全文获取类型
收费全文 | 1805篇 |
免费 | 68篇 |
专业分类
电工技术 | 35篇 |
综合类 | 1篇 |
化学工业 | 314篇 |
金属工艺 | 36篇 |
机械仪表 | 36篇 |
建筑科学 | 47篇 |
矿业工程 | 5篇 |
能源动力 | 48篇 |
轻工业 | 91篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 152篇 |
一般工业技术 | 297篇 |
冶金工业 | 549篇 |
原子能技术 | 15篇 |
自动化技术 | 239篇 |
出版年
2023年 | 12篇 |
2022年 | 11篇 |
2021年 | 32篇 |
2020年 | 22篇 |
2019年 | 37篇 |
2018年 | 29篇 |
2017年 | 35篇 |
2016年 | 43篇 |
2015年 | 32篇 |
2014年 | 49篇 |
2013年 | 60篇 |
2012年 | 38篇 |
2011年 | 87篇 |
2010年 | 57篇 |
2009年 | 52篇 |
2008年 | 58篇 |
2007年 | 60篇 |
2006年 | 44篇 |
2005年 | 52篇 |
2004年 | 36篇 |
2003年 | 35篇 |
2002年 | 26篇 |
2001年 | 26篇 |
2000年 | 26篇 |
1999年 | 29篇 |
1998年 | 167篇 |
1997年 | 95篇 |
1996年 | 62篇 |
1995年 | 41篇 |
1994年 | 42篇 |
1993年 | 38篇 |
1992年 | 15篇 |
1991年 | 18篇 |
1990年 | 19篇 |
1989年 | 24篇 |
1988年 | 20篇 |
1987年 | 25篇 |
1986年 | 21篇 |
1985年 | 24篇 |
1984年 | 11篇 |
1983年 | 19篇 |
1982年 | 14篇 |
1981年 | 26篇 |
1980年 | 16篇 |
1979年 | 11篇 |
1978年 | 24篇 |
1977年 | 25篇 |
1976年 | 45篇 |
1975年 | 15篇 |
1974年 | 17篇 |
排序方式: 共有1873条查询结果,搜索用时 11 毫秒
71.
We have compared the respective efficiencies of off-axis and phase-shifting holography in terms of noise and aliases removal. The comparison is made by analyzing holograms of a USAF target backlit with laser illumination, recorded with a charge-coupled device camera. We show that it is essential to remove the local oscillator beam noise, especially at low illumination levels. 相似文献
72.
73.
Hsiao H Whitestone J Bradtmiller B Whisler R Zwiener J Lafferty C Kau TY Gross M 《Ergonomics》2005,48(4):323-353
Improved human-tractor interface designs, such as well-accommodated operator enclosures (i.e. cabs and protection frames) can enhance operator productivity, comfort and safety. This study investigated farm-worker anthropometry and determined the critical anthropometric measures and 3-D feature envelopes of body landmarks for the design of tractor operator enclosures. One hundred agriculture workers participated in the study. Their body size and shape information was registered, using a 3-D full-body laser scanner. Knee height (sitting) and another eight parameters were found to affect the cab-enclosure accommodation rating and multiple anthropometric dimensions interactively affected the steering wheel and gear-handle impediment. A principal component analysis has identified 15 representative human body models for digitally assessing tractor-cab accommodation. A set of centroid coordinates of 34 body landmarks and the 95% confidence semi-axis-length for each landmark location were developed to guide tractor designers in their placement of tractor control components in order to best accommodate the user population. Finally, the vertical clearance (90 cm) for agriculture tractor enclosure in the current SAE International J2194 standard appeared to be too short as compared to the 99th percentile sitting height of male farm workers in this study (100.6 cm) and in the 1994 National Health and Nutrition Examination Survey III database (99.9 cm) and of the male civilian population in the 2002 Civilian American and European Surface Anthropometric Resource database (100.4 cm). 相似文献
74.
75.
Lauri Wessel Elizabeth Davidson Ana Paula Barquet Hannes Rothe Oliver Peters Herlind Megges 《Information Systems Journal》2019,29(6):1256-1292
In this paper, we develop a new perspective on configuration processes inherent to smart service systems that brings human actors to the theoretical foreground, is informed by practice theory, and is grounded in an intervention study of smart locating systems used in home care of persons with dementia. Maintaining control of the location of persons with dementia is a major source of caregiver burden, and assistive technologies such as smart locating systems hold the promise of enhancing quality of life and reducing caregiver burden. Drawing from research on smart service systems, organizational configuration research, and practice theory, we articulate a conceptual model of configuring in practice to explain how practice elements and the capabilities of smart technologies become mutually configured. Our analysis of study participants' experiences with the locating systems identified three distinctive configurations, characterized as enhanced smartness, degraded smartness, and fragile smartness, which developed through configuring processes. The configuring in practice model we develop here helps explain why unexpected and anticipated configurations develop and thus the conditions that facilitate or inhibit value cocreation in smart service systems. 相似文献
76.
Increased prevalence of Alzheimer's disease-like beta-amyloid deposits in the neuropil and within neurons occurs in the brains of non-demented individuals with heart disease. Heart disease is a prevalent finding in Alzheimer's disease, and may be a forerunner to the dementing disorder. In the cholesterol-fed rabbit model of human coronary heart disease there is production and accumulation of beta-amyloid in the brain. This accumulation of beta-amyloid can be reversed by removing cholesterol from the rabbits' diet. In culture cells, a cholesterol challenge has been shown to increase production of beta-amyloid, and dramatic reductions of cholesterol produced by HMG Co-A reductase inhibitors decrease production of beta-amyloid. Increased beta-amyloid production is also produced by dietary cholesterol in a number of transgenic mouse models of Alzheimer's disease. Administration of HMG Co-A reductase inhibitors may block beta-amyloid production caused by dietary cholesterol in rabbits. Clinical trials testing the benefit of HMG Co-A reductase inhibitors in the treatment of Alzheimer's disease are underway. 相似文献
77.
Gerhard Klasz Hannes Gabriel Helmut Habersack Roland Schmalfuß Christian Baumgartner Dieter Gutknecht 《?sterreichische Wasser- und Abfallwirtschaft》2016,68(5-6):199-207
The Danube east of Vienna was originally an untamed, widely branching river with an approximately stable bed elevation. Regulation in the second half of the 19th century changed its morphology fundamentally—initially through upstream regulation and the consequent bedload deposit resulting in heavy aggradation—and subsequently left the bed elevation and water level almost the same until around the 1940s. Only in the second half of the 20th century did the bed elevation and low and mean water levels decrease significantly, and this trend—amplified by the power plant extension—continues today, despite constant bedload dumps to ensure the tailwater supply for the power plant at Vienna Freudenau. Further east from the Austrian-Slovak stretch of border, congestion due to the Gab?íkovo power plant becomes apparent: most of the bedload is again deposited here. This study investigates these processes using hydrographic observations in their spatial and temporal context, and, based on actual bed elevation measurements, creates a bedload balance and compares it with the results of previous studies. Bed erosion in the Danube floodplains and the local national park has far-reaching consequences, especially through siltation and scrub encroachment in the river’s branches, which are further amplified by flat, fine sediment deposits in the foothills and the formation of embankments. In the long term, flood and other water management objectives will also be adversely affected. 相似文献
78.
We propose a numerical simulation technique to model the process of diffusional creep and stress relaxation that occurs in
Cu-damascene interconnects of integrated circuit devices in processing stage. The mass flow problem is coupled to the stress
analysis through vacancy flux and equilibrium vacancy concentration. The technique is implemented in a software package that
seamlessly integrates the problem-oriented code with commercially available finite element program MSC.Marc. It is utilized
to model the Coble creep phenomenon by introducing the nanoscale grain boundary region having the thickness on the order of
several layers of atoms. As an illustration, the two-dimensional problem of stress relaxation in a single grain subjected
to prescribed displacements and tractions is examined. 相似文献
79.
80.
J. M. Gross J. D. Barnes J. K. Brown 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1970,20(5):162-164
The infra-red spectra of alkali-metal nitrobenzenides are reported and compared with that of nitrobenzene. Tentative assignments of some of the major bands are proposed. 相似文献