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Peter G. Dormer Amude M. Kassim Johnnie L. Leazer Jr. Feng Xu Edward G. Corley Jimmy O. DaSilva David M. Tschaen 《Tetrahedron letters》2004,45(28):5429-5432
A general method for the preparation of syn-2,3-disubstituted-2,3-dihydro-1,4-benzoxathiin rings from 2-mercaptoethanols and quinone ketals is presented. This ring system is produced by Michael addition of a 2-mercaptoethanol to a quinone ketal, followed by cyclization of the initial Michael adduct, and subsequent aromatization to afford a syn-2,3-disubstituted-1,4-benzoxathiin in fair to good chemical yield. Several chiral syn-2,3-disubstituted-2,3-dihydro-1,4-benzoxathiin rings were prepared with this method from enantioenriched 2-mercaptoethanols. No loss of enantiopurity was observed. 相似文献
3.
Davies IW Marcoux JF Wu J Palucki M Corley EG Robbins MA Tsou N Ball RG Dormer P Larsen RD Reider PJ 《The Journal of organic chemistry》2000,65(15):4571-4574
Substituted acetic acids or acetyl chlorides react with phosphorus oxychloride in DMF to yield the vinamidinium salts 3a-j in moderate to excellent recrystallized yields (28-90%). The cations are conveniently isolated as their hexafluorophosphate salts, which are easily handled nonhygroscopic solids. The nitro compound 3l is prepared in 91% yield by nitration of the parent vinamidinium 3k. The X-ray crystal structure is reported for the 2-phenyl isomer 3e and displays minimal overlap of the two pi-systems. 相似文献
4.
Minard KR Timchalk C Corley RA 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2005,173(1):90-96
In a gas-filled material like the lung parenchyma, the transverse relaxation time (T2) for 3He is shortened by the deposition of magnetic microspheres and rapid molecular diffusion through induced field distortions. Here, this unique relaxation process is described theoretically and predicted T2-shortening is validated using pressurized 3He gas in a foam model of alveolar airways. Results demonstrate that: (1) significant T2-shortening is induced by microsphere deposition, (2) shortened 3He T2s are accurately predicted, and (3) measured relaxation times are exploitable for quantifying local deposition patterns. Based on these findings the feasibility of imaging inhaled particulates in vivo with hyperpolarized 3He is examined and performance projections are formulated. 相似文献
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Ohne Zusammenfassung 相似文献
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Elizabeth A. Corley Youngjae Kim Dietram A. Scheufele 《Journal of nanoparticle research》2011,13(12):7041-7055
Despite the significant increase in the use of nanotechnology in academic research and commercial products over the past decade,
there have been few studies that have explored scientists’ perceptions and attitudes about the technology. In this article,
we use survey data from the leading U.S. nano-scientists to explore their perceptions about two issues: the public communication
of research findings and media coverage of nanotechnology, which serves as one relatively rapid outlet for public communication.
We find that leading U.S. nano-scientists do see an important connection between the public communication of research findings
and public attitudes about science. Also, there is a connection between the scientists’ perceptions about media coverage and
their views on the timing of public communication; scientists with positive attitudes about the media are more likely to support
immediate public communication of research findings, while others believe that communication should take place only after
research findings have been published through a peer-review process. We also demonstrate that journalists might have a more
challenging time getting scientists to talk with them about nanotechnology news stories because nano-scientists tend to view
media coverage of nanotechnology as less credible and less accurate than general science media coverage. We conclude that
leading U.S. nano-scientists do feel a sense of responsibility for communicating their research findings to the public, but
attitudes about the timing and the pathway of that communication vary across the group. 相似文献
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Corley M. Thompson Sue G. Taylor William W. McGee 《Journal of polymer science. Part A, Polymer chemistry》1994,32(1):113-120
The kinetics of formation of polyurethane prepolymers is studied by an analytical technique which involves reactive quenching of the isocyanate, separation of the oligomeric species by GPC, and measurement by UV absorbance of the quenched moieties. The precision of the kinetic parameters and the ratios of the oligomers are determined. The effect of changes in reactant stoichiometry on the ratio of oligomers is measured and compared to the value predicted by an equation from Flory. Toluene diisocyanate is shown to give fewer high oligomers than predicted, while methylene diphenylene diisocyanate gives nearly the predicted values. Tetramethylxylene diisocyanate gives more high oligomers than predicted, an unexpected but possibly important result. Catalyst is shown to increase the reaction rate of the last by more than 200 times. © 1994 John Wiley & Sons, Inc. 相似文献
10.
CLAUDIA L. PARKER OSCAR N. VENTURA STAN K. BURT RAÚL E. CACHAU 《Molecular physics》2013,111(17):2659-2668
We present a general purpose QM-MM-MD engine (DYNGA) designed to test alternative hybrid Hamiltonians geared towards the treatment of problems of interest in structural biology including the use of experimental data constraints. In this first presentation we use DYNGA to explore the behaviour of a traditional QM-MM approach in the treatment of the water—water interaction. We find the potential energy hypersurface for the water dimer computed with the HF 4–31G*/TIP3P hybrid Hamiltonian tends to be too flat. We also explore the effect of using traditional QM-MM techniques on proton wires and conclude there is a need for improvement, possibly addressed by using polarizable force fields. 相似文献