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   138篇
  免费   5篇
电工技术   3篇
综合类   1篇
化学工业   31篇
金属工艺   1篇
机械仪表   2篇
建筑科学   13篇
能源动力   2篇
轻工业   13篇
水利工程   5篇
石油天然气   2篇
无线电   11篇
一般工业技术   17篇
冶金工业   15篇
自动化技术   27篇
  2023年   4篇
  2022年   10篇
  2021年   7篇
  2020年   6篇
  2019年   6篇
  2018年   10篇
  2017年   5篇
  2016年   4篇
  2015年   1篇
  2014年   4篇
  2013年   9篇
  2012年   3篇
  2011年   3篇
  2010年   4篇
  2009年   5篇
  2008年   9篇
  2007年   4篇
  2006年   6篇
  2005年   7篇
  2004年   2篇
  2003年   3篇
  2002年   3篇
  2000年   1篇
  1999年   1篇
  1998年   7篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1984年   1篇
  1980年   2篇
  1978年   2篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1973年   1篇
  1962年   1篇
  1954年   1篇
排序方式: 共有143条查询结果,搜索用时 140 毫秒
61.
Seed oils sourced from West Africa are generally not well-characterized, but likely to have an untapped potential. This review aims to make an overview of fatty acid (FA) composition of unconventional seed oils from semi-arid West African trees and evaluate potential for new and enhanced uses and for improving local livelihoods and biodiversity conservation. A total of 111 studies on FA composition were found, covering 31 species. Only 69 of the studies (62%) were included in the review, as 38% had unreliable or incomplete results. There was a clear link between taxonomic kinship and FA composition. Over 20 potentially interesting and underexploited oils were found, including oils with properties similar to palm oil, olive oil, coconut oil, shea butter, and cotton seed oil. About half of the oils have promising potential for cosmetics. One third of the oils were relatively saturated, indicating properties for structuring food and heat resistance. Most of the species had multiple uses and oil production could be profitable in co-production with other non-timber forest products. Furthermore, establishment of sustainable oil production and domestication of oil trees could promote biodiversity conservation. Enhanced oil production in semi-arid West Africa is promising, but several practical constraints remain to be overcome.  相似文献   
62.
63.
The authors investigated how 2-digit Arabic numerals are named by looking at the effects of masked primes on the naming latencies. Target numerals were named faster when prime and target shared a digit at the same position (e.g., the target 28 primed by 18 and 21). In contrast, naming latencies were slower when prime and target shared 1 or 2 digits at noncorresponding places (e.g., the target 28 primed by 82, 86, or 72). Subsequent experiments showed that these priming effects were situated at the level of the verbal production of the Arabic numerals. The data point to a nonsemantically mediated route from visual input to verbal output in the naming of 2-digit Arabic numerals. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
64.
Energy harvesting using piezoelectric materials: Case of random vibrations   总被引:1,自引:0,他引:1  
A dramatic consumption reduction of integrated circuits related to the development of mobile electronic devices has been reached over the past years, enabling the use of ambient energy instead of batteries. The focus is here on the transformation of ambient mechanical vibrations into electrical energy. This paper compares the performances of a vibration-powered electrical generator using PZT piezoelectric ceramics associated to two different power conditioning circuits. A new approach of the piezoelectric power conversion based on a nonlinear voltage processing is presented and implemented using a particular circuit. Theoretical predictions and experimental results show that the new technique may increase the power harvested by a factor up to 4 compared to the Standard technique. The power optimization problem is in particular examined in the case of broadband, random vibrations.  相似文献   
65.
This paper presents a brief introduction and selective up-to-date references related to automotive reliability.  相似文献   
66.
Food preferences and dietary habits are heavily influenced by taste perception. There is growing interest in characterizing taste preferences based on genetic variation. Genetic differences in the ability to perceive key tastes may impact eating behavior and nutritional intake. Therefore, increased understanding of taste biology and genetics may lead to new personalized strategies, which may prevent or influence the trajectory of chronic disease risk. Recent advances show that single nucleotide polymorphisms (SNPs) in the CD36 fat taste receptor are linked to differences in fat perception, fat preference, and chronic-disease biomarkers. Genetic variation in the sweet taste receptor T1R2 has been shown to alter sweet taste preferences, eating behaviors, and risk of dental caries. Polymorphisms in the bitter taste receptor T2R38 have been shown to influence taste for brassica vegetables. Individuals that intensely taste the bitterness of brassica vegetables (“supertasters”) may avoid vegetable consumption and compensate by increasing their consumption of sweet and fatty foods, which may increase risk for chronic disease. Emerging evidence also suggests that the role of genetics in taste perception may be more impactful in children due to the lack of cultural influence compared to adults. This review examines the current knowledge of SNPs in taste receptors associated with fat, sweet, bitter, umami, and salt taste modalities and their contributions to food preferences, and chronic disease. Overall, these SNPs demonstrate the potential to influence food preferences and consequently health.  相似文献   
67.
Bonheiden, in the province of Antwerp in Belgium, lies in a region known for its exceptional natural beauty. Though the surrounding rural setting has remained protected this has often been to the detriment of urban life, as the built environment has been subject to a process of banal suburbanisation. Els Verbakel and Elie Derman explain how they propose to turn this situation around by creating public spaces that use the town's ‘original landscape as the base material’. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
68.
研究了利用2-溴乙烷磺酸钠(BES)选择性抑制产甲烷菌,从而提高微生物电化学系统合成乙酸产率的可行性,并对比了BES添加前后阴极室微生物菌群结构的变化。结果表明,厌氧混合菌接种物未经BES处理时甲烷是电化学系统CO2还原的主导产物,最大生成速率达0.95 mmol·L-1·d-1,8 d反应时间甲烷中电子回收率达55.0%,16S rRNA测序结果显示固态阴极的主要菌群为Methanobacteriaceae。BES的添加基本抑制了产甲烷菌的活动,使得乙酸成为主导产物,其合成速率最高达2.22 mmol·L-1·d-1,系统总电子回收率达67.3%。Rhodocyclaceae (15.1%),Clostridiaceae(11.9%)、Comamonadaceae(11.1%)和Sphingobacteriales(11.0%)为主要菌群。研究结果表明了微生物电化学合成系统中抑制甲烷生成对调控微生态结构,从而调控电化学终产物的重要性。  相似文献   
69.
BACKGROUND: New pomelo and mandarin scion varieties growing under subtropical arid conditions were investigated for total antioxidants in the juice. Four different rootstocks—sour orange (Citrus aurantium (L.); SO), Volkamer lemon (C. volkameriana (Ten & Pasq.)), SB812 (C. sunki (Hort. ex Tan.) × Poncirus trifoliate (L.)) and C. macrophylla (Wester)—were tested. RESULTS: Fruit juice was tested for total antioxidants, ascorbic acid and total polyphenol contents. Cyclic voltammetry (CV) analysis revealed three different antioxidant groups for pomelo and four groups for mandarin. CV analysis for the pomelo scion/rootstock combinations showed that ascorbic acid concentration was highest for scions grafted onto SO. Total polyphenol levels were similar among the pomelo varieties. Mandarin analysis revealed that ‘Merav’ scion/SO had the highest ascorbic acid concentration (1.91 ± 0.01 mmol L?1). Total polyphenol analysis discovered that ‘Merav’ 4/119‐/SB812 gave the highest levels, while ‘Ora Shani’ scion grafted on to any tested rootstock contained the lowest CONCLUSION: We suggest that the SO rootstock is superior to Volka, 812 and macrophylla in terms of juice antioxidant capacity. For the pomelo, both ‘Flamingo’ scions were found to have high antioxidant production capacity, with ‘Flamingo’ 3/73 being slightly superior regardless of the rootstock. The best mandarins were ‘Merav’ hybrids in combination with SO rootstock. Copyright © 2009 Society of Chemical Industry  相似文献   
70.
Commercial applications of microalgae   总被引:11,自引:0,他引:11  
The first use of microalgae by humans dates back 2000 years to the Chinese, who used Nostoc to survive during famine. However, microalgal biotechnology only really began to develop in the middle of the last century. Nowadays, there are numerous commercial applications of microalgae. For example, (i) microalgae can be used to enhance the nutritional value of food and animal feed owing to their chemical composition, (ii) they play a crucial role in aquaculture and (iii) they can be incorporated into cosmetics. Moreover, they are cultivated as a source of highly valuable molecules. For example, polyunsaturated fatty acid oils are added to infant formulas and nutritional supplements and pigments are important as natural dyes. Stable isotope biochemicals help in structural determination and metabolic studies. Future research should focus on the improvement of production systems and the genetic modification of strains. Microalgal products would in that way become even more diversified and economically competitive.  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