全文获取类型
收费全文 | 214篇 |
免费 | 11篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 5篇 |
化学工业 | 62篇 |
金属工艺 | 3篇 |
机械仪表 | 3篇 |
建筑科学 | 13篇 |
能源动力 | 12篇 |
轻工业 | 42篇 |
水利工程 | 1篇 |
无线电 | 15篇 |
一般工业技术 | 35篇 |
冶金工业 | 23篇 |
自动化技术 | 12篇 |
出版年
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 16篇 |
2020年 | 8篇 |
2019年 | 15篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 15篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 18篇 |
2012年 | 6篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2009年 | 9篇 |
2008年 | 12篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 4篇 |
2004年 | 1篇 |
2003年 | 4篇 |
2001年 | 2篇 |
1999年 | 2篇 |
1998年 | 7篇 |
1997年 | 4篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有226条查询结果,搜索用时 15 毫秒
61.
62.
Green vegetable crops irrigated with wastewater are highly contaminated with heavy metals and are the main source of human exposure to the contaminants. In this study accumulation of eight heavy metals (Cu, Ni, Zn, Cr, Fe, Mn, Co and Pb) in green vegetables like Allium cepa, Allium sativum, Solanum lycopersicum and Solanum melongena, irrigated with wastewater in Mardan are studied using Atomic Absorption spectrophotometer. The studied metals in vegetable grown on wastewater irrigated soil were significantly higher than those of tube well water irrigated soil and WHO/FAO permissible limits (P < 0.05). The most heavily contaminated vegetable was wastewater irrigated A. cepa, where the accumulation of Mn (28.05 mg kg?1) in the edible parts was 50-fold greater than A. cepa irrigated with tube well water irrigated soil. It may be concluded that both adults and children consuming these vegetables grown in wastewater irrigated soil ingest significant amount of these metals and thus can cause serious health problems. 相似文献
63.
N. Vedaraman S. Shamshath Begum S. V. Srinivasan 《Clean Technologies and Environmental Policy》2013,15(4):607-616
Ozonation of tannery dye Acid Black 52 in a packed bed reactor has been examined to study the effect of operating variables pH, dye concentration and contact time. In this study, the effect of operating variables on the removal of colour and chemical oxygen demand (COD) was studied using 23 central composite designs using Minitab 15 software. The operating variables were analysed based on the removal efficiency of colour and COD. Experimental results were analysed by regression analysis and analysis of variance statistical methods. The optimum conditions for maximum colour removal (100 %) and COD removal (61 %) were found to be at pH: 1.96, dye concentration: 1,159 mg/L, contact time: 10.6 min (min) and at pH: 4.8, dye concentration: 1,159 mg/L, contact time: 17 min, respectively. The experimental values were in good agreement with the predicted values and the model is found to be highly significant with the correlation coefficient of 0.94 for both colour and COD removal. 相似文献
64.
Legarra J.R. Cusick J. Begum R. Kolda P. Cascone M. 《Electron Devices, IEEE Transactions on》2005,52(5):665-668
Worldwide demand for high-power amplifiers for digital satellite communication at Ka-band frequencies between 27 and 31 GHz is steadily increasing (2003). Communication and Power Industries (CPI) has developed a 500-W periodic permanent magnet focused coupled-cavity traveling wave tube (TWT) for conduction-cooled amplifier systems, which is being introduced into the commercial satellite communication market. The TWT is capable of greater than 500-MHz instantaneous bandwidth and is cathode voltage tunable from 28.3 to 30 GHz. The TWT may be operated saturated at the 500-W output power level or backed off from saturation in the linear mode. CPI's Satcom Division has integrated the TWT into a conduction-cooled transmitter box suitable for antenna hub-mount applications. The amplifier uses predistortion networks to provide a high degree of linear response when operated in output power back-off mode. 相似文献
65.
In previous work, we developed a simplified model for the diffusion controlled bulk polymerization of methyl methacrylate and extended the model to capture the reaction under nanoconfinement. The calorimetric conversion versus time data in bulk and in silanized hydrophobic nanopores was well captured by the model. Here we further extend the model to capture the reaction in native hydrophilic controlled pore glass (CPG) nanopores accounting for catalysis by surface silanol groups. The ability of the model to describe experimental data is tested. In order to fit the data, the parameters describing monomer and active chain diffusion differ from that in hydrophobic pores. 相似文献
66.
An expanded factor analysis model (ME-2) that is capable of taking into account the influence of independent variables such as wind speed, wind direction, time of year and other variables of the measured fine particle matter (PM2.5) concentration data was utilized for identifying sources of airborne pollutants and providing quantitative estimations of the contribution of each source. The chemical composition data used in this study were obtained from PM2.5 samples collected using the Interagency Monitoring of Protected Visual Environments samplers from August 1999 to December 2001 at an urban monitoring site in Washington, DC. The expanded model has been applied to two different data sets based on the particulate carbon variables. Such an approach had been successfully applied previously and provided improved source resolution in simulated and ambient concentration data. Initially, total OC and EC were used in the expanded model and were compared to the results using conventional positive matrix factorization that had been done previously using the individual carbon fractions data. In the other expanded model analysis, the eight carbon fractions were used during the modeling in order to ascertain if additional source information could be extracted from the data. In both cases, it was possible to separate diesel from spark-ignition vehicles. The use of the individual carbon fractions in the model provides information on what appears to be secondary organic aerosol formation. 相似文献
67.
Sujatha T Shatrugna V Vidyasagar P Begum N Padmavathy KS Reddy GC Rao GV 《Food and nutrition bulletin》2003,24(2):193-199
Time-disposition studies are necessary for computing energy requirements of populations. This study captures the rich information on the timed activity pattern of adult women from poor households engaged in home-based work. We studied 34 women beedimakers (cigarette makers), 21 tailors, and 34 homemakers. Data were collected by direct observation of the women's activities on a typical day. Time spent on related activities was pooled and classified as sleep, household work, child care, occupational work, and residual work. These were further categorized on the basis of our published work on the energy cost of women's activities and the World Health Organization (WHO) classification of occupational activities as sedentary, moderate, and heavy. Most of the household activities could be classified as moderate to heavy (> 2.2 times basal metabolic rate [BMR]). Childcare activities were distributed on a scale from sedentary to heavy, whereas occupational activities, such as beedimaking and tailoring, were sedentary (< 2.2 BMR). Homemakers spent significantly more time on moderate to heavy work (p < .05) than beedimakers and tailors. Women working for income spent only four to six hours on occupational work, which was possible because they reduced the time spent on heavy work (i.e., housework), and reduced the time on personal care. Still, more than 80% of women could not put in eight hours of paid work. Thus, women in the home-based sector constantly negotiate among time spent on heavy household work, child care, and occupational work in order to continue in the labor market. 相似文献
68.
Nurul Haque Bhuiyan Aftabuddin Ahmed Sufia Begum 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1979,29(3):169-174
Reactions of molybdenum (VI) oxide with (a) zinc sulphide and (b) cadmium sulphide were studied in the temperature range 723–973 K. Small amounts of mixtures of molybdenum (IV) sulphide and molybdenum (IV) oxide, which are difficult to separate, were produced. When ammonium chloride was added to the reactants, 89.1% pure MoS2 at 773 K and 96.17% pure MoS2 at 798 K were produced in the case of zinc sulphide and cadmium sulphide respectively. 相似文献
69.
Begum Koysuren Mecit Halil Oztop Bekir Gokcen Mazi 《International Journal of Food Science & Technology》2021,56(11):5471-5484
Sesame seed is mostly utilised for its oil but also the waste of the oil processing; the seed meal has also significant potential to be used as an alternative protein source. In this study, the goal is to produce sesame seed protein by using three different techniques; alkaline, salt and enzyme-assisted extraction. A comprehensive physicochemical characterisation of the extracts was performed. Total and soluble protein contents, emulsification activity & emulsion stability, FTIR spectroscopy, hydration behaviour and gelling ability experiments by TD-NMR were conducted for all extracted proteins. Also, SDS-PAGE experiments were performed to observe the effect of extraction conditions on protein folding. Overall, the aqueous phase of enzyme-assisted extracted proteins (E-ACP) had the highest protein content and solubility, which resulted in other improved physicochemical properties. Salt extracted samples were ‘salted-out’, therefore, had poor physicochemical properties. TD-NMR experiments further confirmed the solubility and gelling ability results by measuring the change in the T2 spin relaxation times. Additionally, FTIR spectroscopy confirmed the most critical peaks for the proteins; Amide I (C=O stretching) and Amide II (N–H bending). In summary, depending on the physicochemical property of interest, different extraction methods yielded proteins with different properties. 相似文献
70.
Begum Elibal H. Funda Suzen H. Ayse Aksoy Guldem Ustun Melek Tuter 《International Journal of Food Science & Technology》2011,46(7):1422-1427
Structured lipids containing conjugated linolenic acid (CLNA) were produced separately by enzymatic acidolysis reaction of corn and canola oils (CAO) with bitter gourd (Momordica charantia L) seed oil fatty acids [bitter gourd seed oil fatty acids (BGFA)]. Reactions were conducted using a commercial immobilised sn‐1,3‐specific lipase from Thermomyces lanuginosa (Lipozyme TL IM) in hexane. The effects of reaction time, substrate molar ratio, temperature and enzyme amount on incorporation yield of CLNA were investigated and optimised by response surface methodology with three‐level, two‐factor face‐centred cube design. When reactions were conducted using 10% enzyme for 3 h, the optimum reaction conditions were found for corn oil (CO) as 53.5 °C and 5.9:1 BGFA/CO molar ratio. At these conditions, the incorporation of CLNA into CO was determined as 41.4%. However, CLNA incorporation into CAO was resulted as 37% at optimum conditions which were 54.2 °C and 6.8:1 BGFA/CAO molar ratio. 相似文献