全文获取类型
收费全文 | 353篇 |
免费 | 16篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 8篇 |
综合类 | 2篇 |
化学工业 | 17篇 |
机械仪表 | 2篇 |
建筑科学 | 93篇 |
矿业工程 | 4篇 |
能源动力 | 59篇 |
轻工业 | 50篇 |
水利工程 | 29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 | 21篇 |
出版年
2023年 | 1篇 |
2022年 | 10篇 |
2021年 | 10篇 |
2020年 | 22篇 |
2019年 | 13篇 |
2018年 | 14篇 |
2017年 | 13篇 |
2016年 | 22篇 |
2015年 | 6篇 |
2014年 | 20篇 |
2013年 | 43篇 |
2012年 | 13篇 |
2011年 | 42篇 |
2010年 | 18篇 |
2009年 | 27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377条查询结果,搜索用时 15 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.
As cropland and pasture have replaced forest and cerrado in Brazilian Amazônia, concern has mounted over the effects of changing the biogeochemical and hydrological properties of one of the world's great storehouses of biomass and biodiversity. Although much recent effort has focused on the location, effects, and causes of deforestation and cerrado conversion, much less is known about the basin-wide spatial distribution and density of the land use following conversion for crops or pasture.In this paper, we use census and satellite records to develop maps of the distribution and abundance of major agricultural land uses across 4.5×108 ha of Brazilian Amazônia in 1980 and 1995. Results indicate an overall expansion of 7.0×106 ha in total agricultural area in Brazilian Amazônia between 1980 and 1995. The net change during this period is estimated for three different land-use types: croplands (an increase of 0.8×106 ha), natural pastures (a decrease of 8.4×106 ha), and planted pastures (an increase of 14.7×106 ha). These estimates, the first spatially explicit quantifications of agricultural land-use activities in 1980 and 1995 across Brazilian Amazônia, are shown to be consistent with the results of applying a land use change and secondary regrowth model to published deforestation rates for the period.The resulting time slices, presented for each land-use category at 5-min (∼9 km) spatial resolution, allow for the quantification of land-use changes in this region for biogeochemical, demographic and economic models. Several foci of agricultural change existed within Brazilian Amazônia during this period: in the state of Pará, cropland was lost and planted pasture increased markedly; in Mato Grosso, both cropland and planted pasture increased; in Rondônia, planted pasture replacing forest was the primary route to agricultural expansion. 相似文献
4.
Lázaro Valentin Zuquette Janaina Barrios Palma Osni José Pejon 《Bulletin of Engineering Geology and the Environment》2005,64(3):257-271
There are more than 20,000 uncontrolled sanitary landfill areas in Brazil. The paper reports an integrated study undertaken
to develop an environmental assessment of the uncontrolled sanitary landfill area of the city of Po?os de Caldas, State of
Minas Gerais, Brazil. A number of remedial alternatives were evaluated. The USGS modular 3D finite difference groundwater
flow model (Modflow) and Modular 3D Finite Difference Mass Transport Model (MT3D) software were used to simulate groundwater
flow and contaminant transport modelling, as well as to predict changes due to the proposed remediation measures. The remedial
alternatives considered for normal conditions from 20 to 40 year periods were waste removal, vertical cut-off barriers, extraction
wells and top capping. The results indicated that extraction wells and waste removal are the best alternatives because they
significantly reduce both the extension and levels of the contamination plume even after 5 years. The extraction well proved
a less expensive remedial alternative than waste removal.
相似文献
5.
流动的色彩--巴西著名设计师罗伯特·布雷·马克斯及其风景园林作品 总被引:2,自引:2,他引:0
20世纪中期,世界现代风景园林正经历分娩的阵痛,在南美国家巴西出现了一位让世界瞩目的设计大师,他用自己传奇的经历、独特的个性和不凡的艺术天赋带给世界园林景观新的元素、新的形式及新的艺术观,时至今日,他的影响仍波及世界的每个角落. 相似文献
6.
Paulo Augusto Cunha Libanio 《国际水》2013,38(3):513-533
This article examines the use of output-based aid and payment for environmental services to reduce water pollution in Brazil. Two nationwide initiatives are reviewed. First, the output-based aid concept of the River Basin Clean-up Programme (PRODES) to tackle the problem of sanitation deficit in urban areas is presented. Second, the payment for environmental services scheme supported by Brazil’s National Water Agency (ANA) through the Water Producer Programme to promote water conservation on rural properties is discussed. Both programmes are evaluated not only as financing mechanisms for water conservation but also as strategies for implementing Brazil’s water policy. 相似文献
7.
《Energy Policy》2016
This article describes the electricity consumption in Brazilian residences between 1985 and 2013 through linear regressions. The explanatory variables considered were the number of households, effective consumption of families as a proxy for family income, and electricity tariff for households. To deal with the power generation crisis of 2001 we have introduced a dummy variable in the form of a step function. With such explanatory variables, we were able to account for the reduction of household electricity consumption caused by the policies conducted in 2001 and their permanent consequences. The regression presented coefficient of determination of 0.9892, and the several statistic tests conducted assured the existence of long-term relation between the electricity consumption in residences and the explanatory variables. The obtained elasticities for the household consumption of electricity with respect to number of residences, family income and residential tariff of electricity were 1.534±0.095, 0.189±0.049, and −0.230±0.060, respectively. These results allowed understanding the evolution over time of the household consumption of electricity in Brazil. They suggest that the electric sector in Brazil should pursue an active policy to manage demand of residential electricity using tariffs as a means to control it. 相似文献
8.
Vildes M. Scussel Daniel Manfio Geovana D. Savi Elisa H.S. Moecke 《Journal of food science》2014,79(7):H1443-H1453
In this article, tissue layers and cells characteristics of the Brazil nut (Bertholletia excelsa H.B.K.) shell (tegument), brown skin (testae), and edible part (cotyledons) were identified by stereoscopy (SM) and scanning electron microscopies (SEM). (a) The shell (a lignin rich, protective wall) varies in thickness throughout the nut structure and comprises different tissue types (total 3)/texture (hard/mid‐hard/soft), layers (2 to 5), colors (light to dark brown and white to cream), cell shape (amorphous/flattened on both surfaces; polygonal and cylindrical with thick, porous primary and secondary wall in cross‐section), and vascular distribution (helically and polyedrical thickened vessels at soft tissue and locule/channel structures). These variations are observed either in the shell faces, face corners, nut tips, or locule in testae. (b) The brown skin (shell nut part linked to both the shell and edible part) is made of flattened irregular‐shaped parenchymal cells distributed in several layers with more flexible fibrous, thinner wall tissue than shell. It has both rough and smooth shiny texture on the upper and lower surfaces, respectively. However, the nut (c) edible part, that is the nut storage tissue, shows several different tissue/cell layers starting from epidermis (double/triple cells sequence of round and palisade shapes) layer–the endosperm tissue. The parenchymal tissues show cells of irregular shape with small and larger sizes distributed in regular and randomly layers, respectively, separated by a short meristem tissue layer. The cortex cells increase in size as they approach the cotyledons junction. The Brazil nut part's tissue layers and cells were identified by the SM and SEM microscopy methods applied, which provides knowledge for further understanding of nut alterations that may occur either in the forest or during the factory processing. 相似文献
9.
This paper analyzes the policy landscape of a new configuration for the electricity sector, distributed electricity generation, DG, which was introduced in 2012 and regulated in Brazil by the National Electricity Regulation Agency (ANEEL) through a net-metering regulation. The present analysis focuses on the landscape surrounding the policy problem definition and the subsequent policy goals which were established by the national regulator as primarily related to removing barriers to grid access. The policy context surrounding DG in Brazil is analyzed within the broader scope of electricity planning goals, which is a responsibility of the Ministry of Mines and Energy and still shows strong preference to the centralized regime. The design of the net-metering mechanism and the impact of ANEEL's resolution in terms of the number and spatial distribution of the projects across states are also explored. Lastly, an econometric approach is taken by creating a linear regression model to decipher the determinants of successful policy deployment between states. The analysis shows that the electricity rates have an important impact, while the application of a state tax ICMS has negative effects on project uptake. The strength of solar resources was not a significant variable. 相似文献
10.
P.A.C. Libanio 《国际水》2017,42(4):385-399
Relying on previous experiences of goal-oriented initiatives, an inclusive method for classifying and evaluating subnational water management systems has been implemented nationwide to promote the effective participation of social actors in the establishment of water governance goals. Nowadays, the methodology has been fully adopted by all Brazilian subnational federative entities – 26 states and the Federal District – and, in most cases, it has been used as an instrument for orienting state action. This article describes this methodological approach in the light of Brazil’s legal and institutional framework for water resources management. 相似文献