全文获取类型
收费全文 | 211篇 |
免费 | 13篇 |
国内免费 | 28篇 |
专业分类
化学 | 230篇 |
综合类 | 2篇 |
物理学 | 20篇 |
出版年
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 6篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 1篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 8篇 |
2014年 | 6篇 |
2013年 | 9篇 |
2012年 | 19篇 |
2011年 | 9篇 |
2010年 | 10篇 |
2009年 | 15篇 |
2008年 | 23篇 |
2007年 | 22篇 |
2006年 | 11篇 |
2005年 | 17篇 |
2004年 | 14篇 |
2003年 | 21篇 |
2002年 | 6篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1987年 | 2篇 |
1982年 | 1篇 |
排序方式: 共有252条查询结果,搜索用时 8 毫秒
101.
对一些生物活性分子的合成研究进展,如NADH(nicotinamide adenine dinucleotide hydrogen)模型、类胡萝卡素相关分子、卟啉衍生物的合成研究作 了简要的概述。 相似文献
102.
The present work deals with the use of the porous texture of expanded natural graphite (ENG) as transducer in order to design electrochemical biosensors. The sensing element is a NAD+-dependent dehydrogenase. An electrochemical pretreatment of the ENG is favorable because it allows on one hand generating functional surface groups that may act as mediators for NADH oxidation and, on the other hand, eliminating enzyme-toxic compounds. The electrocatalytic oxidation of NADH on the pretreated material leads to the formation of enzymatically active NAD+. However, some persistent problems, mainly related to enzyme instability, still hamper the development of the biosensors. 相似文献
103.
Multilayer films of multiwalled carbon nanotubes (MWNTs) were homogeneously and stably assembled on a glassy carbon (GC) electrode
using the layer-by-layer (LBL) method based on electrostatic interaction between MWNTs (negatively charged) and a biopolymer
chitosan (CHIT) (positively charged). Scanning electron microscopy (SEM) image of the resulting {CHIT/MWNTs}9 film indicated that the substrate was mostly covered with MWNTs in the form of small bundles or single nanotubes. The multilayer
film was used to study the electrocatalytic oxidation of NADH. The assembled {CHIT/MWNTs}9/GC electrode could decrease the oxidation overpotential of NADH by more than 350 mV. The {CHIT/MWNTs}9/GC electrode exhibited a wide linear response range of 8 × 10−7 to 1.6 × 10−3 mol · L−1 with a correlation coefficient of 0.997 for the detection of NADH. The response time and detection limit (S/N = 3) were determined to be 3 s and 0.3 × 10−6 mol · L−1, respectively. Another attractive characteristic was that the method was simple and the assembled {CHIT/MWNTs}9/GC electrode was highly stable. 相似文献
104.
Xin-Qiang Fang You-Cheng Liu Guan-Wu Wang Yu-Ping Ke 《Research on Chemical Intermediates》2006,32(7):603-611
Thermal reaction of ethyl (2Z)-4-bromo-2-cyano-3-(2-naphthyl)but-2-enoate (BCNB) with coenzyme NADH model 1-benzyl-1,4-dihydronicotinamide (BNAH) gives
the debrominated cyclized product (E)-1-cyano-2-methyl-2-(2-naphthyl)cyclopropane-1-carboxylate (1), debrominated olefinic products ethyl (2E)-2-cyano-3-(2-naphthyl)but-2-enoate (2) and ethyl (2Z)-2-cyano-3-(2-naphthyl)but-2-enoate (3). The formation of 1 proceeds via partial concerted hydride transfer and debromocyclopropanation, whereas the formation of 2 or 3 proceeds via an electron transfer-debromination-hydrogen abstraction mechanism. Nonetheless, they all derived from the same electron-transfer
intermediate complex. 相似文献
105.
Alina Avramescu Thierry NoguerMaria Avramescu Jean-Louis Marty 《Analytica chimica acta》2002,458(1):203-213
Biosensors for d-lactate and acetaldehyde were developed, based on screen-printed electrodes and NAD+-dependent dehydrogenases. Modification of screen-printed electrodes with the mediator Meldola Blue or with Meldola Blue-Reinecke salt resulted in sensitive, low cost and reliable NADH detectors. The biosensors were realised in two configurations, as disposable and reusable devices. Single-use sensors were obtained by simple deposition of enzyme and cofactor on the surface of mediator-modified electrodes. Chronoamperometry was used for the detection of substrates in small volumes of samples (25 μl). Immobilisation of dehydrogenases by entrapment in poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ) allowed sensors to be obtained with sufficient operational stability. Amperometry in stirred solutions was the detection technique with biosensors for multiple use. The 3σ detection limits for acetaldehyde were 1 μM by amperometry and 6 μM by chronoamperometry and for d-lactate-0.03 μM and 0.05 μM for reusable and disposable biosensors respectively. The biosensors were applied in the analysis of some French and Romanian wines. 相似文献
106.
107.
108.
Li Y de Silva PG Xi L van Winkle A Lin JJ Ahmed S Geng ML 《Biomedical chromatography : BMC》2008,22(12):1374-1384
Simultaneous extraction, separation and quantitation of reduced nicotinamide adenine dinucleotide (NADH), reduced nicotinamide adenine dinucleotide phosphate (NADPH), flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) in Chinese Hamster Ovary (CHO) cells were investigated. The separation of flavins and nicotinamide cofactors was performed by capillary electrophoresis with laser-induced fluorescence detection at the excitation wavelength of 325 nm. The separation protocol was established by investigating the excitation wavelength, high voltage and effects of buffer nature, pH and concentration. All endogenous fluorophores riboflavin, FAD, FMN, NADH and NADPH show wide linear range of quantitation. The limits of detection for the five compounds ranged from 4.5 to 23 nM. Extraction conditions were optimized for high-efficiency recovery of all endogenous fluorophores from CHO cells. To account for the complex matrix of cell extracts, a standard addition method was used to quantify FAD, FMN, NADH and NADPH in CHO cells. The quantitative results should be useful to reveal the metabolic status of cells. The protocols for extraction, separation and quantitation are readily adaptable to normal and cancer cell lines for the analysis of endogenous fluorophores. 相似文献
109.
110.
A redox polymer (PAHA‐Ru), modified electrode exhibited excellent catalytic activity for the electrochemical oxidation of β‐nicotinamide adenine dinucleotide (NADH). PAHA‐Ru was composed of carboxyl groups and ruthenium complexes containing 1,10‐phenanthroline‐5,6‐dione (phen‐dione). The stability of the PAHA‐Ru film was increased by incorporating poly(diallyldimethylammonium chloride) (PDDA) owing to the formation of a polyelectrolyte complex between the PAHA‐Ru and PDDA. The catalytic efficiency of the oxidation of NADH using the PAHA‐Ru/PDDA‐modified electrode was also greater than that using a PAHA‐Ru‐modified electrode. NAD‐dependent alcohol dehydrogenase (ADH) was entrapped in the PAHA‐Ru/PDDA film on the surface of the glassy carbon electrode. Electrochemical oxidation of ethanol using the ADH‐entrapped electrode was also observed. 相似文献