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   203篇
  免费   9篇
  国内免费   2篇
化学工业   20篇
机械仪表   4篇
建筑科学   8篇
矿业工程   22篇
能源动力   13篇
轻工业   96篇
石油天然气   14篇
无线电   1篇
一般工业技术   21篇
冶金工业   7篇
原子能技术   5篇
自动化技术   3篇
  2023年   2篇
  2022年   1篇
  2021年   5篇
  2020年   6篇
  2019年   2篇
  2018年   7篇
  2017年   4篇
  2016年   3篇
  2015年   2篇
  2014年   6篇
  2013年   9篇
  2012年   8篇
  2011年   20篇
  2010年   4篇
  2009年   25篇
  2008年   21篇
  2007年   25篇
  2006年   20篇
  2005年   5篇
  2004年   5篇
  2003年   7篇
  2002年   1篇
  2001年   6篇
  2000年   2篇
  1999年   2篇
  1998年   1篇
  1997年   1篇
  1996年   2篇
  1995年   2篇
  1994年   2篇
  1993年   4篇
  1992年   3篇
  1988年   1篇
排序方式: 共有214条查询结果,搜索用时 15 毫秒
11.
White bean seeds were subjected to soaking in distilled water for 1, 2 and 3 days. In order to perform complete processing, the seeds were cooked until soft. Effects of soaking and/or cooking of white bean seeds on antinutritional factors, mineral contents and HCl-extractability were studied. Phytic acid and polyphenol contents of all cultivars were reduced. Soaking alone and soaking, followed by cooking, reduced mineral contents of the cultivars, but HCl-extractability was significantly (P ? 0.01) improved to varying extents, depending on cultivar type. Soaking and/or cooking treatment was thus found to be an effective technique and caused further improvement in the availability of both major and trace minerals in white bean.  相似文献   
12.
CaO is an important inorganic material, which can be used as catalyst, toxic-waste remediation agent, adsorbent etc. In order to make use of CaO, nano-CaO was prepared by thermal-decomposition method using Ca(NO3)2.4H2O as precursor, NaOH aqueous solution as precipitant, and ethylene glycol as medium in this paper. Characteristics of samples were measured by TGA, XRD, TEM et al techniques. The results showed that the size of nano-CaO about 14 nm could be obtained under the conditions (calcinations temperature 500 °C, calcinations time 1.5 h, heating rate of calcinations 5 °C/min). It is a very simple and effective method to prepare nano-CaO.  相似文献   
13.
Three native hazelnut varieties from Turkey, namely, Tombul, Palaz, and Badem, were examined for their proximate composition, minerals, and fatty acid profiles, as well as polyphenol oxidase (PPO), peroxidase (POD), and lipase activities during fruit development stages (early stage: ES, middle stage: MS, and harvest stage: HS). Proximate composition varied considerably (dry weight basis) from ES to MS. Fat was the predominant component at all stages and showed increasing trends. Six essential minerals (calcium, iron, magnesium, phosphorus, potassium, and zinc) were analysed (dry weight basis). Consuming recommended daily amount of 42.5 g hazelnut at HS supplies 23.3–25.0% of phosphorus, 11.6–18.1% of magnesium, 7.0–18.9% of iron, 4.9–8.9% of zinc, 5.1–5.7% of calcium, and 5.1–5.3% of potassium for recommended dietary allowances or adequate intake for adults. Significant (P < 0.05) decreasing trends were found in all mineral contents from early development to maturity, with some exceptions. Sixteen fatty acids were identified, among which 18:1ω9 was by far the most predominant one, followed by 18:2ω6, 16:0, and 18:0. As expected, total monounsaturated fatty acids constituted the main group of fatty acids ranging from 75.51 to 81.07% in Tombul, from 78.21 to 82.71% in Palaz, and from 73.69 to 81.65% in Badem through the maturation stages. In contrast, total polyunsaturated fatty acids showed decreasing trends from ES to HS. No significant changes (P > 0.05) were observed in total saturated fatty acids at different maturation stages. Tombul variety had the lowest PPO activity compared to those of Palaz and Badem. Badem showed highest POD activity compared to Tombul and Palaz at three stages of maturation and significant decreases (P < 0.05) in all hazelnut samples were observed in POD activity from ES to HS. No lipase activity was detected in any hazelnut samples at ES and MS, except in Badem at MS. In contrast, lipase activity was detected in all hazelnut samples at HS. These results suggest that some proximate compositions, minerals, and fatty acids gave good indications during fruit development stages, whereas enzymatic activities of PPO, POD, and lipase behaved differently among varieties and fruit development stages.  相似文献   
14.
Olga Cueva 《LWT》2008,41(3):537-544
The objective was to study the effect of heart healthy nutrients on the physico-chemical, microbiological and sensory characteristics of yogurt. Thiamine (vitamin B1), riboflavin (vitamin B2), niacin (vitamin B3), folic acid (vitamin B9), manganese and magnesium were added during mix preparation at 0%, 30%, 60% and 90% of their respective recommended dietary allowance (RDA). Fiber (Ceolus Fiber DF-17) was added at a constant rate of 176 g/7.570 kg yogurt mix in all the treatments. Total solids in the control were kept constant with non-fat dry milk. Incorporation of the heart healthy nutrients at the 30%, 60% and 90% RDA significantly decreased syneresis, pH, L*, a* values but significantly increased b* value. Product viscosity was significantly increased by the incorporation of the nutrients at 60% of their respective RDA's. The incorporation of the above heart healthy vitamins and minerals at any of the studied rates in yogurts did not significantly affect flavor, appearance, body and texture and microbial counts of the product. Although there were subtle yet significant changes in instrumental color and viscosity these slight changes could not be detected by sensory evaluation. Yogurts can successfully be manufactured with the above heart healthy nutrients.  相似文献   
15.
The spatial distribution of urban population exposures to ambient air particles was investigated as part of the Genotox'ER study conducted in four metropolitan areas (Grenoble, Paris, Rouen and Strasbourg) in France. In each city, 60 to 90 non-smoking adult and children volunteers were selected. Subjects lived in three different urban sectors: one highly exposed to traffic emissions, one influenced by local industrial sources, and a background urban environment. The Harvard Chempass multi-pollutant personal sampler was used to sample PM10 and PM2.5 particles during 48 h during two different seasons ('hot' and 'cold'). The elemental composition of the filters was analysed by Particle-Induced X-ray Emission (PIXE). Sixteen elements were found to be over the method detection limits: Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn and Pb. The relative concentrations of elements of crustal origin (Si, Al, Ca) were higher in the coarse fraction of PM10 filters, while elements associated with combustion processes (traffic emissions or industrial combustion) presented higher relative concentrations in the PM2.5 fraction (S, Ni, V, Pb). Spatial heterogeneity of elemental exposures by urban sector is substantial for some metals of health concern, with 20% to 90% greater exposure values, on average, in the traffic proximity or industrial sectors, compared to the background sector, for Fe, Zn, Cu, V and Cr. This spatial heterogeneity should not be overlooked in epidemiological or risk assessment studies.  相似文献   
16.
The nutritional and antioxidant properties of peels, pulp and seeds of kembayau (Dacryodes rostrata) fruits were evaluated. Kembayau seeds and pulp were rich in fat, while peels had the highest ash contents. Potassium was the most prevalent mineral in peels (380.72-1112.00 mg/100 g). In kembayau fruits, total flavonoid content (1012.74-28,022.28 mg rutin equivalent/100 g) was higher than total phenolic and total monomeric anthocyanin contents. Kembayau seeds exhibited high flavonoid and phenolic contents compared to the contents in peels and pulp. Antioxidant capacities were also higher in seeds as typified by trolox equivalent antioxidant capacity assay (51.39-74.59 mmol TE/100 g), ferric reducing antioxidant power assay (530.05-556.98 mmol Fe2+/100 g) and by 1,1-diphenyl-2-picryl hydrazyl radical scavenging activity (92.18-92.19%) when compared to peels and pulp. Pulp and peels of kembayau fruit may be an important source of energy and minerals for human consumption, while seeds have a good potential as antioxidants.  相似文献   
17.
涂亦楠 《中国矿业》2021,30(S2):16-20
美国关键矿产系列总统令是WTO系列对华资源诉讼的继续,是中美贸易战在资源领域的延伸。其恶化了中国的资源安全形势,对中国的国际资源贸易、海外资源开发合作、矿业技术获取和矿业融资均有不利影响。论文概述了关键矿产的内涵、特点和中国的资源形势,对美国系列关键矿产令的颁布背景、政策目标、内容特点及对中国的影响进行了剖析,并提出了中国的应对建议。具体策略包括:一是,整合各项行政资源,完成我国资源安全保障的顶层设计,理顺政策的框架体系,聚合各项行政、资金、人力资源,开源节流保障供给;二是,结合多边贸易纪律和他国实践,完善矿产资源的管理机制,理顺对美国关键矿产总统令的攻防策略体系;三是,以“一带一路倡议”为纽带,建构并维系“人类资源命运共同体”。  相似文献   
18.
Three Himalayan medicinal plants (Habenaria intermedia, H. edgeworthii, and Roscoea procera), widely used in vitality strengthening Ayurvedic formulations in India, were assessed for nutritional phytochemical constituents, and antioxidant activity. These target species emerged as a good source of minerals and possessed important micro elements. Individually, H. intermedia contained a high content of total phenols, thiamins, tannins, and calcium; R. procera was rich in potassium and iron content; and H. edgeworthii emerged as a good source of sodium. While various antioxidant assays provided evidences on the antioxidant potential of target species, greater antioxidant potential of H. intermedia as compared to the other two species was revealing. This study, therefore, highlighted the possibilities of harnessing nutritional and antioxidant potential of these species.  相似文献   
19.
攀枝花矿产资源特征及循环经济发展策略探讨   总被引:2,自引:0,他引:2  
文章着重描述了攀枝花矿产资源特征、资源矿物流向和资源产品定位,分析了资源矿物使用行业的不同特点,明确了针对攀枝花矿产资源利用的循环经济目标,根据资源循环利用技术水平和资源循环开发现状,提出了攀枝花矿的循环经济发展策略.  相似文献   
20.
青海省能源矿产需求预测研究   总被引:2,自引:0,他引:2  
建立灰色系统模型和回归模型,预测了青海省第一产业、第二产业、第三产业、城乡居民生活对能源矿产的需求强度,预测了青海省人口发展变化情况和产业结构变化情况。在此基础上,采用部门分析法预测了青海省2005年、2010年、2015年和2020年对煤炭、石油、天然气矿产的需求量,同时根据预测结果提出了能源结构调整的建议。  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