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   4304篇
  免费   258篇
  国内免费   14篇
电工技术   5篇
综合类   52篇
化学工业   320篇
金属工艺   2篇
机械仪表   94篇
建筑科学   90篇
矿业工程   3篇
能源动力   125篇
轻工业   3096篇
水利工程   40篇
石油天然气   441篇
无线电   13篇
一般工业技术   166篇
冶金工业   6篇
原子能技术   27篇
自动化技术   96篇
  2024年   17篇
  2023年   53篇
  2022年   74篇
  2021年   177篇
  2020年   158篇
  2019年   105篇
  2018年   104篇
  2017年   195篇
  2016年   205篇
  2015年   209篇
  2014年   231篇
  2013年   298篇
  2012年   256篇
  2011年   290篇
  2010年   293篇
  2009年   294篇
  2008年   183篇
  2007年   226篇
  2006年   225篇
  2005年   153篇
  2004年   176篇
  2003年   139篇
  2002年   108篇
  2001年   73篇
  2000年   60篇
  1999年   67篇
  1998年   45篇
  1997年   28篇
  1996年   37篇
  1995年   15篇
  1994年   19篇
  1993年   12篇
  1992年   4篇
  1991年   5篇
  1990年   10篇
  1989年   3篇
  1988年   5篇
  1987年   7篇
  1986年   2篇
  1985年   10篇
  1984年   4篇
  1983年   1篇
排序方式: 共有4576条查询结果,搜索用时 140 毫秒
51.
英国作家J.A.G.罗伯茨先生的《东食西渐》一书,是从一个真正意义上的西方人的视角,运用丰富翔实的英文书籍资料,包括一些珍贵的历史图片撰写而成,而且这些资料在中国国内几乎是找不到的。他从一个生活在中国本土的中国学者无法做到的研究角度,对中国饮食文化自18世纪以来在西方的传播渗透与普及流行进行了深度的介绍与揭示。其深远的文化意义与历史贡献是不言而喻的。  相似文献   
52.
淮扬饮食文化景观谱系的构建是深度挖掘整理淮扬菜文化基因,形成系统保护与传承体系的基础性工作.在对旅游景观谱系相关研究进行系统梳理的基础上,将饮食文化景观谱系的结构分为景观元、景观点和景观走廊三个层次,结合文献分析和专家意见,构建淮扬饮食文化景观谱系.淮扬饮食文化景观谱系对促进城市旅游资源的深度开发、促进旅游产品内涵拓展具有重要作用,对推进城市旅游转型和推广城市旅游形象等方面也具有重要的价值.  相似文献   
53.
Sensory evaluation is the application of knowledge and skills derived from several different scientific and technical disciplines, physiology, chemistry, mathematics and statistics, human behavior, and knowledge about product preparation practices. This research was aimed to evaluate aftertaste sensory attributes of commercial non-alcoholic beer brands (P1, P2, P3, P4, P5, P6, P7) by several chemometric tools. These attributes were bitter, sour, sweet, fruity, liquorice, artificial, body, intensity and duration. The results showed that the data are in a good consistency. Therefore, the brands were statistically classified in several categories. Linear techniques as Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) were performed over the data that revealed all types of beer are well separated except a partial overlapping between zones corresponding to P4, P6 and P7. In this research, for the confirmation of the groups observed in PCA and in order to calculate the errors in calibration and in validation, PLS-DA technique was used. Based on the quantitative data of PLS-DA, the classification accuracy values were ranked within 49-86%. Moreover, it was found that the classification accuracy of LDA was much better than PCA. It shows that this trained sensory panel can discriminate among the samples except an overlapping between two types of beer. Also, two types of artificial networks were used: Probabilistic Neural Networks (PNN) with Radial Basis Functions (RBF) and FeedForward Networks with Back Propagation (BP) learning method. The highest classification success rate (correct predicted number over total number of measurements) of about 97% was obtained for RBF followed by 94% for BP. The results obtained in this study could be used as a reference for electronic nose and electronic tongue in beer quality control.  相似文献   
54.
Food safety plan is being promoted in the food industry by the Hong Kong Government as a preliminary quality control tool. However, it appears to be a challenging task for Distribution Centers (DC) that handles food inventory since most of them are lack of knowledge and know how technology to manage information in a real time base. This paper proposes a Radio Frequency Identification based Food Operations Assignment System (RFID-FOAS) to help DC facilitates the food safety control activities in receiving areas by generating a proper safety plan. The system has adopted the Radio Frequency Identification (RFID) technology and the Case-Based Reasoning (CBR) technique to facilitate the inventory data-capturing process and assist in formulating decisions, respectively. The developed system aims to help reduce the difficulties in safety plan development using a knowledge-based expert system. The significance and contribution of RFID-FOAS in the context of managing the inventory quality in DC for safety plan development is demonstrated through the adoption of the system in a Hong Kong-based logistics company. The generated results show that the decision-making process of the safety plan development is facilitated. Moreover, the real-time data capturing nature of RFID technology has further improved the efficiency and timeframe requested for the actions. With the support of RFID-FOAS, the data capture system and the decision-making time is minimized. As a result, inventory quality and customer satisfaction level are significantly improved.  相似文献   
55.
In 2002, over a million refrigerated road vehicles, 400,000 refrigerated containers and many thousands of other forms of refrigerated transport systems are used to distribute chilled and frozen foods throughout the world. All these transportation systems are expected to maintain the temperature of the food within close limits to ensure its optimum safety and high quality shelf life.Increasingly, modelling is being used to aid the design and optimisation of food refrigeration systems. Much of this effort has concentrated on the modelling of refrigeration processes that change the temperature of the food such as chilling, freezing and thawing. The purpose of a refrigerated transport system is to maintain the temperature of the food and appears to have attracted less attention from modellers. This paper reviews the work that has been carried out specifically on the modelling of food temperature, microbial growth and other parameters in the transportation of food.  相似文献   
56.
本文研究了微生物对冰箱冷藏食品的影响,研究表明,适冷菌在冰箱冷藏条件下可以生长繁殖,并引起食品腐败。在4℃冷藏条件下,新鲜生菜在冰箱冷藏室存放10天,在杀菌冰箱中生菜上的细菌总数由2.3×106cfu/g下降为4.6×104cfu/g,而在普通冰箱中,细菌总数由2.3×106cfu/g上升为为2.9×108cfu/g,普通冰箱食品上的细菌是杀菌冰箱食品上细菌的6304倍。研究表明,需要对冰箱冷藏食品进行微生物处理。  相似文献   
57.
This study used the technique of response surface approach to analyze the combined effects of heat-shocking temperature and time on anaerobic grass composts. Results indicate that the grass composts under heat-shocking temperature and time of 80°C and 3?h, respectively, could yield high populations of hydrogen-producing microorganisms. Metabolic results demonstrate that the composts are reliable, having considerable hydrogen-producing Clostridia. The multivariate analysis with response surface by considering specific hydrogen-producing potential and rate simultaneously indicate that the cultural media with Fe2+ = 132?mg/L; NH4+ = 537?mg/L; and PO43? = 1,331?mg/L were optimal for the hydrogen-producing Clostridia-rich composts using high-solids food wastes. The specific hydrogen production potential and rate were 77±3?mL?H2/gTVS and 520±20?mL?H2/g?TVS/day, respectively. The former was 38% of theoretical hydrogen-producing potential of Clostridium sp. using glucose. Of these factors, ammonium and phosphate are nutrients for the hydrogen-producing Clostridia growth while iron exerts a synergistic influence on them in the conversion of the food wastes into hydrogen.  相似文献   
58.
食品包装新理念   总被引:2,自引:4,他引:2  
彭珊珊  蒋侬辉 《包装工程》2005,26(2):169-171,182
本世纪食品市场的竞争在很大程度上取决于包装质量的竞争.而食品包装理念也显现出新特色,食品包装要以多样化满足现代人不同层次的消费需求;无菌、方便、智能、个性化是食品包装发展的新时尚;拓展食品包装的功能、减轻包装废弃物对环境污染的绿色包装已成为新世纪食品包装的发展趋势.  相似文献   
59.
食品中甜蜜素的高效液相色谱法   总被引:1,自引:0,他引:1  
本文建立了甜蜜素的高效液相色谱法,结果表明样品中甜蜜素含量为0-1.0 mg/g范围内,峰面积与甜蜜素含量呈良好的线性关系,相关系数为0.9977,对0.1 mg/mL标准溶液连续测定7次,相对标准偏差为3.65%, 加标回收率为95.4%-102.2%之间,食品中共存的苯甲酸、山梨酸、安赛蜜等不影响测定,方法简捷、准确。用于实际样品测定,结果令人满意。  相似文献   
60.
陈炳旭 《制冷》2004,23(4):33-34
本文介绍了随市场经济的建立,我国商业冷库面临的问题、生产方式及储藏业务的变化,就肉类食品在冷库储藏中如何保证其安全性,提出了建议和措施.  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