Buskens EW Steyerberg J Hess JW Wladimiroff DE Grobbee 《Canadian Metallurgical Quarterly》1997,87(6):962-967
OBJECTIVES: This study assessed the potential impact of fetal ultrasound screening on the number of newborns affected by cardiac anomalies. METHODS: A decision model was developed that included the prevalence and history of congenital heart disease, characteristics of ultrasound, risk of abortion, and attitude toward pregnancy termination. Probabilities were obtained with a literature survey; sensitivity analysis showed their influence on expected outcomes. RESULTS: Presently, screening programs may prevent the birth of approximately 1300 severely affected newborns per million second-trimester pregnancies. However, over 2000 terminations of pregnancy would be required, 750 of which would have ended in intrauterine death or spontaneous abortion. Further, 9900 false-positive screening results would occur, requiring referral. Only the sensitivity of routine screening and attitude toward termination of pregnancy appeared to influence the yield substantially. CONCLUSIONS: The impact of routine screening for congenital heart disease appeared relatively small. Further data may be required to fully assess the utility of prenatal screening. 相似文献
13.
14.
Micro- and nanodevices require the controlled delivery of energy to power a variety of processes. The current paradigm of connecting a miniaturized device to a set of macroscopic auxiliary devices, such as power supplies or pumps, for the delivery of electrical and mechanical energy needs to be replaced to enable the design of stand-alone integrated bionanodevices with applications in remote biosensing or nanomedicine. Biological nanomachines, such as the motor protein kinesin, can efficiently convert energy stored in chemical compounds, in particular adenosine 5'-triphosphate (ATP), into mechanical work. This ability is an attractive feature of hybrid devices powered by biomolecular motors, since it removes the need for the storage and conversion of electrical energy. The consequences are a simplified fabrication process and packaging, leading to higher yields and lower costs, and the broadening of the applications, which can now include field-deployable nanodevices. Here, the potential of caged ATP as fuel for such engineering applications is discussed. Caged ATP can be stored in the buffer solution of a bionanodevice, "uncaged" by UV light, and utilized as fuel by many enzymes to catalyze chemical changes or power active transport. We demonstrate that DMNPE-caged ATP can be stored in sufficient amounts in a typical device and that the activation can be triggered with a UV lamp or even sunlight. 相似文献
15.
The appraisal process consists of the subjective evaluation that occurs during an individual's encounter with significant events in the environment, determining the nature of the emotional reaction and experience. Placed in the context of appraisal theories of emotion-elicitation and differentiation, the aim of the present research was to test empirically the hypothesis that the intrinsic pleasantness evaluation occurs before the goal conduciveness evaluation. In two studies, intrinsically pleasant and unpleasant images were used to manipulate pleasantness, and a specific event in a Pacman-type videogame was used to manipulate goal conduciveness. Facial EMG was used to measure facial reactions to each evaluation. As predicted, facial reactions to the intrinsic pleasantness manipulation were faster than facial reactions to the goal conduciveness manipulation. These results provide good empirical support for the sequential nature of the appraisal process. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
16.
Andrea Engl Benno Kunz 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(3):257-261
Studies took place to investigate the effects of different nutrient conditions on the biosorption ability and selectivity of heavy metals by Saccharomyces cerevisiae. After having grown in media supplemented with additional glucose, ammonium, phosphate or cysteine, the yeast was exposed to an equimolar solution of lead, cadmium, zinc and copper. Lead removal from a mixed solution was significantly higher than that of copper, followed by zinc and cadmium. Generally, yeasts from cysteine-rich media showed greatest sorption capacity whereas phosphate addition influenced zinc selectivity. In addition, glucose, fructose and sucrose as carbon sources were examined. Cultures grown in glucose had a better uptake than those cultivated with fructose at an incubation time of 30 min. 相似文献
17.
JS Sheikh M Sharma A Kunath DA Fritz CJ Glueck EV Hess 《Canadian Metallurgical Quarterly》1996,23(7):1288-1291
We describe 2 patients with a Sj?gren-like syndrome apparently secondary to hypertriglyceridemia. Both had bilateral parotitis in addition to musculoskeletal and sicca symptoms. Parotid gland histology revealed fatty infiltration with no inflammation. Therapy with dietary modification and triglyceride lowering drugs resulted in resolution of symptoms and parotid swelling in one patient. In the 2nd patient, hypertriglyceridemia was resistant to triglyceride lowering drugs, and parotid symptoms and swelling continued unabated. Our findings suggest aggressive treatment of hyperlipidemia in pseudo-Sj?gren's syndrome may result in amelioration of musculoskeletal and parotid symptoms. 相似文献
18.
19.
I Woolley H Valdez C Walker A Landay D Zdunek G Hess MM Lederman 《Canadian Metallurgical Quarterly》1998,19(4):408-412
OBJECTIVE: To determine whether postmenopausal oestrogen replacement therapy affects carotid artery pulsatility index. DESIGN: A prospective double-blind placebo controlled trial. SETTING: University associated teaching hospital. PARTICIPANTS: Twenty-eight postmenopausal women who were more than 12 months postmenopausal and who had not taken exogenous oestrogen. INTERVENTIONS: Independent randomisation to receive oral oestradiol (2 mg daily) or placebo for 20 to 24 weeks. MAIN OUTCOME MEASURES: Internal carotid artery Doppler pulsatility index, measured within one centimetre of the carotid bifurcation. RESULTS: Replicate data were available from 27 women. The mean pulsatility index decreased by -0.11 in 15 women receiving oestradiol, compared with a mean rise of 0.05 in the 12 women who received placebo (P = 0.006, 95% CI for treatment difference 0.06-0.31). CONCLUSIONS: Oestrogen replacement decreases postmenopausal carotid artery pulsatility index, probably reflecting decreased peripheral vascular resistance. This is a further mechanism whereby hormone replacement therapy may impart cardiovascular protection. 相似文献
20.
Benno Krachler Mats Eliasson Hans Stenlund Ingegerd Johansson G?ran Hallmans Bernt Lindahl 《Nutrition journal》2006,5(1):34