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131.
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133.
Dr. Cédric Colomban Anthonio H. Tobing Gourab Mukherjee Dr. Chivukula V. Sastri Dr. Alexander B. Sorokin Dr. Sam P. de Visser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(63):14320-14331
The biodegradation of compounds with C−F bonds is challenging due to the fact that these bonds are stronger than the C−H bond in methane. In this work, results on the unprecedented reactivity of a biomimetic model complex that contains an N-bridged diiron-phthalocyanine are presented; this model complex is shown to react with perfluorinated arenes under addition of H2O2 effectively. To get mechanistic insight into this unusual reactivity, detailed density functional theory calculations on the mechanism of C6F6 activation by an iron(IV)-oxo active species of the N-bridged diiron phthalocyanine system were performed. Our studies show that the reaction proceeds through a rate-determining electrophilic C−O addition reaction followed by a 1,2-fluoride shift to give the ketone product, which can further rearrange to the phenol. A thermochemical analysis shows that the weakest C−F bond is the aliphatic C−F bond in the ketone intermediate. The oxidative defluorination of perfluoroaromatics is demonstrated to proceed through a completely different mechanism compared to that of aromatic C−H hydroxylation by iron(IV)-oxo intermediates such as cytochrome P450 Compound I. 相似文献
134.
Dr. Sam P. de Visser 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(24):5308-5327
Mononuclear iron-containing enzymes are highly versatile oxidants that often react stereospecifically and/or regioselectively with substrates. Combined experimental and computational studies on heme monooxygenases, nonheme iron dioxygenases and halogenases have revealed the intricate details of the second-coordination sphere, which determine this specificity and selectivity. These second-coordination sphere effects originate from the positioning of the substrate and oxidant, which involve the binding of the co-factors and substrate into the active site of the protein. In addition, some enzymes affect the selectivity and reactivity through charge-stabilization from nearby bound cations/anions, an induced electric field or through the positioning of salt bridges and hydrogen-bonding interactions to first-coordination sphere iron ligands and/or the substrate. Examples of all of these second-coordination sphere effects in iron-containing enzymes and how these influence structure and reactivity are given. 相似文献
135.
Stephanie M. Delgado Sam C. P. Norris Andrea M. Kasko 《Journal of polymer science. Part A, Polymer chemistry》2022,60(5):825-841
Hydrogels are attractive materials for generating 4D shapes due to their ability to undergo pronounced volume changes in response to several stimuli, including light. We previously reported shape-changing hydrogels actuated by long-wave UV and visible light in the presence of live cells using poly(ethylene glycol) macromers incorporating different photodegradable ortho-nitrobenzyl (o-NB) groups. In this comprehensive study, we determine the effect of chemical structure of different o-NB macromers (which influences molar absorptivity and rate constant of degradation), composition (macromer weight percent), fabrication design (initial gel thickness) and environment (ionic strength of solution) on light-induced hydrogel folding. We demonstrate successful photopolymerization and subsequent photodegradation of hydrogels, multistep folding, and live-cell encapsulation. This hydrogel system may be useful as new tool in stem cell differentiation and developmental biology research, facilitating the in vitro investigation of processes that are sensitive to both physical and temporal stimuli. 相似文献
136.
Back Cover: Integrated Transmission Electron and Single‐Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle (Angew. Chem. Int. Ed. 1/2018)
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137.
Wiranwetchayan Orawan Ruankham Pipat Promnopas Wonchai Choopun Supab Singjai Pisith Chaipanich Arnon Thongtem Somchai 《Journal of Solid State Electrochemistry》2018,22(8):2531-2543
Journal of Solid State Electrochemistry - A simple and inexpensive sparking method was used to deposit body-centered cubic In2O3 film on TiO2 photoanode for 30–180 min for... 相似文献
138.
Integrated Transmission Electron and Single‐Molecule Fluorescence Microscopy Correlates Reactivity with Ultrastructure in a Single Catalyst Particle
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Frank C. Hendriks Sajjad Mohammadian Dr. Zoran Ristanović Dr. Sam Kalirai Dr. Florian Meirer Prof. Dr. Eelco T. C. Vogt Dr. Pieter C. A. Bruijnincx Prof. Dr. Hans C. Gerritsen Prof. Dr. Bert M. Weckhuysen 《Angewandte Chemie (International ed. in English)》2018,57(1):257-261
Establishing structure–activity relationships in complex, hierarchically structured nanomaterials, such as fluid catalytic cracking (FCC) catalysts, requires characterization with complementary, correlated analysis techniques. An integrated setup has been developed to perform transmission electron microscopy (TEM) and single‐molecule fluorescence (SMF) microscopy on such nanostructured samples. Correlated structure–reactivity information was obtained for 100 nm thin, microtomed sections of a single FCC catalyst particle using this novel SMF‐TEM high‐resolution combination. High reactivity in a thiophene oligomerization probe reaction correlated well with TEM‐derived zeolite locations, while matrix components, such as clay and amorphous binder material, were found not to display activity. Differences in fluorescence intensity were also observed within and between distinct zeolite aggregate domains, indicating that not all zeolite domains are equally active. 相似文献
139.
Keun Sam Jang 《Tetrahedron》2008,64(24):5666-5671
After finding in a previous study that naphthalene and quinoline can react via electrophilic aromatic addition reaction (AdEAr), we applied this to anthracene. When anthracene was reacted with bromine in methanol in the presence of NaHCO3 and pyridine, 9,10-dihydro-9,10-dimethoxyanthracene (2) was obtained in 82% yield in the absence of substitution products or oxidative demethylation products like anthraquinone. The same reaction in ethanol produced 9,10-diethoxy-9,10-dihydroanthracene (9) in much lower yield (45%). In addition, we investigated the reactivity of addition product 2. Treatment of 2 with DDQ in benzene at 65 °C for 12 h produced 9,10-dimethoxyanthracene (3) in 62% yield, and 2 was rapidly transformed to 9-methoxyanthracene (4) in methanolic NaOH in 10 min. Moreover, the acid-catalyzed aromatization of 2 in 1-propanol at 75 °C for 10 min gave 9-n-propoxyanthracene (8) in 65% yield. 相似文献
140.
Yongjin Lee Moon Sam Shin Byoungjo Ha Hwayong Kim 《The Journal of chemical thermodynamics》2008,40(5):741-749
In previous work, we developed the crossover lattice equation of state (xLF EOS) for pure fluids and the xLF EOS yielded the saturated vapour pressure and the density values with a much better accuracy than the classical LF EOS over a wide range. In this work, we extended xLF EOS to fluid mixtures. Classical composition-dependent mixing rules with only adjustable two binary interaction parameters same as the LF EOS are used. A comparison is made upon experimental data for fluids mixtures in the one- and two-phase regions. The xLF EOS shows more improved representations than the LF EOS, especially in the critical region. 相似文献