全文获取类型
收费全文 | 1047篇 |
免费 | 21篇 |
专业分类
电工技术 | 18篇 |
化学工业 | 133篇 |
金属工艺 | 16篇 |
机械仪表 | 27篇 |
建筑科学 | 34篇 |
能源动力 | 16篇 |
轻工业 | 93篇 |
水利工程 | 13篇 |
无线电 | 113篇 |
一般工业技术 | 148篇 |
冶金工业 | 317篇 |
原子能技术 | 4篇 |
自动化技术 | 136篇 |
出版年
2022年 | 8篇 |
2021年 | 13篇 |
2020年 | 7篇 |
2019年 | 8篇 |
2018年 | 6篇 |
2017年 | 13篇 |
2016年 | 17篇 |
2015年 | 13篇 |
2014年 | 15篇 |
2013年 | 29篇 |
2012年 | 40篇 |
2011年 | 50篇 |
2010年 | 46篇 |
2009年 | 27篇 |
2008年 | 34篇 |
2007年 | 39篇 |
2006年 | 33篇 |
2005年 | 33篇 |
2004年 | 34篇 |
2003年 | 18篇 |
2002年 | 28篇 |
2001年 | 27篇 |
2000年 | 22篇 |
1999年 | 27篇 |
1998年 | 100篇 |
1997年 | 63篇 |
1996年 | 53篇 |
1995年 | 36篇 |
1994年 | 30篇 |
1993年 | 22篇 |
1992年 | 7篇 |
1991年 | 14篇 |
1990年 | 10篇 |
1989年 | 14篇 |
1988年 | 17篇 |
1987年 | 11篇 |
1986年 | 12篇 |
1985年 | 16篇 |
1984年 | 11篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1978年 | 4篇 |
1977年 | 8篇 |
1976年 | 11篇 |
1975年 | 4篇 |
1974年 | 5篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1970年 | 4篇 |
排序方式: 共有1068条查询结果,搜索用时 15 毫秒
101.
Knowledge-based interpretation of bioelectrical signals 总被引:2,自引:0,他引:2
Glover J.R. Jr. Ktonas P.Y. Jansen B.H. 《IEEE engineering in medicine and biology magazine》1990,9(1):51-54
The integration into one automated system of the qualitative knowledge of the physician, who is accustomed to visually scanning a paper record, with possibly sophisticated signal analysis tools that must replace the visual scanning is addressed. The automated interpretation of bioelectrical signals must combine signal analysis knowledge with knowledge about the application domain of the signal and, as such, requires the knowledge of two experts. The role of event-oriented interpretation and the use of spatial and temporal context is discussed. An architecture for a system tailored to fit the characteristics of automated bioelectrical signal interpretation is described. It contains two separate, cooperating knowledge bases, and it makes use of object-oriented knowledge representation and spatial and temporal operators. An example of the automated detection of epileptogenic electroencephalograph sharp transients is presented. 相似文献
102.
103.
The cholera-pandemic raging in South and Middle America and endemic cholera in other countries call for measures of health protection of the local population, but particularly with respect to the young, old, pregnant and immunocompromised citizens of countries importing food from the areas where the disease has struck. Instead of harshly barring importation, a more humanitarian policy is recommended, relying on assistance of areas presenting risks, with the introduction of and adherence to rigorous measures of longitudinally integrated microbiological safety assurance. This model is equally applicable to other enteric diseases transmitted by food. Examples are given of how canned foods of neutral pH, fishery products, vegetables and certain fruits should be processed for safety. Importation monitoring strategies, linked to this proactive approach to consumer protection, are briefly summarized. 相似文献
104.
The adsorption of ammonia at copper surfaces was studied using Hartree-Fock-Slater LCAO calculations to investigate ammonia interaction with copper clusters. Important factors influencing ammonia adsorption were established from trends in its behaviour at clusters of different size. Adsorption at different coordination sites was examined in light of these results and it was found that a strong electrostatic contribution directs the ammonia towards lower coordination sites. 相似文献
105.
MG Olde Rikkert P Deurenberg RW Jansen MA van't Hof WH Hoefnagels 《Canadian Metallurgical Quarterly》1997,52(3):M137-M141
BACKGROUND: Multifrequency Bioelectrical Impedance Analysis (MFBIA) is a novel method to assess body composition in elderly subjects. However, it is unclear whether MFBIA can detect changes in body water compartments in elders. We aimed to determine the within-subject variability of MFBIA and the responsiveness to a diuretic intervention in aged subjects with a stable fluid balance. METHODS: We selected 12 healthy active elderly subjects (5 male, 7 female) with a mean age of 75 years. Total body water and extracellular fluid (ECF) were measured by deuterium oxide- and potassium bromide-dilution techniques. Within-subject variability in total body MFBIA was assessed by performing four measurements at 1, 5, 50, and 100 kHz within a 2-month period. Subsequently, responsiveness of MFBIA to the ECF loss caused by oral administration of 40 mg of furosemide was determined. RESULTS: Within-subject variability in MFBIA at 1, 5, 50, and 100 kHz expressed as standard deviations was 21, 19, 14, and 14 Ohm (omega), respectively. Furosemide caused a mean weight loss of 1.8 +/- 0.6 kg, which resulted in significant increases in impedance of 57 +/- 24 omega at 1 kHz and 37 +/- 12 omega at 100 kHz (p < .001). The responsiveness of MFBIA for the diuretic intervention was best at 5 kHz (responsiveness index = 1.98). CONCLUSIONS: Within-subject variability of MFBIA was small in healthy elderly subjects with stable fluid balance. Responsiveness of MFBIA to 9% furosemide-induced ECF loss was excellent. These data support the necessity for further clinical assessment of the value of MFBIA in monitoring fluid balance in geriatric patients. 相似文献
106.
Uranium microparticles (radii: 50 nm-1.25 μm) were modelled surrounded by tissue and exposed to natural background radiation, in order to investigate potential dose enhancements from photon interactions. Generally, the results depended on the microparticle size. For a 0.5 μm radius microparticle in an isotropic field, it was found that the combined photon/electron doses deposited in 1 and 10 μm radii shells around it were raised by factors of ~3.8 and ~1.1, respectively; for a typical background photon fluence rate, these would correspond to increased energy depositions of a few 10s and a few 100s of eV y(-1), which are far less than the likely deposition rate resulting from the radioactive decay of a (238)U microparticle. The health hazard from uranium microparticle interactions with background photons was concluded to be negligible. 相似文献
107.
108.
A simple method is reported to determine the absolute configuration of the crystal structure from electron diffraction patterns taken from very small areas. The method is based on the differences in the Friedel reflections, which are in general much larger than for X-rays due to the dynamical behaviour of the electron scattering. We express the absolute configuration with a parameter similar to the one Flack (Acta Cryst. A 39 (1983) 876) introduced in X-ray crystallography. This parameter is added to a refinement procedure that uses a multi-slice calculation to calculate diffraction patterns. The validity and strength of the method are shown with simulated and experimental data sets of GaN in the [0 1 0]-zone and a more complex compound, Ce5Cu19P12 in the [0 0 1] zone. 相似文献
109.
110.
The purpose of this integrated literature review (1980-1997) is to describe and summarize specific nursing interventions that have been devised to aid community-dwelling older adults with self-administration of prescribed medications. Interventions that combine patient education with written information or follow-up phone calls produce the most positive results. By using interventions supported by research, nurses will provide more effective and efficient care to older adults managing medications at home. 相似文献