全文获取类型
收费全文 | 279篇 |
免费 | 35篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 1篇 |
综合类 | 4篇 |
化学工业 | 152篇 |
金属工艺 | 7篇 |
机械仪表 | 2篇 |
建筑科学 | 3篇 |
轻工业 | 113篇 |
石油天然气 | 3篇 |
无线电 | 8篇 |
一般工业技术 | 12篇 |
冶金工业 | 5篇 |
原子能技术 | 2篇 |
自动化技术 | 6篇 |
出版年
2023年 | 7篇 |
2022年 | 22篇 |
2021年 | 16篇 |
2020年 | 15篇 |
2019年 | 10篇 |
2018年 | 10篇 |
2017年 | 7篇 |
2016年 | 17篇 |
2015年 | 14篇 |
2014年 | 22篇 |
2013年 | 16篇 |
2012年 | 17篇 |
2011年 | 19篇 |
2010年 | 14篇 |
2009年 | 7篇 |
2008年 | 13篇 |
2007年 | 10篇 |
2006年 | 13篇 |
2005年 | 8篇 |
2004年 | 7篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 3篇 |
2000年 | 1篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1984年 | 1篇 |
排序方式: 共有318条查询结果,搜索用时 15 毫秒
1.
Andrea Engl Benno Kunz 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(3):257-261
Studies took place to investigate the effects of different nutrient conditions on the biosorption ability and selectivity of heavy metals by Saccharomyces cerevisiae. After having grown in media supplemented with additional glucose, ammonium, phosphate or cysteine, the yeast was exposed to an equimolar solution of lead, cadmium, zinc and copper. Lead removal from a mixed solution was significantly higher than that of copper, followed by zinc and cadmium. Generally, yeasts from cysteine-rich media showed greatest sorption capacity whereas phosphate addition influenced zinc selectivity. In addition, glucose, fructose and sucrose as carbon sources were examined. Cultures grown in glucose had a better uptake than those cultivated with fructose at an incubation time of 30 min. 相似文献
2.
Altschuh Daniele; Tessier Daniel C.; Vernet Thierry 《Protein engineering, design & selection : PEDS》1994,7(6):769-776
The two main catalytic residues Cys25 and Hisl59 of the monomericcysteine protease papain are located on different walls of acleft formed by two domains. This topology suggests a possiblerelationship between relative domain organization and catalyticmechanism. The effect on enzymatic parameters of structuralmodifications at various locations of the twodomain interfaceof papain was examined by individual or double replacementsby Ala of pairs of interacting residues. Most modificationshad no effect on enzyme activity. However, the enzyme's substrateturnover (kcat) decreased following simultaneous alterationof the two most conserved residues, forming an apolar contactlocated 15 Å away from the active site. The pH activityprofile of the double mutant was unchanged, indicating a conservedionization state of the active site thiolate-imidazolium ionpair. This state is strongly dependent on the distance separatingthe two residues, thus suggesting that the active site geometryhas not been significantly altered. Efficient enzymatic activityin papain requires more than a correct active site geometryand is influenced by domain packing properties in a region remotefrom the active site. 相似文献
3.
单扫描极谱法快速测定胱氨酸的研究及应用 总被引:1,自引:0,他引:1
在pH 9.6的H3BO3-NaOH介质中,胱氨酸于-0.56 V(vs.SCE)处产生一灵敏的吸附还原波。用于胱氨酸的测定,波高与0.8~10μmol/L的胱氨酸有线性关系,检测限为0.4μmol/L。许多氨基酸在较高浓度共存情况下不干扰胱氨酸的测定。应用该法测定了人发及胱氨酸片剂中胱氨酸的含量。 相似文献
4.
Pons Jaume; Planas Antoni; Querol Enrique 《Protein engineering, design & selection : PEDS》1995,8(9):939-945
Bacillus 1,3-1,4-ß-glucanases possess a highly conserveddisulfide bridge connecting a ß-strand with a solventexposedloop lying on top of the extended binding site cleft The contributionof the disulfide bond and of both individual cysteines (Cys61and Cys90) in the Bacillus licheniformis enzyme to stabilityand activity has been evaluated by protein engineering methods.Reduction of the disulfide bond has no effect on kinetic parameters,has only a minor effect on the activity-temperature profileat high temperatures, and destabilizes the protein by less than0.7 kcal/mol as measured by equilibrium urea denatu ration at37°C. Replacing either of the Cys residues with Ala destabilizesthe protein and lowers the specific activity. C90A retains 70%of wild-type (wt) activity (in terms of Vmax), whereas C61Aand the double mutant C61AC90A have 10% of wt Vmax. Alarger change in free energy of unfolding is seen by equilibriumurea denaturation for the C61A mutation (loop residue, 3.2 kcal/molrelative to reduced wt) as compared with the C90A mutation (ß-strandresidue, 1.8 kcal/mol relative to reduced wt), while the doublemutant C61AC90A is 0.8 kcal/mol less stable than thesingle C61A mutant. The effects on stability are interpretedas a result of the change in hydrophobic packing that occursupon removal of the sulfur atoms in the Cys to Ala mutations 相似文献
5.
Amino acid-tagging strategies are widespread in proteomics. Because of the central role of mass spectrometry (MS) as a detection technique in protein sciences, the term "mass tagging" was coined to describe the attachment of a label, which serves MS analysis and/or adds analytical value to the measurements. These so-called mass tags can be used for separation, enrichment, detection, and quantitation of peptides and proteins. In this context, cysteine is a frequent target for modifications because the thiol function can react specifically by nucleophilic substitution or addition. Furthermore, cysteines present natural modifications of biological importance and a low occurrence in the proteome that justify the development of strategies to specifically target them in peptides or proteins. In the present review, the mass-tagging methods directed to cysteine residues are comprehensively discussed, and the advantages and drawbacks of these strategies are addressed. Some concrete applications are given to underline the relevance of cysteine-tagging techniques for MS-based proteomics. 相似文献
6.
Dr. Aline D. de Araujo Huy T. Nguyen Prof. David P. Fairlie 《Chembiochem : a European journal of chemical biology》2021,22(10):1784-1789
The conventional S-alkylation of cysteine relies upon using activated electrophiles. Here we demonstrate high-yielding and selective S-alkylation and S-lipidation of cysteines in unprotected synthetic peptides and proteins by using weak electrophiles and a Zn2+ promoter. Linear or branched iodoalkanes can S-alkylate cysteine in an unprotected 38-residue Myc peptide fragment and in a 91-residue miniprotein Omomyc, thus highlighting selective late-stage synthetic modifications. Metal-assisted cysteine alkylation is also effective for incorporating dehydroalanine into unprotected peptides and for peptide cyclisation via aliphatic thioether crosslinks, including customising macrocycles to stabilise helical peptides for enhanced uptake and delivery to proteins inside cells. Chemoselective and efficient late-stage Zn2+-promoted cysteine alkylation in unprotected peptides and proteins promises many useful applications. 相似文献
7.
Possible adducts formed between hydroxymethylfurfural and selected amino acids,and their release in simulated gastric model
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yueyu Zou Kehan Pei Xichun Peng Weibin Bai Caihuan Huang Shiyi Ou 《International Journal of Food Science & Technology》2016,51(4):1002-1009
This work aimed to investigate the reactivity of hydroxymethylfurfural (HMF) with selected amino acids, to identify the produced adducts and to clarify whether or not the adducts release HMF after their digestion under gastric conditions. Results showed that cysteine, glycine and lysine can deplete the added HMF, and their reactivity increased with increasing pH and temperature. Cysteine (25 μmol mL?1) depleted 91.0% of the added HMF (315.3 μg mL?1) at 40 °C in 15 min, lysine did not eliminate HMF until 80 °C, and glycine started to eliminate HMF at 100 °C. Four adducts for cysteine, three adducts for lysine and only one adduct for glycine were identified through HPLC–MS–MS after they reacted with HMF. The adducts formed from the reaction mixture of cysteine, lysine and glycine with HMF only released 1.7%, 2.6% and 10.5% of eliminated HMF, respectively, after their digestion in simulated gastric conditions. 相似文献
8.
Prof. Dr. Ruth Birner‐Gruenberger Prof. Dr. Rolf Breinbauer 《Chembiochem : a European journal of chemical biology》2016,17(16):1488-1490
Recently, Hang and co‐workers developed “acyl‐PEG exchange” (APE), which allows the investigation of protein S‐fatty acylation with mass‐tag labelling and gel electrophoresis, methods that are accessible to any biochemistry laboratory. 相似文献
9.
Dr. Lennart Brewitz Dr. Jos J. A. G. Kamps Dr. Petra Lukacik Claire Strain-Damerell Yilin Zhao Dr. Anthony Tumber Tika R. Malla Dr. Allen M. Orville Dr. Martin A. Walsh Prof. Dr. Christopher J. Schofield 《ChemMedChem》2022,17(9):e202200016
The two SARS-CoV-2 proteases, i. e. the main protease (Mpro) and the papain-like protease (PLpro), which hydrolyze the viral polypeptide chain giving functional non-structural proteins, are essential for viral replication and are medicinal chemistry targets. We report a high-throughput mass spectrometry (MS)-based assay which directly monitors PLpro catalysis in vitro. The assay was applied to investigate the effect of reported small-molecule PLpro inhibitors and selected Mpro inhibitors on PLpro catalysis. The results reveal that some, but not all, PLpro inhibitor potencies differ substantially from those obtained using fluorescence-based assays. Some substrate-competing Mpro inhibitors, notably PF-07321332 (nirmatrelvir) which is in clinical development, do not inhibit PLpro. Less selective Mpro inhibitors, e. g. auranofin, inhibit PLpro, highlighting the potential for dual PLpro/Mpro inhibition. MS-based PLpro assays, which are orthogonal to widely employed fluorescence-based assays, are of utility in validating inhibitor potencies, especially for inhibitors operating by non-covalent mechanisms. 相似文献
10.
Yuanfang Tao Xin Ji Dr. Jian Zhang Yue Jin Nannan Wang Prof. Yubing Si Prof. Weili Zhao 《Chembiochem : a European journal of chemical biology》2020,21(21):3131-3136
Near-infrared (NIR) fluorescent probes are very significant for detecting cysteine in biological systems. Herein, we report a highly selective and sensitive NIR turn-on fluorescent probe (BDP-NIR) based on BODIPY with large Stokes shift (105 nm) for detecting Cys. We clarified the sensing mechanism based on the different thiol-induced SNAr substitution/rearrangement reaction of the probe with cysteine and homocysteine/glutathione, which leads to the corresponding amino- and thiol-BODIPY dyes with distinct photophysical properties. Moreover, a novel mechanism of fluorescence quenching was demonstrated by density functional theory calculation. The reason for the fluorescence quenching of the probe might be intersystem crossing (from singlet to triplet excited state). Moreover, BDP-NIR had a high linear dynamic range of 0–500 μM, which was promising for detecting cysteine quantificationally. Significantly, BDP-NIR was capable of sensing endogenous cysteine in living cells and in vivo. 相似文献