全文获取类型
收费全文 | 666篇 |
免费 | 24篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 129篇 |
金属工艺 | 2篇 |
机械仪表 | 13篇 |
建筑科学 | 22篇 |
能源动力 | 34篇 |
轻工业 | 50篇 |
水利工程 | 7篇 |
石油天然气 | 1篇 |
无线电 | 36篇 |
一般工业技术 | 145篇 |
冶金工业 | 162篇 |
原子能技术 | 3篇 |
自动化技术 | 85篇 |
出版年
2023年 | 3篇 |
2022年 | 17篇 |
2021年 | 20篇 |
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 21篇 |
2017年 | 12篇 |
2016年 | 10篇 |
2015年 | 13篇 |
2014年 | 19篇 |
2013年 | 28篇 |
2012年 | 23篇 |
2011年 | 41篇 |
2010年 | 29篇 |
2009年 | 28篇 |
2008年 | 26篇 |
2007年 | 26篇 |
2006年 | 33篇 |
2005年 | 28篇 |
2004年 | 27篇 |
2003年 | 24篇 |
2002年 | 13篇 |
2001年 | 9篇 |
2000年 | 13篇 |
1999年 | 13篇 |
1998年 | 30篇 |
1997年 | 20篇 |
1996年 | 16篇 |
1995年 | 15篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 8篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 3篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 7篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1968年 | 2篇 |
排序方式: 共有691条查询结果,搜索用时 15 毫秒
71.
Paul Kay Alona Armstrong Adrian McDonald Daniel Parsons Jim Best Jeff Peakall rew Walker Miles Foulger Sarah Gledhill & Martin Tillotson 《Water and Environment Journal》2009,23(1):52-62
Residuum lodges comprise small dams constructed on feeder streams immediately before they enter a reservoir, behind which ponds form, where sediment is deposited. Despite their construction on many impoundment reservoirs (IRE) and catchwaters, little research has previously investigated their efficacy at removing sediments from feeder streams. The current pilot study has, therefore, been carried out at an IRE supplying Halifax, West Yorkshire, UK, where a residuum lodge was recently cleaned out. Sediment concentrations reaching the reservoir were reduced by up to 42% although no certain impacts were noted on the other water quality variables that were measured. Moreover, it was found that the clearance operation did not result in the release of excessive quantities of sediment into the reservoir. It was estimated that the cleared residuum lodge would take 12 years to refill. A survey of other residuum lodges in the Yorkshire region showed there to be considerable differences in their remaining capacities. 相似文献
72.
Deldin Patricia J.; Deveney Christen M.; Kim Andrea S.; Casas Brooks R.; Best Jennifer L. 《Canadian Metallurgical Quarterly》2001,110(2):267
Mood-congruent working memory biases were examined in a delayed matching to sample paradigm using the slow wave (SW) event-related brain potential (ERP) component. Mood-congruent working memory biases, indexed by SW amplitudes, were demonstrated among individuals experiencing a major depressive episode (MDE) and nondepressed controls but not individuals with dysthymia. However, analyses of symptom severity demonstrated that those with dysthymia exhibited significantly less negative SW amplitudes with increasing depressive mood severity, whereas individuals with major depression demonstrated more negative SW amplitudes with increasing depressive mood severity. These results are discussed in the context of diagnostic specificity for cognitive biases associated with working memory of mood-disordered individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
73.
Effect of Silicon Substitution on the Sintering and Microstructure of Hydroxyapatite 总被引:3,自引:0,他引:3
Iain R. Gibson Serena M. Best William Bonfield 《Journal of the American Ceramic Society》2002,85(11):2771-2777
The substitution of between 0 and 1.6 wt% silicon (Si-HA) in hydroxyapatite (HA) inhibited densification at low temperatures (1000°–1150°C), with these effects being more significant as the level of silicon substitution was increased. For higher sintering temperatures (1200°–1300°C), the sintered densities of HA and Si-HA compositions were comparable. Examination of the ceramic microstructures by scanning electron microscopy (SEM) showed that silicon substitution also inhibited grain growth at higher sintering temperatures (1200°–1300°C). The negative effect of silicon substitution on the sintering of HA at low temperatures (1000°–1150°C) was reflected in the hardness values of the ceramics. However, for higher sintering temperatures, e.g., 1300°C, where sintered densities were comparable, the hardness values of Si-HA compositions were equal to or greater than that of HA, reflecting the smaller grain sizes observed for the former. 相似文献
74.
A noncontact optical system using high speed image analysis to measure local tissue deformations and axial strains along skeletal muscle is described. The spatial resolution of the system was 20 pixels/cm and the accuracy was +/- 0.125 mm. In order to minimize the error associated with discrete data used to characterize a continuous strain field, the displacement data were fitted with a third order polynomial and the fitted data differentiated to measure surface strains using a Lagrangian finite strain formulation. The distribution of axial strain along the muscle-tendon unit was nonuniform and rate dependent. Despite a variation in local strain distribution with strain rate, the maximum axial strain, Exx = 0.614 +/- 0.045 mm/mm, was rate insensitive and occurred at the failure site for all tests. The frequency response of the video system (1000 Hz) and the measurement of a continuous strain field along the entire length of the structure improve upon previous noncontact optical systems for measurement of surface strains in soft tissues. 相似文献
75.
K Nagamoto-Combs KM Piech JA Best B Sun AW Tank 《Canadian Metallurgical Quarterly》1997,272(9):6051-6058
76.
77.
SCALING IN SITU BIOREMEDIATION PROBLEMS BY APPLICATION OF MULTIPHASE, MULTICOMPONENT TRANSPORT THEORY 总被引:1,自引:0,他引:1
Robert J. Mackinnon Keith A. Schimmel Cynthia A. Loehr James F. Best James H. Wolfram 《Chemical Engineering Communications》1997,158(1):123-156
A methodology for scaling in situ bioremediation problems is presented. This methodology is based on multiphase, muiticomponent transport theory and employs inspectional analysis and numerical sensitivity studies. A general mathematical model that describes subsurface aerobic biotransformation of organic chemical species in a multiphase setting is first presented. This general model is applied to the specific case of microbial enhanced vapor-vacuum extraction (MEVVE) in a one-dimensional zone of immobile liquids. The resulting simplified MEVVE model considers rate-dependent interphase mass transfer, a flowing gaseous phase, a single hydrocarbon pseudo-component, and either oxygen or hydrocarbon limited microbial activity. By inspectional analysis a set of dimensionless groups are derived that represent the various model parameters. A scries of numerical sensitivity studies are presented that examine the impact of selected dimensionless groups on overall system biotransformation rates. This analysis demonstrates that overall biotranformation rates can be significantly limited not only by insufficient transport of oxygen in the gaseous phase, but also by interfacial mass transfer resistance between nonaqueous phase liquid globules and adjacent fluids. Finally, an examination of the selected dimensionless groups reveals the parameter requirements for properly scaled MEVVE tests. These results indicate the need for further investigation of the importantance of fluid distributions in the pore space and their impact on the design of laboratory and field tests. 相似文献
78.
Heinrich Best 《Computers and the Humanities》1991,25(2-3):163-171
Historical social research has developed with the availability of computer technology and has received increasing acceptance with the use of PCs. Methodological standards created by empirical social research are transferred to historical matters. Major contributors are: extension of the factual basis of history, correction of misjudgements, opening of whole groups of mass sources to historical research and bridging the gap between theory and empirical knowledge in the science of history. It complements a philosophical historiography without replacing it. In Germany historical social research has developed outside the traditional university institutes; the Zentrum fur Historische Sozialforschung and Quantum e.V. in Cologne are the major institutions in this context.Heinrich Best (D. Phil.) is a professor of sociology at the University of Cologne. He is director of the Social Science Information Centre (Bonn), director of the scientific advisory board of the Centre for Historical Social Research at his university, and president of the Association for Quantification and Formal Methods in Historical Social Research. Among his publications are Die Männer von Bildung and Besitz (1990) and Computers in the Humanities and Social Sciences (1991). 相似文献
79.
Mitchell Peter; Ropar Danielle; Ackroyd Katie; Rajendran Gnanathusharan 《Canadian Metallurgical Quarterly》2005,31(5):996
In 3 experiments the authors investigate how errors in perception produce errors in drawings. In Experiment 1, when Shepard stimuli were shown as a pair of tables, participants made severe errors in trying to adjust 1 part of the stimulus to match the other. When the table legs were removed, revealing a pair of parallelograms with minimal perspective cues, the illusion was weaker. The authors predicted that participants would err when drawing the table but not the parallelogram stimuli. The results of Experiment 2 support the prediction and establish a direct link between degree of perceptual distortion of the table stimuli and the severity of error in drawing. When drawing only the right-hand part of the figure, participants also erred to a greater degree in drawing the table than the parallelogram (Experiment 3). Collectively, the results suggest that perceptual distortion is linked with errors in drawing the table stimuli. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
80.