全文获取类型
收费全文 | 159篇 |
免费 | 4篇 |
专业分类
化学 | 142篇 |
力学 | 1篇 |
数学 | 3篇 |
物理学 | 17篇 |
出版年
2023年 | 1篇 |
2022年 | 7篇 |
2021年 | 8篇 |
2020年 | 7篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 6篇 |
2012年 | 9篇 |
2011年 | 15篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 13篇 |
2007年 | 18篇 |
2006年 | 14篇 |
2005年 | 4篇 |
2004年 | 4篇 |
2003年 | 8篇 |
2002年 | 8篇 |
2001年 | 4篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1993年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有163条查询结果,搜索用时 15 毫秒
111.
Beatriz Arévalo Verónica Serafín Susana Campuzano Paloma Yáñez-Sedeño José M. Pingarrón 《Electroanalysis》2021,33(9):2096-2104
This paper reports a dual immunosensor for the simultaneous determination of two important fertility-related hormones: 17β-estradiol, E2, and follicle-stimulating hormone, FSH. The implemented method involves direct competitive (E2) or sandwich-type (FSH) immunoassays carried out on magnetic microparticles (MBs) and amperometric detection at screen-printed dual carbon electrodes (SPdCEs) involving the hydroquinone (HQ)/H2O2 system. The developed immune platform demonstrates LOD values of 6.88 pg mL−1 and 0.11 mIU mL−1 for E2 and FSH standards, respectively and usefulness for the determination in saliva samples collected from different volunteers, giving results in agreement with the conventional ELISA methodologies. 相似文献
112.
García-Aparicio MP Ballesteros M Manzanares P Ballesteros I González A Negro MJ 《Applied biochemistry and biotechnology》2007,137(1-12):353-365
In this study, different enzyme preparations available from Novozymes were assessed for their efficiency to hydrolyze lignocellulosic materials. The enzyme mixture was evaluated on a pretreated cellulose-rich material, and steam-exploded barley straw pretreated under different temperatures (190, 200, and 210 degrees C, respectively) in order to produce fermentable sugars. Results show that xylanase supplementation improves initial cellulose hydrolysis effectiveness of water-insoluble solid fraction from all steam-exploded barley straw samples, regardless of the xylan content of substrate. The mixture constituted by cellulase: beta-glucosidase: endoxylanase of the new kit for lignocellulose conversion at a ratio 10:1:5% ([v/w], enzyme [E]/substrate [S]) provides the highest increment of cellulose conversion in barley straw pretreated at 210 degrees C, for 10 min. 相似文献
113.
A novel progesterone immunosensor using a colloidal gold-graphite-Teflon-tyrosinase composite biosensor as amperometric transducer is reported. A sequential competitive configuration between the analyte and progesterone labelled with alkaline phosphatase (AP) was used. Phenyl phosphate was employed as the AP-substrate and the enzyme reaction product, phenol, was oxidized by tyrosinase to o-quinone, which is subsequently reduced at −0.1 V at the biocomposite electrode. Variables such as the concentration of phenyl phosphate, the amount of antibody attached to the electrode surface, immersion time in a 2% BSA solution, working pH and incubation times in progesterone and AP conjugate were optimized. A linear calibration graph for progesterone was obtained between 0 and 40 ng mL−1 with a slope value of −82.3 nA ng−1 mL, and a detection limit of 0.43 ng mL−1. The time needed to reach the steady-state current from the addition of phenyl phosphate was 30-40 s. These analytical characteristics improve substantially those reported for other progesterone immunosensors. A lifetime of 14 days with no need to apply any regeneration procedure was also achieved. The usefulness of the immunosensor was evaluated by determining progesterone in milk samples spiked with the analyte at 5.0 and 1.5 ng mL−1 concentration levels. Following a very simple procedure, involving only sample dilution, mean recoveries (n = 7) of 98 ± 3% and 99 ± 3%, respectively, were obtained. 相似文献
114.
Vidal P Pedregal C Díaz N Broughton H Aceña JL Jiménez A Espinosa JF 《Organic letters》2007,9(21):4123-4126
A novel approach for determining the absolute configuration of a chiral compound is proposed. The methodology is based on the distinct conformational effects imposed on a chiral substrate by each enantiomer of a chiral derivatizing agent. As a proof of concept, it is shown that the absolute configuration of 2-arylpyrrolidines can easily be determined by inspection of the multiplicity of the NMR signal of the methine proton of the pyrrolidine ring in the corresponding Mosher's amides. 相似文献
115.
Pérez-Mayoral E Soler-Padrós J Negri V Cerdán S Ballesteros P 《Molecules (Basel, Switzerland)》2007,12(8):1771-1795
Magnetic Resonance Imaging (MRI) methods are currently used in the clinic for the non invasive detection and characterization of a wide variety of pathologies. Increases in the diagnostic efficiency of MRI have been helped by both the design of dedicated MR sequences revealing specific aspects of the pathology and by the development of more sensitive and selective Contrast Agents (CAs), capable of more precisely delineating the borderline regions. In the present review we focus on the synthetic strategies used to obtain MRI CAs containing heterocyclic rings. 相似文献
116.
Zachary O. Battaglia Jordan T. Kersten Elise M. Nicol Paloma Whitworth Kraig A. Wheeler Charlie L. Hall Jason Potticary Victoria Hamilton Simon R. Hall Gemma D. D'Ambruoso Masaomi Matsumoto Stephen D. Warren Matthew E. Cremeens 《Acta Crystallographica. Section C, Structural Chemistry》2023,79(6):217-226
Two crystal structures of chalcones, or 1,3-diarylprop-2-en-1-ones, are presented; both contain a p-methyl substitution on the 3-Ring, but differ with respect to the m-substitution on the 1-Ring. Their systematic names are (2E)-3-(4-methylphenyl)-1-(3-{[(4-methylphenyl)methylidene]amino}phenyl)prop-2-en-1-one (C24H21NO) and N-{3-[(2E)-3-(4-methylphenyl)prop-2-enoyl]phenyl}acetamide (C18H17NO2), which are abbreviated as 3′-(N=CHC6H4-p-CH3)-4-methylchalcone and 3′-(NHCOCH3)-4-methylchalcone, respectively. Both chalcones represent the first reported acetamide-substituted and imino-substituted chalcone crystal structures, adding to the robust library of chalcone structures within the Cambridge Structural Database. The crystal structure of 3′-(N=CHC6H4-p-CH3)-4-methylchalcone exhibits close contacts between the enone O atom and the substituent arene ring, in addition to C…C interactions between the substituent arene rings. The structure of 3′-(NHCOCH3)-4-methylchalcone exhibits a unique interaction between the enone O atom and the 1-Ring substituent, contributing to its antiparallel crystal packing. In addition, both structures exhibit π-stacking, which occurs between the 1-Ring and R-Ring for 3′-(N=CHC6H4-p-CH3)-4-methylchalcone, and between the 1-Ring and 3-Ring for 3′-(NHCOCH3)-4-methylchalcone. 相似文献
117.
John B. Sheridan Paloma Gmez Elipe Ian Manners 《Macromolecular rapid communications》1996,17(5):319-324
The first examples of poly(ferrocenylsilane)-poly(carbosilane) random copolymers have been prepared via the transition metal-catalyzed ring-opening copolymerization of silicon-bridged [1]ferrocenophanes and disila- or benzosilacyclobutane. 相似文献
118.
Paloma Arranz Mascars Rafael Cuesta Martos Christopher Glidewell John N. Low 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(6):o326-o328
In the title compound, NH4+·C7H8N5O4−·H2O, the independent components are linked into bilayers by an extensive series of two‐centre N—H⃛O hydrogen bonds [H⃛O = 1.85–1.96 Å, N⃛O = 2.776 (2)–2.840 (2) Å and N—H⃛O = 149–172°], and by asymmetric three‐centre N—H⃛(O)2, O—H⃛(N,O) and O—H⃛(O)2 hydrogen bonds. 相似文献
119.
Paloma Arranz Mascars M. Dolores Gutirrez Valero John N. Low Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(4):o210-o212
The title compound, C10H13N5O6, exhibits a highly polarized molecular–electronic structure and the conformation is influenced by two intramolecular N—H⃛O hydrogen bonds. The molecules are linked into a single framework by hydrogen bonds of types O—H⃛O [O—H = 1.22, H⃛O = 1.38, O⃛O = 2.558 (6) Å and O—H⃛O = 160°], N—H⃛O [H⃛O = 2.26, N⃛O = 2.866 (6) Å and N—H⃛O = 126°] and O—H⃛N [O—H = 1.26, H⃛N = 1.56, O⃛N = 2.811 (6) Å and O—H⃛N = 170°]. The substructure generated by the O—H⃛O and N—H⃛O hydrogen bonds takes the form of a double helix. 相似文献
120.
Paloma Ovejero Mercedes Cano Elena Pinilla M.Rosario Torres 《Helvetica chimica acta》2002,85(6):1686-1690
A crossed ‘torch' structure and a short Au⋅⋅⋅Au contact was established by X‐ray analysis for the dimeric complex [Au(pz)(PPh3)]2 (pz=3,5‐disubstituted pyrazolato, RCnH2n+1 O C6H4, n=4; 1 ). The complex is a representative member of a new well‐characterized family of derivatives containing the pyrazolato ligand in an uncommon monodentate coordination form. In addition, 1 is luminescent in the solid state at 77 K. 相似文献