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81.
82.
Using the state-of-the-art ab initio electronic structure calculations, we explain why alpha-Po prefers the simple cubic structure (it is due to the relativistic mass-velocity and Darwin terms), elucidate its extreme elastic anisotropy (this is an intrinsic property of the simple cubic crystal structure), and predict a transformation to a mixture of two trigonal structures at pressures of 1-3 GPa. 相似文献
83.
Porous and Shape‐Anisotropic Single Crystals of the Semiconductor Perovskite CH3NH3PbI3 from a Single‐Source Precursor 下载免费PDF全文
Tom Kollek Dominik Gruber Julia Gehring Eugen Zimmermann Prof. Dr. Lukas Schmidt‐Mende Prof. Dr. Sebastian Polarz 《Angewandte Chemie (International ed. in English)》2015,54(4):1341-1346
Significant progress in solar‐cell research is currently made by the development of metal–organic perovskites (MOPs) owing to their superior properties, such as high absorption coefficients and effective transport of photogenerated charges. As for other semiconductors, it is expected that the properties of MOPs may be significantly improved by a defined nanostructure. However, their chemical sensitivity (e.g., towards hydrolysis) prohibits the application of methods already known for the synthesis of other nanomaterials. A new and general method for the synthesis of various (CH3NH3)PbI3 nanostructures from a novel single‐source precursor is presented. Nanoporous MOP single crystals are obtained by a crystal‐to‐crystal transformation that is accompanied by spinodal demixing of the triethylene glycol containing precursor structure. Selective binding of a capping agent can be used to tune the particle shape of the MOP nanocrystals. 相似文献
84.
Dominik Grtner Andr Luiz Stein Sabine Grupe Johannes Arp Axel JacobivonWangelin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(36):10691-10695
Stable C O linkages are generally unreactive in cross‐coupling reactions which mostly employ more electrophilic halides or activated esters (triflates, tosylates). Acetates are cheap and easily accessible electrophiles but have not been used in cross‐couplings because the strong C O bond and high propensity to engage in unwanted acetylation and deprotonation. Reported herein is a selective iron‐catalyzed cross‐coupling of diverse alkenyl acetates, and it operates under mild reaction conditions (0 °C, 2 h) with a ligand‐free catalyst (1–2 mol %). 相似文献
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Dehydrogenative TEMPO‐Mediated Formation of Unstable Nitrones: Easy Access to N‐Carbamoyl Isoxazolines 下载免费PDF全文
Andrea Gini Marwin Segler Dominik Kellner Prof. Dr. Olga García Mancheño 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(34):12053-12060
N‐carbamoyl nitrones represent an important class of reagents for the synthesis of a variety of natural and biologically active compounds. These compounds are generally converted into valuable 4‐isoxazolines upon cyclization reaction with dipolarophiles. However, these types of N‐protected nitrones are highly unstable, which limits their synthesis, storage and practical use, enforcing alternative lengthy or elaborated synthetic routes. In this work, a 2,2,6,6‐tetramethylpiperidin‐1‐oxyl (TEMPO)‐mediated formal “dehydrogenation” of N‐protected benzyl‐, allyl‐ and alkyl‐substituted hydroxylamines followed by in situ trapping of the generated unstable nitrones into N‐carbamoyl 4‐isoxazolines is presented. A plausible mechanism is also proposed, in which the dipolarophile shows an important assistant role in the generation of the active nitrone intermediate. This simple protocol avoids the problematic isolation of N‐carbamoyl protected nitrones, providing new synthetic possibilities in isoxazoline chemistry. 相似文献
89.
We explore recurrence properties arising from dynamical approach to the van der Waerden theorem and similar combinatorial problems. We describe relations between these properties and study their consequences for dynamics. In particular, we present a measure-theoretical analog of a result of Glasner on multi-transitivity of topologically weakly mixing minimal maps. We also obtain a dynamical proof of the existence of a C-set with zero Banach density. 相似文献
90.
This is a survey on recent progress concerning maximal regularity of non-autonomous equations governed by time-dependent forms on a Hilbert space. It also contains two new results showing the limits of the theory. 相似文献