全文获取类型
收费全文 | 376篇 |
免费 | 56篇 |
国内免费 | 14篇 |
专业分类
综合类 | 21篇 |
化学工业 | 184篇 |
金属工艺 | 1篇 |
建筑科学 | 2篇 |
轻工业 | 217篇 |
石油天然气 | 2篇 |
无线电 | 1篇 |
一般工业技术 | 17篇 |
自动化技术 | 1篇 |
出版年
2024年 | 6篇 |
2023年 | 6篇 |
2022年 | 22篇 |
2021年 | 20篇 |
2020年 | 8篇 |
2019年 | 7篇 |
2018年 | 17篇 |
2017年 | 6篇 |
2016年 | 16篇 |
2015年 | 17篇 |
2014年 | 20篇 |
2013年 | 27篇 |
2012年 | 38篇 |
2011年 | 26篇 |
2010年 | 18篇 |
2009年 | 22篇 |
2008年 | 18篇 |
2007年 | 31篇 |
2006年 | 34篇 |
2005年 | 20篇 |
2004年 | 20篇 |
2003年 | 13篇 |
2002年 | 5篇 |
2001年 | 7篇 |
2000年 | 7篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有446条查询结果,搜索用时 31 毫秒
81.
Catherine Grassin Denis Dubourdieu 《Journal of the science of food and agriculture》1989,48(3):369-376
The syringaldazine assay was adapted for quantitative determination of laccase (EC 1.10.3.2) activity from Botrytis cinerea Pers in musts and new wines. This colorimetric method is fast, specific and sensitive. It makes it possible to assess the level of contamination of crops by Botrytis cinerea. The assay can be performed in the presence of tyrosinase but the phenolic compounds of the grape must first be eliminated because of their inhibition of syringaldazine oxidation by laccase. When measured in botrytised grape, laccase activity is related to the stages of development of the fungus. 相似文献
82.
漆酶用于硫酸盐竹浆TCF漂白 总被引:1,自引:0,他引:1
利用两种漆酶或漆酶/介体系统处理硫酸盐竹浆,并进行TCF漂白。结果表明,硫酸盐竹浆进行漆酶/介体系统处理的OLQP漂白,漂白浆可以达到与传统的CEH漂白相近的白度,并且保持了更好的纸浆强度;从白腐菌HG产生的漆酶在HBT存在下处理硫酸盐竹浆,经OLQP漂白后,浆的白度可达80.7%ISO,黏度在800mL·g~(-1)以上。在没有外加介体的情况下,该漆酶处理纸浆仍具有较好的脱木素效果,经OL~0QPL~0,(无外加介体)漂白后,纸浆白度可达76.7%ISO,比OQP漂后浆的白度提高23.2%ISO。同时以苄甲基木素模型物藜芦醇为例,结合商品漆酶考察了白腐菌HG酶液催化氧化黎芦醇的反应动力学。 相似文献
83.
84.
Laccase activity in plants results in the formation of a number of brown pigments, often referred to as tannins. Laccase-dependent pigment production is also catalogued in numerous fungal and bacterial species. The laccase of the haploid yeast Cryptococcus neoformans forms melanin-like pigmentation outside the cell wall in the presence of exogenous substrates. While this process is a contributing factor to its virulence in humans, the evolutionary intent for the laccase function remains a mystery. We show here that C. neoformans and Bacillus subtilis have the ability to create melanin-like pigments from a variety of flavonoid molecules across a range of conformations, preferring those with 3',4'-dihydroxylations. Since flavonoids are ubiquitous plant molecules and often-considered antimicrobial agents, we postulate that they are the intended natural targets of laccase activity and result in the formation of a defensive melanin-like coat. These results suggests a new mechanism by which flavonoid-melanin formation may occur, using not only A- and C-ring linkages, but also monomer links through the B-ring of the flavonoid structure. We also show that resveratrol and other non- and mono-hydroxylated polyphenol substrates have the ability to restrict pigment formation and may be potent inhibitors of laccase activity. 相似文献
85.
漆酶/介体处理纸浆的反应性能及动力学研究 总被引:1,自引:0,他引:1
采用溶解氧分析仪对漆酶和漆酶/介体处理未漂KP浆过程中的氧气质量浓度进行测定,研究了不同条件下漆酶/介体处理纸浆的反应性能,通过对实际动力学曲线的拟合,建立了漆酶/介体体系催化氧化反应的动力学模型。结果表明:不同的介体中,丁香酸甲酯(MS)协同漆酶处理纸浆表现出较活跃的反应性能。漆酶单独处理MS(无纸浆)也消耗一定的氧气。单加漆酶处理纸浆时,初始几分钟内反应速率较快,之后体系中氧气质量浓度基本不变。漆酶/MS处理未漂KP浆时,在30 min内即可消耗完密闭反应体系中的氧气。漆酶/MS对纸浆中木素的催化氧化反应符合一级指数幂函数动力学特征。 相似文献
86.
Ishfaq Ahmed Huan Chen Jiale Li Bin Wang Zhenxing Li Gonghua Huang 《Comprehensive Reviews in Food Science and Food Safety》2021,20(6):5856-5879
Food allergy has become a major global public health concern. In the past decades, enzymatic crosslinking technique has been employed to mitigate the immunoreactivity of food allergens. It is an emerging non-thermal technique that can serve as a great alternative to conventional food processing approaches in developing hypoallergenic food products, owing to their benefits of high specificity and selectivity. Enzymatic crosslinking via tyrosinase (TYR), laccase (LAC), peroxidase (PO), and transglutaminase (TG) modifies the structural and biochemical properties of food allergens that subsequently cause denaturation and masking of the antigenic epitopes. LAC, TYR, and PO catalyze the oxidation of tyrosine side chains to initiate protein crosslinking, while TG initiates isopeptide bonding between lysine and glutamine residues. Enzymatic treatment produces a high molecular weight crosslinked polymer with reduced immunoreactivity and IgE-binding potential. Crosslinked allergens further inhibit mast cell degranulation due to the lower immunostimulatory potential that assists in the equilibration of T-helper (Th)1/Th2 immunobalance. This review provides an updated overview of the studies carried out in the last decade on the potential application of enzymatic crosslinking for mitigating food allergenicity that can be of importance in the context of developing hypoallergenic/non-allergenic food products. 相似文献
87.
Evaluation of potential side activities of commercial enzyme preparations used in winemaking 总被引:1,自引:0,他引:1
Giovanna Fia Valentina Canuti Iolanda Rosi 《International Journal of Food Science & Technology》2014,49(8):1902-1911
Twenty‐one commercial enzyme preparations used in winemaking were characterised for the α‐L‐rhamnosidase, α‐L‐arabinosidase, β‐D‐xylosidase, ?β‐D‐galactosidase, β‐D‐glucosidase, esterase, protease, cinnamoyl esterase and laccase activities. A new rapid fluorimetric method to assay esterase activity was developed. Enzyme preparations differed for the level of each enzyme activity assayed rather than for the type of enzymatic activity detected. High levels of protease, glycosidase, esterase and cinnamoyl esterase activity were found among enzyme preparations for different technological applications. A drastic reduction in the level of cinnamoyl esterase was observed in commercial grape juice, pH 3.6, total acidity 5.3 g L?1, sugar 170 g L?1. Protease activity was only weakly reduced, from 10 to 20%, in commercial grape juice. β‐glucosidase activity levels are reduced in the presence of increasing concentration of glucose but are still present at the higher glucose concentration (100 g L?1). The extent of the reduction observed was dependent on the enzymatic preparations tested. 相似文献
88.
云芝漆酶粗酶液降解2-氯苯酚的研究 总被引:3,自引:0,他引:3
研究了影响云芝液培养所产的漆酶粗酶液降解2-氯苯酚的主要因素(如降解时间、酶用量、2-氯苯酚浓度、pH值、温度),并对粗酶液和经Sephadex G-75初步纯化后的酶液的降解效果进行了对比.结果表明,在适宜的条件下,漆酶粗酶液可有效降解2-氯苯酚.一般而言,一定的反应体系下,2-氯苯酚的降解率随酶剂量的增加和时间的延长而增加,但在较低的酶用量下(<0.20U/mL),延长反应时间并不能得到较高的降解率.在相同酶用量条件下,氯酚的平均降解速率随底物浓度的增加而增加,浓度小于3000 mg/L时,对漆酶没有抑制作用,但总降解率却随之下降.粗酶液降解2-氯苯酚时较佳的pH值和温度范围分别为5.0~7.0和45~70℃.经过初步纯化后的酶液,其降解2-氯苯酚的效率反而略低于粗酶液的降解效率. 相似文献
89.
研究了硬毛粗毛盖孔菌Funalia trogii以稻草为培养基质进行固体发酵产生高活性漆酶。在筛选合适的碳源、氮源和硫酸铜浓度的基础上,开展四因素正交实验,筛选出最优培养方案,即以稻草粉为基质,淀粉0.5%、尿素0.3%、硫酸铜1%(质量分数),湿度为70%的条件下培养7天后漆酶活性即可达到145.42 U/gds。在最优方案条件下连续培养,发现该菌在稻草粉培养基质上培养28天产生的漆酶活性能达到最高,为1 518.76 U/gds。而在增加培养规模的情况下,以最优方案培养28天的漆酶活性平均能达到1 753.49 U/gds。 相似文献
90.