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排序方式: 共有305条查询结果,搜索用时 15 毫秒
291.
Xue Liang Yan‐Ping Wu Jing‐Hong Qiu Kai Zhong Hong Gao 《Journal of food science》2014,79(9):C1643-C1648
This article focuses on finding the novel antibrowning agents from the pine needles of Cedrus deodara and studying its antibrowning effect. By bioassay guide of tyrosinase inhibitory activity, the main active compound was isolated and purified from 50% methanol extract of pine needles of C. deodara through macroporous resin Diaion HP‐20 column chromatography and high‐performance liquid chromatography. Based on mass and nuclear magnetic resonance data, the active compound was identified as 2R,3R‐dihydromyricetin, which showed the potent monophenolase and diphenolase inhibitory activities. Moreover, 2R,3R‐dihydromyricetin exhibited a strong ABTS radical scavenging activity with a dose‐dependent manner. The antibrowning efficacy of 2R,3R‐dihydromyricetin was evaluated by monitoring the changes of L*, a*, and b* values and total color difference (△E) on fresh‐cut apple slices. It was found that 2R,3R‐dihydromyricetin was effective in inhibiting the browning of apple slices treated with a concentration as low as 0.05% at 25 °C for 24 h. Its antibrowning effect was significantly better than ascorbic acid (0.5%) alone. Furthermore, 2R,3R‐dihydromyricetin showed a good synergistic antibrowning effect with ascorbic acid. This is the first report that 2R,3R‐dihydromyricetin from pine needles of C. deodara may be used as a potential antibrowning agent in protecting against food browning. 相似文献
292.
氧化白藜芦醇是一种重要的活性天然产物,是反式二苯乙烯类天然产物白藜芦醇(Resveratrol)的2'-位羟基化衍生物,具有美白、抗癌、保肝、抗氧化、抗衰老、抗炎等作用。本研究在建立了精确检测氧化白藜芦醇高效液相色谱(HPLC)方法基础上,以桑根为原料,研究了氧化白藜芦醇的提取分离、稳态化包埋及对酪氨酸酶活性的抑制作用。结果表明:以80%乙醇为提取溶剂,在提取温度70℃,时间1.5 h,液料比4:1,提取次数3次条件下,氧化白藜芦醇提取得率为94.32%;在固形物含量为40%,进风温度为190℃,雾化盘转速为16000 r/min,进料速度为1.78 L/h条件下,氧化白藜芦醇微胶囊稳态化包埋率为98.91%;氧化白藜芦醇标准品、氧化白藜芦醇微胶囊样品具有对酪氨酸酶活性抑制作用,且抑制强弱呈剂量依赖型。 相似文献
293.
Wiechers JW Rawlings AV Garcia C Chesné C Balaguer P Nicolas JC Corre S Galibert MD 《International journal of cosmetic science》2005,27(2):123-132
Synopsis Octadecenedioic acid is known as a skin whitening agent but its activity is not mediated via a direct inhibition of tyrosinase. Based on the secondary properties of this molecule, such as its anti-inflammatory and anti-ageing effects, we postulated that octadecenedioic acid interacted with the peroxisome proliferator-activated receptor (PPAR) as this nuclear receptor also mediates these effects. Using reporter gene technology, we were indeed able to demonstrate binding of octadecenedioic acid to all three PPAR subtypes, in particular PPARgamma with an EC(50)-value of approx. 1 x 10(-6) m. Binding to PPARgamma of octadecenedioic acid or rosiglitazone, a known pharmaceutical PPARgamma agonist, led to reduced melanogenesis. Subsequently also tyrosinase mRNA (as measured by real-time polymerase chain reaction) and tyrosinase levels (as measured by Western blot) were reduced, suggesting the existence of a complete novel mechanism of skin whitening agents: binding to PPARgamma results in reduced tyrosinase mRNA expression which in turn results in less tyrosinase being formed. This in turn leads to reduced melanogenesis both in vitro and in vivo Because octadecenedioic acid binds not only to PPARgamma but also to PPARalpha and PPARdelta, other efficacies mediated via these receptors may also be expected. 相似文献
294.
295.
本实验采用Lineweaver-Burk双倒数法探讨了曲酸与阿魏酸对蘑菇酪氨酸酶催化L-DOPA氧化的抑制作用并推测其抑制机理。通过对曲酸与阿魏酸的IC50与抑制常数KI的测定可知,曲酸对酪氨酸酶的抑制作用明显高于阿魏酸。分别采用分光光度法和ImageJ图像分析与处理软件定量地测定曲酸与阿魏酸对虾血淋巴和苹果褐变的抑制作用。曲酸对虾血淋巴褐变的抑制作用优于阿魏酸;对于苹果褐变,阿魏酸的抑制作用则高于曲酸。 相似文献
296.
Tengamnuay P Pengrungruangwong K Pheansri I Likhitwitayawuid K 《International journal of cosmetic science》2006,28(4):269-276
The heartwood extract of Artocarpus lakoocha Roxb. was evaluated for the in vitro tyrosinase inhibitory activity and the in vivo melanin-reducing efficacy in human volunteers. The IC(50) of the extract and oxyresveratrol, its major active ingredient, against mushroom tyrosinase was determined to be 0.76 and 0.83 mug mL(-1), respectively. The extract dissolved in propylene glycol was subsequently tested in female volunteers using a parallel clinical trial with self-control (n = 20 per group). The first group received the 0.25% w/v A. lakoocha solution as the test solution, whereas the second and the third group, respectively, received 0.25% licorice extract and 3% kojic acid as the reference solutions in the same solvent. The subjects in each group twice daily applied the test (or reference) solution in one of her upper arm, whereas the remaining arm was treated with only propylene glycol (self-control) for 12 weeks. The melanin content of each application site was measured using Mexameter every week and calculated as % reduction in melanin content relative to the initial melanin value (% whitening). The value of % whitening was then compared between the product-treated and the propylene glycol-treated arms within the same subject using paired t-test (alpha = 0.05). The A. lakoocha extract was the most effective agent, giving the shortest onset of significant whitening effect after only 4 weeks of application (P < 0.05), followed by 3% kojic acid (6 weeks) and 0.25% licorice extract (10 weeks). The effect also increased with time with maximum whitening observed at week 12 for A. lakoocha extract. When the extract was formulated as an oil-in-water emulsion, its whitening efficacy was further enhanced. Daily application of 0.1% w/w A. lakoocha lotion to the upper arms (n = 25) and cheeks (n = 15) of volunteers produced significant whitening over the lotion base after 2 and 3 weeks, respectively (P < 0.05). Thus, the preliminary study suggested that the heartwood extract of A. lakoocha may have a promising potential for use as an effective and economical skin-whitening agent. 相似文献
297.
在30℃,pH 6.8的Na2HPO4-NaH2PO4的缓冲体系中,采用酶促动力学方法,研究了白藜芦醇对酪氨酸酶单酚酶和二酚酶的抑制作用。结果表明,白藜芦醇对酪氨酸酶、单酚酶和二酚酶均有抑制作用,对单酚酶抑制活性的IC50值(抑制率达到50%时的白藜芦醇质量浓度)约为5.1mg/mL,对二酚酶抑制活性的IC50值约为5.6 mg/mL。此外,白藜芦醇可延长单酚酶的迟滞效应,8 mg/mL的白藜芦醇能使迟滞时间从22 s延长至62 s,而对二酚酶则无此迟滞作用。Lineweav-er-Burk图分析表明,白藜芦醇对酪氨酸酶的抑制作用为混合型抑制,对游离酶的抑制常数(KI)和对酶-底物络合物的抑制常数(KIS)分别为3.4 mg/mL和35.98 mg/mL。 相似文献
298.
青梅花提取物的酪氨酸酶抑制作用及机理研究 总被引:3,自引:2,他引:1
目的:以青梅花为原料,探讨其提取物(PF)在体外对酪氨酸酶的抑制作用及机理。方法:首先采用多巴速率氧化法体外测定PF酪氨酸酶的抑制活性,并绘制Lineweaver-Burk曲线,推断其抑制类型。分别采用化学发光法和铁氰化钾还原法测定PF的清除自由基能力及还原力。结果表明:PF能显著抑制酪氨酸酶活性,其半抑制浓度IC50为(98.89±6.34)ug/mL,抑制类型为混合型抑制。PF对酪氨酸酶的抑制作用可能与提取物中绿原酸等多酚物质、较强的自由基清除能力和还原力有关。结论:PF是一种有前途的酪氨酸酶抑制剂,可应用于果蔬等食品的加工和贮藏。 相似文献
299.
300.
研究了不同溶剂及提取方式对白附子中酪氨酸酶抑制成分的影响,并应用活性追踪法对白附子中酪氨酸酶活性抑制成分进行考察。结果表明,以20%乙醇水溶液为溶剂从白附子中提取的粗提物对酪氨酸酶活性的抑制作用最强,抑制率可达到96.35%,与恒温水浴振荡提取法相比,超声波辅助提取法对活性成分的提取效果更好。在此提取条件下所得白附子粗提物对酪氨酸酶的半抑制浓度IC50为24.69mg/mL。该粗提物依次经乙醚和正丁醇萃取,所得正丁醇萃取组分对酪氨酸酶的抑制率达71.94%。对高活性的正丁醇萃取组分进行分离,获得了一种酪氨酸酶抑制率高达98.82%的组分,是一种潜在的酪氨酸酶抑制剂。研究结果对白附子及其活性组分在医药和食品领域的应用有指导意义。 相似文献