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461.
Dr. Joyce C. Leung Dr. Aaron A. Bedermann Prof. Jón T. Njardarson Prof. David A. Spiegel Prof. Graham K. Murphy Dr. Naoto Hama Dr. Barry M. Twenter Dr. Ping Dong Prof. Tatsuya Shirahata Dr. Ivar M. McDonald Dr. Munenori Inoue Dr. Nobuaki Taniguchi Dr. Travis C. McMahon Dr. Christopher M. Schneider Dr. Nancy Tao Prof. Brian M. Stoltz Prof. John L. Wood 《Angewandte Chemie (International ed. in English)》2018,57(7):1991-1994
Described herein is a synthetic strategy for the total synthesis of (±)‐phomoidride D. This highly efficient and stereoselective approach provides rapid assembly of the carbocyclic core by way of a tandem phenolic oxidation/intramolecular Diels–Alder cycloaddition. A subsequent SmI2‐mediated cyclization cascade delivers an isotwistane intermediate poised for a Wharton fragmentation that unveils the requisite bicyclo[4.3.1]decene skeleton and sets the stage for synthesis completion. 相似文献
462.
Tyler A. Sullens Jessica A. Byrd Travis H. Bray 《Journal of solid state chemistry》2006,179(4):1192-1201
Three novel Th(IV) compounds containing heavy oxoanions, Th(SeO3)(SeO4) (1), Th(IO3)2(SeO4)(H2O)3·H2O (2), and Th(CrO4)(IO3)2 (3), have been synthesized under mild hydrothermal conditions. Each of these three distinct structures contain trigonal pyramidal and tetrahedral oxoanions. Compound 1 adopts a three-dimensional structure formed from ThO9 tricapped trigonal prisms, trigonal pyramidal selenite, SeO32-, anions containing Se(IV), and tetrahedral selenate, SeO42-, anions containing Se(VI). The structure of 2 contains two-dimensional porous sheets and occluded water molecules. The Th centers are found as isolated ThO9 tricapped trigonal prisms and are bound by four trigonal pyramidal iodate anions, two tetrahedral selenate anions, and three coordinating water molecules. In the structure of 3, the Th(IV) cations are found as ThO9 tricapped trigonal prisms. Each Th center is bound by six IO31- anions and three CrO42- anions forming a chiral three-dimensional structure. Second-harmonic generation of 532 nm light from 1064 nm radiation by a polycrystalline sample of 3 was observed. Crystallographic data (193 K, MoKα, λ=0.71073): 1; monoclinic, P21/c; , , , β=103.128(1), Z=4, R(F)=2.47% for 91 parameters with 1462 reflections with I>2σ(I); 2, monoclinic, P21/n, , , , β=100.142(2), Z=4, R(F)=4.71% for 158 parameters with 2934 reflections with I>2σ(I); 3, orthorhombic, P212121, , , , Z=4, R(F)=2.04% for 129 parameters with 2035 reflections with I>2σ(I). 相似文献
463.
Bec J. Roldan Travis A. Hammerstad Matthew S. Galliher Mitchell H. Keylor Prof. Dr. Derek A. Pratt Prof. Dr. Corey R. J. Stephenson 《Angewandte Chemie (International ed. in English)》2023,62(34):e202305801
A simple method for accessing trans-2,3-diaryl dihydrobenzofurans is reported. This approach leverages the equilibrium between quinone methide dimers and their persistent radicals. This equilibrium is disrupted by phenols that yield comparatively transient phenoxyl radicals, leading to cross-coupling between the persistent and transient radicals. The resultant quinone methides with pendant phenols rapidly cyclize to form dihydrobenzofurans (DHBs). This putative biomimetic access to dihydrobenzofurans provides superb functional group tolerance and a unified approach for the synthesis of resveratrol-based natural products. 相似文献
464.
Alisina Bazrafshan Travis A. Meyer Hanquan Su Joshua M. Brockman Aaron T. Blanchard Selma Piranej Yuxin Duan Yonggang Ke Khalid Salaita 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(24):9601-9608
Inspired by biological motor proteins, that efficiently convert chemical fuel to unidirectional motion, there has been considerable interest in developing synthetic analogues. Among the synthetic motors created thus far, DNA motors that undertake discrete steps on RNA tracks have shown the greatest promise. Nonetheless, DNA nanomotors lack intrinsic directionality, are low speed and take a limited number of steps prior to stalling or dissociation. Herein, we report the first example of a highly tunable DNA origami motor that moves linearly over micron distances at an average speed of 40 nm/min. Importantly, nanomotors move unidirectionally without intervention through an external force field or a patterned track. Because DNA origami enables precise testing of nanoscale structure-function relationships, we were able to experimentally study the role of motor shape, chassis flexibility, leg distribution, and total number of legs in tuning performance. An anisotropic rigid chassis coupled with a high density of legs maximizes nanomotor speed and endurance. 相似文献
465.
466.
Ivor Smajlagic Brenden Carlson Nicholas Rosano Hayden Foy Travis Dudding 《Tetrahedron》2019,75(51):130757
Charge-enhanced catalysis has emerged as a powerful alternative to the mainstream use of neutral catalysis.With this in mind, we report a catalytic Friedel?Crafts alkylation method catalyzed by a charged thiourea incorporating a cationic cyclopropenium moiety. Mechanistic studies, including density functional theory computational calculations, variable time normalization analysis, and 1H NMR binding studies, collectively reveal this charge-enhanced reactivity proceeds by a dual hydrogen bond-mediated LUMO-lowering mode of substrate activation. Key to these findings is the observed steady-state concentration of the catalyst with in situ derived monomeric catalytic species predominating under the reaction conditions. 相似文献
467.
Colt R. Heathman Travis S. Grimes Santa Jansone-Popova Santanu Roy Vyacheslav S. Bryantsev Peter R. Zalupski 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(10):2545-2555
The thermodynamic influence of a pre-organized N-donor group on the coordination of trivalent actinides and lanthanides by an aqueous aminopolycarboxylate complexant has been investigated. The synthesized reagent, N-2-methylpicolinate-ethylenediamine-N,N′,N′-triacetic acid (EDTA-Mpic), resembles ethylenediamine-N,N,N′,N′-tetraacetic acid (EDTA) with a single acetate pendant arm replaced by a 6-carboxypyridin-2-ylmethyl group. The rigid N-donor picolinate functionality has a profound impact on ligand protonation and trivalent f element complexation equilibria, as demonstrated by potentiometric, spectroscopic, and liquid/liquid metal-partitioning studies as well as by molecular dynamics calculations. Relative to diethylenetriamine-N,N,N′,N′′,N′′-pentaacetic acid (DTPA), the ability to preferentially bind trivalent actinides over trivalent lanthanides was moderately lowered due to the presence of the N-(6-carboxypyridin-2-ylmethyl) substituent. The structural modification substantially amplifies the total ligand acidity of EDTA-Mpic. As a result the complexant sustains the metal complexation and efficient An3+/Ln3+ differentiation in aqueous mixtures of unprecedented acidity for this class of reagents. 相似文献