全文获取类型
收费全文 | 6344篇 |
免费 | 475篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 96篇 |
综合类 | 14篇 |
化学工业 | 2111篇 |
金属工艺 | 63篇 |
机械仪表 | 133篇 |
建筑科学 | 237篇 |
矿业工程 | 16篇 |
能源动力 | 161篇 |
轻工业 | 1863篇 |
水利工程 | 64篇 |
石油天然气 | 49篇 |
武器工业 | 1篇 |
无线电 | 240篇 |
一般工业技术 | 804篇 |
冶金工业 | 182篇 |
原子能技术 | 12篇 |
自动化技术 | 779篇 |
出版年
2024年 | 18篇 |
2023年 | 95篇 |
2022年 | 367篇 |
2021年 | 410篇 |
2020年 | 223篇 |
2019年 | 254篇 |
2018年 | 268篇 |
2017年 | 265篇 |
2016年 | 314篇 |
2015年 | 215篇 |
2014年 | 329篇 |
2013年 | 500篇 |
2012年 | 491篇 |
2011年 | 517篇 |
2010年 | 353篇 |
2009年 | 364篇 |
2008年 | 298篇 |
2007年 | 271篇 |
2006年 | 192篇 |
2005年 | 161篇 |
2004年 | 132篇 |
2003年 | 112篇 |
2002年 | 121篇 |
2001年 | 78篇 |
2000年 | 57篇 |
1999年 | 56篇 |
1998年 | 50篇 |
1997年 | 41篇 |
1996年 | 36篇 |
1995年 | 25篇 |
1994年 | 17篇 |
1993年 | 20篇 |
1992年 | 15篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 18篇 |
1988年 | 10篇 |
1987年 | 15篇 |
1986年 | 9篇 |
1985年 | 20篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1972年 | 9篇 |
1970年 | 2篇 |
排序方式: 共有6825条查询结果,搜索用时 15 毫秒
991.
José S. Torrecilla John C. Cancilla Gemma Matute Pablo Díaz-Rodríguez Ana I. Flores 《Journal of food engineering》2013
A nonlinear algorithm based on chaotic parameters (CPs) has been employed to determine the nature of different output signals obtained from UV–vis spectrophotometer (UV) measurements. These signals come from UV scans of adulterated samples of extra virgin olive oil (EVOO) with refined olive oil or refined olive pomace oil, or from pure samples of EVOO with white random or sinusoidal white random noises. The data collected from this equipment was used to calculate CP values. Then, a self-organizing map was used to detect different types of signals. Using this method, the signals can be identified and classified into five groups depending on their type, the percentage of noise added, and the concentration of adulterant agents, with a misclassification rate of less than 1.3%. 相似文献
992.
Ana López Tarek El-Naggar Montserrat Dueñas Teresa Ortega Isabel Estrella Teresa Hernández Mª Pilar Gómez-Serranillos Olga Mª Palomino Mª Emilia Carretero 《Food chemistry》2013
Legumes are the base´s diet in several countries. They hold a high nutritional value, but other properties related to human health are nowadays being studied. The aim of this work was to study the influence of processes (boiling or germination) on the phenolic composition of dark beans (Phaseolus vulgaris L. c.v. Tolosana) and their effect on their antioxidant, neuroprotective and anticancer ability. Phenolic composition of raw and processed dark beans was analysed by HPLC-PAD and HPLC–ESI/MS. The antioxidant activity was evaluated by ORAC. Astrocytes cultures (U-373) have been used to test their neuroprotective effect. Anticancer activities were evaluated on three different cell lines (renal adenocarcinoma (TK-10), breast adenocarcinoma (MCF-7) and melanoma (UACC-62)) by sulphorhodamine B method. Qualitative and quantitative differences in phenolic composition have been observed between raw and processed dark beans that influence the antioxidant activity, mainly for germinated samples which show a decrease of antioxidant capacity. Although every assayed extracts decreased reactive oxygen species release and exhibited cytotoxicity activities on cancer cell lines, raw beans proved to be the most active in neuroprotective and antitumoral effects; this sample is especially rich in phenolic compounds, mainly anthocyanins. This study further demonstrated that phenolic composition of dark beans is related with cooking process and so with their neuroprotective and anticancer activity; cooking of dark beans improves their digestion and absorption at intestinal level, while maintaining its protective ability on oxidative process at cellular level. 相似文献
993.
Total Diet Studies to estimate dietary exposure to food contaminants need to evaluate laboratory measurements data variance. In this process it is critical that data from analytical methods are reliable to correctly scrutinize and compare values over time and between countries. In Europe it is widely recognized that the evaluation of measurement uncertainty is an important parameter when assessing the sources of analytical data variability. Two approaches are considered to estimate uncertainty in analytical measurement. Arsenic, Lead, Chromium and Cadmium, content in several food matrix determined by Inductively Coupled Mass Spectrometry (ICP-MS) microwave digestion assisted, are used as examples. The aim of the present research work is to compare both approaches accepted by Eurolab and GUM: Mathematical modeling to assess uncertainty components based on a classical model (bottom up) and an empirical method (top down), based on either experimental data obtained from a single laboratory validation data or inter-laboratory data from Proficiency Testing schemes. Relative expanded uncertainty calculated by both approaches agree when U (%) <20%. These values are concordant with RSDR reported in collaborative studies of EN 15763 (2009), which were assumed as target uncertainty. The top down approach described is simple and easy to use when compared with the mathematical modeling approach providing considerable benefits to those who assess data produced by several laboratories. 相似文献
994.
Raquel Martín-Venegas M.Teresa Brufau Ana Maria Guerrero-Zamora Yves Mercier Pierre-André Geraert Ruth Ferrer 《Food chemistry》2013
dl-2-hydroxy-(4-methylthio)butanoic acid (HMTBA) is a source of dietary methionine (Met) that is widely used in poultry nutrition. We have previously shown that HMTBA is preferentially diverted to the transsulfuration pathway, which gives antioxidant metabolites such as taurine and glutathione. Therefore, here we hypothesize that this Met source can protect epithelial barrier function in an in vitro model of intestinal inflammation of Caco-2 cells. The results show that HMTBA prevents the increase in paracellular permeability induced by H2O2 or tumour necrosis factor-α. This effect can be attributed to the increased production of taurine and reduced glutathione. Similar results were obtained for dl-Met, although the protective role of the amino acid was less pronounced than that of the hydroxy analogue. In conclusion, the diversion to the transsulfuration pathway means that this Met precursor is of greater value than previously thought, due to its capacity to improve intestinal homeostasis and the quality of poultry products destined for human consumption. 相似文献
995.
Lamb loins were subjected to sous-vide cooking at different combinations of temperature (60, 70, and 80 °C) and time (6, 12, and 24 h). Different physicochemical, histological and structural parameters were studied. Increasing cooking temperatures led to higher weight losses and lower moisture contents, whereas the effect of cooking time on these variables was limited. Samples cooked at 60 °C showed the highest lightness and redness, while increasing cooking temperature and cooking time produced higher yellowness values. Most textural variables in a texture profile analysis showed a marked interaction between cooking temperature and time. Samples cooked for 24 h showed significantly lower values for most of the studied textural parameters for all the temperatures considered. Connective tissue granulation at 60 °C and gelation at 70 °C were observed in the SEM micrographs. The sous-vide cooking of lamb loins dramatically reduced microbial population even with the less intense heat treatment studied (60 °C–6 h). 相似文献
996.
Ana María Martín-Sánchez Gelmy Ciro-Gómez Estrella Sayas José Vilella-Esplá Jamel Ben-Abda José Ángel Pérez-Álvarez 《Meat science》2013
Date palm is an interesting source of bioactive compounds that could be used as ingredient in meat products; thus a campagne type pork liver pâté was elaborated using fresh date by-products (0, 5, 10 and 15%). Physicochemical properties, pigment and lipid oxidation, residual nitrite level, texture and sensory analysis during 4 days after the elaboration process were evaluated. Date paste mostly incorporated moisture, fibre and phenolic compounds. Physicochemical parameters, myoglobin content and heme iron stability were not severely affected. Addition of 10% of date was enough to avoid lipid oxidation through all storage times. Colour was the most affected parameter; however, in terms of overall acceptability, panellists preferred samples with added date. 相似文献
997.
Ana Cvetkovi Stevan Blagojevi Jovan Hranisavljevi Duan Vu
eli 《Journal of the Institute of Brewing》1997,103(3):183-186
Two basic glycoproteins homologous with thaumatin- and pathogen-related proteins of the PR-5 family were isolated from grain of brewers barley cultivar. The proteins inhibit fermentation and respiration of brewers yeast and exert a lethal effect on the yeast cells. In addition a significant release of cell constituents was registered. All these effects are dose dependent and tend to saturation at higher dosage. These results suggest that cell membrane damage causes the impairment of vital cell functions. Tracing these proteins in the course of the brewing process revealed that thermal treatment at the mashing stage of brewing leads to their disappearance due to denaturation. 相似文献
998.
Ana Carolina P. Vital Camila Croge Sandra Maria Gomes‐da‐Costa Paula T. Matumoto‐Pintro 《International Journal of Food Science & Technology》2017,52(6):1483-1490
The residue from a hydroalcoholic extract of the mushroom Agaricus blazei (MAR) was evaluated for phenolic compounds, flavonoids and antioxidant activity. The ability of MAR to slow the oxidation of Omega‐3 resulting from light exposure in milk matrix, and its bioavailability after in vitro digestion was investigated. MAR presented phenolic compounds and flavonoids and showed antioxidant activity. At each concentration, addition of MAR to Omega‐3‐supplemented milk inhibited the production of conjugated dienes and malonaldehyde compared with samples without MAR. The bioavailability assay showed that polyphenols were still present after in vitro digestion and had antioxidant activity. 相似文献
999.
1000.