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41.
G. Denigès J. Eggert und Lotte Zipfel 《Fresenius' Journal of Analytical Chemistry》1923,63(3-4):137-138
Ohne Zusammenfassung 相似文献
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Marie Kjærgaard Bjørk Marie K. K. Nielsen Lotte Ø. Markussen Helene B. Klinke Kristian Linnet 《Analytical and bioanalytical chemistry》2010,396(7):2393-2401
A high-performance liquid chromatography (LC)–tandem mass spectrometry (MS/MS) method has been developed and validated for
the determination of 19 drugs of abuse and metabolites and used in whole blood. The following compounds were included: amphetamine,
methylenedioxyamphetamine, methylenedioxyethylamphetamine, methylenedioxymethamphetamine, methamphetamine, cocaine, benzoylecgonine,
morphine, 6-acetylmorphine, codeine, methadone, buprenorphine, norbuprenorphine, ketobemidone, tramadol, O-desmethyltramadol, zaleplone, zolpidem, and zopiclone. The sample pretreatment consisted of solid-phase extraction using
mixed-mode columns (Isolute Confirm HCX). Deuterated analogues were used as internal standards for all analytes, except for
ketobemidone and O-desmethyltramadol. The analytes were separated by a methanol/ammonium formate gradient using high-performance LC (Agilent
HPLC 1100) with a 3 mm × 100 mm Varian Pursuit 3 C18 column, 3-μm particle size, and were quantified by MS/MS (Waters Quattro micro tandem quadrupole mass spectrometer) using
multiple reaction monitoring in positive mode. Two transitions were used for all analytes, except for tramadol and O-desmethyltramadol. The run time of the method was 35 min including the equilibration time. For all analytes, responses were
linear over the range investigated, with R
2 > 0.99. One-point calibration was found to be adequate by validation, thereby saving analysis of multiple calibrators. The
limits of quantification (LOQs) for the analytes ranged from 0.0005 to 0.01 mg/kg. Absolute recoveries of the analytes were
from 34 to 97%, except for zaleplone (6%). Both the interday precision and the intraday precision were less than 15% (20%
at the LOQ) for all analytes, except buprenorphine, norburprenorphine, and zaleplone (less than 18%). Accuracy (bias) was
within ±15% (±20% at the LOQ) for all analytes, except MDMA and O-desmethyltramadol (within ±19%). No ion suppression or enhancement was seen nor was suppression from coeluted analytes seen.
Matrix effects were found to be less than 23% for all analytes, except zopiclone (64%). High-concentration and low-concentration
quality control samples gave acceptable values, and the method has been tried in international proficiency test schemes with
good results. The present LC-MS/MS method provides a simple, specific, and sensitive solution for the quantification of some
of the most frequent drugs of abuse and their metabolites in whole blood. The quantification by LC-MS/MS was successfully
applied to 412 forensic cases from October 2008 to mid February 2009, where 267 cases were related to zero-tolerance traffic
legislation. 相似文献
44.
Electrospray ionization mass spectrometry (ESI/MS) has allowed the discovery of novel dimer ions emerging from solutions of metalloporphyrin salts and their investigation by collision‐induced dissociation (CID) with N2 molecules. ESI mass spectra have been recorded for the formation of the oxygen or chloride‐bridged dimer ions [(FeTPP)2OH]+, [(MnTPP)2OH]+, [(FeTPP)2Cl]+ and [(MnTPP)2Cl]+ derived from various solutions of FeTPPCl and MnTPPCl salts. The CID of [(FeTPP)2OH]+ proceeds mainly by neutral loss of (FeTPP)OH to form [FeTPP]+ and, to a minor extent, to form the charge‐reversed products. The CID of [(MnTPP)2OH]+ exhibits exclusively the product ion [MnTPP]+ by loss of neutral (MnTPP)OH. [(FeTPP)2Cl]+ and [(MnTPP)2Cl]+ dissociate by loss of (Fe/MnTPP)Cl to give rise to [Fe/MnTPP]+. [(FeTPP)2O]+ and [(FeTPP)2OH]+ were generated from a solution of the dimer, (FeTPP)2O. Dissociation of [(FeTPP)2O]+ yields two product ions, [FeTPP]+ and [(FeTPP)O]+, with higher onsets compared to the equivalent fragments formed from [(FeTPP)2OH]+. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
45.
Nielsen LJ Eyley S Thielemans W Aylott JW 《Chemical communications (Cambridge, England)》2010,46(47):8929-8931
Cellulose nanocrystals were converted into ratiometric pH-sensing nanoparticles by dual fluorescent labelling employing a facile one-pot procedure. A simple and versatile three-step procedure was also demonstrated extending the number of fluorophores available for grafting. In this method an amine group was introduced via esterification followed by a thiol-ene click reaction. 相似文献
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A Bioinspired Molybdenum Complex as a Catalyst for the Photo‐ and Electroreduction of Protons
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Jean‐Philippe Porcher Thibault Fogeron Dr. Maria Gomez‐Mingot Dr. Etienne Derat Lise‐Marie Chamoreau Dr. Yun Li Prof. Marc Fontecave 《Angewandte Chemie (International ed. in English)》2015,54(47):14090-14093
A molybdenum–dithiolene–oxo complex was prepared as a model of some active sites of Mo/W‐dependent enzymes. The ligand, a quinoxaline–pyran‐fused dithiolene, mimics molybdopterin present in these active sites. For the first time, this type of complex was shown to be active as a catalyst for the photoreduction of protons with excellent turnover numbers (500) and good stability in aqueous/organic media and for the electroreduction of protons in acetonitrile with remarkable rate constants (1030 s?1 at ?1.3 V versus Ag/AgCl). DFT calculations provided insight into the catalytic cycle of the reaction, suggesting that the oxo ligand plays a key role in proton exchange. These results provide a basis to optimize this new class of H2‐evolving catalysts. 相似文献
50.
Poulsen JA 《The Journal of chemical physics》2011,134(3):034118
We consider the Dirac-Frenkel variational principle in Wigner phase-space and apply it to the Wigner-Liouville equation for both imaginary and real time dynamical problems. The variational principle allows us to deduce the optimal time-evolution of the parameter-dependent Wigner distribution. It is shown that the variational principle can be formulated alternatively as a "principle of least action." Several low-dimensional problems are considered. In imaginary time, high-temperature classical distributions are "cooled" to arrive at low-temperature quantum Wigner distributions whereas in real time, the coherent dynamics of a particle in a double well is considered. Especially appealing is the relative ease at which Feynman's path integral centroid variable can be incorporated as a variational parameter. This is done by splitting the high-temperature Boltzmann distribution into exact local centroid constrained distributions, which are thereafter cooled using the variational principle. The local distributions are sampled by Metropolis Monte Carlo by performing a random walk in the centroid variable. The combination of a Monte Carlo and a variational procedure enables the study of quantum effects in low-temperature many-body systems, via a method that can be systematically improved. 相似文献