全文获取类型
收费全文 | 1066篇 |
免费 | 69篇 |
专业分类
电工技术 | 3篇 |
综合类 | 3篇 |
化学工业 | 325篇 |
金属工艺 | 12篇 |
机械仪表 | 10篇 |
建筑科学 | 18篇 |
能源动力 | 20篇 |
轻工业 | 499篇 |
水利工程 | 4篇 |
石油天然气 | 6篇 |
无线电 | 28篇 |
一般工业技术 | 91篇 |
冶金工业 | 36篇 |
原子能技术 | 3篇 |
自动化技术 | 77篇 |
出版年
2024年 | 3篇 |
2023年 | 8篇 |
2022年 | 47篇 |
2021年 | 45篇 |
2020年 | 24篇 |
2019年 | 17篇 |
2018年 | 36篇 |
2017年 | 37篇 |
2016年 | 36篇 |
2015年 | 34篇 |
2014年 | 50篇 |
2013年 | 60篇 |
2012年 | 75篇 |
2011年 | 79篇 |
2010年 | 55篇 |
2009年 | 45篇 |
2008年 | 63篇 |
2007年 | 49篇 |
2006年 | 51篇 |
2005年 | 54篇 |
2004年 | 40篇 |
2003年 | 33篇 |
2002年 | 27篇 |
2001年 | 18篇 |
2000年 | 9篇 |
1999年 | 15篇 |
1998年 | 17篇 |
1997年 | 13篇 |
1996年 | 25篇 |
1995年 | 10篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 10篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 6篇 |
1984年 | 1篇 |
1976年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
排序方式: 共有1135条查询结果,搜索用时 0 毫秒
91.
This article presents a generic project risk management process that has been particularized for construction projects from the point of view of the owner and the consultant who may be assisting the owner. The process could also be adapted to the needs of other project participants, and many points referred to in the article can be directly applied to them. Any project risk management process must be tailored to the particular circumstances of the project and of the organization undertaking it. First, the article explains a complete or generic project risk management process to be undertaken by organizations with the highest level of risk management maturity in the largest and most complex construction projects. After that, factors influencing possible simplifications of the generic process are identified, and simplifications are proposed for some cases. Then the application to a real project is summarized. As a final validation, a Delphi analysis has been developed to assess the project risk management methodology explained here, and the results are presented. 相似文献
92.
Gloria Urbano María López‐Jurado Jesús M Porres Sławomir Frejnagel Elena Gómez‐Villalva Juana Frías Concepción Vidal‐Valverde Pilar Aranda 《Journal of the science of food and agriculture》2007,87(7):1356-1363
The effect of treatment with α‐galactosidase, tannase or a cell‐wall‐degrading enzyme complex under optimal conditions of pH, temperature and length of incubation time on the chemical composition and nutritive utilisation of protein and carbohydrates from pea (Pisum sativum L.) flour was studied. Soaking of pea flours in combination with enzyme treatment led to reductions of 77–90% in the levels of α‐galactosides, and of 60–80% in the levels of trypsin inhibitor activity, increasing the content of total available sugars, which was highest in the pea flour treated with the cell‐wall‐degrading enzyme complex. All the treatments assayed caused a significant improvement in daily food intake, whereas the nutritive utilisation of protein was not increased in any of the pea products tested when compared to the raw pea flour. However, all the soaking and enzymatic treatments led to a significant improvement in daily weight gain associated with a higher dietary intake of food and total available sugars. Copyright © 2007 Society of Chemical Industry 相似文献
93.
94.
The great urban and industrial development of the towns surrounding Madrid has caused an irreversible and rapid soil loss. In this paper, soil sealed evolution in Guadalajara province during the past 15 years, mainly in the capital, industrial district and small municipalities near Madrid, has been studied. This province has experimented a sharp reduction of the most fertile soils, located on the Henares valley, due to the action of new models of local and regional development. The main goal of this paper is the mapping of the covered soils in a pilot area of Spain. Supervised classification of Landsat images from 1989 to 2002 has been carried out. Geo-referred image analysis allows us to detect precisely the amount of covered soils and where this phenomenon has taken place. 相似文献
95.
Antimicrobial activity of reuterin in combination with nisin against food-borne pathogens 总被引:1,自引:0,他引:1
Arqués JL Fernández J Gaya P Nuñez M Rodríguez E Medina M 《International journal of food microbiology》2004,95(2):225-229
Antimicrobial activity of reuterin individually or in combination with nisin against different food-borne Gram-positive and Gram-negative pathogens in milk was investigated. Reuterin (8 AU/ml) exhibited bacteriostatic activity against Listeria monocytogenes, whereas its activity was slightly bactericidal against Staphylococcus aureus at 37 degrees C. Higher bactericidal activity was detected against Escherichia coli O157:H7, Salmonella choleraesuis subsp. choleraesuis, Yersinia enterocolitica, Aeromonas hydrophila subsp. hydrophila and Campylobacter jejuni. A significant synergistic effect on L. monocytogenes and a slight additive effect on S. aureus after 24 h at 37 degrees C were observed when reuterin was combined with nisin (100 IU/ml). The combination of reuterin with nisin did not enhance the antimicrobial effect of reuterin against Gram-negative pathogens. 相似文献
96.
Navas J Ortiz S López P López V Martínez-Suárez JV 《Journal of food protection》2007,70(12):2851-2854
This study aimed to evaluate the effect of different enrichment procedures on the detection of Listeria monocytogenes in food, by a comparison of subculture onto chromogenic agar with real-time PCR. Two different culture media, the primary and secondary enrichment broths of the U.S. Food Safety and Inspection Service (FSIS) method used for PCR detection of L. monocytogenes, were compared for the primary enrichment of retail ground chicken samples. L. monocytogenes was detected after the completion of each enrichment procedure in 63% (complete FSIS procedure) and 60% (plain FSIS secondary enrichment broth incubated for 48 h) of the samples by both culture and PCR, whereas a combination of the results for the two enrichment procedures revealed 86% of the samples to be positive. Most of the samples analyzed contained a mixture of lineage I and II strains, and their ratio varied for each enrichment procedure. This mixture could have a significant effect on the result of detection of L. monocytogenes for each individual sample, explaining the increase in positive samples when the results of the two enrichment procedures were combined. The use of different isolation procedures can affect the specific samples identified as positive and the specific strains isolated. 相似文献
97.
Ananías Pascoal Marta Prado Pilar Calo Alberto Cepeda Jorge Barros-Velázquez 《European Food Research and Technology》2005,220(3-4):444-450
The identification of beef in animal foods is a major concern not only for the prevention of commercial fraud, but also to avoid safety risks deriving from the presence of prohibited bovine material that might be harmful to both human and animal health. Here we report a novel set of bovine-specific primers, CYTbos1 (forward) and CYTbos2 (reverse), which allow the specific amplification of a 115 base pair fragment of the bovine cytochrome b gene (cytb) between nt 844 (mitochondrial site 15,590) and nt 958 (mitochondrial site 15,704), no cross-reaction being observed with DNA from another 12 frequent commercial meat species. The polymerase chain reaction product obtained is cleaved specifically by endonucleases ScaI and TspE1 to achieve further confirmation evidence. The sensitivity of the proposed method was 0.025%. The CYTbos primers successfully detected bovine DNA in meat samples processed for 20 min at 133 °C/300 kPa or for 2 h at 121 °C. CYTbos primers also detected bovine DNA in heat-processed commercial meat products exhibiting a complex nature, as well as in bovine specific risk materials. The proposed polymerase chain reaction method, aimed at detecting a small and specific fragment of the bovine mitochondrial DNA, may be especially useful for the direct identification of bovine DNA in foodstuffs subjected to severe heating under overpressure conditions. 相似文献
98.
Gloria Urbano Sławomir Frejnagel Jesús M. Porres Pilar Aranda Elena Gomez-Villalva Juana Frías María López-Jurado 《European Food Research and Technology》2007,226(1-2):105-111
The effect of dephytinization of Pisum sativum, L. flour on the bioavailability of Mg and Zn was evaluated in growing rats. Processing of legume flours under optimal conditions
for phytase activity (pH 5.5, 37 °C, 60 min) and subsequent removal of the soaking solution led to a 42 and 61% reduction
in the content of Mg and Zn, respectively. Treatment with phytase led to an additional reduction in the concentration of the
above-mentioned seed flour components, compared to the raw pea flour (69% and 74% for Mg and Zn, respectively). The considerable
reduction in the content of inositol phosphates with high degree of phosphorylation attained under both processing conditions
did not affect the digestive utilization of Mg, whereas the metabolic utilization of this mineral increased significantly.
The digestive and metabolic utilization of Zn increased significantly in response to both processes assayed, reaching the
highest values in the experimental group that was fed the phytase-treated pea flour diet. The amount of Mg retained by the
experimental animals was reflected in the content of this mineral in the different tissues studied (femur, sternum, kidney,
and heart), whereas no correlation was found in the case of Zn. 相似文献
99.
Carmen García-Domingo Pilar Rupérez F. Saura-Calixto 《European Food Research and Technology》1997,204(1):43-47
Profiles of flavonoid compounds of Apis mellifera and Melipona spp. honeys from Venezuela were analysed to evaluate entomological-dependent differences. The presence of ellagic acid was
a characteristic of A. mellifera honeys from Venezuela, but its presence was variable in Melipona spp. samples. The number of flavonoid types present in individual samples did not exceed six and occasionally only one phenolic
type was present. The diversity of flavonoid compounds in tropical honeys from Venezuela was lower than that previously measured
in temperate honeys. Flavonoids such as myricetin, an unidentified chalcone and a flavonol glycoside were only found in Melipona honeys but not in all the samples; therefore, they cannot be foreseen as entomological markers to differentiate between the
Apis and Melipona honeys under study. A preliminary discussion is made regarding flavonoids present in Melipona honeys and their probable link with the putative anticataract action of stingless bee-honeys.
Received: 22 February 1996 相似文献
100.
Pilar Miranzo Eugenio García Cristina Ramírez Jesús González-Julián Manuel Belmonte M. Isabel Osendi 《Journal of the European Ceramic Society》2012,32(8):1847-1854
Silicon nitride (Si3N4) composites containing carbon nanotubes (CNTs) or graphene nanoplateles (GNPs) are of great relevance in the electronic and aerospace industries where the search for new materials with enhanced and anisotropic thermal conductivity to work in harsh environments is a strategic guideline. Here we study thermal conduction in Si3N4 composites with different amounts of carbon nanostructures. The effects of the nanostructure orientation respect the heat flux, the testing temperature and the α/β Si3N4 phase ratio are analyzed. The addition of CNTs and GNPs leads to an anisotropic thermal response, decreasing the through-thickness thermal conductivity of the Si3N4 composites and raising the in-plane thermal conductivity, especially for GNPs that enhance it up to twice that of the monolithic Si3N4. This effect is related to the preferred orientation of the nanostructures that gives a less resistive network in the in-plane direction and the intrinsic anisotropy of their thermal conductivity. 相似文献