全文获取类型
收费全文 | 1578篇 |
免费 | 88篇 |
专业分类
电工技术 | 11篇 |
综合类 | 2篇 |
化学工业 | 506篇 |
金属工艺 | 30篇 |
机械仪表 | 27篇 |
建筑科学 | 103篇 |
矿业工程 | 6篇 |
能源动力 | 47篇 |
轻工业 | 245篇 |
水利工程 | 14篇 |
石油天然气 | 12篇 |
无线电 | 68篇 |
一般工业技术 | 223篇 |
冶金工业 | 199篇 |
原子能技术 | 8篇 |
自动化技术 | 165篇 |
出版年
2024年 | 7篇 |
2023年 | 18篇 |
2022年 | 67篇 |
2021年 | 92篇 |
2020年 | 45篇 |
2019年 | 48篇 |
2018年 | 43篇 |
2017年 | 51篇 |
2016年 | 55篇 |
2015年 | 44篇 |
2014年 | 49篇 |
2013年 | 103篇 |
2012年 | 84篇 |
2011年 | 115篇 |
2010年 | 81篇 |
2009年 | 69篇 |
2008年 | 66篇 |
2007年 | 52篇 |
2006年 | 36篇 |
2005年 | 48篇 |
2004年 | 33篇 |
2003年 | 31篇 |
2002年 | 33篇 |
2001年 | 34篇 |
2000年 | 16篇 |
1999年 | 26篇 |
1998年 | 60篇 |
1997年 | 38篇 |
1996年 | 30篇 |
1995年 | 23篇 |
1994年 | 23篇 |
1993年 | 18篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1986年 | 7篇 |
1985年 | 9篇 |
1984年 | 7篇 |
1982年 | 4篇 |
1981年 | 6篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1977年 | 7篇 |
1976年 | 12篇 |
1975年 | 2篇 |
1973年 | 3篇 |
1968年 | 2篇 |
1963年 | 2篇 |
排序方式: 共有1666条查询结果,搜索用时 15 毫秒
1.
Esteban Vera Pingitore María Silvina Juárez Tomás Birgitt Wiese 《Drug development and industrial pharmacy》2015,41(6):942-952
Context: The administration of pharmabiotics is a promising alternative to antimicrobial drugs for the treatment and/or prevention of female urogenital infections.Objective: To design pharmabiotic formulations including bioactive ingredients of microbial origin combined with non-microbial substances and then to evaluate the stability of the combinations during freeze-drying and storage.Materials and methods: Different formulations including Lactobacillus gasseri CRL 1263, Lactobacillus salivarius CRL 1328, salivaricin CRL 1328 (a bacteriocin) and non-microbial compounds (lactose, inulin and ascorbic acid) were assayed, and the ingredients were freeze-dried together or separately. The formulations were stored in gelatin capsules at 4?°C for 360?d.Results: The viability of lactobacilli was affected to different extents depending on the strains and on the formulations assayed. L. salivarius and ascorbic acid were successfully combined only after the freeze-drying process. Salivaricin activity was not detected in formulations containing L. gasseri. However, when combined with ascorbic acid, lactose, inulin or L. salivarius, the bacteriocin maintained its activity for 360?d. The selected microorganisms proved to be compatible for their inclusion in multi-strain formulations together with lactose, inulin and ascorbic acid. Salivaricin could be included only in a L. salivarius CRL 1328 single-strain formulation together with non-microbial substances.Conclusions: This study provides new insights into the design of urogenital pharmabiotics combining beneficial lactobacilli, salivaricin CRL 1328 and compounds with different functionalities. 相似文献
2.
Joaquín Cortés Eliana Valencia Gonzalo Aguila Esteban Orellana Paulo Araya 《Catalysis Letters》2008,126(1-2):63-71
An experimental study is made of the time decay of activity of the CO–NO reaction on a Pd/Al2O3 looking at the effect on reaction order and apparent activation energy. The optimum kinetics parameters fitting the steady state data at moderate pressures are determined. The time decay curves are analyzed through various catalyst deactivation models. 相似文献
3.
P Navarro J Sarasa D Sierra S Esteban J L Ovelleiro 《Water science and technology》2005,51(1):113-120
Wine industry wastewaters contain a high concentration of organic biodegradable compounds as well as a great amount of suspended solids. These waters are difficult to treat by conventional biological processes because they are seasonal and a great flow variation exists. Photocatalytic advanced oxidation is a promising technology for waters containing high amounts of organic matter. In this study we firstly investigated the application of H2O2 as oxidant combined with light (artificial or natural) in order to reduce the organic matter in samples from wine industry effluents. Secondly, we studied its combination with heterogeneous catalysts: titanium dioxide and clays containing iron minerals. The addition of photocatalysts to the system reduces the required H2O2 concentration. Although the H2O2/TiO2 system produces higher efficiencies, the H2O2/clays system requires a H2O2 dosage between three and six times lower. 相似文献
4.
N Benito A Nú?ez M de Górgolas J Esteban T Calabuig MC Rivas ML Fernández Guerrero 《Canadian Metallurgical Quarterly》1997,157(14):1577-1580
BACKGROUND: Fever is commonly observed in patients with human immunodeficiency virus (HIV) disease and frequently eludes diagnosis. The role of bone marrow biopsy in the diagnosis of fever of unknown origin in patients infected with HIV remains controversial. PATIENTS AND METHODS: One hundred twenty-three consecutive patients with 137 episodes of fever lasting 10 or more days without diagnosis after 1 week of hospitalization were evaluated by bone marrow biopsy. RESULTS: Overall, a specific diagnosis was achieved in 52 episodes by means of culture and histopathological examination (diagnostic yield, 37.9%). Three types of disease were found: mycobacterial infections (n = 36, 69% of documented episodes), including 18 patients with disseminated tuberculosis and 14 with Mycobacterium avium-intracellulare complex infections; non-Hodgkin lymphomas (n = 12, 23%); and visceral leishmaniasis (n = 4, 8%). Although bone marrow cultures were more sensitive than microscopic examination with special stains for the diagnosis of mycobacterial infections, the pathological examination of bone marrow led to a more rapid diagnosis of disease. In addition, the histopathological examination of bone marrow alone led to the diagnosis of a specific condition in 43 episodes (31.3% of all episodes). CONCLUSIONS: Bone marrow biopsy is a useful procedure for the diagnosis of fever in patients with advanced HIV disease, particularly in areas where tuberculosis and leishmaniasis are prevalent. Involvement of the marrow may be the first indication of the existence of extranodal non-Hodgkin lymphoma. For Mycobacterium avium-intracellulare complex infection, blood cultures were more sensitive than bone marrow biopsy. 相似文献
5.
Alfredo D. Mazzoni Esteban E Aglietti Enrique Pereira 《Journal of the American Ceramic Society》1993,76(9):2337-2340
β'-Sialons are phases of the Si-Al-O-N system. The carbonitriding of clays and kaolins is a preparation method. The reaction mechanism of clay carbonitriding is verified by means of the relation among crystalline phases formed and the weight loss produced in the samples during the reaction. Two clays were previously mixed with carbon black and pressed into pellets, flowing through N2 atmosphere, at five temperatures within the range 1335–1427°C. The phases formed (XRD)—mullite, SiC, β'A-sialon, and oxynitrides—were related to the weight loss measured in the pellet independently of reaction temperature and time. The β'A-sialon and the nitrogenous phases were formed from SiC and mullite. A z value decrease for β'A-sialon was observed during reaction progression. 相似文献
6.
The Journal of Supercomputing - This article presents a set of linear regression models to predict the impact of task migration on different objectives, like performance and energy consumption. It... 相似文献
7.
Effect of atmospheric pollutants on the corrosion of high power electrical conductors: Part 1. Aluminium and AA6201 alloy 总被引:2,自引:0,他引:2
Rosa Vera 《Corrosion Science》2006,48(10):2882-2900
The aim of this study was to evaluate the joint effect of marine and industrial pollutants on the atmospheric corrosion of aluminium and its AA6201 alloy. Weight loss was determined after 4, 11, 16 and 24 months exposure being morphology and attack intensity analysed through SEM-EDX. Both materials showed the most intense attack for the highest SO2 contents. Good correlation among weight loss, attack depth and tensile strength to rupture with time and with pollutant contents was determined for both materials in most sites. The cause for low aggressiveness of the heaviest Cl− polluted atmosphere on aluminium was electrochemically demonstrated. 相似文献
8.
Effect of the exposure angle in the corrosion rate of plain carbon steel in a marine atmosphere 总被引:1,自引:0,他引:1
This investigation aims to analyse the effect of the exposure angle on the corrosion rate of mild steel. Test samples were exposed to a marine environment at 0°, 30°, 45° and 90° inclination. To determine the effects of contaminants on the protective characteristics of the rusts, Cl and SO2 contents in the atmosphere as well as SEM-EDX analyses and polarisation curves on the weathered samples were performed. Results demonstrated that the exposure angle influences the corrosion rate, as also the morphology of the rust, but with no effect on rust composition. 相似文献
9.
Carlos R. Vera Carlos L. Pieck Kiyoyuki Shimizu Jos M. Parera 《Applied Catalysis A: General》2002,230(1-2):137-151
An assessment of the influence of the crystal structure, surface hydroxylation state and previous oxidation/reduction pretreatments on the activity of sulfate-zirconia catalysts for isomerization of n-butane was performed using crystalline and amorphous zirconia supports. Different sulfation methods were used for the preparation of bulk and supported SO42−-ZrO2 with monoclinic, tetragonal and tetragonal+monoclinic structures. Activity was important only for the samples that contained tetragonal crystals. The catalysts prepared from pure monoclinic zirconia showed negligible activity. SO42−-ZrO2 catalysts prepared by sulfation of crystalline zirconia displayed sites with lower acidity and cracking activity than those sulfated in the amorphous state. Prereduction of the zirconia samples with H2 was found to greatly increase the catalytic activity, and a maximum rate was found at a reduction temperature of 550–600 °C, coinciding with a TPR peak supposedly associated with the removal of lattice oxygen and the creation of lattice defects. A weaker dependence of catalytic activity on the density or type of surface OH groups on zirconia (before sulfation) was found in this work.
A model of active site generation was constructed in order to stress the dependence on the crystal structure and crystal defects. Current and previous results suggest that tetragonal structure in active SO42−-ZrO2 is a consequence of the stabilization of anionic vacancies in zirconia. Anionic vacancies are in turn supposed to be related to the catalytic activity for n-butane isomerization through the stabilization of electrons from ionized intermediates. 相似文献
10.
The objective of our research was to develop assistive technology for visually impaired people, with a high appreciation for the human potential to achieve, to learn, and to achieve goals. In this document, we describe a virtual white cane made of a combination of a Smartphone and a laser pointer. In our device, the laser pointer beam reflection is captured by the Smartphone camera. The distance from the virtual white cane to the reflection is computed through active triangulation. Then, a personalized vibration, the magnitude of which corresponds to distance, is generated in the Smartphone. In this way, the users receive information that could prevent collisions with obstacles in the environment. Our contributions include the development of a virtual white cane around a Smartphone and other off-the-shelf accessories and a methodology to provide personalized vibratory feedback to the user. Our experiments show that to navigate, our instrument is better option, in terms of travel time, that the use of the hands. However, the travel time is still better using a traditional white cane than our instrument. 相似文献