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91.
In this work, we present theoretical simulations of laser-driven vibrational control of NO adsorbed on a gold surface. Our goal is to tailor laser pulses to selectively excite specific modes and vibrational eigenstates, as well as to favor photodesorption of the adsorbed molecule. To this end, various control schemes and algorithms are applied. For adsorbates at metallic surfaces, the creation of electron-hole pairs in the substrate is known to play a dominant role in the transfer of energy from the system to the surroundings. These nonadiabatic couplings are included perturbatively in our reduced density matrix simulations using a generalization of the state-resolved position-dependent anharmonic rate model we recently introduced. An extension of the reduced density matrix is also proposed to provide a sound model for photodesorption in dissipative systems. 相似文献
92.
Hydrogen‐Bond and Supramolecular‐Contact Mediated Fluorescence Enhancement of Electrochromic Azomethines
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Dr. Monika Wałęsa‐Chorab Marie‐Hélène Tremblay Prof. Dr. William G. Skene 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(32):11382-11393
An electronic push–pull fluorophore consisting of an intrinsically fluorescent central fluorene capped with two diaminophenyl groups was prepared. An aminothiophene was conjugated to the two flanking diphenylamines through a fluorescent quenching azomethine bond. X‐ray crystallographic analysis confirmed that the fluorophore formed multiple intermolecular supramolecular bonds. It formed two hydrogen bonds involving a terminal amine, resulting in an antiparallel supramolecular dimer. Hydrogen bonding was also confirmed by FTIR and NMR spectroscopic analyses, and further validated theoretically by DFT calculations. Intrinsic fluorescence quenching modes could be reduced by intermolecular supramolecular contacts. These contacts could be engaged at high concentrations and in thin films, resulting in fluorescence enhancement. The fluorescence of the fluorophore could also be restored to an intensity similar to its azomethine‐free counterpart with the addition of water in >50 % v/v in tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), and acetonitrile. The fluorophore also exhibited reversible oxidation and its color could be switched between yellow and blue when oxidized. Reversible electrochemically mediated fluorescence turn‐off on turn‐on was also possible. 相似文献
93.
94.
Tay LL Tremblay RG Hulse J Zurakowski B Thompson M Bani-Yaghoub M 《The Analyst》2011,136(8):1620-1626
Brain injury can lead to irreversible tissue loss and functional deficit along with significant health care costs. Raman spectroscopy can be used as a non-invasive technique to provide detailed information on the molecular composition of diseased and damaged tissues. This technique was used to examine acute mouse brain injury, focusing on the motor cortex, a region directly involved in controlling execution of movement. The spectral profile obtained from the injured brain tissue revealed a markedly different signature, particularly in the amide I and amide III vibrational region when compared to that of healthy brain tissue. Most noticeably, there was a significant reduction of the amide I vibration at the acute injury site and the appearance of two distinct features at 1586 and 1618 cm(-1). Complementary immunohistochemical analysis of the injured brain tissue showed an abundant expression of Caspase 3 (a cysteine protease marker used for apoptosis), suggesting that the injury-induced specific Raman shifts may be correlated with cell death. Taken together, this study demonstrates that Raman spectroscopy can play an important role in detecting the changes that occur in the injured brain and provide a possible technology for monitoring the recovery process. 相似文献
95.
P. G. T. Petersen A. M. Dubowitzki N. I. Krjutschkow H. R. Ambler S. Kagan T. C. Sutton J. Happel D. W. Robertson H. Tropsch W. J. Mattox S. Mischonsniky J. R. Branham M. Shepherd A. Luszczak H. Seebaum W. Oppelt W. Zwieg F. Kossendey M. P. Matuszak H. Kahle B. H. Wilsdon F. J. McConnell E. K. Gerling A. Grebel J. A. Shaw J. L. Tremblay 《Analytical and bioanalytical chemistry》1935,102(11-12):428-438
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97.
Patrice Tremblay Martine M Savard Anna Smirnoff Real Paquin 《Rapid communications in mass spectrometry : RCM》2009,23(14):2213-2220
Gaseous membrane permeation (MP) technologies have been combined with continuous‐flow isotope ratio mass spectrometry for on‐line δ13C measurements. The experimental setup of membrane permeation‐gas chromatography/combustion/isotope ratio mass spectrometry (MP‐GC/C/IRMS) quantitatively traps gas streams in membrane permeation experiments under steady‐state conditions and performs on‐line gas transfer into a GC/C/IRMS system. A commercial polydimethylsiloxane (PDMS) membrane sheet was used for the experiments. Laboratory tests using CO2 demonstrate that the whole process does not fractionate the C isotopes of CO2. Moreover, the δ13C values of CO2 permeated on‐line give the same isotopic results as off‐line static dual‐inlet IRMS δ13C measurements. Formaldehyde generated from aqueous formaldehyde solutions has also been used as the feed gas for permeation experiments and on‐line δ13C determination. The feed‐formaldehyde δ13C value was pre‐determined by sampling the headspace of the thermostated aqueous formaldehyde solution. Comparison of the results obtained by headspace with those from direct aqueous formaldehyde injection confirms that the headspace sampling does not generate isotopic fractionation, but the permeated formaldehyde analyzed on‐line yields a 13C enrichment relative to the feed δ13C value, the isotopic fractionation being 1.0026 ± 0.0003. The δ13C values have been normalized using an adapted two‐point isotopic calibration for δ13C values ranging from ?42 to ?10‰. The MP‐GC/C/IRMS system allows the δ13C determination of formaldehyde without chemical derivatization or additional analytical imprecision. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
98.
99.
Some new configurations of helical CO2-TEA lasers (TEA-H) generate a converging lens effect. Experimental investigations on the temporal evolution of the lensing effect in these lasers are reported. 相似文献
100.
A 200 joule TEA-CO2 laser has been mode-locked by injection of a nanosecond pulse into a regenerative amplifier operating in an above threshold regime. 25 gigawatt pulses have been obtained. 相似文献