全文获取类型
收费全文 | 1075篇 |
免费 | 58篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 361篇 |
金属工艺 | 8篇 |
机械仪表 | 9篇 |
建筑科学 | 39篇 |
矿业工程 | 1篇 |
能源动力 | 20篇 |
轻工业 | 207篇 |
水利工程 | 4篇 |
石油天然气 | 2篇 |
无线电 | 68篇 |
一般工业技术 | 172篇 |
冶金工业 | 80篇 |
原子能技术 | 6篇 |
自动化技术 | 147篇 |
出版年
2024年 | 1篇 |
2023年 | 18篇 |
2022年 | 42篇 |
2021年 | 57篇 |
2020年 | 16篇 |
2019年 | 24篇 |
2018年 | 32篇 |
2017年 | 23篇 |
2016年 | 31篇 |
2015年 | 18篇 |
2014年 | 45篇 |
2013年 | 65篇 |
2012年 | 64篇 |
2011年 | 88篇 |
2010年 | 70篇 |
2009年 | 70篇 |
2008年 | 60篇 |
2007年 | 73篇 |
2006年 | 47篇 |
2005年 | 46篇 |
2004年 | 32篇 |
2003年 | 36篇 |
2002年 | 33篇 |
2001年 | 14篇 |
2000年 | 17篇 |
1999年 | 16篇 |
1998年 | 15篇 |
1997年 | 13篇 |
1996年 | 9篇 |
1995年 | 14篇 |
1994年 | 10篇 |
1993年 | 5篇 |
1992年 | 9篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1974年 | 2篇 |
1969年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有1133条查询结果,搜索用时 15 毫秒
61.
The local spatial autocorrelation and the kernel method for identifying black zones. A comparative approach 总被引:3,自引:0,他引:3
This article aims to determine the location and the length of road sections characterized by a concentration of accidents (black zones). Two methods are compared: one based on a local decomposition of a global autocorrelation index, the other on kernel estimation. After explanation, both methods are applied and compared in terms of operational results, respective advantages and shortcomings, as well as underlying conceptual elements. The operationality of both methods is illustrated by an application to one Belgian road. 相似文献
62.
Analysis of octyl- and nonylphenol and their ethoxylates in water and sediments by liquid chromatography/tandem mass spectrometry 总被引:10,自引:0,他引:10
The ubiquitous presence of alkylphenol ethoxylates in the environment as well as concern for endocrine disruption effects in biota caused by their degradation products (such as octyl- and nonylphenol) has raised interest in the environmental fate of these compounds. As part of an effort to model their behavior in a subestuary of the Chesapeake Bay, a quantitative method for the analysis of octyl- and nonylphenol, and their ethoxylates (1-5) in water and sediment was developed. Extraction procedures are based on solid-phase extraction techniques. Identification and quantitation of the analytes is done by liquid chromatography coupled to tandem mass spectrometry. Instrument detection limits for the compounds ranged from 0.1 to 9 pg injected on column, which allowed method detection limits of 0.04-3 ng/L in water and 0.2-13 ng/g of dry weight in sediment. The method was used to analyze water and sediment from the Back River, MD, where concentrations for the individual compounds ranged from <8 to 200 ng/L in water and <9 to 6700 ng/g of dry weight in sediment. Additionally, structural information obtained in the mass spectrometer is presented that supports previous observations that nonylphenol and its ethoxylates are composed mainly of isomers with a tertiary alpha-carbon. 相似文献
63.
64.
Boutet Isabelle; Milgram Norton W.; Freedman Morris 《Canadian Metallurgical Quarterly》2007,121(3):270
Using a comparative neuropsychological approach, the authors compared performance of younger and healthy older adults ages 65 and over on tasks originally developed to measure cognition in animals. A battery of 6 tasks was used to evaluate object discrimination, egocentric spatial abilities, visual and spatial working memory, and response shifting. Older adults performed more poorly than younger adults on tasks that evaluate egocentric spatial abilities, response shifting, and to a lesser extent object recognition. The two groups did not differ for tasks that evaluate spatial working memory and object discrimination. The impairments the authors observed in tasks that evaluate response shifting and object recognition are consistent with those found in canines and primates as well as those found in Alzheimer's disease. The results are consistent with the notion that cognitive processes supported by the amygdala and the orbitofrontal cortex are among the first to decline with increasing age in both humans and animals. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
65.
This paper addresses the control design problem for a certain class of continuous-time nonlinear systems subject to actuator saturations. The system under consideration consists of a system with two nested nonlinearities of different type: saturation nonlinearity and cone-bounded nonlinearity. The control law investigated for stabilization purposes depends on both the state and the cone-bounded nonlinearity. Constructive conditions based on LMIs are then provided to ensure the regional or global stability of the system. Different points, like other approaches issued from the literature, are quickly discussed. An illustrative example allows to show the interest of the approach proposed. 相似文献
66.
Richard Marchal Isabelle Tabary Michel Valade Dominique Moncomble Laurence Viaux Bertrand Robillard Philippe Jeandet 《Journal of the science of food and agriculture》2001,81(14):1371-1378
Qualitative effects of Botrytis cinerea infection were studied by comparing the foaming properties of Champagnes obtained from healthy grapes with those from grapes infected by B cinerea. This is of particular interest when it is considered that the foaming properties of Champagne wines are important in terms of product attractiveness for the consumer. Experiments using artificial viewing equipment clearly showed the dramatic effects on Champagne foam characteristics when grape berries were highly infected. The speed at which liquid separated from the foam (expressed as liquid height LS) in the glass depended largely on the level of infection for Chardonnary and Pinot noir wines (+268% for Chardonnary wines at 40% infection and +627% for Pinot noir wines at 20% infection). B cinerea infection reduced the time (LT) at which liquid first appeared in the glass; for Pinot noir wines an infection level of 20% caused very rapid drainage. The time of pouring (PT, ie the time to fill the glass under controlled conditions) also diminished considerably at an infection level of 20% for both Pinot noir and Pinot meunier wines (?74 and ?58% respectively). Mouldiness considerably altered the foam height observed 80 s (H80) after the start of pouring (?83% for Pinot noir and ?89% for Pinot meunier at 20% infection). Champagne foamability was also quantified using a sparging technique to standardise effervescence. Foamability suffered considerably (?60 to ?65%) when the B cinerea infection level was 20% as compared to control Champagnes. All wines studied had low and very similar protein contents. Differences in the concentrations of these compounds, which are generally implicated in the formation of foam in sparkling wines, could not explain the differences in Champagne foaming properties observed here. © 2001 Society of Chemical Industry 相似文献
67.
This study evaluated the effect of aluminum phosphate (AlPO4 ) additions on the crystallization behavior and bioactivity of potassium fluorrichterite glasses and glass–ceramics. Four glass compositions with increasing amounts of AlPO4 were melted. Mica and fluorrichterite were present in all glass–ceramics after crystallization. The microstructure consisted of platelet-shaped mica and prismatic fluorrichterite crystals. After incubation in simulated body fluid, a layer consisting of spherical-nanosized particles was present on the surface of the glasses. X-ray diffraction revealed the presence of hydroxyapatite after incubation of the glass and glass–ceramic powders. The addition of AlPO4 promoted mica nucleation and bioactivity in K-fluorrichterite glass–ceramics. 相似文献
68.
69.
Levine Brian; Dawson Deirdre; Boutet Isabelle; Schwartz Michael L.; Stuss Donald T. 《Canadian Metallurgical Quarterly》2000,14(4):491
Standard neuropsychological tests administered in a constrained and artificial laboratory environment are often insensitive to the real-life deficits faced by patients with traumatic brain injury (TBI). The Revised Strategy Application Test (R-SAT) creates an unstructured environment in the laboratory in which environmental cues and internal habits oppose the most efficient strategy, thus mimicking the real-life situations that are problematic for patients with TBI. In this study, R-SAT performance was related both to severity of TBI (i.e., depth of coma) sustained 2–3 years earlier and to quality of life outcome as assessed by the Sickness Impact Profile. This relationship held after accounting for variance attributable to TBI-related slowing and inattention. These findings support the validity of the R-SAT and suggest that behavioral correlates of quality of life outcome in TBI can be assessed in the laboratory with unstructured tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
70.