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21.
Thermally reversible formation of microspheres through non-covalent polymer cross-linking 总被引:3,自引:0,他引:3
Thibault RJ Hotchkiss PJ Gray M Rotello VM 《Journal of the American Chemical Society》2003,125(37):11249-11252
Bis-thymine units were used to noncovalently cross-link a complementary diamidopyridine-functionalized copolymer. Upon combination in noncompetitive solvents, discrete micron-scale spherical aggregates were formed arising from specific three-point polymer-cross-linker hydrogen bonding interactions. The diameter of these microspheres could be controlled through spacer structure. The cross-linking process was fully thermally reversible, with complete dissolution observed at 50 degrees C and reformation of the aggregates upon return to ambient temperature. This process could be repeated multiply, with lower particle dispersity observed arising from the annealing process. 相似文献
22.
Dr. Aurélien Adenot Dr. Lucile Anthore-Dalion Dr. Emmanuel Nicolas Jean-Claude Berthet Dr. Pierre Thuéry Dr. Thibault Cantat 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(72):18047-18053
An air-tolerant Cu-catalyzed sulfonylative Hiyama cross-coupling reaction enabling the formation of diaryl sulfones is described. Starting from aryl silanes, DABSO and aryliodides, the reaction tolerates a large variety of polar functional groups (amines, ketones, esters, aldehydes). Control experiments coupled with DFT calculations shed light on the mechanism, characterized by the formation of a Cu(I)-sulfinate intermediate via fast insertion of a SO2 molecule. 相似文献
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25.
John V. Hanna Dr. Kevin J. Pike Dr. Thibault Charpentier Dr. Thomas F. Kemp Dr. Mark E. Smith Prof. Bryan E. G. Lucier Robert W. Schurko Prof. Lindsay S. Cahill Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(10):3222-3239
A variable B0 field static (broadline) NMR study of a large suite of niobate materials has enabled the elucidation of high‐precision measurement of 93Nb NMR interaction parameters such as the isotropic chemical shift (δiso), quadrupole coupling constant and asymmetry parameter (CQ and ηQ), chemical shift span/anisotropy and skew/asymmetry (Ω/Δδ and κ/ηδ) and Euler angles (α, β, γ) describing the relative orientation of the quadrupolar and chemical shift tensorial frames. These measurements have been augmented with ab initio DFT calculations by using WIEN2k and NMR‐CASTEP codes, which corroborate these reported values. Unlike previous assertions made about the inability to detect CSA (chemical shift anisotropy) contributions from NbV in most oxo environments, this study emphasises that a thorough variable B0 approach coupled with the VOCS (variable offset cumulative spectroscopy) technique for the acquisition of undistorted broad (?1/2?+1/2) central transition resonances facilitates the unambiguous observation of both quadrupolar and CSA contributions within these 93Nb broadline data. These measurements reveal that the 93Nb electric field gradient tensor is a particularly sensitive measure of the immediate and extended environments of the NbV positions, with CQ values in the 0 to >80 MHz range being measured; similarly, the δiso (covering an approximately 250 ppm range) and Ω values (covering a 0 to approximately 800 ppm range) characteristic of these niobate systems are also sensitive to structural disposition. However, their systematic rationalisation in terms of the Nb? O bond angles and distances defining the immediate NbV oxo environment is complicated by longer‐range influences that usually involve other heavy elements comprising the structure. It has also been established in this study that the best computational method(s) of analysis for the 93Nb NMR interaction parameters generated here are the all‐electron WIEN2k and the gauge included projector augmented wave (GIPAW) NMR‐CASTEP DFT approaches, which account for the short‐ and long‐range symmetries, periodicities and interaction‐potential characteristics for all elements (and particularly the heavy elements) in comparison with Gaussian 03 methods, which focus on terminated portions of the total structure. 相似文献
26.
Thibault Damour Axel Kleinschmidt Hermann Nicolai 《Communications in Mathematical Physics》2011,302(3):755-788
In the conjectured correspondence between supergravity and geodesic models on infinite-dimensional hyperbolic coset spaces,
and E
10/K(E
10) in particular, the constraints play a central role. We present a Sugawara-type construction in terms of the E
10 Noether charges that extends these constraints infinitely into the hyperbolic algebra, in contrast to the truncated expressions
obtained in Damour et al. (Class. Quant. Grav. 24:6097, 2007) that involved only finitely many generators. Our extended constraints are associated to an infinite set of roots which are
all imaginary, and in fact fill the closed past light-cone of the Lorentzian root lattice. The construction makes crucial
use of the E
10 Weyl group and of the fact that the E
10 model contains both D = 11 supergravity and D = 10 IIB supergravity. Our extended constraints appear to unite in a remarkable manner the different canonical constraints
of these two theories. This construction may also shed new light on the issue of ‘open constraint algebras’ in traditional
canonical approaches to gravity. 相似文献
27.
Inside Cover: Selective Protein Hyperpolarization in Cell Lysates Using Targeted Dynamic Nuclear Polarization (Angew. Chem. Int. Ed. 36/2016)
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28.
A Bioinspired Molybdenum Complex as a Catalyst for the Photo‐ and Electroreduction of Protons
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Jean‐Philippe Porcher Thibault Fogeron Dr. Maria Gomez‐Mingot Dr. Etienne Derat Lise‐Marie Chamoreau Dr. Yun Li Prof. Marc Fontecave 《Angewandte Chemie (International ed. in English)》2015,54(47):14090-14093
A molybdenum–dithiolene–oxo complex was prepared as a model of some active sites of Mo/W‐dependent enzymes. The ligand, a quinoxaline–pyran‐fused dithiolene, mimics molybdopterin present in these active sites. For the first time, this type of complex was shown to be active as a catalyst for the photoreduction of protons with excellent turnover numbers (500) and good stability in aqueous/organic media and for the electroreduction of protons in acetonitrile with remarkable rate constants (1030 s?1 at ?1.3 V versus Ag/AgCl). DFT calculations provided insight into the catalytic cycle of the reaction, suggesting that the oxo ligand plays a key role in proton exchange. These results provide a basis to optimize this new class of H2‐evolving catalysts. 相似文献
29.
Varin T Schuffenhauer A Ertl P Renner S 《Journal of chemical information and modeling》2011,51(7):1528-1538
Identification of meaningful chemical patterns in the increasing amounts of high-throughput-generated bioactivity data available today is an increasingly important challenge for successful drug discovery. Herein, we present the scaffold network as a novel approach for mapping and navigation of chemical and biological space. A scaffold network represents the chemical space of a library of molecules consisting of all molecular scaffolds and smaller "parent" scaffolds generated therefrom by the pruning of rings, effectively leading to a network of common scaffold substructure relationships. This algorithm provides an extension of the scaffold tree algorithm that, instead of a network, generates a tree relationship between a heuristically rule-based selected subset of parent scaffolds. The approach was evaluated for the identification of statistically significantly active scaffolds from primary screening data for which the scaffold tree approach has already been shown to be successful. Because of the exhaustive enumeration of smaller scaffolds and the full enumeration of relationships between them, about twice as many statistically significantly active scaffolds were identified compared to the scaffold-tree-based approach. We suggest visualizing scaffold networks as islands of active scaffolds. 相似文献
30.
Forensic examinations of ink have been performed since the beginning of the 20th century. Since the 1960s, the International Ink Library, maintained by the United States Secret Service, has supported those analyses. Until 2009, the search and identification of inks were essentially performed manually. This paper describes the results of a project designed to improve ink samples' analytical and search processes. The project focused on the development of improved standardization procedures to ensure the best possible reproducibility between analyses run on different HPTLC plates. The successful implementation of this new calibration method enabled the development of mathematical algorithms and of a software package to complement the existing ink library. 相似文献