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71.
Regioselective Ring‐Opening Polymerization of a Polyhydroxycarboxylic Acid for the Synthesis of a Nanoscale Carrier Material with pH‐Dependent Stability and Sustained Drug Release 下载免费PDF全文
Dipl.‐Chem. Alexander Ewe Dr. Anita Jansen de Salazar Dipl.‐Phys. Katharina Lemmnitzer Michael Marsch Prof. Dr. Achim Aigner Prof. Dr. Armin Geyer 《Angewandte Chemie (International ed. in English)》2015,54(21):6364-6369
Synthetic polyesters are usually composed of monohydroxycarboxylic acids to avoid the problem of regioselectivity during ring‐opening polymerization. In contrast, the linear polyester BICpoly contains four secondary OH groups and is nevertheless esterified regioselectively at only one of these positions. Neither the synthesis of the tricyclic monomers nor the ring‐opening polymerization requires protecting groups, making BICpoly an attractive novel and biocompatible polymer. BICpoly nanoparticles can be loaded with low‐molecular weight drugs or coated onto surfaces as thin films. The release of loaded compounds makes BICpoly an attractive depot for drug release, as shown herein by loading BICpoly with dyes or the cytostatic drug doxorubicin. BICpoly is distinguishable from other polymers by its characteristic pH‐dependent degradation. 相似文献
72.
M.Sc. Katharina Heller M.Sc. Philipp Ochtrop M.Sc. Michael F. Albers Florian B. Zauner Prof. Dr. Aymelt Itzen Prof. Dr. Christian Hedberg 《Angewandte Chemie (International ed. in English)》2015,54(35):10327-10330
We present a new protein labeling method based on the covalent enzymatic phosphocholination of a specific octapeptide amino acid sequence in intact proteins. The bacterial enzyme AnkX from Legionella pneumophila has been established to transfer functional phosphocholine moieties from synthetically produced CDP‐choline derivatives to N‐termini, C‐termini, and internal loop regions in proteins of interest. Furthermore, the covalent modification can be hydrolytically removed by the action of the Legionella enzyme Lem3. Only a short peptide sequence (eight amino acids) is required for efficient protein labeling and a small linker group (PEG‐phosphocholine) is introduced to attach the conjugated cargo. 相似文献
73.
Fragment‐Based De Novo Design Reveals a Small‐Molecule Inhibitor of Helicobacter Pylori HtrA 下载免费PDF全文
Thomas P. Schmidt Dr. Manja Böhm Katharina Stutz Daniel Reker Dr. Bernhard Pfeiffer Prof. Dr. Karl‐Heinz Altmann Prof. Dr. Steffen Backert Prof. Dr. Silja Wessler Prof. Dr. Gisbert Schneider 《Angewandte Chemie (International ed. in English)》2015,54(35):10244-10248
Sustained identification of innovative chemical entities is key for the success of chemical biology and drug discovery. We report the fragment‐based, computer‐assisted de novo design of a small molecule inhibiting Helicobacter pylori HtrA protease. Molecular binding of the designed compound to HtrA was confirmed through biophysical methods, supporting its functional activity in vitro. Hit expansion led to the identification of the currently best‐in‐class HtrA inhibitor. The results obtained reinforce the validity of ligand‐based de novo design and binding‐kinetics‐guided optimization for the efficient discovery of pioneering lead structures and prototyping drug‐like chemical probes with tailored bioactivity. 相似文献
74.
Heterophase Photocatalysts from Water‐Soluble Conjugated Polyelectrolytes: An Example of Self‐Initiation under Visible Light 下载免费PDF全文
Saman Ghasimi Dr. Simon Prescher Zi Jun Wang Prof. Katharina Landfester Dr. Jiayin Yuan Dr. Kai A. I. Zhang 《Angewandte Chemie (International ed. in English)》2015,54(48):14549-14553
We herein report a new design route to stable, heterophase photocatalysts, which function as highly dispersible conjugated polymer nanoparticles and porous monoliths under visible light in aqueous medium. They were constructed by attachment of the ionic‐liquid species 1‐alkyl‐3‐vinylimidazolium bromide onto the side chains of a photoactive polymer. The structure configuration allows not only photocatalysis in aqueous environment but also a unique self‐initiation radical cross‐linking process to transform the water‐soluble photoactive polymer into a heterophase system, either as nanoparticles or a porous monolith. High photocatalytic activity and reusability of the heterophase system were demonstrated in the degradation of organic dyes and reduction of CrVI into CrIII in water under visible‐light irradiation. 相似文献
75.
Ultraviolet Absorption Induces Hydrogen‐Atom Transfer in G⋅C Watson–Crick DNA Base Pairs in Solution 下载免费PDF全文
Dr. Katharina Röttger Hugo J. B. Marroux Dr. Michael P. Grubb Philip M. Coulter Hendrik Böhnke Dr. Alexander S. Henderson Dr. M. Carmen Galan Prof. Friedrich Temps Prof. Andrew J. Orr‐Ewing Dr. Gareth M. Roberts 《Angewandte Chemie (International ed. in English)》2015,54(49):14719-14722
Ultrafast deactivation pathways bestow photostability on nucleobases and hence preserve the structural integrity of DNA following absorption of ultraviolet (UV) radiation. One controversial recovery mechanism proposed to account for this photostability involves electron‐driven proton transfer (EDPT) in Watson–Crick base pairs. The first direct observation is reported of the EDPT process after UV excitation of individual guanine–cytosine (G?C) Watson–Crick base pairs by ultrafast time‐resolved UV/visible and mid‐infrared spectroscopy. The formation of an intermediate biradical species (G[?H]?C[+H]) with a lifetime of 2.9 ps was tracked. The majority of these biradicals return to the original G?C Watson–Crick pairs, but up to 10 % of the initially excited molecules instead form a stable photoproduct G*?C* that has undergone double hydrogen‐atom transfer. The observation of these sequential EDPT mechanisms across intermolecular hydrogen bonds confirms an important and long debated pathway for the deactivation of photoexcited base pairs, with possible implications for the UV photochemistry of DNA. 相似文献
76.
Spontaneous Formation of Microgroove Arrays on the Surface of p‐Type Porous Silicon Induced by a Turing Instability in Electrochemical Dissolution 下载免费PDF全文
Prof. Dr. Kazuhiro Fukami Tomoko Urata Prof. Dr. Katharina Krischer Prof. Dr. Naoya Nishi Prof. Dr. Tetsuo Sakka Dr. Atsushi Kitada Prof. Dr. Kuniaki Murase 《Chemphyschem》2015,16(8):1613-1618
Self‐organization plays an imperative role in recent materials science. Highly tunable, periodic structures based on dynamic self‐organization at micrometer scales have proven difficult to design, but are desired for the further development of micropatterning. In the present study, we report a microgroove array that spontaneously forms on a p‐type silicon surface during its electrodissolution. Our detailed experimental results suggest that the instability can be classified as Turing instability. The characteristic scale of the Turing‐type pattern is small compared to self‐organized patterns caused by the Turing instabilities reported so far. The mechanism for the miniaturization of self‐organized patterns is strongly related to the semiconducting property of silicon electrodes as well as the dynamics of their surface chemistry. 相似文献
77.
Controlled Formation of Polymer Nanocapsules with High Diffusion‐Barrier Properties and Prediction of Encapsulation Efficiency 下载免费PDF全文
Ines Hofmeister Prof. Dr. Katharina Landfester Dr. Andreas Taden 《Angewandte Chemie (International ed. in English)》2015,54(1):327-330
Polymer nanocapsules with high diffusion‐barrier performance were designed following simple thermodynamic considerations. Hindered diffusion of the enclosed material leads to high encapsulation efficiencies (EEs), which was demonstrated based on the encapsulation of highly volatile compounds of different chemical natures. Low interactions between core and shell materials are key factors to achieve phase separation and a high diffusion barrier of the resulting polymeric shell. These interactions can be characterized and quantified using the Hansen solubility parameters. A systematic study of our copolymer system revealed a linear relationship between the Hansen parameter for hydrogen bonding (δh) and encapsulation efficiencies which enables the prediction of encapsulated amounts for any material. Furthermore EEs of poorly encapsulated materials can be increased by mixing them with a mediator compound to give lower overall δh values. 相似文献
78.
Sonja Kracht Dr. Matthias Messerer Dr. Matthieu Lang Dr. Sonja Eckhardt Dr. Miriam Lauz Prof. Bernard Grobéty Prof. Katharina M. Fromm Prof. Bernd Giese 《Angewandte Chemie (International ed. in English)》2015,54(10):2912-2916
Some microorganisms perform anaerobic mineral respiration by reducing metal ions to metal nanoparticles, using peptide aggregates as medium for electron transfer (ET). Such a reaction type is investigated here with model peptides and silver as the metal. Surprisingly, Ag+ ions bound by peptides with histidine as the Ag+‐binding amino acid and tyrosine as photoinducible electron donor cannot be reduced to Ag nanoparticles (AgNPs) under ET conditions because the peptide prevents the aggregation of Ag atoms to form AgNPs. Only in the presence of chloride ions, which generate AgCl microcrystals in the peptide matrix, does the synthesis of AgNPs occur. The reaction starts with the formation of 100 nm Ag@AgCl/peptide nanocomposites which are cleaved into 15 nm AgNPs. This defined transformation from large nanoparticles into small ones is in contrast to the usually observed Ostwald ripening processes and can be followed in detail by studying time‐resolved UV/Vis spectra which exhibit an isosbestic point. 相似文献
79.
Inside Cover: Spontaneous Formation of Microgroove Arrays on the Surface of p‐Type Porous Silicon Induced by a Turing Instability in Electrochemical Dissolution (ChemPhysChem 8/2015) 下载免费PDF全文
80.
Patrick C. Dolder Matthias E. Liechti Katharina M. Rentsch 《Analytical and bioanalytical chemistry》2015,407(6):1577-1584