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81.
Binay K. Singh Narendra S. Rawat 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1994,61(1):57-65
The factors affecting the rate processes involved in the removal of phenolic compounds, e.g. initial phenol concentration, particle size, impregnation of fly ash (IFA), pH and temperature have been studied. The removal rate of phenols varied in the order p-nitrophenol m-nitrophenol > o-nitrophenol > p-cresol > phenol > m-cresol > o-cresol. The process followed first order rate kinetics. The sorption data generally fit the Lagergren equation and the intraparticle diffusion rate equation from which adsorption rate constants, diffusion rate constants and diffusion coefficients were determined. Intraparticle diffusion was found to be the rate-limiting step. These kinetic parameters were compared for various phenols under different conditions using fly ash (FA) and impregnated fly ash (IFA). 相似文献
82.
Unfiltered water, surface film, sediment, and biota samples were collected from the Bay of Quinte between May and September 1978 and analyzed for chlorophenols (CPs). Sectioned sediment cores were dated using 210Pb and 137Cs analyses. Pentachlorophenol (PCP) was found at high concentrations adjacent to a point source and was detected in all compartments examined throughout the bay (a bioaccumulation factor of 104 was observed for PCP in fish). The ratio of 2,3,4,6- and 2,3,5,6-tetrachlorophenols (TTCPs) to PCP increased with distance from the source in the water column and surface film. Photochemical reduction was proposed to account for the phenomenon. CP concentrations in sectioned cores suggested that settling particles adsorb CPs in similar proportion to that observed in the water column and little further change occurs after burial. 相似文献
83.
Antonio Bevilacqua Marianna Cannarsi Mariangela Gallo Milena Sinigaglia Maria Rosaria Corbo 《Journal of food science》2010,75(1):M53-M60
ABSTRACT: Enterobacter cloacae can be recovered in the spontaneous fermentations of Italian table olives. In this study, the effects of salt (20 to 100 g/L), temperature (10 to 37 °C), pH (4 to 5 and 8 to 10), p -coumaric and vanillic acids (0.5 to 2 g/L), and the acidification of the medium through lactic, citric, and ascorbic acids were investigated on 15 strains of E. cloacae , isolated from Italian table olives "Bella di Cerignola." Finally, a confirmatory experiment in synthetic brine was run. The strains were inhibited only by an NaCl amount of 70 to 80 g/L and by p -coumaric acid; on the other hand, they showed the ability to grow also at low temperatures (10 to 15 °C). The confirmatory experiment highlighted their ability to survive both at 15 °C and at pH 5. Enterobacter cloacae could be a real problem for the fermentation of table olives in southern Italy; some hurdles could be used (salt or brine acidification), but some environmental conditions (for example, the temperature) should be controlled carefully to maintain olive safety at acceptable levels. 相似文献
84.
85.
JimmyA. van Rijn Martin Lutz LarsS. vonChrzanowski AnthonyL. Spek Elisabeth Bouwman Eite Drent 《Advanced Synthesis \u0026amp; Catalysis》2009,351(10):1637-1647
A new catalytic method has been investigated to obtain either O‐ or C‐allylated phenolic products using allyl alcohol or diallyl ether as the allyl donor. With the use of new cationic ruthenium(II) complexes as catalyst, both reactions can be performed with good selectivity. Active cationic Ru(II) complexes, having cyclopentadienyl and bidentate phosphine ligands are generated from the corresponding Ru(II) chloride complexes with a silver salt. The structures of three novel (diphosphine)Ru(II)CpCl catalyst precursor complexes are reported. It appears that the structure of the bidentate ligand has a major influence on catalytic activity as well as chemoselectivity. In addition, a strong cocatalytic effect of small amounts of acid is revealed. Model experiments are described that have been used to build a reaction network that explains the origin and evolution in time of both O‐allylated and C‐allylated phenolic products. Some mechanistic implications of the observed structure vs. performance relation of the [(diphosphine)RuCp]+ complexes and the cocatalytic role of added protons are discussed. 相似文献
86.
To the consumer, beer should be an agreeable beverage of attractive colour, clarity, pleasing flavour and should carry no toxic substances. One of the major constituents of barley is phenolic acids and their direct effect on the quality of beer is still a mystery. The aim of the study therefore was to investigate the relationship between phenolic acids during mashing at different temperatures and the quality of the beer. The mash regime and liquor to malt ratios were optimised and the carbohydrates obtained were analysed at 3.5 L of water per kg of malt and a total mash time of 105 min. Carbohydrate and phenolic acid analyses were performed by HPLC coupled with a UV‐vis detector. The three different malts used had a phenolic acid content of 33.25 μg/mL, 25.44 μg/mL and 19.98 μg/mL for malt A, B and C, respectively. The plot of 1/T versus Ln(t) gave a negative slope with activation energy (Ea) = 209 KJ/mol, rate constant (k) = 4.6 × 10?4 mg/L min, which are comparable to similar data reported in the literature. The kinetics studies showed that the optimised mashing temperature of 90°C was adequate to form 4‐vinylguaiacol by thermal decarboxylation from the hydroxycinnamic acids. This study has shown that there is no direct correlation between phenolic acids and oxidative flavour stability of beer while the corresponding volatile phenols may affect beer flavour. 相似文献
87.
Juliana Milheiro Luís Filipe-Ribeiro Alice Vilela Fernanda Cosme 《Critical reviews in food science and nutrition》2019,59(9):1367-1391
The presence of 4-ethylphenol, 4-ethylguaiacol and 4-ethylcatechol in red wines affect negatively their aroma conferring horsy, barnyard, smoky and medicinal aromatic notes. These volatile phenols formed from free hydroxycinnamic acids and their ethyl esters by Dekkera/Brettanomyces yeasts, can contaminate wines. Their formation can cause serious negative economic impact to the wine industry worldwide as consumers tend to reject these wines. For these reasons various preventive and remedial treatments have been studied. This review summarises the wine microbial volatile phenols formation, preventive measures during winemaking and remedial treatments in finished wines along with their advantages and limitations for dealing with this sensory defect and impact on wine quality. Also it is important to control the levels of volatile phenols in wines using fast and convenient analytical methods namely with a detection limit below their olfactory perception threshold. The analytical methods available for quality control and performance characteristics as well their advantages and disadvantages when dealing with a complex matrix like wine are discussed in detail. 相似文献
88.
The influence of malt and wort processing on spirit character: the lost styles of Scotch malt whisky
George N. Bathgate 《Journal of the Institute of Brewing》2019,125(2):200-213
Over the last 50 years there has been considerable analytical research on the malt parameters which govern the flavour and aroma, i.e. the ‘character’, of Scotch malt whisky. This has led to a standard format, the Flavour Wheel, to describe the attributes of any malt spirit and to relate them to a common group of malt parameters. What has not been well documented in the same period are the changes in malt processing technology which have led to a gradual but significant change in the concentrations of reference compounds used in the Flavour Wheel relating to sulphury, nutty/burnt/smoky, peaty and fruity/estery characters. This review covers the most significant of these changes, which have become common practice across the industry, and specifically demonstrates how different malting barley varieties, malt kilning and peating, wort recovery, yeast management, and wash still heating have all contributed to the loss of some styles of malt whisky. © 2019 The Institute of Brewing & Distilling 相似文献
89.
选取昌吉遗韵酒庄酿酒葡萄赤霞珠为实验材料,分别在果实5%转色至成熟及果实100%转色至成熟两个生长期采用遮光率为50%(网1)、20%(网2)的遮阳网在不同时期对果树树体顶端进行遮光处理,利用高效液相色谱-质谱(HPLC-MS)法检测葡萄果实果皮中非花色苷酚的含量,并对非花色苷酚组分构成进行偏最小二乘法(PLS-DA)分析,探究葡萄果实不同生长发育阶段搭建遮阳网对葡萄果实非花色苷酚结构组分及含量的影响。结果显示在果实5%转色至完全成熟搭建遮光率50%、20%遮阳网处理(Q1、Q2)及果实100%转色至完全成熟期间搭建遮光率20%遮阳网处理(H2)非花色苷酚总量均显著高于对照组,运用PLS-DA分析可得到,遮光处理会影响葡萄果实中黄烷-3-醇、槲皮素类物质、杨梅酮类物质的积累。 相似文献
90.
Kapila N. Seneviratne & Dissanayake M. Sudarshana Dissanayake 《International Journal of Food Science & Technology》2008,43(4):597-602
Phenolic compounds present in the nonsaponifiable fraction of coconut oil were analysed by high‐performance liquid chromatography with florescence detection. Mass spectra of the phenolic compounds were also obtained separately by LC–MS to confirm the presence of the phenolic compounds. Caffeic acid, p‐coumaric acid, ferulic acid and (+/?) catechin were observed in coconut oil. Phenolic acid fraction of the coconut oil prepared by boiling coconut milk (traditional coconut oil) was more complex compared with that of coconut oil prepared by pressing copra (commercial coconut oil). Total phenol content of traditional coconut oil was nearly seven times higher than that of commercial coconut oil (618 ± 46 vs. 91 ± 11 mg kg?1), suggesting that the phenol content varies with the extraction method. 相似文献