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51.
52.
A Mannich-type reaction was used to attach flavin adenine dinucleotide (FAD) covalently to aminosilane derivatized indium/tin
oxide-coated glass plates. The aminosilane was activated with formaldehyde to give an intermediate that attached specifically
to the adenine amino group of FAD. The presence of the intermediate also was demonstrated by coupling hydroquinone to the
formaldehyde activated support. The immobilized FAD and hydroquinone were characterized by cyclic or differential pulse voltammetry.
The immobilized FAD was shown to reduce the overpotential for NADH oxidation by 180 mV. In keeping with results for FAD on
glassy carbon, FAD attached to indium/tin oxide at the adenine amino group did not lead to reconstitution of activity with
apoglucose oxidase.
On leave from University of Madras, India. 相似文献
53.
Jaswanth Kumar Inamadugu Rajasekhar Damaramadugu Ramesh Mullangi Venkateswarlu Ponneri 《Biomedical chromatography : BMC》2010,24(10):1059-1074
An LC‐MS/MS method for the simultaneous quantitation of niacin (NA) and its metabolites, i.e. nicotinamide (NAM), nicotinuric acid (NUA) and N‐methyl‐2‐pyridone‐5‐carboxamide (2‐Pyr), in human plasma (1 mL) was developed and validated using nevirapine as an internal standard (IS). Extraction of the NA and its metabolites along with the IS from human plasma was accomplished using a simple liquid–liquid extraction. The chromatographic separation of NA, NAM, NUA, 2‐Pyr and IS was achieved on a Hypersil‐BDS column (150 ¥ 4.6 mm, 5 mm) column using a mobile phase consisting of 0.1% formic acid : acetonitrile (20:80 v/v) at a flow rate of 1 mL/min. The total run time of analysis was 2 min and elution of NA, NAM, NUA, 2‐Pyr and IS occurred at 1.37, 1.46, 1.40, 1.06 and 1.27 min, respectively. A detailed validation of the method was performed as per the FDA guidelines and the standard curves were found to be linear in the range of 100–20000 ng/mL for NA; 10–1600 ng/mL for NUA and NAM and 50–5000 ng/mL for 2‐Pyr with mean correlation coefficient of ≥0.99 for each analyte. The method was sensitive, specific, precise, accurate and suitable for bioequivalence and pharmacokinetic studies. The developed assay method was successfully applied to a pharmacokinetic study in humans. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
54.
Yosuke Hisamatsu 《Tetrahedron letters》2007,48(4):617-621
A new macrocyclic host, which contains a 2,6-bis(oxazol-2-yl)pyridine unit and a 2,7-dialkoxynaphthalene unit tethered by the appropriate length of alkyl side chains is prepared. This host undergoes highly selective complex formation with an adenine nucleobase, accompanied by a fluorescence response in CHCl3 by a combination of multiple hydrogen bonding and π-π stacking interactions. 相似文献
55.
56.
Christopher J. Woltermann Yuri A. Lapin Kevin B. Kunnen David R. Tueting Ignacio H. Sanchez 《Tetrahedron》2004,60(15):3445-3449
A novel synthesis for preparing 9-(3-O-benzyl-5-O-tetrahydropyranyl-β-d-arabinofuranosyl)adenine (6) has been developed which does not require sub zero temperatures or exotic reagents. A key step in this synthesis is the selective protection of the 3′-OH of ara-A with a benzyl group. The 5′-OH is then selectively protected with DHP to yield 6, a potentially useful intermediate. A synthesis of 9-(2,3-dideoxy-2-fluoro-β-d-threo-pentofuranosyl)adenine (1, FddA), an anti-viral compound, is given to illustrate the utility of this new approach. 相似文献
57.
58.
Among all the DNA components, extremely redox-active guanine (G) and adenine (A) bases are subject to facile loss of an electron and form cation radicals (G+· and A+·) when exposed to irradiation or radical oxidants. The subsequent deprotonation of G+· and A+· can invoke DNA damage or interrupt hole transfer in DNA. However, compared with intensive reports for G+·, studies on the deprotonation of A+· are still limited at present. Herein, we investigate the deprotonation behavior of A+· by time-resolved laser flash photolysis. The deprotonation product of A(N6-H)· is observed and the deprotonation rate constant, (2.0±0.1)×107 s-1, is obtained at room temperature. Further, the deprotonation rate constants of A+· are measured at temperatures varying from 280 K to 300 K, from which the activation energy for the N6-H deprotonation is determined to be (17.1±1.0) kJ/mol by Arrhenius equation. In addition, by incorporating the aqueous solvent effect, we perform density functional theory calculations for A+· deprotonation in free base and in duplex DNA. Together with experimental results, the deprotonation mechanisms of A+· in free base and in duplex DNA are revealed, which are of fundamental importance for understanding the oxidative DNA damage and designing DNA-based electrochemical devices. 相似文献
59.
K. Györyová V. Balek B. H. Behrens A. Matuschek A. Kettrup 《Journal of Thermal Analysis and Calorimetry》1997,48(6):1263-1271
The new zinc(II) complexes of general formula Zn(CH3CH2CH2COO)2· nL (whereL = caffeine, nicotinamide, theobromine;n=1 or 2) were prepared and identified.Thermal properties of these compounds were investigated by thermal analysis (TG/DTG, DTA, DSC/DDSC).Gaseous products of thermal decomposition were detected by IR spectroscopy and Mass spectroscopy. Final products of thermal decomposition were determined by X-ray powder diffraction patterns.This work was supported by the Slovak Ministry of Education Grant No. 1/3230/96. This financial support is gratefully acknowledged. 相似文献
60.
以离子液体1-丁基-3-甲基咪唑六氟磷酸盐为粘合剂制备了碳糊电极,然后将氧化石墨烯滴涂到碳糊电极表面制成了一种新型的氧化石墨烯修饰碳离子液体电极。研究了鸟嘌呤和腺嘌呤在修饰电极上的电化学行为。实验结果表明,在0.1 mol/L醋酸盐缓冲溶液中(pH4.5),鸟嘌呤和腺嘌呤在该修饰电极上具有良好的电化学行为,在2.0×10-7~1.5×10-5mol/L浓度范围内鸟嘌呤和腺嘌呤的浓度在该电极上与电化学响应信号呈良好的线性关系,相关系数分别为为0.992和0.996。信噪比为3时,检出限为1.0×10-8mol/L。 相似文献