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排序方式: 共有449条查询结果,搜索用时 11 毫秒
441.
Nazeeruddin MK Wegh RT Zhou Z Klein C Wang Q De Angelis F Fantacci S Grätzel M 《Inorganic chemistry》2006,45(23):9245-9250
A highly luminescent novel cationic iridium complex [iridium bis(2-phenylpyridine)(4,4'-(dimethylamino)-2,2'-bipyridine)]PF6 was synthesized and characterized using NMR, UV-visible absorption, and emission spectroscopy and electrochemical methods. This complex displays intense photoluminescence maxima in the green-blue region of the visible spectrum and exhibits unprecedented phosphorescence quantum yields, 80 +/- 10% with an excited-state lifetime of 2.2 mus in a dichloromethane solution at 298 K. Single-layer light-emitting electrochemical cells with the charged complex as conducting and electroluminescent material sandwiched between indium-tin oxide and Ag electrodes were fabricated, which emit green-blue light with an onset voltage as low as 2.5 V. Density functional theory calculations were performed to provide insight into the electronic structure of the [iridium bis(2-phenylpyridine)(4,4'-(dimethylamino)-2,2'-bipyridine)]PF6 complex, comparing these results with those obtained for [iridium bis(2-phenylpyridine)(4,4'-tert-butyl-2,2'-bipyridine)]PF6. 相似文献
442.
We report a first principles density functional theory/time-dependent density functional theory (DFT/TDDFT) computational investigation on a prototypical perylene dye anchored to realistic ZnO nanostructures, approaching the size of the ZnO nanowires used in dye-sensitized solar cells devices. DFT calculations were performed on (ZnO)(n) clusters of increasing size, with n up to 222, of 1.3 × 1.5 × 3.4 nm dimensions, and for the related dye-sensitized models. We show that quantum confinement in the ZnO nanostructures substantially affects the dye/semiconductor alignment of energy levels, with smaller ZnO models providing unfavourable electron injection. An increasing broadening of the dye LUMO is found moving to larger substrates, substantially contributing to the interfacial electronic coupling. TDDFT excited state calculations for the investigated dye@(ZnO)(222) system are fully consistent with experimental data, quantitatively reproducing the red-shift and broadening of the visible absorption spectrum observed for the ZnO-anchored dye compared to the dye in solution. TDDFT calculations on the fully interacting system also introduce a contribution to the dye/semiconductor admixture, due to configurational excited state mixing. Our results highlight the importance of quantum confinement in dye-sensitized ZnO interfaces, and provide the fundamental insight lying at the heart of the associated DSC devices. 相似文献
443.
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445.
Adriano Pinto Mariano Caliane Bastos Borba Costa Dejanira de Franceschi de Angelis Francisco Maugeri Filho Daniel Ibraim Pires Atala Maria Regina Wolf Maciel Rubens Maciel Filho 《Applied biochemistry and biotechnology》2009,159(2):366-381
In this work, the mathematical optimization of a continuous flash fermentation process for the production of biobutanol was
studied. The process consists of three interconnected units, as follows: fermentor, cell-retention system (tangential microfiltration),
and vacuum flash vessel (responsible for the continuous recovery of butanol from the broth). The objective of the optimization
was to maximize butanol productivity for a desired substrate conversion. Two strategies were compared for the optimization
of the process. In one of them, the process was represented by a deterministic model with kinetic parameters determined experimentally
and, in the other, by a statistical model obtained using the factorial design technique combined with simulation. For both
strategies, the problem was written as a nonlinear programming problem and was solved with the sequential quadratic programming
technique. The results showed that despite the very similar solutions obtained with both strategies, the problems found with
the strategy using the deterministic model, such as lack of convergence and high computational time, make the use of the optimization
strategy with the statistical model, which showed to be robust and fast, more suitable for the flash fermentation process,
being recommended for real-time applications coupling optimization and control. 相似文献
446.
Jian‐An Huang Mansoureh Z. Mousavi Giorgia Giovannini Yingqi Zhao Aliaksandr Hubarevich Miguel A. Soler Walter Rocchia Denis Garoli Francesco De Angelis 《Angewandte Chemie (International ed. in English)》2020,59(28):11423-11431
The SERS‐based detection of protein sequences with single‐residue sensitivity suffers from signal dominance of aromatic amino acid residues and backbones, impeding detection of non‐aromatic amino acid residues. Herein, we trap a gold nanoparticle in a plasmonic nanohole to generate a single SERS hot spot for single‐molecule detection of 2 similar polypeptides (vasopressin and oxytocin) and 10 distinct amino acids that constitute the 2 polypeptides. Significantly, both aromatic and non‐aromatic amino acids are detected and discriminated at the single‐molecule level either at individual amino acid molecules or within the polypeptide chains. Correlated with molecular dynamics simulations, our results suggest that the signal dominance due to large spatial occupancy of aromatic rings of the polypeptide sidechains on gold surfaces can be overcome by the high localization of the single hot spot. The superior spectral and spatial discriminative power of our approach can be applied to single‐protein analysis, fingerprinting, and sequencing. 相似文献
447.
Abbotto A Barolo C Bellotto L De Angelis F Grätzel M Manfredi N Marinzi C Fantacci S Yum JH Nazeeruddin MK 《Chemical communications (Cambridge, England)》2008,(42):5318-5320
A novel heteroleptic ruthenium complex carrying a heteroaromatic-4,4'-pi-conjugated 2,2'-bipyridine [Ru(II)LL'(NCS)(2)] (L = 4,4'-bis[(E)-2-(3,4-ethylenedioxythien-2-yl)vinyl]-2,2'-bipyridine, L' = 4,4'-(dicarboxylic acid)-2,2'-bipyridine) was synthesized and used in dye-sensitized solar cells, yielding photovoltaic efficiencies of 9.1% under standard global AM 1.5 sunlight. 相似文献
448.
De Angelis F Fantacci S Sgamellotti A Cariati E Ugo R Ford PC 《Inorganic chemistry》2006,45(26):10576-10584
We present a combined density functional theory (DFT)/time-dependent density functional theory (TDDFT) study of the geometry, electronic structure, and absorption and emission properties of the tetranuclear "cubane" Cu4I4py4 (py = pyridine) system. The geometry of the singlet ground state and of the two lowest triplet states of the title complex were optimized, followed by TDDFT excited-state calculations. This procedure allowed us to characterize the nature of the excited states involved in the absorption spectrum and those responsible for the dual emission bands observed for this complex. In agreement with earlier experimental proposals, we find that while in absorption the halide-to-pyridine charge-transfer excited state (XLCT*) has a lower energy than the cluster-centered excited state (CC*), a strong geometrical relaxation on the triplet cluster-centered state surface leads to a reverse order of the excited states in emission. 相似文献
449.
Dr. Claudio Iacobucci Dr. Alexandre Lebon Prof. Francesco De Angelis Dr. Antony Memboeuf 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(52):18690-18694
Copper‐catalysed azide alkyne cycloaddition (CuAAC) has been considered a breakthrough transformation over the last 15 years. Its debated mechanism arouses continuously growing interest. By means of a mass spectrometer modified ad hoc, the entire catalytic cycle of CuAAC reaction has been investigated in the gas phase. Ion‐molecule reactions were performed inside the mass spectrometer to reproduce step‐by‐step, at a molecular level, the complete catalytic cycle of the click reaction. We successfully challenged the reactivity of elusive mono‐ and bis‐copper intermediates by ion‐molecule reactions leading to the production of mass‐characterized triazole products, paving the way for detailed energetic studies to be performed in the gas phase. The structures of the relevant species, calculated at a DFT level, helped rationalise our experimental results. 相似文献