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411.
Influence of actinic wavelength on properties of light‐cured interpenetrating polymer networks 下载免费PDF全文
Feyza Karasu Caroline Rocco Maxime Lecompère Céline Croutxé‐Barghorn Xavier Allonas Yujing Zhang A. Catarina C. Esteves Leendert G. J. van der Ven Rolf A. T. M. van Benthem Gijsbertus de With 《Journal of polymer science. Part A, Polymer chemistry》2016,54(10):1378-1390
Interpenetrating polymer networks (IPNs) composed of different acrylate/epoxide ratios, were synthesized under UV and visible‐LED curing conditions. The formation of the IPNs was explored in terms of phase separation, polymerization mechanisms, final mechanical properties and surface morphology. For these purpose, we uniquely combined results of miscibility investigations, confocal Raman microscopy, dynamical mechanical analysis and atomic force microscopy. Transparent films were obtained for all compositions and both irradiation sources. The thermo‐mechanical properties of different IPNs were associated to the presence of acrylate‐ or epoxide‐rich phases, as well as, mixed interphases, resulting from the high interpenetration between both networks. Although the final conversions were similar under UV and visible‐LED irradiation, we have found evidence that the visible‐cured samples provide higher IPN homogeneity and lower Tg, for a higher epoxide content. To explain this trend, the mechanisms and sequence of the acrylate or epoxide networks formation, under UV or LED irradiation, is discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1378‐1390 相似文献
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413.
Highly oxygenated cyclohexanes (known as cyclitols or carba-sugars) were synthesized regiospecifically and stereoselectively via a key inverse electron demand Diels–Alder cycloaddition of electron poor 2-pyrones with electron rich tert-butyldimethylsilyl vinyl ether. The resulting [2.2.2]oxabicyclic lactones proved to be versatile synthons; syn-dihydroxylations were achieved with very high stereocontrol, with up to five stereocenters being produced from commercially available or easily prepared planar starting materials. 相似文献
414.
Dr. Maxime Debost Dr. Paul B. Klar Dr. Nicolas Barrier Dr. Edwin B. Clatworthy Dr. Julien Grand Dr. Fabien Laine Dr. Petr Brázda Dr. Lukas Palatinus Dr. Nikolai Nesterenko Dr. Philippe Boullay Dr. Svetlana Mintova 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):23697-23701
Small-pore zeolites such as chabazite (CHA) are excellent candidates for the selective separation of CO2; however, the current synthesis involves several steps and the use of organic structure-directing agent (OSDA), increasing their cost and energy requirements. We report the synthesis of small-pore zeolite crystals (aluminosilicate) with CHA-type framework structure by direct synthesis in a colloidal suspension containing a mixture of inorganic cations only (Na+, K+, and Cs+). The location of CO2 molecules in the host structure was revealed by 3D electron diffraction (3D ED). The high sorption capacity for CO2 (3.8 mmol g−1 at 121 kPa), structural stability and regenerability of the discreate CHA zeolite nanocrystals is maintained for 10 consecutive cycles without any visible degradation. The CHA zeolite (Si:Al=2) reaches an almost perfect CO2 storage capacity (8 CO2 per unit cell) and high selectivity (no CH4 was adsorbed). 相似文献
415.
Dragos Astanei François Faubert Stéphane Pellerin Bogdan Hnatiuc Maxime Wartel 《Plasma Chemistry and Plasma Processing》2018,38(5):1115-1132
The ignition sparks provided by the conventional spark plug do not always ensure a fast and complete combustion of the hydrocarbon-air mixture. For this reason, we offer a new type of plug with a double spark using two simultaneous discharges generated by a pulsed high voltage-power supply. This work presents the comparison of two spark plugs, a classical one and a double spark plug, by analyzing the unburned hydrocarbon gases from the exhaust pipe of the engine. For a first gasoline engine, we measure the oxygen concentration in the exhaust gases with a lambda probe and the unburned hydrocarbon by the use of GC–MS coupled with SPME extraction technique. We can observe a clear decrease of total unburned hydrocarbon (THC). For a second motor test bench, powered with propane, we complete measures in function of air/fuel ratio of the THC, NOx, CO2 and CO. These results confirm that we obtained a better combustion especially for leaner mixtures. 相似文献
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417.
Back Cover: Structural Basis of Microtubule Stabilization by Laulimalide and Peloruside A (Angew. Chem. Int. Ed. 6/2014) 下载免费PDF全文
418.
Well‐Defined Dinuclear Gold Complexes for Preorganization‐Induced Selective Dual Gold Catalysis 下载免费PDF全文
Vincent Vreeken Dr. Daniël L. J. Broere Anne C. H. Jans Marianne Lankelma Prof. Dr. Joost N. H. Reek Dr. Maxime A. Siegler Dr. Jarl Ivar van der Vlugt 《Angewandte Chemie (International ed. in English)》2016,55(34):10042-10046
The synthesis, reactivity, and potential of well‐defined dinuclear gold complexes as precursors for dual gold catalysis are explored. Using the preorganizing abilities of the ditopic PNHPiPr ( LH ) ligand, dinuclear AuI–AuI complex 1 and mixed‐valent AuI–AuIII complex 2 provide access to structurally characterized chlorido‐bridged cationic species 3 and 4 upon halide abstraction. For 2 , this transformation involves unprecedented two‐electron oxidation of the redox‐active ligand, generating a highly rigidified environment for the Au2 core. Facile reaction with phenylacetylene affords the σ,π‐activated phenylacetylide complex 5 . When applied in the dual gold heterocycloaddition of a urea‐functionalized alkyne, well‐defined precatalyst 3 provides high regioselectivities for the anti‐Markovnikov product, even at low catalyst loadings, and outperforms common mononuclear AuI systems. This proof‐of‐concept demonstrates the benefit of preorganization of two gold centers to enforce selective non‐classical σ,π‐activation with bifunctional substrates. 相似文献
419.
Maxime Daigle Audrey Picard‐Lafond Eliane Soligo Prof. Jean‐François Morin 《Angewandte Chemie (International ed. in English)》2016,55(6):2042-2047
Novel nanographenes were prepared by a photochemical cyclodehydrochlorination (CDHC) reaction. Chlorinated precursors were irradiated in acetone in the presence of a base or in pure benzene and underwent multiple (up to four) regioselective cyclization reactions to provide rigid π‐conjugated molecules. Pure compounds were recovered in good yields by simple filtration at the end of the reaction. The CDHC reaction showed compatibility with both electron‐poor and electron‐rich substrates, thus allowing the synthesis of pyridine‐ and thiophene‐fused nanographenes. It also enabled the synthesis of sterically hindered contorted π‐conjugated molecules without causing full aromatization. A kinetic study showed that the CDHC reaction under the conditions used is a very fast process, and some reactions are completed within minutes. The CDHC reaction thus shows great potential as an alternative to other reactions involving harsher conditions for the preparation of nanographenes. 相似文献
420.
Maxime Beau Sunhee Lee Sooyeon Kim Won‐Sik Han Olivier Jeannin Marc Fourmigu Emmanuel Aubert Enrique Espinosa Ie‐Rang Jeon 《Angewandte Chemie (International ed. in English)》2021,60(1):366-370
Crystal engineering based on σ‐hole interactions is an emerging approach for realization of new materials with higher complexity. Neutral inorganic clusters derived from 1,2‐dicarba‐closo‐dodecaborane, substituted with ‐SeMe, ‐TeMe, and ‐I moieties on both skeletal carbon vertices are experimentally demonstrated herein as outstanding chalcogen‐ and halogen‐bond donors. In particular, these new molecules strongly interact with halide anions in the solid‐state. The halide ions are coordinated by one or two donor groups (μ1‐ and μ2‐coordinations), to stabilize a discrete monomer or dimer motifs to 1D supramolecular zig‐zag chains. Crucially, the observed chalcogen bond and halogen bond interactions feature remarkably short distances and high directionality. Electrostatic potential calculations further demonstrate the efficiency of the carborane derivatives, with Vs,max being similar or even superior to that of reference organic halogen‐bond donors, such as iodopentafluorobenzene. 相似文献