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501.
Stanislav Rádl Jan Stach Ondřej Píša Josef Cinibulk Jaroslav Havlíček Markéta Zajícová Tomáš Pekárek 《Journal of heterocyclic chemistry》2016,53(6):1738-1749
An improved process for the active pharmaceutical ingredient of a new HIV integrase inhibitor elvitegravir ( 1 ) has been developed. It starts from commercially available 2,4‐dimethoxyacetophenone, which is selectively halogenated into the position 5. The 5‐halo acetophenones are condensed with dialkyl carbonates to give the corresponding benzoylacetates. Their treatment with N,N‐dimethylformamide dimethyl acetal followed by (S)‐valinol then provided the corresponding intermediate benzoyl acrylates. Cyclization to the required 1,4‐dihydroquinolin‐4‐oxo derivatives by aromatic nucleophilic substitution of the 2‐methoxy group was achieved by treatment with N,O‐bis(trimethylsilyl)‐acetamide, which also protected the OH group as the trimethylsilyl derivative. Finally, the Negishi coupling with 2‐fluoro‐3‐chlorobenzylzinc bromide and the following hydrolysis provided elvitegravir ( 1 ). The preferred variant, the seven‐step procedure starting from 2,4‐dimethoxyacetophenone, provides elvitegravir in 29.3% yield. 相似文献
502.
Hang Liu Michaela Zagler Prof. Dr. Michael Nase Prof. Dr. Katharina Weber Prof. Dr. Joachim Albrecht 《Chemphyschem》2023,24(20):e202300671
The surface topography of biodegradable polymer foils is modified by mechanical imprinting on a submillimeter length scale. The created patterns strongly influence the wetting behavior and allow the preparation of hydrophobic surfaces with controlled solid-liquid interaction. A detailed analysis of anisotropic surface patterns reveals that the observed effect arises from a combination of topographical and compositional changes that are introduced to the surface. As a main result it is found that an individual combination of material and structure is required for the production of water-repellent biopolymer foils that are highly attractive for packaging applications. 相似文献
503.
Michaela Harmošová Mária Vilková Martin Kello Lukáš Smolko Erika Samol'ová Dominika Šebová Ivan Potočňák 《Acta Crystallographica. Section C, Structural Chemistry》2023,79(8):316-323
A new zirconium(IV) complex, diaquabis(8-hydroxyquinoline-2-carboxylato-κ3N,O2,O8)zirconium(IV) dimethylformamide disolvate, [Zr(C10H5NO3)2(H2O)2]·2C3H7NO or [Zr(QCa)2(H2O)2]·2DMF ( 1 ) (HQCaH is 8-hydroxyquinoline-2-carboxylic acid and DMF is dimethylformamide), was prepared and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray structure analysis. Complex 1 is a mononuclear complex in which the ZrIV atoms sit on the twofold axis and they are octacoordinated by two N and six O atoms of two tridentate anionic QCa2− ligands, and two aqua ligands. Outside the coordination sphere are two DMF molecules bound to the complex unit by hydrogen bonds. The structure and stability of complex 1 in dimethyl sulfoxide were verified by NMR spectroscopy. The cytotoxic properties of 1 and HQCaH were studied in vitro against eight cancer cell lines, and their selectivity was tested on the BJ-5ta noncancerous cell line. Both the complex and HQCaH exhibited low activity, with IC50 > 200 µM. DNA and human serum albumin (HSA) binding studies showed that 1 binds to calf thymus (CT) DNA via intercalation and is able to bind to the tryptophan binding site of HSA (Trp-214). 相似文献
504.
Försterová M Svobodová I Lubal P Táborský P Kotek J Hermann P Lukes I 《Dalton transactions (Cambridge, England : 2003)》2007,(5):535-549
New bifunctional H(4)dota-like ligands with three acetic acid and one phosphinic acid pendant arms and propionate (H(5)do3ap(PrA)) or 4-aminobenzyl (H(4)do3ap(ABn)) reactive groups bound to the phosphorus atom were investigated. Potentiometric studies showed that the ligands have a similar basicity to the parent H(4)dota and the stability constants of their complexes with sodium(i) and selected lanthanide(III) ions are also similar. Formation and acid-assisted decomplexation kinetics of yttrium(III) complexes with a series of H(4)dota-like ligands (H(4)dota and its phosphinic/phosphonic acid analogues) were studied and the reactions are sensitive to a slight modification of the ligand structure. The (2-carboxyethyl)phosphinic acid derivative H(5)do3ap(PrA) and the phosphonic acid ligand H(5)do3ap form complexes faster than H(4)dota. The most kinetically inert complex is that with H(4)do3ap(ABn). Rates of complexation and decomplexation can depend on the ability to transfer proton(s) outside/inside the complex cavity and, therefore, on the hydrophobicity of the ligands. The results demonstrate that the new bifunctional ligands are suitable for labelling biomolecules with yttrium(iii) radioisotopes for utilization in nuclear medicine. 相似文献
505.
Lhoták P Bílá A Budka J Pojarová M Stibor I 《Chemical communications (Cambridge, England)》2008,(14):1662-1664
The least accessible calix[4]arene conformers-1,2-alternates-can be very easily prepared using a proximal dialkylation and subsequent peralkylation reaction sequence. 相似文献
506.
C Kisielowski B Freitag M Bischoff H van Lin S Lazar G Knippels P Tiemeijer M van der Stam S von Harrach M Stekelenburg M Haider S Uhlemann H Müller P Hartel B Kabius D Miller I Petrov E A Olson T Donchev E A Kenik A R Lupini J Bentley S J Pennycook I M Anderson A M Minor A K Schmid T Duden V Radmilovic Q M Ramasse M Watanabe R Erni E A Stach P Denes U Dahmen 《Microscopy and microanalysis》2008,14(5):469-477
The ability of electron microscopes to analyze all the atoms in individual nanostructures is limited by lens aberrations. However, recent advances in aberration-correcting electron optics have led to greatly enhanced instrument performance and new techniques of electron microscopy. The development of an ultrastable electron microscope with aberration-correcting optics and a monochromated high-brightness source has significantly improved instrument resolution and contrast. In the present work, we report information transfer beyond 50 pm and show images of single gold atoms with a signal-to-noise ratio as large as 10. The instrument's new capabilities were exploited to detect a buried Sigma3 {112} grain boundary and observe the dynamic arrangements of single atoms and atom pairs with sub-angstrom resolution. These results mark an important step toward meeting the challenge of determining the three-dimensional atomic-scale structure of nanomaterials. 相似文献
507.
Shan ZW Wiezorek JM Stach EA Follstaedt DM Knapp JA Mao SX 《Physical review letters》2007,98(9):095502
It is believed that the dynamics of dislocation processes during the deformation of nanocrystalline materials can only be visualized by computational simulations. Here we demonstrate that observations of dislocation processes during the deformation of nanocrystalline Ni with grain sizes as small as 10 nm can be achieved by using a combination of in situ tensile straining and high-resolution transmission electron microscopy. Trapped unit lattice dislocations are observed in strained grains as small as 5 nm, but subsequent relaxation leads to dislocation recombination. 相似文献
508.
Tarcea N Harz M Rösch P Frosch T Schmitt M Thiele H Hochleitner R Popp J 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,68(4):1029-1035
We report on the great advantages of using deep UV Raman system for in situ planetary applications. Among them are to be mentioned: (I) higher scattering efficiency compared to VIS-IR Raman excitation wavelengths, (II) electronic resonance effects which increase the intrinsically weak Raman signal thus improving the S/N ratio of the detected Raman signals and (III) spectral separation of Raman and fluorescence signals. All these advantages are making UV Raman a valuable technique for in situ planetary applications. Mineral as well as biological samples were analyzed using Raman deep UV excitation and the results are presented. For the mineral samples a comparison with excitation in the NIR-VIS spectral regions is made. The impact of fluorescence on Raman data acquisition at different laser excitation wavelengths is assessed. Making use of the resonance effects, spectra of microorganisms were recorded with a high S/N ratio, allowing afterwards a very precise identification and classification (to the strain level) of the measured samples. 相似文献
509.
Roman Dück Volker Wulf Margit Geißler Hans-Ulrich Baier Michaela Wirtz Hans-Willi Kling Siegmar Gäb Oliver J. Schmitz 《Analytical and bioanalytical chemistry》2010,396(6):2273-2283
The class of fatty alcohol alkoxylates describes surfactants that are synthesised by reaction of fatty alcohols with alkoxides
such as ethylene oxide or propylene oxide or a combination of both as copolymers. Such alkoxylates are used, for example,
as nonionic surfactants in home and industrial cleaning and washing agents. Chemical characteristics of such alkoxylate copolymers,
for example the degree of alkoxylation, the arrangement of building blocks (random or block polymerisation), the type of the
starter, and endcapping, play an important role in application behaviour. The analysis of these characteristics is challenging
because in many cases such copolymers have high polydispersity and a large number of constitutional isomers depending on the
degree of alkoxylation. Furthermore, the alkoxylates often occur in a complex multicomponent matrix. Here we present a method
for characterization of silylated fatty alcohol alkoxylates in the low-molecular-weight range by means of comprehensive two-dimensional
gas chromatography–mass spectrometry with electron impact and chemical ionisation. This method also enables detailed analysis
of the alkoxylates in a complex matrix such as modern detergents. 相似文献
510.
N. Hessler M. Dolch E. B. Kester E. J. Schneider F. W. Jung K. Drees G. Kowalski S. Hellmann F. Roll E. Stach N. N. Gawrilow L. A. Weissbrut R. A. Mott R. V. Wheeler K. Bunte W. Ludewig B. G. imek F. Coufalík und Z. Beránek 《Fresenius' Journal of Analytical Chemistry》1935,102(7-8):294-299
Ohne Zusammenfassung 相似文献