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Jing?Ye Stéphane?AndreEmail authorView authors OrcID profile Laurent?Farge Nicolas?Louvet 《Rheologica Acta》2018,57(6-7):505-520
Micromechanical deformation phenomena such as those leading to macroscopic viscoelastic and plastic behavior must be studied from a thermodynamic viewpoint, as they induce complex and partly irreversible heat effects. Calorimetric measurements of the intrinsic volumetric thermomechanical heat sources (THS) activated in the material bulk during mechanical loads can produce valuable information with respect to that aim. They can be based on infrared imaging if submitted to inverse algorithms that allow a correct reconstruction of THS to be produced. Here, an inverse method relying on a diffusion-advection heat transfer model is applied to experimental temperature maps recorded during tensile tests. These are made on a semi-crystalline polymer that shows a strong development of plastic instabilities. Along with simultaneous kinematic observables produced with a digital image correlation system, the competition between advection and diffusion phenomena may be clearly established. 1-D profiles of the reconstructed THS and measured strain rates illustrate clearly that thermomechanical effects associated with necking onset and propagation follow the kinematic variable in a rather direct manner. Finally, we show for tensile experiments that THS estimations lead to analyze plasticity as a rheological behavior controlled by the flow stress, responsible of necking development and propagation. 相似文献
3.
Heng Zhang Fangfang Chen Oier Lakuntza Uxue Oteo Lixin Qiao Maria Martinez‐Ibaez Haijin Zhu Javier Carrasco Maria Forsyth Michel Armand 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(35):12198-12203
Suppressing the mobility of anionic species in polymer electrolytes (PEs) is essential for mitigating the concentration gradient and internal cell polarization, and thereby improving the stability and cycle life of rechargeable alkali metal batteries. Now, an ether‐functionalized anion (EFA) is used as a counter‐charge in a lithium salt. As the salt component in PEs, it achieves low anionic diffusivity but sufficient Li‐ion conductivity. The ethylene oxide unit in EFA endows nanosized self‐agglomeration of anions and trapping interactions between the anions and its structurally homologous matrix, poly(ethylene oxide), thus suppressing the mobility of negative charges. In contrast to previous strategies of using anion traps or tethering anions to a polymer/inorganic backbone, this work offers a facile and elegant methodology on accessing selective and efficient Li‐ion transport in PEs and related electrolyte materials (for example, composites and hybrid electrolytes). 相似文献
4.
Alia Jouhara Eric Quarez Franck Dolhem Michel Armand Nicolas Dupr Philippe Poizot 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(44):15827-15831
The ever‐increasing demand for rechargeable batteries induces significant pressure on the worldwide metal supply, depleting resources and increasing costs and environmental concerns. In this context, developing the chemistry of anion‐inserting electrode organic materials could promote the fabrication of molecular (metal‐free) rechargeable batteries. However, few examples have been reported because little effort has been made to develop such anionic‐ion batteries. Here we show the design of two anionic host electrode materials based on the N‐substituted salts of azaaromatics (zwitterions). A combination of NMR, EDS, FTIR spectroscopies coupled with thermal analyses and single‐crystal XRD allowed a thorough structural and chemical characterization of the compounds. Thanks to a reversible electrochemical activity located at an average potential of 2.2 V vs. Li+/Li, the coupling with dilithium 2,5‐(dianilino)terephthalate (Li2DAnT) as the positive electrode enabled the fabrication of the first all‐organic anionic rechargeable batteries based on crystallized host electrode materials capable of delivering a specific capacity of ≈27 mAh/gelectrodes with a stable cycling over dozens of cycles (≈24 Wh/kgelectrodes). 相似文献
5.
Maxime Jarret Victor Turpin Aurlien Tap Jean‐Franois Gallard Cyrille Kouklovsky Erwan Poupon Guillaume Vincent Laurent Evanno 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(29):9966-9970
Reported is the enantioselective total syntheses of mavacuran alkaloids, (+)‐taberdivarine H, (+)‐16‐hydroxymethyl‐pleiocarpamine, and (+)‐16‐epi‐pleiocarpamine, and their postulated biosynthetic precursor 16‐formyl‐pleiocarpamine. This family of monoterpene indole alkaloids is a target of choice since some of its members are subunits of intricate bisindole alkaloids such as bipleiophylline. Inspired by the biosynthetic hypothesis, an oxidative coupling approach from the geissoschizine framework to form the N1?C16 bond was explored. Quaternization of the aliphatic nitrogen center was key to achieving the oxidative coupling induced by KHMDS/I2 as it masks the nucleophilicity of the aliphatic nitrogen center and locks in the required cis conformation. 相似文献
6.
Hassan Osseili Khai‐Nghi Truong Thomas P. Spaniol Laurent Maron Ulli Englert Jun Okuda 《Angewandte Chemie (International ed. in English)》2019,58(6):1833-1837
Facile α‐H elimination from tetrakis(trimethylsilylmethyl)titanium precursors to give adducts of (alkylidene)bis(alkyl)titanium complexes is induced by light alkali metal amides of the NNNN‐type macrocyclic anionic ligand Me3TACD [(Me3TACD)H=1,4,7‐trimethyl‐1,4,7,10‐tetraazacyclododecane]. In the crystal, the alkali metal interacts with the carbene carbon atom or with the CH2 group of the trimethylsilymethyl ligand. The nucleophilic character of the carbene carbon atom was shown by the reaction with benzophenone and terminal acetylenes. 相似文献
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Corinne Rondeau-Mouro Mireille Cambert Laurent Blondel Yves Diascorn Léo Mbaya Nor Nadiah Binti Ahmad Nazari Sarah Helary Tiphaine Lucas 《Magnetic resonance in chemistry : MRC》2022,60(7):678-691
A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample. 相似文献
10.
Matveev Vladimir B. Semenov-Tian-Shansky Michel 《Letters in Mathematical Physics》2019,109(6):1269-1270
Letters in Mathematical Physics - 相似文献