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排序方式: 共有509条查询结果,搜索用时 15 毫秒
1.
Ina Heckelmann Zifei Lu Dr. Joseph C. A. Prentice Dr. Florian Auras Dr. Tanya K. Ronson Prof. Dr. Richard H. Friend Prof. Dr. Jonathan R. Nitschke Dr. Sascha Feldmann 《Angewandte Chemie (International ed. in English)》2023,62(12):e202301806
Organic semiconductors are promising for efficient, printable optoelectronics. However, strong excited-state quenching due to uncontrolled aggregation limits their use in devices. We report on the self-assembly of a supramolecular pseudo-cube formed from six perylene diimides (PDIs). The rigid, shape-persistent cage sets the distance and orientation of the PDIs and suppresses intramolecular rotations and vibrations, leading to non-aggregated, monomer-like properties in solution and the solid state, in contrast to the fast fluorescence quenching in the free ligand. The stabilized excited state and electronic purity in the cage enables the observation of delayed fluorescence due to a bright excited multimer, acting as excited-state reservoir in a rare case of benign inter-chromophore interactions in the cage. We show that self-assembly provides a powerful tool for retaining and controlling the electronic properties of chromophores, and to bring molecular electronics devices within reach. 相似文献
2.
Dr. Nicolas D'Imperio Dr. Valentina Pelliccioli Dr. Sara Grecchi Dr. Alberto Bossi Prof. Francesca Vasile Prof. Silvia Cauteruccio Dr. Anna I. Arkhypchuk Dr. Arvind Kumar Gupta Prof. Dr. Andreas Orthaber Prof. Dr. Sascha Ott Prof. Emanuela Licandro 《European journal of organic chemistry》2023,26(4):e202201209
The first examples of a π-conjugated benzo[b]phosphole P-oxide in which two phosphole P-oxide units are connected by a carbon-carbon double bond are described. The molecules are synthesized as E isomers with respect to the carbon-carbon double bond and exist as stable cis and trans isomers (chiral and meso one respectively) relatively to the two stereogenic P atoms. The optical and electrochemical properties of both isomers have been investigated by experiment and computations. 相似文献
3.
Dr. Thomas Schwarze Janine Riemer Dr. Sascha Eidner Prof. Hans‐Jürgen Holdt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(32):11306-11310
A highly K+‐selective two‐photon fluorescent probe for the in vitro monitoring of physiological K+ levels in the range of 1–100 mM is reported. The two‐photon excited fluorescence (TPEF) probe shows a fluorescence enhancement (FE) by a factor of about three in the presence of 160 mM K+, independently of one‐photon (OP, 430 nm) or two‐photon (TP, 860 nm) excitation and comparable K+‐induced FEs in the presence of competitive Na+ ions. The estimated dissociation constant (Kd) values in Na+‐free solutions (KdOP=(28±5) mM and KdTP=(36±6) mM ) and in combined K+/Na+ solutions (KdOP=(38±8) mM and KdTP=(46±25) mM ) reflecting the high K+/Na+ selectivity of the fluorescent probe. The TP absorption cross‐section (σ2PA) of the TPEF probe+160 mM K+ is 26 GM at 860 nm. Therefore, the TPEF probe is a suitable tool for the in vitro determination of K+. 相似文献
4.
5.
Grégoire Sieg Quentin Pessemesse Sascha Reith Stefan Yelin Prof. Dr. Christian Limberg Prof. Dr. Dominik Munz Dr. C. Gunnar Werncke 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(67):16760-16767
Carbonyl and iminyl based radical anions are reactive intermediates in a variety of transformations in organic synthesis. Herein, the isolation of ketyl, and more importantly unprecedented ketiminyl and aldiminyl radical anions coordinated to cobalt and iron complexes is presented. Insights into the electronic structure of these unusual metal bound radical anions is provided by X-Ray diffraction analysis, NMR, IR, UV/Vis and Mössbauer spectroscopy, solid and solution state magnetometry, as well as a by a detailed computational analysis. The metal bound radical anions are very reactive and facilitate the activation of intra- and intermolecular C−H bonds. 相似文献
6.
Sascha Kurz 《Designs, Codes and Cryptography》2017,85(1):97-106
A partial \((k-1)\)-spread in \({\text {PG}}(n-1,q)\) is a collection of \((k-1)\)-dimensional subspaces with trivial intersection. So far, the maximum size of a partial \((k-1)\)-spread in \({\text {PG}}(n-1,q)\) was known for the cases \(n\equiv 0\pmod k\), \(n\equiv 1\pmod k\), and \(n\equiv 2\pmod k\) with the additional requirements \(q=2\) and \(k=3\). We completely resolve the case \(n\equiv 2\pmod k\) for the binary case \(q=2\). 相似文献
7.
Lukas Martin Müller-Wirtz Daniel Kiefer Sven Ruffing Timo Brausch Tobias Hüppe Daniel I. Sessler Thomas Volk Tobias Fink Sascha Kreuer Felix Maurer 《Molecules (Basel, Switzerland)》2021,26(11)
Exhaled aliphatic aldehydes were proposed as non-invasive biomarkers to detect increased lipid peroxidation in various diseases. As a prelude to clinical application of the multicapillary column–ion mobility spectrometry for the evaluation of aldehyde exhalation, we, therefore: (1) identified the most abundant volatile aliphatic aldehydes originating from in vitro oxidation of various polyunsaturated fatty acids; (2) evaluated emittance of aldehydes from plastic parts of the breathing circuit; (3) conducted a pilot study for in vivo quantification of exhaled aldehydes in mechanically ventilated patients. Pentanal, hexanal, heptanal, and nonanal were quantifiable in the headspace of oxidizing polyunsaturated fatty acids, with pentanal and hexanal predominating. Plastic parts of the breathing circuit emitted hexanal, octanal, nonanal, and decanal, whereby nonanal and decanal were ubiquitous and pentanal or heptanal not being detected. Only pentanal was quantifiable in breath of mechanically ventilated surgical patients with a mean exhaled concentration of 13 ± 5 ppb. An explorative analysis suggested that pentanal exhalation is associated with mechanical power—a measure for the invasiveness of mechanical ventilation. In conclusion, exhaled pentanal is a promising non-invasive biomarker for lipid peroxidation inducing pathologies, and should be evaluated in future clinical studies, particularly for detection of lung injury. 相似文献
8.
Sandra Grebenteuch Clemens Kanzler Stefan Klaußnitzer Lothar W. Kroh Sascha Rohn 《Molecules (Basel, Switzerland)》2021,26(4)
Lipid oxidation and the resulting volatile organic compounds are the main reasons for a loss of food quality. In addition to typical compounds, such as alkanes, aldehydes and alcohols, methyl ketones like heptan-2-one, are repeatedly described as aroma-active substances in various foods. However, it is not yet clear from which precursors methyl ketones are formed and what influence amino compounds have on the formation mechanism. In this study, the formation of methyl ketones in selected food-relevant fats and oils, as well as in model systems with linoleic acid or pure secondary degradation products (alka-2,4-dienals, alken-2-als, hexanal, and 2-butyloct-2-enal), has been investigated. Elevated temperatures were chosen for simulating processing conditions such as baking, frying, or deep-frying. Up to seven methyl ketones in milk fat, vegetable oils, and selected model systems have been determined using static headspace gas chromatography-mass spectrometry (GC-MS). This study showed that methyl ketones are tertiary lipid oxidation products, as they are derived from secondary degradation products such as deca-2,4-dienal and oct-2-enal. The study further showed that the position of the double bond in the precursor compound determines the chain length of the methyl ketone and that amino compounds promote the formation of methyl ketones to a different degree. These compounds influence the profile of the products formed. As food naturally contains lipids as well as amino compounds, the proposed pathways are relevant for the formation of aroma-active methyl ketones in food. 相似文献
9.
Christoph Peschel Stefan van Wickeren Yves Preibisch Verena Naber Denis Werner Lars Frankenstein Dr. Fabian Horsthemke Prof. Dr. Urs Peuker Prof. Dr. Martin Winter Dr. Sascha Nowak 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(22):e202200485
Herein we report on an analytical study of dry-shredded lithium-ion battery (LIB) materials with unknown composition. Samples from an industrial recycling process were analyzed concerning the elemental composition and (organic) compound speciation. Deep understanding of the base material for LIB recycling was obtained by identification and analysis of transition metal stoichiometry, current collector metals, base electrolyte and electrolyte additive residues, aging marker molecules and polymer binder fingerprints. For reversed engineering purposes, the main electrode and electrolyte chemistries were traced back to pristine materials. Furthermore, possible lifetime application and accompanied aging was evaluated based on target analysis on characteristic molecules described in literature. With this, the reported analytics provided precious information for value estimation of the undefined spent batteries and enabled tailored recycling process deliberations. The comprehensive feedstock characterization shown in this work paves the way for targeted process control in LIB recycling processes. 相似文献
10.
Tim Steinke Dr. Patrick Wonner Dr. Richard M. Gauld Dr. Sascha Heinrich Prof. Dr. Stefan M. Huber 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(47):e202200917
Recently, chalcogen bonding has been investigated in more detail in organocatalysis and the scope of activated functionalities continues to increase. Herein, the activation of imines in a Povarov [4+2] cycloaddition reaction with bidentate cationic chalcogen bond donors is presented. Tellurium-based Lewis acids show superior properties compared to selenium-based catalysts and inactive sulfur-based analogues. The catalytic activity of the chalcogen bonding donors increases with weaker binding anions. Triflate, however, is not suitable due to its participation in the catalytic pathway. A solvent screening revealed a more efficient activation in less polar solvents and a pronounced effect of solvent (and catalyst) on endo : exo diastereomeric ratio. Finally, new chiral chalcogen bonding catalysts were applied but provided only racemic mixtures of the product. 相似文献