首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   672篇
  免费   41篇
电工技术   4篇
综合类   11篇
化学工业   217篇
金属工艺   8篇
机械仪表   9篇
建筑科学   40篇
矿业工程   4篇
能源动力   17篇
轻工业   159篇
水利工程   6篇
石油天然气   6篇
无线电   25篇
一般工业技术   79篇
冶金工业   67篇
原子能技术   4篇
自动化技术   57篇
  2023年   9篇
  2022年   21篇
  2021年   32篇
  2020年   16篇
  2019年   13篇
  2018年   23篇
  2017年   13篇
  2016年   19篇
  2015年   30篇
  2014年   29篇
  2013年   49篇
  2012年   29篇
  2011年   36篇
  2010年   31篇
  2009年   31篇
  2008年   43篇
  2007年   26篇
  2006年   32篇
  2005年   24篇
  2004年   25篇
  2003年   19篇
  2002年   21篇
  2001年   10篇
  2000年   10篇
  1999年   7篇
  1998年   7篇
  1996年   6篇
  1995年   11篇
  1994年   12篇
  1993年   4篇
  1992年   10篇
  1991年   6篇
  1990年   4篇
  1989年   3篇
  1988年   3篇
  1987年   2篇
  1986年   2篇
  1985年   3篇
  1983年   2篇
  1980年   2篇
  1979年   2篇
  1978年   4篇
  1977年   2篇
  1976年   2篇
  1968年   2篇
  1957年   1篇
  1956年   1篇
  1954年   1篇
  1948年   13篇
  1919年   1篇
排序方式: 共有713条查询结果,搜索用时 15 毫秒
101.
Fabrics are pliable, breathable, lightweight, ambient stable, and have unmatched haptic perception. Here, a vapor deposition method is used to transform off‐the‐shelf plain‐woven fabrics, such as linen, silk, and bast fiber fabrics, into metal‐free conducting electrodes. These fabric electrodes are resistant to wear, stable after laundering and ironing, and can be body‐mounted with little detriment to their performance. A unique by‐product of conformally vapor coating plain‐woven fabrics is that textile parameters, such as thread material and fabric porosity, significantly affect the conductivity of the resulting fabric electrodes. The resistivities of the electrodes reported herein are linearly, not exponentially, dependent on length, meaning that they can be feasibly incorporated into garments and other large‐area body‐mounted devices. Further, these fabric electrodes possess the feel, weight, breathability, and pliability of standard fabrics, which are important to enable adoption of wearable devices.  相似文献   
102.
The aim of this study was to evaluate the effect of an intervention comprising education and support in performing frequent and structured work preparation meetings with broad participation. Such work preparation meetings were expected to have positive effects on safety climate by emphasizing the value of safety at the work site, and on perceived influence at work. The study was a longitudinal, matched before and after questionnaire study, with six construction sites within a large Swedish construction company, randomly assigned to the intervention or the comparison group. Contrary to expectations, the intervention group reported a decrease in safety climate, while this increased in the comparison group. Perceived influence at work showed a tendency to decrease at the interventions sites. Frequent work preparation meetings may provide ample opportunity for obtaining perceptual safety climate cues. But the effect is dependent on how these meetings are performed, and what priorities are conveyed.  相似文献   
103.
This study used a cross-national framework to examine country, region, and gender differences in emotional availability (EA), a prominent index of mutual socioemotional adaptation in the parent-child dyad. Altogether 220 Argentine, Italian, and U.S. mothers and their daughters and sons from both rural and metropolitan areas took part in home observations when the children were 20 months old. In terms of country, Italian mothers were more sensitive and optimally structuring, and Italian children were more responsive and involving, than Argentine and U.S. dyads. In terms of region, rural mothers were more intrusive than metropolitan mothers, and boys from metropolitan areas were more responsive than boys from rural areas. In terms of gender, mothers of girls were more sensitive and optimally structuring than mothers of boys, and daughters were more responsive and involving than sons. Understanding how country, region, and gender influence EA exposes forces that shape child development, parent-infant interaction, and family systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
104.
Peroxy-organic acids are formed by the chemical reaction between organic acids and hydrogen peroxide. The peroxy-acid process was applied to two Superfund site soils provided by the U.S. Environmental Protection Agency (EPA). Initial small-scale experiments applied ratios of 3:5:7 (v/v/v) or 3:3:9 (v/v/v) hydrogen peroxide:acetic acid:deionized (DI) water solution to 5g of Superfund site soil. The experiment using 3:5:7 (v/v/v) ratio resulted in an almost complete degradation of the 14 EPA regulated polycyclic aromatic hydrocarbons (PAHs) in Bedford LT soil during a 24-h reaction period, while the 3:3:9 (v/v/v) ratio resulted in no applicable degradation in Bedford LT lot 10 soil over the same reaction period. Specific Superfund site soil characteristics (e.g., pH, total organic carbon content and particle size distribution) were found to play an important role in the availability of the PAHs and the efficiency of the transformation during the peroxy-acid process. A scaled-up experiment followed treating 150g of Bedford LT lot 10 soil with and without mixing. The scaled-up processes applied a 3:3:9 (v/v/v) solution resulting in significant decrease in PAH contamination. These findings demonstrate the peroxy-acid process as a viable option for the treatment of PAH contaminated soils. Further work is necessary in order to elucidate the mechanisms of this process.  相似文献   
105.
Metabolic footprinting as a tool for discriminating between brewing yeasts   总被引:5,自引:0,他引:5  
The characterization of industrial yeast strains by examining their metabolic footprints (exometabolomes) was investigated and compared to genome-based discriminatory methods. A group of nine industrial brewing yeasts was studied by comparing their metabolic footprints, genetic fingerprints and comparative genomic hybridization profiles. Metabolic footprinting was carried out by both direct injection mass spectrometry (DIMS) and gas chromatography time-of-flight mass spectrometry (GC-TOF-MS), with data analysed by principal components analysis (PCA) and canonical variates analysis (CVA). The genomic profiles of the nine yeasts were compared by PCR-restriction fragment length polymorphism (PCR-RFLP) analysis, genetic fingerprinting using amplified fragment length polymorphism (AFLP) analysis and microarray comparative genome hybridizations (CGH). Metabolomic and genomic analysis comparison of the nine brewing yeasts identified metabolomics as a powerful tool in separating genotypically and phenotypically similar strains. For some strains discrimination not achieved genomically was observed metabolomically.  相似文献   
106.
In recent years, there has been a growing interest in the design of novel nonthermal processing systems that minimally modify sensory, nutritional, and functional properties of fruit and vegetable juices and beverages. The benefits of nonthermal treatments are strongly dependent on the food matrix. Thus, an understanding of the effects that these technologies exert on the properties of juices and beverages is important to design and optimize technological parameters to produce value‐added products. This review covers research on nonthermal electrical treatments, high pressure processing, ultrasound, radiation processing, inert gas treatments, cold plasma, and membrane processing. Advances towards optimization of processing conditions, and combined technologies approaches have been also extensively reviewed. This information could be useful to: (1) manage processing systems and optimize resources; (2) preserve nutritional value and organoleptic properties, and (3) provide processing conditions for validation of these technologies at the industrial scale.  相似文献   
107.
Three approaches that allow the tailoring of long period gratings based refractometric sensors for concentration measurement in fuel blends are employed to assess the fuel quality in biodiesel and biodiesel-petrodiesel blend. To allow the analysis of fuel samples with refractive index higher than fiber cladding one, the samples refractive indices were changed by thermo-optic effect and by dilution in a standard substance with low refractive index. The obtained results show the sensor can detect oil concentration in biodiesel samples with resolution as better as 0.07% and biodiesel concentration in biodiesel-petrodiesel samples with average resolution of 0.09%.  相似文献   
108.
Thin film deposits of carbon and tungsten on stainless steel substrate were prepared by RF sputtering of a tungsten target in acetylene atmosphere. At the target bias of − 1700 V and the target current of 30 mA cm− 2, a rather uniform film containing 50 at.% of C and 50 at.% of W was deposited. The thickness of the deposited film was about 1 μm. Samples were exposed to highly dissociated hydrogen plasma created by a microwave discharge at the power of 1000 W. Some samples were heated additionally by concentrated solar radiation. After plasma treatment, the samples were characterized by X-Ray Diffraction and Auger Electron Spectroscopy. The results showed that aggressive hydrogen plasma allows for the removal of carbon from the deposits at moderated temperatures. Prolonged treatment showed formation of highly crystalline pure tungsten, and finally the tungsten film interacted with the substrate forming a thin film rich of Fe7W6 compound. The range of temperature and/or treatment time for the removal of carbon from the W-C film was found very narrow.  相似文献   
109.
The objective was to prepare sheared gels of potato protein concentrate and evaluate the effect of pH (3, ~4, ~7), ionic strength (15 or 200 mM) and protein drying conditions (spray or freeze drying) on the final appearance and rheological characteristics. Heat‐set gels 3 % (w/w) at a high ionic strength (200 mM) resulted in an inhomogeneous appearance with presence of clots, while low ionic strength (15 mM) gave homogenous structures. Gels prepared at pH 3 became transparent while preparation above pH 3.0 resulted in high turbidity. Heat treatment and cooling resulted in gelation for all samples except freeze dried powder at pH 3.0. Flow curves during shear from 0.1 to 100 s?1 were fitted by the Herschel–Bulkley model indicating shear thinning behavior for all samples except the freeze dried sample at pH 3 which displayed a Newtonian behavior. Oscillatory measurements after shear indicated viscus behavior (phase angle above 45°) for the spray dried sample at pH 3, and gelled behavior (phase angle above 45°) for the remaining gelled samples. Structure recovery was observed after shear in all samples except at pH 3.0. The data shows potato protein can be used as ingredient in protein beverages.  相似文献   
110.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号