全文获取类型
收费全文 | 88篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
化学 | 55篇 |
晶体学 | 2篇 |
力学 | 11篇 |
数学 | 13篇 |
物理学 | 10篇 |
出版年
2022年 | 2篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2016年 | 1篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 5篇 |
2012年 | 6篇 |
2011年 | 7篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 5篇 |
2007年 | 3篇 |
2006年 | 4篇 |
2005年 | 1篇 |
2004年 | 4篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1977年 | 5篇 |
1969年 | 1篇 |
1899年 | 2篇 |
排序方式: 共有91条查询结果,搜索用时 15 毫秒
31.
Lukas Hyzak Susanne Giese Hans-Willi Kling Volker Wulf David Melchior Michael Köhler Oliver J. Schmitz 《Analytical and bioanalytical chemistry》2013,405(4):1417-1424
A recently developed solvent-free compressed-sample technique for matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) analysis allows the reproducible analysis of synthetic polymers and peptides up to 3,500 Da. In this work, we present an improvement in resolution, an increase in intensity and a decrease of the variation coefficient, as illustrated by the analysis of PEG 2000 and MALDI imaging experiments. These advantages were achieved by homogenization of the electrical field, which was disturbed by the drills in the original MALDI target. In order to homogenize the electrical field, a new target with smaller drills was developed, metal powder was added to the matrix/analyte mixture and a round laser raster was used. Furthermore, a ball mill was implemented for the sample preparation to replace the extremely user-dependent grinding in a mortar. The new conditions were successfully applied to the quantification of several peptides of higher molecular weight and gave higher precision than had previously been achieved with the compressed-sample technique. 相似文献
32.
33.
In path tracking design, the dynamic of actuators must be taken intoaccount in order to reduce overshoots appearing for small displacements.A new approach to path tracking using fractional differentiation isproposed with its application on a XY cutting table. It permits thegeneration of optimal movement reference-input leading to a minimum pathcompletion time, taking into account both maximum velocity, accelerationand torque and the bandwidth of the closed-loop system. Fractionaldifferentiation is used here through a Davidson–Cole filter. Amethodology aiming at improving the accuracy especially on checkpointsis presented. The reference-input obtained is compared with splinefunction. Both are applied to an XY cutting table model and actuatoroutputs compared. 相似文献
34.
Silvia Del Piero Rosalisa Fedele Andrea Melchior Pierluigi Polese Roberto Portanova Marilena Tolazzi 《Journal of solution chemistry》2008,37(4):543-551
The thermodynamic functions of the complexation of Ag(I) by the tripodal ligands, tris(2-(methylamino)ethyl)amine (Me3tren) and tris(2-(dimethylamino)ethyl)amine (Me6tren) (L), are determined in dimethyl sulfoxide (DMSO) by potentiometric and calorimetric techniques at 298.0 K and 0.1 mol⋅dm−3 ionic strength (Et4NClO4). A comparison is made between previous data concerning Ag(I) complex formation with the non-alkylated tripodal 2,2′,2″-triaminotriethylamine
(tren), in order to analyze the influence of N-methylation on this type of branched donor, and with those relative to the
linear triethylenetetramine (trien) and 1,1,4,7,10,10-hexamethyltriethylenetetramine (Me6trien). The results are discussed taking into account different σ-donating properties, geometric arrangement of the ligands, steric repulsions and solvation effects. 相似文献
35.
Kuixiang Ma Tobias Ekblad Marcel Klein Koerkamp Henry Kelderman Melchior van Wijlen Ankur Duarah 《International journal of environmental analytical chemistry》2015,95(4):366-378
An inhibition assay for detection of Bisphenol A (BPA) in treated water has been developed and validated for the MiniLab? system from Optiqua Technologies. This biosensor-based analytical system can be used for detection of specific contaminants in solution. The system uses an integrated optic Mach-Zehnder interferometer chip that is functionalised with a biochemical interface layer. The sensor chip surface was first coated with aminodextran which formed a hydrophilic layer suitable for further modification. 4,4-bis(4-hydroxyphenyl) valeric acid (BVA), which is a structural analogue of BPA, was then successfully coupled to the aminodextran layer. This surface chemistry was used in a qualitative inhibition assay format for the selective detection of the presence of BPA. The assay was developed and optimised using a polyclonal anti-BPA antibody. Samples from 12 different water matrices of Singapore were spiked with known amounts of BPA and tested with the MiniLab? system. The working range of the BPA inhibition assay is from 0.5 to 5 µg/L. Intra- and inter-assay variations were measured, with calculated relative standard deviation averaging of about 15%. BPA concentrations of the spiked samples were also verified and confirmed with LC-MS. Such functionalised biosensor chip can be reused for more than 200 sample injections over a period longer than 6 months. Developed as a robust, user-friendly and cost-effective system that can be field deployed, the MiniLab? system enables target-specific assays currently only available in the lab to become available in the field. 相似文献
36.
37.
38.
39.
The thermodynamic selectivity for Gd(3+) relative to Ca(2+), Zn(2+), and Fe(3+) of two ligands of potential interest as magnetic resonance imaging (MRI) contrast agents has been determined by NMR spectroscopy and potentiometric and spectrophotometric titration. The two hexadentate ligands TREN-6-Me-3,2-HOPO (H(3)L2) and TREN-bisHOPO-TAM-EA (H(4)L3) incorporate 2,3-dihydroxypyridonate and 2,3-dihydroxyterephthalamide moieties. They were chosen to span a range of basicity while maintaining a structural motif similar to that of the parent ligand, TREN-1-Me-3,2-HOPO (H(3)L1), in order to investigate the effect of the ligand basicity on its selectivity. The 1:1 stability constants (beta(110)) at 25 degrees C and 0.1 M KCl are as follows. L2: Gd(3+), 20.3; Ca(2+), 7.4; Zn(2+), 11.9; Fe(3+), 27.9. L3: Gd(3+), 24.3; Ca(2+), 5.2; Zn(2+), 14.6; Fe(3+), 35.1. At physiological pH, the selectivity of the ligand for Gd(3+) over Ca(2+) increases with the basicity of the ligand and decreases for Gd(3+) over Fe(3+). These trends are consistent with the relative acidities of the various metal ions;- more basic ligands favor harder metals with a higher charge-to-radius ratio. The stabilities of the Zn(2+) complexes do not correlate with basicity and are thought to be more influenced by geometric factors. The selectivities of these ligands are superior to those of the octadentate poly(aminocarboxylate) ligands that are currently used as MRI contrast agents in diagnostic medicine. 相似文献
40.
Melchior M Rettig SJ Liboiron BD Thompson KH Yuen VG McNeill JH Orvig C 《Inorganic chemistry》2001,40(18):4686-4690
Simple, high-yield, large-scale syntheses of the V(III) complexes tris(maltolato)vanadium(III), V(ma)3, tris(ethylmaltolato)vanadium(III), V(ema)3, tris(kojato)vanadium(III) monohydrate, V(koj)3-H2O, and tris(1,2-dimethyl-3-hydroxy-4-pyridinonato)vanadium(III) dodecahydrate, V(dpp)3-12H2O, are described; the characterization of these complexes by various methods and, in the case of V(dpp)3-12H2O, by an X-ray crystal structure determination, is reported. The ability of these complexes to normalize glucose levels in the STZ-diabetic rat model has been examined and compared with that of the benchmark compound BMOV (bis(maltolato)oxovanadium(IV)), an established insulin-enhancing agent. 相似文献