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41.
42.
Reverse Engineering of Conjugated Microporous Polymers: Defect Structures of Tetrakis(4‐ethynylphenyl)stannane Networks
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M. Sc. Andrea C. Uptmoor M. Sc. Jan Freudenberg M. Sc. S. Thimon Schwäbel Dipl. Chem. Fabian Paulus Dr. Frank Rominger Dr. Felix Hinkel Prof. Uwe H. F. Bunz 《Angewandte Chemie (International ed. in English)》2015,54(49):14673-14676
Two different conjugated microporous polymers (CMPs) based on tetrakis(4‐ethynylphenyl)stannane as the repeating unit were synthesized and their BET surfaces and thermal properties were investigated. The first direct method to elucidate the molecular structure of the organic linkers between the tin centers by digestion of the CMP is described. Selective cleavage of the tin–carbon bonds with chloroacetic acid afforded the isolated bridging units and provided insight into the surprisingly varied chemical composition of these networks. 相似文献
43.
Susan Torabi Lukas Hammerschmidt Elena Voloshina Beate Paulus 《International journal of quantum chemistry》2014,114(14):943-951
The performance of wavefunction‐based correlation methods in theoretical solid‐state chemistry depends on reliable Hartree–Fock (HF) results for infinitly extended systems. Therefore, we optimized basis sets of valence‐triple‐ζ quality based on HF calculations for the periodic system of group‐12‐metal difluorides. Scalar‐relativistic effects were included in the case of the metal‐ions by applying small‐core pseudopotentials. To assess the quality of the proposed basis sets, the structural parameters, bulk moduli as well as cohesive and lattice energies of the systems were evaluated at the HF and the density functional theory levels. In addition to these two mean‐field approaches and to assess further employment of our basis sets to wavefunction‐based correlation methods we performed periodic local MP2 computations. Finally, the possibilities of pressure induced structural phase transitions occurring in the ZnF2, CdF2, and HgF2 were investigated. © 2014 Wiley Periodicals, Inc. 相似文献
44.
Lange H Maultzsch J Meng W Mollenhauer D Paulus B Peica N Schlecht S Thomsen C 《Langmuir : the ACS journal of surfaces and colloids》2011,27(11):7258-7264
We demonstrate a phase transfer method to create stable colloidal solutions of Au nanoparticles with 4-methoxypyridine ligands. We then investigate the adsorption behavior of 4-methoxypyridine onto gold surfaces by Raman spectroscopy, DFT calculations, and (1)H NMR. In contrast to unsubstituted pyridine and the frequently used (N,N-dimethylamino)pyridine (DMAP), a flat adsorption of 4-methoxypyridine on gold was found. 相似文献
45.
Geisberger G Paulus S Carraro M Bonchio M Patzke GR 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(16):4619-4625
Chitosan and its derivates continue to attract considerable research interest as effective drug carriers with good biocompatibility and high cellular uptake rates. We used these versatile features to tap the considerable biomedical potential of polyoxometalates (POMs) through their encapsulation into a carboxymethyl chitosan (CMC) matrix. The nanocapsules were prepared by ionic gelification with Ca(2+); their size distribution ranges from 60 to 150 nm. Because [Co(4)(H(2)O)(2)(PW(9)O(34))(2)](10-) is well known for its manifold properties, such as antiviral activity, it was selected as a model POM. The resulting composites were characterised with a wide range of analytical methods, which pointed to quantitative encapsulation of intact POMs within the CMC matrix. We studied the biocompatibility of the POM/CMC nanocomposites on HeLa cells through MTT and proliferation assays. Even after prolonged incubation times at high concentrations, the composites did not display cytotoxicity, thereby drastically reducing the side effects of the pristine POMs. This opens up new avenues for designing novel inorganic drug prototypes from bioactive POMs. 相似文献
46.
47.
I. Baumann R. Brinkmann M. Dinand W. Sohler L. Beckers C. Buchal M. Fleuster H. Holzbrecher H. Paulus K.-H. Müller T. Gog G. Materlik O. Witte H. Stolz W. von der Osten 《Applied Physics A: Materials Science & Processing》1996,64(1):33-44
The erbium incorporation into LiNbO3 by diffusion doping is investigated in detail by means of Secondary Ion Mass Spectrometry, Secondary Neutral Mass Spectrometry,
Rutherford Backscattering, Atomic Force Microscopy, X-ray Standing Wave technique and optical site-selective spectroscopy.
The diffusion of erbium in LiNbO3 can be described by Fick’s laws of diffusion with a concentration-independent diffusion coefficient. The diffusion constants
and activation energies for Z-cut (X-cut) LiNbO3 are 4.8×10-5 cm2/s (12.0×10-5 cm2/s) and 2.28 eV (2.44 eV), respectively. A limited solubility of erbium in LiNbO3 has to be taken into account increasing exponentially with rising temperature. During the first step of diffusion an Er
x
Nb
y
-oxide layer is formed at the surface of the sample acting as diffusion reservoir. Erbium is incorporated into LiNbO3 on vacant Li-sites slightly shifted from the original Li-position along the (-c)-direction. Site-selective spectroscopy found
four distinguishable energetically different erbium centres at this lattice site resulting from locally different symmetries
of the crystal field.
Received: 21 March 1996 / Accepted: 12 August 1996 相似文献
48.
Hiroshi Kageyama Takashi Watanabe Yoshihiro Tsujimoto Atsushi Kitada Yuji Sumida Kazuyoshi Kanamori Kazuyoshi Yoshimura Naoaki Hayashi Shigetoshi Muranaka Mikio Takano Monica Ceretti Werner Paulus Clemens Ritter Gilles Andr 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2008,120(31):5824-5829
49.
Thermally stimulated recovery behaviour of amorphous polymers is described in terms of a continuous distribution of sharply defined elementary softening processes in the polymer. It is proposed that each of these elementary processes is the result of a co-operative site-change mechanism. On exceeding the activation temperature for the process, the viscoelastic time constants fall abruptly by many orders of magnitude, as opposed to following an Arrhenius-type law. The implications of this type of behaviour are discussed.
Prof. Schwarzl zum 60. Geburtstag gewidmet. 相似文献
50.
The crystal and molecular structure of ferricinium tetrachloroferrate was studied by X-ray diffraction. The compound crystallizes in space group Pna21 with 4 molecules C10H10Cl4Fe2 per unit cell. Data analysis was relatively difficult and direct methods of phase determination were very useful in the interpretation of the Patterson synthesis. The two rings in ferricinium are nearly parallel. The structural parameters are very similar to those previously published by others for ferrocene. This molecular structure and its vibrational properties seem to be in contrast to a general rule previously formulated by others for the infrared spectra of cyclopentadienyl compounds. 相似文献