全文获取类型
收费全文 | 5230篇 |
免费 | 352篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 4篇 |
综合类 | 96篇 |
化学工业 | 90篇 |
金属工艺 | 4篇 |
机械仪表 | 21篇 |
建筑科学 | 14篇 |
矿业工程 | 3篇 |
能源动力 | 3篇 |
轻工业 | 5216篇 |
水利工程 | 2篇 |
石油天然气 | 26篇 |
无线电 | 19篇 |
一般工业技术 | 66篇 |
冶金工业 | 2篇 |
原子能技术 | 6篇 |
自动化技术 | 23篇 |
出版年
2024年 | 24篇 |
2023年 | 64篇 |
2022年 | 175篇 |
2021年 | 220篇 |
2020年 | 237篇 |
2019年 | 219篇 |
2018年 | 201篇 |
2017年 | 215篇 |
2016年 | 204篇 |
2015年 | 229篇 |
2014年 | 284篇 |
2013年 | 363篇 |
2012年 | 448篇 |
2011年 | 430篇 |
2010年 | 211篇 |
2009年 | 192篇 |
2008年 | 201篇 |
2007年 | 307篇 |
2006年 | 313篇 |
2005年 | 262篇 |
2004年 | 169篇 |
2003年 | 159篇 |
2002年 | 111篇 |
2001年 | 89篇 |
2000年 | 67篇 |
1999年 | 59篇 |
1998年 | 26篇 |
1997年 | 19篇 |
1996年 | 17篇 |
1995年 | 9篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 4篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有5595条查询结果,搜索用时 15 毫秒
71.
A Strategy to Design Efficient Fermentation Processes for Traditional Beverages Production: Prickly Pear Wine 总被引:1,自引:0,他引:1
J.L. Navarrete‐Bolaños E. Fato‐Aldeco K. Gutiérrez‐Moreno J.E. Botello‐Álvarez H. Jiménez‐Islas R. Rico‐Martínez 《Journal of food science》2013,78(10):M1560-M1568
This paper describes a methodology to establish an optimal process design for prickly pear wine production that preserves the peculiar and unique traits of traditional products, generating at the same time, technical information for appropriate design of both bioreactor and overall process. The strategy includes alcoholic fermentation optimization by the mixed native culture composed by Pichia fermentans and Saccharomyces cerevisiae, followed by malolactic fermentation optimization by Oenococcus oeni. The optimization criteria were based on multiple output functions: alcohol content, volatile compounds profile, organic acids profile, and compound contents related to color, which were analyzed by spectroscopy–chromatography methods and sensory analysis. The results showed that the mixed culture inoculated into a bioreactor containing prickly pear juice with 20 °Bx of fermentable sugars concentration, processed at a constant temperature of 20 °C for 240 h, leads to a fermented product with 9.93% (v/v) total alcohol content, and significant abundance of volatile compounds, which provide fruity and ethereal aromatic notes, complemented by a lively but not unpleasant acidity. This young wine was further subjected to malolactic fermentation at constant temperature (16 °C) for 192 h, decreasing malic acid, and balancing volatile compounds contents, thus resulting in a product with better aroma and flavor perception, and a velvety feeling of long aftertaste. Repeated assays showed that the process is stable, predictable, controllable, and reproducible. These results were used for process design and spreadsheet construction in order to simulate the process, and properly select and size the equipment required for such process. 相似文献
72.
The purpose of this work is to evaluate the phenolic profile and the antioxidant activity of commercial dealcoholised wines and monitor the stability of their composition over time. This work also aims to test the influence of reverse osmosis (RO) process on phenolic compounds and on the antioxidant activity (AA) of dealcoholised wine.AA was measured by ORAC, DPPH and FRAP assays. Phenolic compounds were determined by LC-DAD.In the commercial dealcoholised wines, AA fell by between 33% and 54% and the concentration of phenolic compounds decreased significantly after 30 days of storage. However, RO process did not significantly affect any phenolic acids, regardless of their chemical structure (benzoic acids, cinnamic acids) and alcoholic degree. The AA and phenolic compounds of these products were monitored for seven months. No significant changes were observed. RO process therefore makes it possible to obtain a healthy, low-alcohol (<2% v/v) product with bioactive compounds that are stable in the product and are similar to those found in the original wine. 相似文献
73.
Ruo‐Si Fang Ya‐Chen Dong Teng‐Yang Xu Guo‐Qing He Qi‐He Chen 《International Journal of Food Science & Technology》2013,48(12):2551-2556
Ethyl carbamate (EC) is a potential carcinogenic compound present in most of the fermented foods. In this work, EC was inhibited through different strategies during vinification of Chinese yellow rice wine. EC can be inhibited by the use of ornithine in contrast to the control at peak point. However, the utilisation of urease resulted in little inhibitive effect on EC. The comparative data of intracellular ornithine transcarbamylase (OTCase) and arginine deiminase (ADI) among four experiments showed that EC was positively regulated by intracellular OTCase, but ADI was not determined. Extracellular urea and citrulline content was significantly increased by adding ornithine (P < 0.05), whereas ethanol played a minor role in EC formation. The correlation analysis between EC and OTCase or urea revealed a linear association (correlation coefficients above 0.8). These findings suggested that OTCase may be a required factor regulating EC formation during the brewing of Chinese yellow rice wine. 相似文献
74.
The objective of the paper is to identify some of the determinants of foreign investment of the largest multinational enterprises (MNEs) operating in the wine industry. The factors that drive firms to invest abroad and those that determine the location of those investments are examined in the case of the world wine industry. The list of the largest MNEs has been compiled using financial databases and company websites. Spearman rank correlation values are calculated between the ranking of the location popularity of host countries and the ranking of the independent variables or indices for the same period. The results of this study have some important implications. They indicate that location-specific advantages of host countries do provide an explication of the internationalization of firms in some preferred countries rather than others. 相似文献
75.
葡萄酒中的金属元素对人体健康非常有益.用硝酸-高氯酸对葡萄酒进行消化处理,采用原子吸收光谱法测定、处理溶液中铜、铁、锌、镁的含量.结果表明:使用原子吸收光谱法测定葡萄酒中金属元素的方法可行、准确、简便、快速. 相似文献
76.
Sustainable recovery of grape skins for use in an apple beverage with antiglycation properties 下载免费PDF全文
Vera Lavelli Pedapati S.C. Sri Harsha Maria Piochi Luisa Torri 《International Journal of Food Science & Technology》2017,52(1):108-117
An apple puree formulated with red grape skins was developed on pilot scale as a new beverage with antiglycation properties. The addition level of grape skins was selected by a liking test with 70 consumers. The selected formulation was a fibre‐rich source and delivered grape anthocyanins, flavonols and flavanols resulting in ~ twofold higher antiglycation activity than the apple puree. Pasteurisation (3‐D in the target microorganism Alicyclobacillus acidoterrestris) did not affect the antiglycation activity, which decreased by 30% upon sterilisation. Storage for 1 month in the temperature range 15–35 °C affected the contents of anthocyanins, monomeric, dimeric and oligomeric flavanols, while chlorogenic acid, flavonols and dihydrochalcones were stable. About 90% antiglycation activity was retained after one‐month storage at 15 °C. The use of red grape skin as ingredient could represent an opportunity for the apple processing industry to develop a value‐added product. 相似文献
77.
78.
79.
Silvia Baena‐Ruano Carlos Jiménez‐Ot Inés M. Santos‐Dueñas Jorge E. Jiménez‐Hornero José L. Bonilla‐Venceslada Carmen Álvarez‐Cáliz Isidoro García‐García 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(7):908-912
BACKGROUND: The acetification process needs an overall study of the variables influencing it in order to establish their optimum values. Based on industrial experience and available literature, including a recently proposed model by the authors, among the variables most strongly influencing the acetification process are the ethanol concentration at the time the reactor is unloaded, the unloaded volume and the loading rate. To ensure economically efficient industrial production of vinegar, and to check the predictions of the aforementioned model, the influence of the final ethanol concentration at unloading time on the mean acetification rate and on productivity has been studied in this work. RESULTS: An increase in the final ethanol concentration from 0.5 to 3.5% (v/v) increased the mean overall acetification rate and acetic acid production by 38 and 26%, respectively. The increase was established mainly during the loading phase. CONCLUSIONS: The final ethanol concentration is a key variable for process optimization. If a high rate is desired then a product containing much unused substrate will be obtained, which may be industrially unacceptable. These results suggest the necessity to investigate other possibilities when high values for yield and productivity must to be achieved. Copyright © 2010 Society of Chemical Industry 相似文献
80.
A gas-chromatography-olfactometric detection (GCO) using a direct estimation of odor intensities with the finger span (FSCM) was used to establish aroma profiles of three wines of gewürztraminer from different ‘terroirs’ of the Alsace region. The GCO-FSCM analyses of their hydroalcoholic wine extracts were performed using a group of untrained assessors. Forty-four olfactory signals were perceived by at least four assessors out of six and their intensities were scored in triplicate in each of the three wine extracts, amongst which ten of them were found discriminant between wines. The reliability of each assessor was studied on the basis of the finger span estimation repeatability, from the number of discriminant variables and the mean finger span values found for the assessor. These untrained assessors appear to be able to achieve self-calibration from odor intensities without using any internal of external quantitative reference. The results suggest that GCO-FSCM may be performed by naive assessors to analyse and compare odor profiles of complex extracts without time-consuming training periods. 相似文献