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321.
Spatial heterodyne spectrometers (SHS) can achieve high resolution with excellent optical throughput. We demonstrate a planar waveguide SHS incorporating 64 asymmetric Mach-Zehnder interferometers and show measurements that verify 1 GHz resolution across a 64 GHz measurement range. 相似文献
322.
Thermotropic Luminescent Clustomesogen Showing a Nematic Phase: A Combination of Experimental and Molecular Simulation Studies
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Dr. Maria Amela Cortes Frederick Dorson Marianne Prévôt Dr. Aziz Ghoufi Dr. Bruno Fontaine Dr. Florent Goujon Prof. Régis Gautier Dr. Viorel Cîrcu Cristelle Mériadec Dr. Franck Artzner Prof. Hervé Folliot Dr. Stéphane Cordier Dr. Yann Molard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(28):8561-8565
Octahedral Mo6 nanoclusters are functionalized with two organic ligands containing cyanobiphenyl (CB) units, giving luminescent hybrid liquid crystals (LC). Although the mesogenic density around the bulky inorganic core is constant, the two hybrids show different LC properties. Interestingly, one of them shows a nematic phase, which is particularly rare for this kind of supermolecular system. This surprising result is explained by using large‐scale molecular dynamic simulations. 相似文献
323.
324.
Aharonian F Akhperjanian AG Bazer-Bachi AR Beilicke M Benbow W Berge D Bernlöhr K Boisson C Bolz O Borrel V Braun I Breitling F Brown AM Bühler R Büsching I Carrigan S Chadwick PM Chounet LM Cornils R Costamante L Degrange B Dickinson HJ Djannati-Ataï A Drury LO Dubus G Egberts K Emmanoulopoulos D Espigat P Feinstein F Ferrero E Fiasson A Fontaine G Funk S Funk S Gallant YA Giebels B Glicenstein JF Goret P Hadjichristidis C Hauser D Hauser M Heinzelmann G Henri G Hermann G Hinton JA Hofmann W 《Physical review letters》2006,97(22):221102
The detection of gamma rays from the source HESS J1745-290 in the Galactic Center (GC) region with the High Energy Spectroscopic System (HESS) array of Cherenkov telescopes in 2004 is presented. After subtraction of the diffuse gamma-ray emission from the GC ridge, the source is compatible with a point source with spatial extent less than 1.2;{'}(stat) (95% C.L.). The measured energy spectrum above 160 GeV is compatible with a power law with photon index of 2.25+/-0.04(stat)+/-0.10(syst) and no significant flux variation is detected. It is finally found that the bulk of the very high energy emission must have non-dark-matter origin. 相似文献
325.
Pignat J Cantin S Liu RC Goldmann M Fontaine P Daillant J Perrot F 《The European physical journal. E, Soft matter》2006,20(4):387-394
The effect of subphase pH (5.5 and 10.5) on the structure of behenic-acid monolayers was investigated during Mg2+ adsorption by means of Grazing Incidence X-ray Diffraction (GIXD) and Brewster Angle Microscopy (BAM). The final phase corresponding
to an ion superlattice commensurate to the behenic-acid cell is pH-independent. In contrast, the sequence of phases evidenced from the initial L2-phase to this final state presents at pH 10.5 an additional stage associated to a film condensation toward the L'
2-phase. The structures of the intermediate states preceding the superstructure nucleation are slightly different, both with
a short-range fatty-acid order. Finally, a laser light effect that could result from visible light absorption by the inorganic
complexes is evidenced in the final state as well as in the intermediate phases. 相似文献
326.
Frédéric-Georges Fontaine 《Journal of organometallic chemistry》2006,691(22):4595-4600
Reaction of 2 equiv. of (C4Me4P)Li(tmeda) (tmeda = tetraethylenediamine) with 1 equiv. of ScCl3(THF)3 gave the new compound (η5-C4Me4P)2ScCl2Li(tmeda) (1), which was characterized by X-ray crystallography. A phospholyl moiety in 1 is labile, as demonstrated by reactions of 1 with LiCH(SiMe3)2 and Cp∗Li (Cp∗ = C5Me5) to afford, respectively, (η5-Me4C4P)Sc[CH(SiMe3)2]Cl2Li(tmeda) (4) and (η5-Me4C4P)Cp∗ScCl2Li(tmeda) (5). Attempts to generate alkyl derivatives of the general type (η5-C4Me4P)2ScR (R = alkyl) were unsuccessful. 相似文献
327.
Jacquemin D Preat J Wathelet V Fontaine M Perpète EA 《Journal of the American Chemical Society》2006,128(6):2072-2083
The structure and visible spectra of a large panel of thioindigo dyes and derivatives have been evaluated using a TD-PBE0/6-311+G(2d,p)//PBE0/6-311G(d,p) approach explicitly taking bulk solvent effects into account by means of the polarizable continuum model. The influence of the solvent characteristics, the trans-cis isomerization, and the chemical substitution on the benzene rings have been investigated. In addition, hemi-thioindigo dyes, thiazine-indigo, chromophore-like molecules, and selenoindigo have been considered. Though the relative oscillator strengths of the two allowed visible transitions in the nonplanar cis isomers are not always correctly reproduced by theory, the agreement between theoretical and experimental results is far above expectations. For the 170 cases studied, we obtained a mean unsigned error on the predicted lambda(max) limited to 6.9 nm or 0.03 eV, with only 6 (4) cases for which the difference exceeds 20 nm (0.10 eV). These errors are 1 order of magnitude smaller than what has previously been reported for indigoids. A linear correlation between the central double bond length and the lambda(max) has been established, while the bond length and vibrational frequency of the carbonyl groups do not correlate with the thioindigo color. The higher excitation energies of the cis conformers, compared to the trans structures, result from a less stabilized LUMO in the former case. Indeed, for cis thioindigo, the two electron-rich (in the excited state) carbonyl units lie close to each other. 相似文献
328.
Guan B Fontaine NK Djordjevic SS Cheung S Scott RP Geisler DJ Yoo SJ 《Optics letters》2012,37(3):341-343
This Letter demonstrates a measurement technique based on frequency-to-time mapping and coherent detection, which enables the complete (i.e., amplitude and phase) characterization of dynamically reconfigurable photonic filters. We apply this technique to a unit cell from a silicon CMOS-compatible photonic lattice filter that has a rapidly changing transfer function with an 8.33 ns update time, 120 MHz spectral resolution, and 12 GHz bandwidth. These dynamic measurements allow characterization of transients, thermal effects, filter fidelity, and other time-dependent phenomena during switching. 相似文献
329.
Coralie Assailly Clarisse Bridot Dr. Amélie Saumonneau Paul Lottin Dr. Benoit Roubinet Dr. Eva-Maria Krammer Francesca François Federica Vena Dr. Ludovic Landemarre Dr. Dimitri Alvarez Dorta Dr. David Deniaud Dr. Cyrille Grandjean Dr. Charles Tellier Dr. Sagrario Pascual Dr. Véronique Montembault Dr. Laurent Fontaine Dr. Franck Daligault Dr. Julie Bouckaert Dr. Sébastien G. Gouin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(9):3142-3150
Bacterial sialidases (SA) are validated drug targets expressed by common human pathogens such as Streptococcus pneumoniae, Vibrio cholerae, or Clostridium perfringens. Noncovalent inhibitors of bacterial SA capable of reaching the submicromolar level are rarely reported. In this work, multi- and polyvalent compounds are developed, based on the transition-state analogue 2-deoxy-2,3-didehydro-N-acetylneuraminic (DANA). Poly-DANA inhibits the catalytic activity of SA from S. pneumoniae (NanA) and the symbiotic microorganism B. thetaiotaomicron (BtSA) at the picomolar and low nanomolar levels (expressed in moles of molecules and of DANA, respectively). Each DANA grafted to the polymer surpasses the inhibitory potential of the monovalent analogue by more than four orders of magnitude, which represents the highest multivalent effect reported so far for an enzyme inhibition. The synergistic interaction is shown to operate exclusively in the catalytic domain, and not in the flanked carbohydrate-binding module (CBM). These results offer interesting perspectives for the multivalent inhibition of other SA families lacking a CBM, such as viral, parasitic, or human SA. 相似文献
330.
Kinetic decomposition models for the thermal decomposition of a high‐performance polymeric material (Polyimide, PI) were determined from specific techniques. Experimental data from thermogravimetric analysis (TGA) and previously elucidated decomposition mechanism were combined with numerical simulating tool to establish a comprehensive kinetic model for the decomposition of PI under three atmospheres: nitrogen, 2% oxygen, and synthetic air. Multistaged kinetic models with subsequent and competitive reactions were established by taking into consideration the different types of reactions that may be occurring during the thermal decomposition of the material (chain scission, thermo‐oxidation, char formation). The decomposition products and decomposition mechanism of PI which was established in our previous report allowed for the elucidation of the kinetic decomposition models. A three‐staged kinetic thermal decomposition pathway was a good fit to model the thermal decomposition of PI under nitrogen. The kinetic model involved an autocatalytic type of reaction followed by successive nth order reactions. Such types of models were set up for the evaluation of the kinetics of the thermal decomposition of PI under 2% oxygen and in air, leading to models with satisfactory fidelity. 相似文献