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461.
Kazuo Nakajima Toshihiro Kusunoki Yukinaga Azuma Noritaka Usami Kozo Fujiwara Toru Ujihara Gen Sazaki Toetsu Shishido 《Journal of Crystal Growth》2002,240(3-4):373-381
The effect of the supply of depleted Si solute elements on the compositional variation in the Si-rich SiGe bulk crystals was studied using the method which was used to grow Ge-rich SiGe single crystals with a uniform composition. By selecting the proper pulling rate, we can obtain Si-rich Si1−xGex bulk crystals with uniform composition of x=0.1 without using the supply mechanism of depleted Si solute elements. When the supply mechanism of Si solute elements was used, the initial composition in Si-rich SiGe crystals can be much more easily determined by controlling the growth temperature than that in Ge-rich crystals because the Si seed crystal is not melted down. The supply of Si solute elements is very effective to change the compositional variation even for Si-rich SiGe crystals. 相似文献
462.
Azuma M Carlsson S Rodgers J Tucker MG Tsujimoto M Ishiwata S Isoda S Shimakawa Y Takano M Attfield JP 《Journal of the American Chemical Society》2007,129(46):14433-14436
The valence state change of BiNiO3 perovskite under pressure has been investigated by a powder neutron diffraction study and electronic-state calculations. At ambient pressure, BiNiO3 has the unusual charge distribution Bi(3+)(0.5)Bi(5+)(0.5)Ni(2+)O3 with ordering of Bi(3+) and Bi(5+)charges on the A sites of a highly distorted perovskite structure. High-pressure neutron diffraction measurements and bond valence sum calculations show that the pressure-induced melting of the charge disproportionated state leads to a simultaneous charge transfer from Ni to Bi, so that the high-pressure phase is metallic Bi(3+)Ni(3+)O3. This unprecedented charge transfer between A and B site cations coupled to electronic instabilities at both sites leads to a variety of ground states, and it is predicted that a Ni-charge disproportionated state should also be observable. 相似文献
463.
Aoki K Obata T Yamazaki Y Mori Y Hirokawa H Koseki J Hattori T Niitsu K Takeda S Aburada M Miyamoto K 《Chemical & pharmaceutical bulletin》2007,55(2):255-267
We found previously that 7-[3-(cyclohexylmethyl)ureido]-3-{1-methyl-1H-pyrrolo[2,3-b]pyridin-3-yl}quinoxalin-2(1H)-one (7d-6) has considerable potency as a PDGF inhibitor. This compound showed potent inhibitory activity in a PDGF-induced CPA (Cell Proliferation Assay) and APA (Auto-Phosphorylation Assay) (IC50 = 0.05 micromol/l in CPA, 0.03 micromol/l in APA). Therefore, we tried to develop a novel and effective PDGF-betaR inhibitor by optimizing a series of its derivatives. We found that trifluoroacetic acid (TFA)-catalyzed coupling of pyrrolo[2,3-b]pyridines with quinoxalin-2-ones proceeded efficiently under mild oxidation condition with manganese(IV) oxide (MnO2) in situ, so this method was applied to prepare a series of derivatives. Results of in vitro screening of newly synthesized derivatives identified compound 7d-9 as having potent (IC50 = 0.014 micromol/l in CPA, 0.007 micromol/l in APA) and selective [IC50 values against vascular endothelial growth factor receptor 2 (VEGFR2, kinase domain region, KDR), epidermal growth factor receptor (EGFR), c-Met (hepatocyte growth factor receptor) and insulin growth factor I receptor (IGF-IR)/IC50 against PDGFR were each >1000] inhibitory activity. Moreover, in this series of derivatives, 7b-2 showed potent inhibitory activity toward both PDGF- and VEGF-induced signaling (PDGFR: IC50 = 0.004 micromol/l in CPA, 0.0008 micromol/l in APA, KDR: IC50 = 0.008 micromol/l in APA). Herein we report a new and convenient synthetic method for this series of derivatives and its SAR study. 相似文献
464.
Katsuhiko Ariga Ryutaro Tanaka Naoko Takagi Jun-Ichi Kikuchi 《Supramolecular chemistry》2013,25(2):87-94
In order to develop a supramolecular receptor through a self-assembling process, a site-specific host and an inclusion-type host were mixed as a Langmuir monolayer, and guest binding and pressure-induced fluorescence emission were investigated. A guanidinium amphiphile and several cyclophanes carrying hydrophobic moieties were used as the host molecules; molecular recognition of an aqueous fluorescent guest, 6-p-toluidino-2-naphthalenesulfonic acid (TNS) by binary mixed receptor monolayers was evaluated by a surface pressure-molecular area (π-A) isotherm and a surface fluorescence measurement. An apparent increase in fluorescence intensity was observed when the mixed monolayers of the guanidinium and cyclophane amphiphiles were compressed on an aqueous TNS solution. In contrast, single-component monolayers of the guanidinium or the cyclophane did not show a significant increase in fluorescence emission. In the mixed monolayers, the guest TNS would be bound to the interface by strong electrostatic interaction with the guanidinium, and inclusion of the formed complex probably suppresses the quenching effect in polar medium and/or self-quenching. Experiments with various mixing ratios of these components suggest selective formation of an equimolar cooperative receptor of the guanidinium and the cyclophane. Investigation of the cyclophane structures by fluorescence emission and a competitive binding experiment with another guest were also carried out. 相似文献
465.
Satake A Azuma S Kuramochi Y Hirota S Kobuke Y 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(3):855-865
Porphyrin‐based supramolecular nanostructures have been produced by the self‐assembly of porphyrin macrorings with three benzoic acid groups (Acid‐R) on each side of the rings through cooperative carboxyl–carboxyl hydrogen bonds. Structures of the organized Acid‐R were analyzed by AFM, and two clear distribution peaks were observed at 3 and 27 nm in the height‐distribution histogram. From the overall assessment, the higher objects are considered to be one‐dimensional structures standing vertically on the mica substrate. The height corresponds to an 11‐mer of a unit Acid‐R. Light‐harvesting functions were examined by using fluorescence titration, whereby an energy‐acceptor molecule (Tripod 2 ) was employed that strongly interacted with Acid‐R units (association constant: 2.0×108 M ?1), specifically from the inner pore. The titration results showed that the apparent stoichiometry [Tripod 2 ]/[Acid‐R] was <0.5, and that the value was concentration dependent. Titration results reasonably account for the scheme in which Tripod 2 only interacts with each terminal in the organized Acid‐R. The number of organization was fitted to a 10‐mer of Acid‐R in a 6.8×10?7 M solution, and was consistent with that estimated from the AFM results. In the composites of organized Acid‐R/Tripod 2 , a singlet excitation energy transfer occurred among the Acid‐R units, and to Tripod 2 . The energy‐transfer rate constants were estimated by using the decamer model, which employed kinetic parameters obtained from steady‐state and time‐resolved fluorescence experiments. 相似文献
466.
O. Arimoto M. Watanabe T. Tsujibayashi J. Azuma M. Kamada S. Nakanishi H. Itoh M. Itoh 《Radiation measurements》2010,45(3-6):356-358
Production of radiation defects in a widely used scintillation material BaF2 has been studied by means of a combination spectroscopy of synchrotron radiation (SR) and laser, in which defects produced by SR irradiation are sensitively detected by observing the luminescence stimulated by laser light. The photostimulated luminescence arises from the recombination of self-trapped holes (VK centers) with electrons released from trapped centers by laser light. The obtained result reveals that the production efficiency of radiation defects is drastically dependent on the excitation photon energy of valence or core excitons. 相似文献
467.
Shingo Sato Takeshi Watanabe Hironobu Kumagai Nobuo Kitamura Shigeru Matsuba Toshihiro Kumazawa Jun-Ichi Onodera Masanobu Suzuki 《Journal of heterocyclic chemistry》1999,36(5):1189-1193
Condensation of 2-hydroxyacetophenone with benzaldehyde in the presence of 70% perchloric acid in ethyl orthoformate gave the corresponding 4-ethoxyflavylium perchlorate, which was treated with aqueous ammonia or methylamine solution to afford 1,6,7,8-substituted 2-(3′,4′-substituted-phenyl)-4-quinolone in fair to good yield. 相似文献
468.
Peter Fulde Patrick Unger Jun-Ichi Igarashi 《International journal of quantum chemistry》1997,63(3):645-653
Until now, solids with strongly correlated electrons can be treated only by model Hamiltonians. Even then a calculation of spectral densities is not simple, because the strong Coulomb interactions prevent us from treating correlations perturbatively. We show that projection and partitioning techniques are a very valuable tool here. The method is applied to computations of the density of states of transition metals, in particular, Ni. Here, the band narrowing and the sattlite peak at 6 eV due to correlations are reproduced. A second application concerns the spectral density of doped and undoped Cu(SINGLE BOND)O planes which are part of the high-Tc superconducting materials. © 1997 John Wiley & Sons, Inc. J Quant Chem 63: 645–653, 1997 相似文献
469.
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