全文获取类型
收费全文 | 598篇 |
免费 | 23篇 |
专业分类
电工技术 | 24篇 |
综合类 | 1篇 |
化学工业 | 112篇 |
金属工艺 | 7篇 |
机械仪表 | 23篇 |
建筑科学 | 43篇 |
能源动力 | 39篇 |
轻工业 | 91篇 |
水利工程 | 1篇 |
石油天然气 | 4篇 |
无线电 | 23篇 |
一般工业技术 | 80篇 |
冶金工业 | 65篇 |
原子能技术 | 4篇 |
自动化技术 | 104篇 |
出版年
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 19篇 |
2020年 | 9篇 |
2019年 | 11篇 |
2018年 | 15篇 |
2017年 | 10篇 |
2016年 | 15篇 |
2015年 | 13篇 |
2014年 | 22篇 |
2013年 | 32篇 |
2012年 | 26篇 |
2011年 | 46篇 |
2010年 | 30篇 |
2009年 | 34篇 |
2008年 | 22篇 |
2007年 | 30篇 |
2006年 | 25篇 |
2005年 | 17篇 |
2004年 | 13篇 |
2003年 | 15篇 |
2002年 | 22篇 |
2001年 | 9篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 12篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1973年 | 6篇 |
1930年 | 3篇 |
排序方式: 共有621条查询结果,搜索用时 15 毫秒
591.
Rule following and tacit knowledge 总被引:1,自引:1,他引:0
Kjell S Johannessen 《AI & Society》1988,2(4):287-301
592.
The condensation of resin compounds during drying of wet mixtures consisting of resin and filler was examined by gel permeation chromatography of resins extracted from various intermediates being dried. The influence of pH (wet mixture), temperature, and drying time upon the molecular growth was studied. 相似文献
593.
The prevalence of symptoms compatible with the Sick Building Syndrome (SBS) was measured in a questionnaire study among 4 943 office workers. An assessment of the relation between SBS symptoms and personal, physical and psychosocial exposure factors was made. In contrast to males, the majority of females were lower-grade staff Females reported annoyance from physical climate factors more often, both at work and at home. Males reported a better psychosocial situation than females. Female gender, asthmalrhinitis, paper and VDT work were related to an increased prevalence of SBS symptoms. The prevalence of facial skin symptoms increased markedly with the amount of VDT work. Psychosocial workload intensifid this relation. Inequalities in physical climate and psychosocial conditions associated with different positions held in the offices can be of importance for the increased occurrence of symptoms among females. 相似文献
594.
K. Burg G. -A. Euteneuer A. Slibar A. M. Freudenthal Jan Hult Inge L. Ryhming H. Leipholz U. Müller H. Bednarczyk K. Oswatitsch J. Zierep C. A. Wogrin J. Y. Parlange K. -O. Felsch 《Acta Mechanica》1967,4(1):128-136
Ohne Zusammenfassung 相似文献
595.
Ragnar Hellborg Kjell Håkansson 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,235(3):407-413
An inexpensive gas-handling system has been designed and built utilizing standard components. The design of the system and the different safety features are described. Results of a test on the purity of the gas are given. 相似文献
596.
Urban Kjellén 《Accident; analysis and prevention》1984,16(4):307-323
In Part II of this paper measures of the significance of deviations with respect to the risk of accidents and criteria for the assessment of methods for the collection of data on deviations are operationalized. Empirical research on relations between deviations and accidents and on methods for data collection are reviewed on the basis of these measures and criteria. It is concluded that the deviation concept provides a valid basis for the design of information systems for the efficient control of accidents in production systems in operation. Considerations for the design of information systems for the collection, storing, processing, and feedback of information on deviations for accident prevention purposes are discussed. 相似文献
597.
The crystallization of melt-spun amorphous Zr1-xCox alloys with 0.20 ≤ x ≤ 0.41 has been studied under both isothermal and non-isothermal conditions by use of DSC-technique. Up to three peaks were observed. The crystallization temperature varies with composition from 631 K for x = 0.20 to 746 K for x = 0.41. Isothermal annealing of x = 0.41 shows that the kinetics of the crystallization can be described by the Johnson-Mehl-Avrami equation with n ≈ 2.85 at lower annealing temperatures (712.5 – 725 K) while in the temperature range 725 K to 740 K n increases with increasing annealing temperature. The phases formed during the crystallization process have been identified by means of X-ray diffraction techniques and electron microscope studies. For compositions around x = 0.33 microcrystalline phases are formed upon crystallization. 相似文献
598.
Hergum T Bjåstad T Kristoffersen K Torp H 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2007,54(2):271-280
Parallel beamforming is frequently used to increase the acquisition rate of medical ultrasound imaging. However, such imaging systems will not be spatially shift invariant due to significant variation across adjacent beams. This paper investigates a few methods of parallel beam-forming that aims at eliminating this flaw and restoring the shift invariance property. The beam-to-beam variations occur because the transmit and receive beams are not aligned. The underlying idea of the main method presented here is to generate additional synthetic transmit beams (STB) through interpolation of the received, unfocused signal at each array element prior to beamforming. Now each of the parallel receive beams can be aligned perfectly with a transmit beam--synthetic or real--thus eliminating the distortion caused by misalignment. The proposed method was compared to the other compensation methods through a simulation study based on the ultrasound simulation software Field II. The results have been verified with in vitro experiments. The simulations were done with parameters similar to a standard cardiac examination with two parallel receive beams and a transmit-line spacing corresponding to the Rayleigh criterion, wavelength times f-number (lambda x f#). From the results presented, it is clear that straightforward parallel beamforming reduces the spatial shift invariance property of an ultrasound imaging system. The proposed method of using synthetic transmit beams seems to restore this important property, enabling higher acquisition rates without loss of image quality. 相似文献
599.
Lin Y Bolca S Vandevijvere S De Keyzer W Van Oyen H Van Camp J De Backer G De Henauw S Huybrechts I 《International journal of molecular sciences》2011,12(3):1836-1853
The objectives were to assess total dietary fiber intake, identify the major sources of dietary fiber, and examine its association with socio-economic factors among Flemish preschoolers. Three-day estimated dietary records were collected from a representative sample of preschoolers 2.5-6.5 years old (n = 661; 338 boys, 323 girls). The mean dietary fiber intake (13.4 g/d) was lower than the intake level recommended by the Belgian Superior Health Council (70% boys and 81% girls below the guidelines). The most important contributor was the group of bread and cereals (29.5%), followed by fruits (17.8%), potatoes and grains (16.0%), energy-dense, low-nutritious foods (12.4%), and vegetables (11.8%). Multiple linear regression analyses showed that total fiber intake was associated with maternal education and parents' employment. Overall, fiber intakes from high-nutritious foods (vegetables and fruits) were higher in preschoolers of higher educated mothers and those with one or both parents being employed. In conclusion, the majority of the preschoolers had dietary fiber intakes below the recommended level. Hence, dietary fiber should be promoted among parents of preschoolers and low socio-economic status families should be addressed in particular. 相似文献
600.
Corrections for diffuse irradiance measured with shadowbands 总被引:1,自引:0,他引:1
The reduction of measured diffuse irradiance due to the use of a shadowband is evaluated. For cloudless sky, an exact mathematical model was developed. Measurements throughout the year confirm the model results. The values are close to the semiempirical model developed by Drummond only during noon hours. Towards morning and afternoon a contribution from reflected direct solar irradiance from inside the shadowband reduces the loss and, at very low sun angle, can even provide a gain in the measured diffuse irradiance. The albedo of the inner band surface is of importance for the amount of this gain.During overcast sky the loss of measured diffuse irradiance varies with the season: During the winter months when only a small section of the sky is obstructed by band, 3 per cent are lost, during summer this value is between 8 and 10 per cent. 相似文献