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   1520篇
  免费   103篇
  国内免费   4篇
电工技术   1篇
综合类   135篇
化学工业   284篇
金属工艺   2篇
机械仪表   9篇
建筑科学   7篇
轻工业   1116篇
水利工程   10篇
石油天然气   2篇
无线电   2篇
一般工业技术   23篇
冶金工业   23篇
原子能技术   2篇
自动化技术   11篇
  2025年   11篇
  2024年   76篇
  2023年   66篇
  2022年   148篇
  2021年   162篇
  2020年   122篇
  2019年   118篇
  2018年   72篇
  2017年   71篇
  2016年   53篇
  2015年   61篇
  2014年   71篇
  2013年   115篇
  2012年   62篇
  2011年   48篇
  2010年   46篇
  2009年   26篇
  2008年   37篇
  2007年   47篇
  2006年   22篇
  2005年   20篇
  2004年   17篇
  2003年   18篇
  2002年   16篇
  2001年   32篇
  2000年   21篇
  1999年   9篇
  1998年   8篇
  1997年   1篇
  1996年   7篇
  1995年   6篇
  1994年   7篇
  1993年   5篇
  1992年   6篇
  1991年   4篇
  1990年   3篇
  1989年   4篇
  1988年   2篇
  1987年   3篇
  1986年   1篇
  1985年   1篇
  1983年   1篇
  1979年   1篇
排序方式: 共有1627条查询结果,搜索用时 15 毫秒
1.
饮食的变化与癌症的发病率有很明显的联系,本文着重论述了饮食营养中脂肪、蛋白质、维生素、矿物质同癌症之间的关系。  相似文献   
2.
To develop a soft meat product for a dysphagia diet, high-pressure technology was applied. Pressure-heat-treated ground pork meat (PH) was prepared from ground pork mixed with water (ground meat: water, 1:0.5 or 1:1) and salt (1.5%). PH-gels were made from these meat homogenates by treatment at 400 MPa for 20 min, followed by heat treatment. Heat-treated pork meat homogenates (H) were also prepared. The hardness and adhesiveness of the 1:1PH-gel was lower than those of the 1:1H-gel. The PH-gel scored higher in sensory evaluations of elasticity, smoothness and ease of swallowing. Scanning electron micrographs indicated that the superior textural property of the 1:1PH-gel was caused by a network of myosin filaments. Videofluoroscopic examination of swallowing revealed that the 1:1PH-gel was easy to swallow and left little residue in the oropharynx. These results proved the utility of pressurization in creating a dysphagia meat diet.  相似文献   
3.
Two methods were tested for suppressing the depressive effect of N-free diets on the digestive secretions in pigs: the blood perfusion of amino acids (AA) or the peptide alimentation method. In the latter, enzymically hydrolysed casein (EHC), composed of oligopeptides and free AA, was used as the source of nitrogen. The unabsorbed dietary N molecules were discarded from the ileal digesta by ultrafiltration or gel filtration, assuming that the endogenous fraction did not contain significant amounts of small molecules. The AA supply by blood perfusion had no effect on the ileal endogenous AA losses (8·0 g AA kg−1 DM intake) in growing pigs (±50 kg), compared with the N-free diet alone (8·3 g), whereas the EHC supplementation significantly increased them (18·0 g). The increase was due to both endogenous and dietary N. The presence of unabsorbed dietary AA in the ileal digesta was confirmed by the AA profile of the soluble molecules with a very low molecular mass (<3 kDa), which was close to that of EHC. Both ultrafiltration (cut-offs of 3 or 10 kDa) and gel filtration methods, utilised to discard the remaining dietary molecules, also eliminated a significant proportion of endogenous AA.  相似文献   
4.
论茶籽油的营养价值与保健功能   总被引:5,自引:0,他引:5  
为了提高对茶籽油营养价值的认识,介绍了古代医书中茶籽油的功效、民间对茶籽油的认识、国际上对茶油籽的认识、茶籽油的营养成分、茶籽油对膳食平衡的作用及茶籽油的保健功能,说明茶籽油是一种营养、卫生、具有保健功能的优质食用油。  相似文献   
5.
基于我国饮食类非物质文化遗产在政策层面、实施层面、科研层面的现状,文章从传承体系、保护体系、人文思想体系、普及体系和传播渠道的五个维度提出了我国饮食类非遗保护传承的路径。  相似文献   
6.
We present our experiment about adding anthocyanins to the daily food of mice. Three kinds of anthocyanins (cyanidin-3-glucoside, cyanidin-3-rutinoside and pelargonidin-3-glucoside) purified from Chinese mulberry (Morus australis Poir) were evaluated for suppressing body weight gain of the male C57BL/6 mice fed with high-fat diet (HFD). The results from a 12-week experiment show that consumption of purified mulberry anthocyanins (MACN) of 40 or 200 mg/kg can significantly inhibit body weight gain, reduce the resistance to insulin, lower the size of adipocytes, attenuate lipid accumulation and decrease the leptin secretion. Thus, dietary supplementation with MACN can protect against body weight gain of the diet-induced obese mice.  相似文献   
7.
The use of pesticides and other chemicals has become a common practice in modern agriculture to enhance and stabilise crop yield, protect the nutritional integrity of food, facilitate food storage to assure year-round supplies, and provide attractive and appealing food products. With the adoption of strict good agricultural practice (GAP), only minimal amounts of pesticide residues should remain on the crops or in connected foods of animal origin up the food chain. To assess their associated health risk to local people, the dietary exposure of Hong Kong adults to residues of four groups of pesticides or their metabolites – organophosphorus pesticides (OPPs), carbamates, pyrethrins and pyrethroids, and dithiocarbamate (DTC) metabolites – is estimated in the first Hong Kong Total Diet Study (TDS). A total of 150 commonly consumed food items were collected and prepared “as consumed”. A total of 600 composite food samples were analysed for 85 pesticides or their metabolites by liquid chromatography-tandem mass spectrometry (LC-MS/MS). These pesticides were primarily found at low levels (highest mean = 350 μg kg?1) in food samples of plant origin such as vegetables and fruits. Dietary exposures to pesticide residues were estimated based on the analytical results and the food consumption data of the local residents. The estimated dietary exposures of Hong Kong adults to all individual pesticides were well below their respective acceptable daily intakes (ADIs). The percentage contributions of the estimated mean and 95th percentile dietary exposures to the ADIs of individual pesticides were <6% and <24% for the OPPs, <1% for the carbamates and pyrethrins and pyrethroids, and <1% and <4% for the DTC metabolites, respectively. The findings indicate that dietary exposures to all the pesticide residues analysed in this study were unlikely to pose unacceptable health risks to the Hong Kong population.  相似文献   
8.
The objective of the study was to determine the mean polyphenol composition of different varieties of virgin olive oil (VOO) habitually consumed in the region of southern Spain and to estimate the dietary exposure to olive oil polyphenols in that population. There were statistically significant differences in total polyphenols among varieties, with the Picual variety containing the largest amount with a mean value of 591.8 mg kg–1. The main phenolic compounds found in the VOOs under study were tyrosol and hydroxytyrosol. The highest amounts of both substances were found in Picual olive oils with concentrations of 2.3–6.6 mg kg?1. The total intake of polyphenols from VOO ranged between 8.2 mg day–1 (SD = 4.14) for the under 19 year olds and 21.3 mg day–1 (SD = 3) for the over 50 year olds. Some polyphenols, including tyrosol and hydroxytyrosol, were consumed principally as olive oil. The intake of these compounds in the studied population was in the range of 88.5–237.4 μg day–1. This has particular importance as recent studies have demonstrated that hydroxytyrosol helps to improve plasma lipids levels and repair oxidative damage related to cardiovascular disease. There was a greater dietary consumption of polyphenols in olive oil among the participants who more closely followed the Mediterranean diet pattern. A higher consumption of olive oil and therefore a greater exposure to polyphenols was observed in females versus males and in participants of normal weight versus those who were overweight. The total intake of polyphenols from VOO significantly increased with higher age, reflecting the greater intake of this oil by older people, who also show a closer adherence to the Mediterranean diet. The over 50-year-old age group showed the greatest consumption of this olive oil and therefore of phenolic compounds, which are healthy protectors in the human diet that contribute to the acknowledged benefits of the Mediterranean diet.  相似文献   
9.
A sensitive and selective GC-MS method was developed and used for simultaneous analysis of di-(2-ethylhexyl) adipate (DEHA) and 20 selected phthalates in the food samples from the 2013 Canadian Total Diet Study. At least one of the 21 target chemicals was detected in 141 of the 159 different food composite samples analysed. However, only seven of the 21 target chemicals were detected, with di-(2-ethylhexyl) phthalate (DEHP) and DEHA being detected most frequently, in 111 and 91 different food composite samples, respectively, followed by di-n-butyl phthalate (DBP) (n = 44), n-butyl benzyl phthalate (BBzP) (32), di-iso-butyl phthalate (DiBP) (27), di-ethyl phthalate (DEP) (3), and di-cyclohexyl phthalate (DCHP) (1). Levels of DEP (di-ethyl phthalate), DiBP, DBP, BBzP and DCHP were low, in general, with average concentrations of 9.63, 8.26, 23.2, 12.4 and 64.9 ng g–1, respectively. Levels of DEHA and DEHP varied widely, ranging from 1.4 to 6010 ng g–1 and from 14.4 to 714 ng g–1, respectively. High levels of DEHA were found mainly in the composite samples where the individual food items used to prepare the composite were likely packaged in polyvinyl chloride (PVC) wrapping film, while the highest DEHP levels were found in the vegetable and fruit samples.  相似文献   
10.
The potential adverse effects on health of diet-derived advanced glycation end-products (AGEs) is of current interest, due to their proposed involvement in the disease progression of diabetic and uraemic conditions. However, accurate information about levels of AGEs in foods is lacking. The objective of this investigation was to determine the level of one particular AGE, Nε-(carboxymethyl)lysine (CML), a marker of AGE formation, in a wide range of foods commonly consumed in a Western style diet. Individual foods (= 257) were mixed, lyophilised, ground, reduced, fat-extracted, hydrolysed, and underwent solid-phase extraction. Extracts were analysed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Cereal (2.6 mg/100 g food) and fruit and vegetable (0.13 mg/100 g food) categories had the highest and lowest mean level of CML, respectively, when expressed in mg/100 g food. These data can be used for estimating potential consumer intakes, and provide information that can be used to educated consumers on how to reduce their CML intake.  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