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   2790篇
  免费   180篇
  国内免费   2篇
电工技术   12篇
综合类   4篇
化学工业   816篇
金属工艺   16篇
机械仪表   44篇
建筑科学   103篇
矿业工程   1篇
能源动力   48篇
轻工业   574篇
水利工程   22篇
石油天然气   13篇
无线电   107篇
一般工业技术   319篇
冶金工业   624篇
原子能技术   14篇
自动化技术   255篇
  2024年   13篇
  2023年   32篇
  2022年   130篇
  2021年   150篇
  2020年   57篇
  2019年   67篇
  2018年   106篇
  2017年   99篇
  2016年   117篇
  2015年   75篇
  2014年   120篇
  2013年   176篇
  2012年   148篇
  2011年   180篇
  2010年   144篇
  2009年   131篇
  2008年   124篇
  2007年   113篇
  2006年   101篇
  2005年   92篇
  2004年   72篇
  2003年   58篇
  2002年   57篇
  2001年   35篇
  2000年   37篇
  1999年   31篇
  1998年   46篇
  1997年   40篇
  1996年   38篇
  1995年   27篇
  1994年   30篇
  1993年   24篇
  1992年   34篇
  1990年   23篇
  1989年   22篇
  1988年   17篇
  1987年   23篇
  1986年   16篇
  1985年   15篇
  1984年   22篇
  1982年   8篇
  1981年   23篇
  1980年   10篇
  1979年   16篇
  1978年   10篇
  1977年   11篇
  1976年   9篇
  1975年   7篇
  1974年   7篇
  1972年   6篇
排序方式: 共有2972条查询结果,搜索用时 15 毫秒
91.
92.
Abstract: This study examined the effectiveness of fat and water soluble antioxidants on the oxidative stability of omega (ω)‐3 rich table spreads, produced using novel multiple emulsion technology. Table spreads were produced by dispersing an oil‐in‐water (O/W) emulsion (500 g/kg 85 camelina/15 fish oil blend) in a hardstock/rapeseed oil blend, using sodium caseinate and polyglycerol polyricinoleate as emulsifiers. The O/W and oil‐in‐water‐in‐oil (O/W/O) emulsions contained either a water soluble antioxidant (green tea extract [GTE]), an oil soluble antioxidant (α‐Tocopherol), or both. Spreads containing α‐Tocopherol had the highest lipid hydroperoxide values, whereas spreads containing GTE had the lowest (P < 0.05), during storage at 5 °C, while p‐Anisidine values did not differ significantly. Particle size was generally unaffected by antioxidant type (P < 0.05). Double emulsion (O/W/O) structures were clearly seen in confocal images of the spreads. By the end of storage, none of the spreads had significantly different G′ values. Firmness (Newtons) of all spreads generally increased during storage (P < 0.05). Practical Application: Lipid oxidation is a major problem in omega‐3 rich oils, and can cause off‐odors and off‐flavors. Double emulsion technology was used to produce omega‐3 enriched spreads (O/W/O emulsions), wherein the omega‐3 oil was incorporated into the inner oil phase, to protect it from lipid oxidation. Antioxidants were added to further protect the spreads by reducing lipid oxidation. Spreads produced had good oxidative stability and possessed functional (omega‐3 addition) properties.  相似文献   
93.
Effects of slaughter weight and sex on carcass characteristics and lamb meat quality of Manchega Spanish breed were analysed. Forty-five lambs were divided into two slaughter weight groups: light (LW=21.7±0.16 kg; n=24) and medium (MW=27.8±0.16 kg; n=21). Dressing proportion and conformation were significantly different between groups and sex. There were also differences between light and medium group in fatness but not between males and females. Water holding capacity decreased with increasing slaughter weight (p<0.05) and was lower in females than in males (p<0.001). The increase in weight was associated with a decrease in L* (p<0.01), while a* showed an increase which failed to reach statistical significance. Slaughter weight and sex affected neither pH and its decrease post-slaughter nor meat toughness. ?  相似文献   
94.
95.
BACKGROUND: The distillation of vinification by‐products to obtain alcoholic drinks is potentially an important source of income for the producing countries and avoids the environmental problem of waste management. Traditional technologies of distillation involve an important cost in terms of time and staff. Nowadays, companies install new distillation equipment, with high capacity and equipped with rectification columns, which is an important advance. Nevertheless, few studieshave been published concerning their correct management. In this study, the major volatile compounds were determined by gas chromatography in 61 samples of grape pomace distillate, corresponding to the fractions collected during seven complete distillation cycles. RESULTS: With a high degree of significance, the concentrations of 1,1‐diethoxyethane, propanol, hexanoate and ethyl acetate present positive correlations with the ethanol. However, those of benzyl alcohol, 2‐phenylethanol, furfurol, lactate, ethyl mirystate and diethyl succinate, were negative, which indicates that both groups of compounds were vented in the fractions of major or minor alcoholic degree, respectively. In addition, knowledge of the relationships between the volatile compounds contributes to improved management of an industrial distillation unit. CONCLUSION: The correlations established between the concentrations of the different volatile compounds indicate their physico‐chemical affinities or their biochemical origin. Copyright © 2009 Society of Chemical Industry  相似文献   
96.
This study evaluates effect of tumbling time and cooking temperature on cooking rate, cooking loss (CL), colour, water activity and water‐holding capacity of cooked restructured ham rolls. In experiment were investigated three tumbling times (2, 4 and 6 h) at constant temperature (+4 °C) and three cooking temperatures (76, 86 and 96 °C). It was observed that CL decreased (P < 0.01) from 5.41% to 3.22% with tumbling time (2 h vs. 6 h) but increased (P < 0.01) from 2.35% to 7.25% along with cooking temperature (76 °C vs. 96 °C). In contrast, pH value increased (P < 0.01) from 6.18 to 6.24 with tumbling time (2 h vs. 6 h) but decreased (P < 0.01) from 6.22 to 6.17 along with cooking temperature (76 °C vs. 96 °C). In addition, high temperature had higher efficiency for thermal lethality than low temperature (F0 values were 19 and 92 min at 96 and 76 °C, respectively). Intermediate tumbling (4 h) and cooking (86 °C) could be preferential.  相似文献   
97.
The main objective of this study was the sensory characterization, by a taste and a consumers’ panel, of fresh sausages from 140 culled goats and 140 culled ewes. Species and type of preparation effects were studied. All data were previously analyzed by analysis of variance. Taste panel data were analyzed by a Generalized Procrustes Analysis (GPA). Consumers’ panel data were analyzed by Preference Mapping. The 1st 2 factors explained 88.22% of total variation in GPA. Different sausages samples were perfectly differentiated by assessors. Goat sausages have been considered harder, more fibrous, and less juicy than sheep sausages. The panelists observed that sheep sausages without paprika had greater intensity of flavor, tasted spicy, and had an off‐odor, while goat sausages with paprika were considered sweeter. Consumers’ panel did not show any preference for the different types of sausages. This means that all types of sausages can have market opportunity.  相似文献   
98.
Requested raw data from a sample of authors in 1 issue of 4 psychological journals which vary from "hard" to "soft" scientific methodology in the articles published. Despite differences between the authors in the "hard" and "soft" journals, replies indicate that at present there is a greater tendency toward sharing data than has been reported previously. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
99.
The aim of this study was to develop fruit powders (apple, banana and strawberry) enriched with a probiotic strain (Lactobacillus plantarum 299v). Two methodologies were proposed: (i) drying of the fruit with probiotic culture incorporated (by convection) or (ii) drying of fruit (by convection) and addition of spray‐dried probiotic culture. In the first methodology, processing caused a notable reduction in probiotic viable counts in apple, but this reduction was lower during drying of banana and strawberry. A large reduction in viable cells was also recorded during storage. In the second methodology, the survival of L. plantarum 299v was considerably higher during spray‐drying, and fruit powders with a microbial content suitable for a probiotic food (108–10cfu g?1) were obtained. The fruit powders incorporating L. plantarum 299v can be stored at 4 °C or at room temperature, for at least 3 months. This preliminary study demonstrated that fruit powders are good carriers of probiotic cultures, but the techniques used to produce them should be carefully considered.  相似文献   
100.
The commercial wine spirit used for this study revealed that the aldehyde content mainly comprises acetaldehyde but other aldehydes such as propionaldehyde, 2‐methylbutyraldehyde, isovaleraldehyde, methylglyoxal, benzaldehyde and others are also present in significant amounts. A typical grape must was used to assess the influence of wine spirit in the analytical and sensorial characteristics of fortified wines. Decreasing levels of anthocyanins, as well the increase in the red colour and tanning capacity, were observed, and seem to be positively correlated with the increase of the aldehyde content present in the wine spirits used to fortify the must. Using the CIE L*a*b* system, this aldehyde content present in the spirit used seemed to be correlated with the decrease of the wines' lightness (darkening effect), the displacement of the hue angle to higher values (yellowing effect) and the increase of the chromaticity (colour saturation) of the wines. Copyright © 2005 Society of Chemical Industry  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