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881.
pH‐Responsive Hybrid Organic–Inorganic Ruthenium Nanoparticles for Controlled Release of Doxorubicin 下载免费PDF全文
Hana Buchtelova Vladislav Strmiska Simona Dostalova Petr Michalek Sona Krizkova Pavel Kopel David Hynek Lukas Richtera Vojtech Adam Zbynek Heger 《Particle & Particle Systems Characterization》2017,34(11)
The current study aims at preparing biocompatible hybrid organic–inorganic ruthenium core–shell nanostructures (RuNPs) coated with polyvinylpyrrolidone (PVP) and polyoxyethylene stearate (POES). Thereafter, the core/shell RuNPs are loaded with doxorubicin (to form RuPDox) with a loading efficiency > 60%. RuPDox possesses exceptional stability and pH‐responsive release kinetics with approx. 50% release of doxorubicin at up to 1 h exposure to an acidic endosomal environment. The cytotoxic effects of RuPDox are tested in vitro against breast cancer (MDA‐MB‐231), ovarian cancer (A2780), and neuroblastoma (UKF‐NB‐4) cells. Notably, although RuNPs have slight cytotoxicity only, RuPDox causes a synergistic enhancement of cytotoxicity when compared to free doxorubicin. Significant increase in free radicals formation, enhanced activity of executioner caspases 3/7, and higher expression of p53 and metallothionein is further identified due to the RuPDox treatment. Single‐cell gel electrophoresis reveals no additional contribution of RuNPs to genotoxicity of doxorubicin. Moreover, RuPDox promotes significantly increased stability of doxorubicin in human plasma and pronounced hemocompatibility assayed on human red blood cells. The results imply a high potential of biocompatible hybrid RuNPs with PVP‐POES shell as versatile nanoplatforms to enhance the efficiency of cancer treatment. 相似文献
882.
We show that strong clustering of links in complex networks, i.e., a high probability of triadic closure, can induce a localization-delocalization quantum phase transition (Anderson-like transition) of coherent excitations. For example, the propagation of light wave packets between two distant nodes of an optical network (composed of fibers and beam splitters) will be absent if the fraction of closed triangles exceeds a certain threshold. We suggest that such an experiment is feasible with current optics technology. We determine the corresponding phase diagram as a function of clustering coefficient and disorder for scale-free networks of different degree distributions P(k) approximately k;{-lambda}. Without disorder, we observe no phase transition for lambda<4, a quantum transition for lambda>4, and an additional distinct classical transition for lambda>4.5. Disorder reduces the critical clustering coefficient such that phase transitions occur for smaller lambda. 相似文献
883.
This article points at some critical issues which are connected with the theoretical formulation of the thermodynamics of solid–fluid mixtures of frictional materials. It is our view that a complete thermodynamic exploitation of the second law of thermodynamics is necessary to obtain the proper parameterizations of the constitutive quantities in such theories. These issues are explained in detail in a recently published book by Schneider and Hutter (Solid–Fluid Mixtures of Frictional Materials in Geophysical and Geotechnical Context, 2009), which we wish to advertize with these notes. The model is a saturated mixture of an arbitrary number of solid and fluid constituents which may be compressible or density preserving, which exhibit visco-frictional (visco-hypoplastic) behavior, but are all subject to the same temperature. Mass exchange between the constituents may account for particle size separation and phase changes due to fragmentation and abrasion. Destabilization of a saturated soil mass from the pre- and the post-critical phases of a catastrophic motion from initiation to deposition is modeled by symmetric tensorial variables which are related to the rate independent parts of the constituent stress tensors. 相似文献
884.
Lukas J. Hilpert Simon V. Sieger Alexander M. Haydl Bernhard Breit 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3416-3419
A complementing Pd‐ and Rh‐catalyzed dynamic kinetic resolution (DKR) of racemic allenes leading to N‐allylated pyrazoles is described. Such compounds are of enormous interest in medicinal chemistry as certified drugs and potential drug candidates. The new methods feature high chemo‐, regio‐ and enantioselectivities aside from displaying a broad substrate scope and functional group compatibility. A mechanistic rational accounting for allene racemization and trans‐alkene selectivity is discussed. 相似文献
885.
886.
Guodong Zhang Zhiyong Hu Florian Belitz Yang Ou Nico Pirkl Lukas J. Gooßen 《Angewandte Chemie (International ed. in English)》2019,58(19):6435-6439
In the presence of a [Cp*RhCl2]2 catalyst, the Lewis acid In(OTf)3, and the mild base Na2CO3, aromatic carboxylates and α,β‐unsaturated ketones undergo a unique hydroarylation/Claisen/retro‐Claisen process to give the corresponding indanones. In this carboxylate‐directed ortho‐C?H annelation, the C?COR bond of the ketone and the CO?OH group of the aromatic carboxylate are cleaved, and the hydroxy group is transferred from the aromatic to the aliphatic acyl residue. This reactivity is synthetically useful, particularly when starting from cyclic ketones, which are converted into indanones bearing aliphatic carboxylate side chains, thus greatly increasing the molecular complexity of aromatic carboxylates in a single step. 相似文献
887.
Cedric J. Stress Basilius Sauter Lukas A. Schneider Timothy Sharpe Dennis Gillingham 《Angewandte Chemie (International ed. in English)》2019,58(28):9570-9574
Here we show a seven‐step chemical synthesis of a DNA‐encoded macrocycle library (DEML) on DNA. Inspired by polyketide and mixed peptide‐polyketide natural products, the library was designed to incorporate rich backbone diversity. Achieving this diversity, however, comes at the cost of the custom synthesis of bifunctional building block libraries. This study outlines the importance of careful retrosynthetic design in DNA‐encoded libraries, while revealing areas where new DNA synthetic methods are needed. 相似文献
888.
Philip Weber Thorsten Scherpf Ilja Rodstein Dominik Lichte Lennart T. Scharf Lukas J. Gooßen Viktoria H. Gessner 《Angewandte Chemie (International ed. in English)》2019,58(10):3203-3207
Ylide‐functionalized phosphine ligands (YPhos) were rationally designed to fit the requirements of Buchwald–Hartwig aminations at room temperature. This ligand class combines a strong electron‐donating ability comparable to NHC ligands with high steric demand similar to biaryl phosphines. The active Pd species are stabilized by agostic C?H???Pd rather than by Pd–arene interactions. The practical advantage of YPhos ligands arises from their easy and scalable synthesis from widely available, inexpensive starting materials. Benchmark studies showed that YPhos‐Pd complexes are superior to the best‐known phosphine ligands in room‐temperature aminations of aryl chlorides. The utility of the catalysts was demonstrated by the synthesis of various arylamines in high yields within short reaction times. 相似文献
889.
Chiara Mazzoni Rasmus Due Jacobsen Jacob Mortensen Jacob Rune Jrgensen Lukas Vaut Jette Jacobsen Carsten Gundlach Anette Müllertz Line Hagner Nielsen Anja Boisen 《Macromolecular bioscience》2019,19(5)
Oral delivery of proteins and peptides is one of the main challenges in pharmaceutical drug development. Microdevices have the possibility to protect the therapeutics until release is desired, avoiding losses by degradation. One type of microdevice is polymeric microcontainers. In this study, lysozyme is chosen as model protein and loaded into microcontainers with the permeation enhancer sodium decanoate (C10). The loaded microcontainers are sealed and functionalized by applying polymeric lids onto the cavity of the devices. The first lid is poly(lactic‐co‐glycolic) acid (PLGA) and on top of this either polyethylene glycol (PEG) or chitosan is applied (PLGA+PEG or PLGA+chitosan, respectively). The functionalization is evaluated in vitro for morphology, drug release, and mucoadhesive properties. These are coupled with in vitro and ex vivo studies using Caco‐2 cells, Caco‐2/HT29‐MTX‐E12 co‐cultures, and porcine intestinal tissue. PLGA+chitosan shows slower release compared to PLGA+PEG or only PLGA in buffer and the transport of lysozyme across cell cultures is not enhanced compared to the bulk powder. Microcontainers coated with chitosan or PEG demonstrate a three times stronger adhesion during ex vivo mucoadhesion studies compared to samples without coatings. Altogether, functionalized microcontainers with mucoadhesive properties and tunable release for oral protein delivery are developed and characterized. 相似文献
890.
Markus Nentwig Dr. Simon D. Kloß Dr. Lukas Neudert Lucien Eisenburger Prof. Dr. Wolfgang Schnick Prof. Dr. Oliver Oeckler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(63):14382-14387
The lanthanum oxonitridophosphate La21P40O46N57 was synthesized by high-pressure metathesis from partially hydrolysed LiPN2 and LaCl3 at 750–950 °C and 7–9 GPa. The combination of transmission electron microscopy (TEM) and diffraction using microfocused synchrotron radiation revealed a monoclinic crystal structure (space group P21/n, a=14.042(4), b=7.084(3), c=41.404(10) Å, β=97.73(3)° and Z=2), which is characterized by loop-branched 21 member single chains of P(O,N)4 tetrahedra that extend along [2 0 1]. These chains are related to the loop-branched dreier single chains with dreier-ring loops in stillwellite (CeBSiO5). In La21P40O46N57, these chains are characterized by a complex long-periodic conformation and exhibit disorder that involves La/N and P split positions. This is an extraordinarily long periodicity with respect to branched single chains of tetrahedra. La21P40O46N57 constitutes the first rare-earth oxonitridophosphate exhibiting a chain structure. Single-crystal data are consistent with electron and powder X-ray diffraction. 相似文献