全文获取类型
收费全文 | 201篇 |
免费 | 6篇 |
专业分类
化学 | 197篇 |
力学 | 1篇 |
数学 | 2篇 |
物理学 | 7篇 |
出版年
2024年 | 3篇 |
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 7篇 |
2012年 | 15篇 |
2011年 | 21篇 |
2010年 | 10篇 |
2009年 | 10篇 |
2008年 | 16篇 |
2007年 | 18篇 |
2006年 | 19篇 |
2005年 | 10篇 |
2004年 | 15篇 |
2003年 | 10篇 |
2002年 | 6篇 |
2001年 | 10篇 |
2000年 | 6篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
排序方式: 共有207条查询结果,搜索用时 0 毫秒
201.
Orth ES Wanderlind EH Medeiros M Oliveira PS Vaz BG Eberlin MN Kirby AJ Nome F 《The Journal of organic chemistry》2011,76(19):8003-8008
The phosphorylation of imidazole by two activated phosphate diesters and a triester gives phosphorylimidazole derivatives that are stable enough in aqueous solution to be observed and identified by ESI-MS/MS and NMR. Half-lives ranging from hours to days (in the case of the monoethyl ester) show that it is possible to design molecules with variable half-lives with potential to be used for biological intervention experiments as possible inhibitors of biosignaling processes or as haptens for the generation of antibodies. 相似文献
202.
Lisboa Cda S Santos VG Vaz BG de Lucas NC Eberlin MN Garden SJ 《The Journal of organic chemistry》2011,76(13):5264-5273
The oxidative addition of anilines (2) with 1,4-naphthoquinone (3) to give N-aryl-2-amino-1,4-naphthoquinones (1) was found to be catalyzed by copper(II) acetate. In the absence of the catalyst, the reactions are slower and give lower yields with the formation of many colateral products. In the presence of 10 mol % hydrated copper(II) acetate, the reactions are generally more efficient in that they are cleaner, higher yielding, and faster. 相似文献
203.
Zecchin KG Alberici LC Riccio MF Eberlin MN Vercesi AE Graner E Catharino RR 《Rapid communications in mass spectrometry : RCM》2011,25(3):449-452
Fatty acid synthase (FASN) is the metabolic enzyme responsible for the endogenous synthesis of the saturated long-chain fatty acid palmitate. In contrast to most normal cells, FASN is overexpressed in a variety of human cancers including cutaneous melanoma, in which its levels of expression are associated with a poor prognosis and depth of invasion. Recently, we have demonstrated the mitochondrial involvement in FASN inhibition-induced apoptosis in melanoma cells. Herein we compare, via electrospray ionization mass spectrometry (ESI-MS), free fatty acids (FFA) composition of mitochondria isolated from control (EtOH-treated cells) and Orlistat-treated B16-F10 mouse melanoma cells. Principal component analysis (PCA) was applied to the ESI-MS data and found to separate the two groups of samples. Mitochondria from control cells showed predominance of six ions, that is, those of m/z 157 (Pelargonic, 9:0), 255 (Palmitic, 16:0), 281 (Oleic, 18:1), 311 (Arachidic, 20:0), 327 (Docosahexaenoic, 22:6) and 339 (Behenic, 22:0). In contrast, FASN inhibition with Orlistat changes significantly mitochondrial FFA composition by reducing synthesis of palmitic acid, and its elongation and unsaturation products, such as arachidic and behenic acids, and oleic acid, respectively. ESI-MS of mitochondria isolated from Orlistat-treated cells presented therefore three major ions of m/z 157 (Pelargonic, 9:0), 193 (unknown) and 199 (Lauric, 12:0). These findings demonstrate therefore that FASN inhibition by Orlistat induces significant changes in the FFA composition of mitochondria. 相似文献
204.
Masterson TA Dill AL Eberlin LS Mattarozzi M Cheng L Beck SD Bianchi F Cooks RG 《Journal of the American Society for Mass Spectrometry》2011,22(8):1326-1333
Desorption electrospray ionization mass spectrometry (DESI-MS) has been successfully used to discriminate between normal and
cancerous human tissue from different anatomical sites. On the basis of this, DESI-MS imaging was used to characterize human
seminoma and adjacent normal tissue. Seminoma and adjacent normal paired human tissue sections (40 tissues) from 15 patients
undergoing radical orchiectomy were flash frozen in liquid nitrogen and sectioned to 15 μm thickness and thaw mounted to glass
slides. The entire sample was two-dimensionally analyzed by the charged solvent spray to form a molecular image of the biological
tissue. DESI-MS images were compared with formalin-fixed, hematoxylin and eosin (H&E) stained slides of the same material.
Increased signal intensity was detected for two seminolipids [seminolipid (16:0/16:0) and seminolipid (30:0)] in the normal
tubule testis tissue; these compounds were undetectable in seminoma tissue, as well as from the surrounding fat, muscle, and
blood vessels. A glycerophosphoinositol [PI(18:0/20:4)] was also found at increased intensity in the normal testes tubule
tissue when compared with seminoma tissue. Ascorbic acid (i.e., vitamin C) was found at increased amounts in seminoma tissue
when compared with normal tissue. DESI-MS analysis was successfully used to visualize the location of several types of molecules
across human seminoma and normal tissues. Discrimination between seminoma and adjacent normal testes tubules was achieved
on the basis of the spatial distributions and varying intensities of particular lipid species as well as ascorbic acid. The
increased presence of ascorbic acid within seminoma compared with normal seminiferous tubules was previously unknown. 相似文献
205.
Marques Lde A Catharino RR Bruns RE Eberlin MN 《Rapid communications in mass spectrometry : RCM》2006,20(24):3654-3658
A fast procedure to classify perfumes and identify counterfeit samples is described. Dilution of a few microL of the sample in a 1:1 methanol/water solution is followed by detection of its major polar components via direct infusion electrospray ionization mass spectrometry (ESI-MS) in the positive ion mode. As proof-of-principle cases, three famous brands of perfumes were used. The ESI+-MS fingerprints of authentic samples were very characteristic, showing distinctive sets of polar markers for each sample. Principal component analysis (PCA) placed samples of the three perfume brands in well-defined groups. Counterfeit samples were also clearly detected owing to contrasting ESI-MS fingerprints, with PCA placing these samples far away from the authentic samples. 相似文献
206.
Can mass dissociation patterns of transition‐metal complexes be predicted from electrochemical data?
Toma SH Alexiou AD Toma HE Araki K Eberlin MN 《Journal of mass spectrometry : JMS》2009,44(3):361-367
The Cooks kinetic method has been very convenient to correlate the relative dissociation rates obtained by collision-induced fragmentation experiments with the energies of two related bonds in molecules and complexes in the gas phase. Reliable bond energy data are, however, not always available, particularly for polynuclear transition-metal complexes, such as the triruthenium acetate clusters of the general formula [Ru(3) (micro(3)-O)(micro-CH(3)COO)(6)(py)(2)(L)](+), where L = ring substituted N-heterocyclic ligands. Accordingly, their gas-phase collision-induced tandem mass spectrometry (CID MS/MS) dissociation patterns have been analyzed pursuing a relationship with the more easily accessible redox potentials (E(1/2)) and Lever's E(L) parameters. In fact, excellent linear correlations of ln(1/2A(L)/A(py)), where A(py) and A(L) are the abundance of the fragments retaining the pyridine (py) and L ligand, respectively, with E(1/2) and E(L) were found. This result shows that those electrochemical parameters are correlated with bond energies and can be used in the analysis of the dissociation data. Such modified Cooks method can be used, for example, to determine the electronic effects of substituents on the metal-ligand bonds for a series of transition-metal complexes. 相似文献
207.