全文获取类型
收费全文 | 389篇 |
免费 | 8篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 9篇 |
综合类 | 3篇 |
化学工业 | 17篇 |
机械仪表 | 2篇 |
建筑科学 | 102篇 |
矿业工程 | 5篇 |
能源动力 | 70篇 |
轻工业 | 52篇 |
水利工程 | 30篇 |
石油天然气 | 25篇 |
无线电 | 9篇 |
一般工业技术 | 39篇 |
冶金工业 | 19篇 |
自动化技术 | 22篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 12篇 |
2021年 | 13篇 |
2020年 | 25篇 |
2019年 | 19篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 28篇 |
2015年 | 6篇 |
2014年 | 21篇 |
2013年 | 43篇 |
2012年 | 14篇 |
2011年 | 42篇 |
2010年 | 18篇 |
2009年 | 28篇 |
2008年 | 14篇 |
2007年 | 22篇 |
2006年 | 11篇 |
2005年 | 11篇 |
2004年 | 12篇 |
2003年 | 17篇 |
2002年 | 5篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有404条查询结果,搜索用时 0 毫秒
1.
Alexandre Szklo Giovani Machado Roberto Schaeffer Jacqueline Mariano Janaí na Sala Marina Tavares 《Catalysis Today》2005,106(1-4):123-128
This paper assesses the impacts of a GTL plant on the expansion of Brazil's oil refining segment. The GTL plant (50,000 bpd) was sized to start up operations in 2015, producing diesel and naphtha through the indirect route (FT-synthesis). This plant will consume the non-associated natural gas production from the recent discoveries at the Santos Basin (around 419 Bm3), and the associated gas production from the Campos Basin. Both basins are located in the Southeast of Brazil, the most populated, rich and industrialized region of the country. Two different criteria for refinery expansion were simulated in order to meet oil product demand scenarios. Findings show that depending on the refinery expansion criteria considered GTL will play a fundamental hole to meet the oil product demand forecast to Brazil in the next 10 years. 相似文献
2.
R. Oliva A. L. Gemal A. W. N brega A. C. P. Araú jo 《Food Additives & Contaminants》2003,20(8):758-763
The structure of the recently introduced Brazilian government programme for monitoring pesticide residues in six major agricultural products is described. Residues found from the analysis of samples of tomatoes and strawberries are discussed in detail. The much greater frequency of detection of pesticide residues, many of which are not approved for use in Brazil, in produce being sold on the domestic market, as opposed to that produced for export, is of major concern. It is perceived that this new monitoring programme will become permanent and be used to underpin enforcement actions that will need to be taken to reduce the numbers of incidents of illegal residues occurring, particularly in fresh fruits and vegetables. 相似文献
3.
4.
Claudio de A. Loural Romulo A. Zanco Filho Antonio Carlos G. Bordeaux Rego Rogrio C. de Oliveira 《Telematics and Informatics》2006,23(4):294-315
Brazilian telecommunications sector has undergone important modifications in the last 40 years. From a badly structured system of municipal level operators in 1960, with barely one million fixed lines to a large, nation-wide system with about 50 million fixed plus another 75 million mobile lines in 2005. This work paper reviews the institutional framework of telecommunications industrial and technological policy in Brazil in the last four decades, its results and present situation. Infrastructure and services modernisation and expansion process that happened in early 1970s were carried out at the expense of massive import of products and technology. A government strategy was, then, devised to stimulate local industrial and technological development in telecommunications, under the general guidelines of import substitution policy. Essential to this strategy was the creation of an innovation system around TELEBRÁS Research and Development Centre. This technological development model was successful while a protectionist economic policy existed. When economic and political circumstances could not anymore sustain an import substitution approach, in the 1990-decade, the model fell apart and has not been replaced by any other sectorial policy. A critical assessment is carried out, analysing the adopted actions in face of the digital technology maturing process that occurred in meantime. 相似文献
5.
为提高巴西棉单唛纺C 18.2 tex针织纱的质量,针对巴西棉含杂含糖较高,适纺性较差特点对棉花进行了消糖处理.调整了清梳联打手速度、尘棒角度工艺,梳棉机速度、隔距和并条牵伸工艺合理配置,粗纱采用重定量,细纱优选牵伸工艺,最终使C 18.2 tex针织纱质量达到较好的水平. 相似文献
6.
7.
利用电子探针、X射线光电子能谱仪、紫外-可见光光度计和傅里叶变换红外光谱仪对产自巴西MinasGerais地区、不同颜色的彩色电气石样品进行了宝石矿物学特征研究。电子探针测试结果显示,该电气石样品中Al2O3和Na2O的质量分数较高,FeO的质量分数相对较低,且含有一定量的MnO和Cr2O3;X射线光电子能谱分析初步证实该样品为锂电气石;结合化学成分与紫外-可见光透过光谱的分析结果认为,微量元素Fe^2+,Fe^3+,Mn^3+,Ti^4+和Cr^2+是巴西Minas Gerais彩色电气石样品致色的主要因素之一;红外吸收光谱测试结果显示,该样品在1200~1450cm。范围内存在强的B-O基团致伸缩振动带,含有BO3原子团;其在3000-3750cm。范围内具有H2O和羟基离子致双峰伸缩谱带。比较不同颜色电气石样品的红外吸收光谱发现,其光谱频带数及位置与电气石中的类质同象和化学成分有关。 相似文献
8.
Otniel Freitas-Silva Armando Venâncio 《Food research international (Ottawa, Ont.)》2011,44(5):1434-1440
The monotypic type genus Bertholletia produces commercially nutritionally harvested edible seeds, Brazil nuts. It is an important product from the Amazon forest in the food production chain, with a 2008 annual world production of 78,000 tonnes, being Brazil responsible for approximately 40% of it. Although there are beneficial nutritional properties, the prevailing mycobiota of Brazil nuts include fungi that are producers of aflatoxins, such as Aspergillus flavus, A. parasiticus and A. nomius. Aflatoxins have deleterious effects in consumption considering the global distribution chain, affecting major exporting countries. The present review is focused on the importance of Brazil nuts for the Amazon rainforest, emphasizing on the social and environmental impact of its production, on the mycobiota contamination of seeds, and on the presence of mycotoxins and related food safety aspects. 相似文献
9.
Neil Brenner 《Architectural Design》2016,86(4):118-127
What defines the urban? And can the non-urban necessarily always be classified as rural? Neil Brenner , Director of the Urban Theory Lab at Harvard University Graduate School of Design, reflects on the lack of an overarching theory to describe these realms, and argues that what we call the countryside or the hinterland has become key to the process of capitalist urbanisation. 相似文献
10.
Rosângela De A. Epifanio Danielle L. Martins Roberto Villaça Rebecca Gabriel 《Journal of chemical ecology》1999,25(10):2255-2265
The feeding-deterrence properties of crude extracts of three Brazilian octocoral species, Neospongodes atlantica Kükenthal (Alcyonacea, Nephtheidae), Plexaurella regia Castro (Gorgonacea, Plexauridae), and Phyllogorgia dilatata Esper (Gorgonacea, Gorgoniidae), were investigated. All the extracts were incorporated into food strips at the concentrations occurring in the living organisms. Crude extract and its ethyl acetate fraction obtained from P. dilatata collected in Armação dos Búzios (Rio de Janeiro State), when incorporated into artificial diets and tested in the habitat of origin, reduced consumption of food strips by fishes, relative to controls. Crude extracts from two octocoral species collected at the National Marine Park of Abrolhos (Bahia State), N. atlantica and P. regia, had no apparent feeding-deterrence properties; in fact, they seemed to stimulate feeding. Bioassay-guided fractionation of the bioactive P. dilatata crude extract revealed that the deterrent property was restricted to a medium polarity fraction. Field palatability experiments with two pure compounds isolated from this fraction revealed that the furanocembranolide 11,12-epoxypukalide is a potent feeding deterrent produced by P. dilatata against fish. Apparently, furanocembranolides are a particular class of compounds with feeding deterrent properties, protecting some octocorals from potential fish predator species in both tropical and temperate environments. 相似文献