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   205篇
  免费   15篇
综合类   2篇
化学工业   100篇
机械仪表   1篇
建筑科学   1篇
能源动力   2篇
轻工业   112篇
石油天然气   2篇
  2024年   1篇
  2023年   5篇
  2022年   8篇
  2021年   8篇
  2020年   4篇
  2019年   10篇
  2018年   5篇
  2017年   4篇
  2016年   4篇
  2015年   6篇
  2014年   7篇
  2013年   18篇
  2012年   5篇
  2011年   7篇
  2010年   4篇
  2009年   6篇
  2008年   4篇
  2007年   5篇
  2006年   9篇
  2005年   10篇
  2004年   6篇
  2003年   5篇
  2002年   2篇
  2001年   8篇
  2000年   6篇
  1999年   4篇
  1998年   2篇
  1997年   5篇
  1996年   7篇
  1995年   7篇
  1994年   11篇
  1993年   14篇
  1992年   8篇
  1991年   2篇
  1990年   3篇
排序方式: 共有220条查询结果,搜索用时 31 毫秒
81.
The role of nanoparticles and nanofluid additives for biodiesel has gained consistent position in the current trend as they contribute to increase the performance of the engine with lower emission. In addition, additives also help to increase the engine reliability and lifespan. In this work, the effects of canola biodiesel blends of 20% proportions with diesel were investigated at 100% of engine load. The fuel is tested in a multi-cylinder water-cooled direct ignition (DI) engine. There are numerous notable works on nanofluid; however, the addition of TiO2 nanoparticle as additive to produce canola biodiesel fuel is very limited. With the addition of the TiO2 nanoparticle on Canola biodiesel blend in the DI engine, the exhaust property of gases such as CO, HC and NOX is reduced. Furthermore, the combustion characteristics of the engine are improved. The canola biodiesel blends also resulted in lower NOx emission as well as low smoke.  相似文献   
82.
This experiment used 18 lactating Holstein cows in a 3 x 3 Latin square replicated 6 times to determine the effectiveness of processing with moist heat or moist heat combined with lignosulfonate (LSO3) for increasing the ruminal undegradable fraction of canola meal for use as a protein supplement for lactating dairy cows. Diets were formulated to be isonitrogenous and contained one of 3 forms of canola meal; untreated canola meal (UCM), heat-treated canola meal (HTCM) or heat-and LSO3-treated canola meal (LSO3CM). Total collection of urine and feces was taken from each cow during the last 5 d of each 42-d experimental period. Milk production was greater for cows fed the LSO3CM diet (36.6 kg/d) than for cows fed the UCM diet (34.8 kg/d) but did not differ from cows fed the HTCM diet (35.3 kg/d). Digestibility of crude protein was lower for cows supplemented with LSO3CM and they had reduced concentrations of ruminal ammonia N, blood urea N, and milk urea N compared with cows supplemented with UCM or HTCM. Dry matter intake and apparent digestibilities of neutral and acid detergent fiber were increased in cows fed the LSO3CM diet. Urinary N excretion (as % of N intake) was reduced in cows fed the LSO3CM diet. These results indicate that moist heat combined with LSO3 treatment of canola meal was effective in increasing the proportion of crude protein digested in the lower digestive tract of lactating cows and was therefore used more effectively as a source of protein than UCM or HTCM.  相似文献   
83.
Silica hydrogels acidified with strong mineral acids, such as sulfuric acid, are highly effective chlorophyll and phospholipid adsorbents relative to traditional acid-activated bleaching earth (ABE), but they are not effective β-carotene adsorbents. When an acidified silica is used as the only bleaching agent, sulfuric acid leaches into the oil, and after deodorization, Tintometer red and yellow (R/Y) numbers are higher than those for ABE-bleached and deodorized oils. The fixed R/Y colors do not arise solely from the decomposition of β-carotene during deodorization. Sequential treatments of canola oils with sulfuric acid/silica and ABE can be performed to overcome all of the drawbacks associated with sulfuric acid/silica treatment alone, such that finished oils can be produced by lower overall adsorbent dosages.  相似文献   
84.
An analysis of pigments responsible for color formation during bleaching and deodorization of canola oils treated with activated bleaching earth (ABE) or novel mineral-acid/silica (AS) adsorbents is presented. The chromophores are trace glycerides and were concentrated by silica column chromatography. The concentrated color bodies were hydrolyzed and analyzed as free acids or methyl esters by reversed-phase high-performance liquid chromatography with photodiode array and mass spectrometry detection,1H and13C nuclear magnetic resonance and infrared spectroscopies. Absorbance in deodorized oils is mostly from oxygenated C18 and C20 fatty acids with 1 to 4 double bonds. High-wavelength absorbance in AS-bleached oils is from conjugated pentane fatty acids that are not observed for ABE-bleached oils. Thus, both the bleaching agent and the deodorization treatment affect the distribution and concentration of such stable chromophores.  相似文献   
85.
The compound 1-O-β-D glucopyranosyl sinapate (GPS), a phenolic glycoside, was separated from ethanolic extracts of defatted canola meal by a two-step chromatographic method. The first step involved Sephadex LH-20 chromatography with methanol as the eluting solvent. The solvent from the fraction containing GPS was evaporated, and glucopyranosyl sinapate was subsequently separated by a semi-preparative high-performance liquid chromatography method with an RP-18 column and a mobile phase consisting of water/acetonitrile/acetic acid (88∶10∶2, vol/vol/vol).  相似文献   
86.
Blends of high-oleic sunflower oil and fully hydrogenated canola oil were subjected to enzymatic and chemical interesterification using Candida antarctica lipase (5%) and sodium methoxide (0.3%), respectively. The effect of each interesterification process was determined by comparing the triacylglycerol (TAG) composition, solid fat content (SFC) profiles and thermal properties of the blends before and after interesterification. Interesterification resulted in a decrease in the concentration of triunsaturated and trisaturated TAG and an increase in the proportion of mono- and disaturated TAG. These alterations in TAG composition and the presence of a greater variety of TAG species upon interesterification was correlated with a broader melting transition by differential scanning calorimetry and, ultimately, a lower melting point for the interesterified blends. Much broader ranges in plasticity were observed for the interesterified blends (chemically and enzymatically) compared to the physical blends. Even though ideal solubility of stearin in oil was observed, the value predicted by the Hildebrand model was higher than the actual amount. Crystallization kinetic parameters (Avrami index and rate constant) were similar for the non-interesterified, enzymatically interesterified and chemically interesterified blends when compared as a function of SFC. Results from this work will aid in the formulation of more healthy fat and oil products and address a critical industrial demand in terms of formulation options for spreads, margarines and shortenings.  相似文献   
87.
88.
In this research, the reinforcing effect of fillers including canola stalk, paulownia and nanoclay, in polypropylene (PP) has been investigated. In the sample preparation, 50 wt% of lignocellulosic materials and 0, 3, and 5 wt% of nanoclay particles were used. The results showed that while flexural and tensile properties were moderately enhanced by the addition of nanoclay in the matrix, notched Izod impact strengths decreased dramatically. However, with increase in the nanoclay content (5 wt%), the flexural and tensile properties decreased considerably. The mechanical properties of composites filled with paulownia are generally greater than canola stalk composites, due to the higher aspect ratio. The thickness swelling and water absorption of the composites significantly decreased with the increase in nanoclay loading. Except tensile modulus, the differences between the type of fibrous materials and nanoclay contents had significant influence on physicomechanical properties. Morphologies of the composites were analyzed using transmission electron microscopy (TEM) and X‐ray diffraction (XRD), and the results showed increased d‐spacing of clay layers indicating enhanced compatibility among PP, clay, and lignocellulosic material. TEM micrographs also confirmed that the composites containing 3 wt% nanoclay had uniform dispersion and distribution of clay layers in the polymer matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   
89.
BACKGROUND: World interest in biodiesel production from canola seed is expanding. There is little information on the nutritive value of biodiesel by‐products produced from micro‐scale production processes. Hence this trial was conducted to determine the nutritional value of regular and green canola biodiesel press cake for broilers. RESULTS: The digestibility of dry matter, neutral detergent fibre, and nitrogen retention were higher (P < 0.05) for birds fed regular or green canola press cake compared with canola meal. Ether extract digestibility was higher (P < 0.05) for birds fed regular press cake than canola meal, while green press cake and canola meal did not differ. There was no improvement in body weight gain (P > 0.05), while feed conversion was only modestly improved (P < 0.05) by the inclusion of regular or green canola press cake. CONCLUSIONS: Since the performance of broilers fed canola biodiesel press cakes was similar to those fed canola meal, it is difficult to justify a premium to be paid for canola press cake over canola meal. In addition, there was no difference in the performance of broilers fed biodiesel press cake obtained from green or regular canola seed. As green seeds are generally available at a lower price than regular seed, there may be some incentive to choose green canola seed for producing biodiesel and biodiesel press cake for use in poultry production. Copyright © 2009 Society of Chemical Industry  相似文献   
90.
Wastage of byproducts such as canola meal is a pressing environmental concern, and canola protein isolate (CPI)?chitosan (Ch) coacervates have a good potential to utilize and convert the wastes into a high value added product. Yet so far, there is very limited rheological and microstructural information to assist in proper utilization of CPI ‐Ch complex coacervates. The rheological and microstructural properties of the complex coacervates formed from CPI and chitosan Ch at various CPI‐to‐Ch mixing ratios (1:1, 16:1, 20:1, and 30:1) and pH values (5.0, 6.0, and 7.0) were therefore investigated. These CPI?Ch complex coacervate phases were found to exhibit elastic behavior as evidenced by significantly higher elastic modulus (G?) compared to viscous modulus (G″) in all the tested ratios and pH ranges. They also exhibited shear‐thinning behavior during viscous flow. The complex coacervates formed at the optimum CPI‐to‐Ch ratio of 16:1 and pH of 6.0 demonstrated the highest G?, G″, and shear viscosity, which correlated well with the high strength of electrostatic interaction and thick‐walled, sponge‐like, less‐porous microstructure at this condition. The higher shear viscosity of the coacervate at pH 6.0 was most likely induced by stronger attractive electrostatic interactions between CPI and Ch molecules, due to the formation of a rather densely packed complex coacervate structure. Hence, it can be concluded that the microstructural observations of denser structure correlated well with the rheological findings of stronger intermolecular bonds at the optimum CPI‐to‐Ch ratio of 16:1 and pH of 6.0. The complex coacervate phase formed at a CPI‐to‐Ch ratio of 16:1 and pH of 6.0 also showed glassy consistency at low temperatures and rubbery consistency above its glass‐transition temperature. This study identified the potential for the newly developed CPI–Ch complex coacervate to be used as an encapsulating material due to its favorable strength. This would drastically reduce the wastage of byproducts, provide a solution to tackle the pressing global issue of wastage of byproducts, and bring about a more environmentally friendly paradigm.  相似文献   
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