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991.
Dr. Jacy K. Conrad Prof. Aliaksandra Lisouskaya Prof. Stephen P. Mezyk Prof. David M. Bartels 《Chemphyschem》2023,24(24):e202300465
The reactivity of chromium(III) species with the major oxidizing and reducing radiolysis products of water was investigated in aqueous solutions at temperatures up to 150 °C. The reaction between the hydrated electron (eaq−) and Cr(III) species showed a positive temperature dependence over this temperature range. The reaction was also studied in pH 2.5 and 3.5 solutions for the first time. This work also studied the reaction between acidic Cr(III) species and the hydroxyl radical (⋅OH). It was found that Cr3+ did not react significantly with the ⋅OH radical, but the first hydrolysis species, Cr(OH)2+, did with a rate coefficient of k= (7.2±0.3)×108 M−1 s−1 at 25 °C. The oxidation of Cr(OH)2+ by the ⋅OH radical formed an absorbing product species that ultimately oxidized to give Cr(VI). These newly measured reaction rates allow for the development of improved models of aqueous chromium speciation for the effective remediation of liquid high-level nuclear waste via vitrification processes. 相似文献
992.
Zih-Yu Lin Dr. Jiaonan Sun Dr. Stephen B. Shiring Prof. Letian Dou Prof. Brett M. Savoie 《Angewandte Chemie (International ed. in English)》2023,62(33):e202305298
Two-dimensional (2D) halide perovskites are an attractive class of hybrid perovskites that have additional optoelectronic tunability due to their accommodation of relatively large organic ligands. Nevertheless, contemporary ligand design depends on either expensive trial-and-error testing of whether a ligand can be integrated within the lattice or conservative heuristics that unduly limit the scope of ligand chemistries. Here, the structural determinants of stable ligand incorporation within Ruddlesden-Popper (RP) phase perovskites are established by molecular dynamics (MD) simulations of over ten-thousand RP-phase perovskites and training of machine learning classifiers capable of predicting structural stability based solely on generalizable ligand features. The simulation results show near-perfect predictions of positive and negative literature examples, predict trade-offs between several ligand features and stability, and ultimately predict an inexhaustibly large 2D-compatible ligand design-space. 相似文献
993.
Yuchu Liu Huanyu Lei Qing-Yun Guo Xianyou Liu Xinghan Li Yuean Wu Weiyi Li Wei Zhang Geng Xin Liu Xiao-Yun Yan Stephen Z.D.Cheng 《高分子科学》2023,41(5):607-620
The construction of complex superlattices using homogenous soft matter has great potential for the bottom-up fabrication of complex, nanoscale structures. This topic is not only interested in scientific exploring for new concepts of supramolecular crystals with nanometer in sizes, which is about thousand times larger in volumes than those of normal crystals, but also practically important to provide construction principles of metamaterials which are artificially structured materials for controll... 相似文献
994.
A series of commercial monomeric and polymeric C(18), C(27), and C(30) stationary phases were compared with immobilized poly(ethylene-co-acrylic acid) stationary phases synthesized in-house. The columns were characterized on the basis of methylene selectivity, silanol activity, metal activity, pore size, shape selectivity, and the ability to separate tocopherol isomers and carotenoid isomers. Monomeric and polymeric C(30) phases were shown to yield excellent separations of the tocopherol isomers while the polymeric C(30) and polyethylene phases were more appropriate to the separation of carotenoids. 相似文献
995.
Ronson TK Lazarides T Adams H Pope SJ Sykes D Faulkner S Coles SJ Hursthouse MB Clegg W Harrington RW Ward MD 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(36):9299-9313
The complexes [Pt(bipy){CC-(4-pyridyl)}(2)] (1) and [Pt(tBu(2)bipy){CC-(4-pyridyl)}(2)] (2) and [Pt(tBu(2)-bipy)(CC-phen)(2)] (3) all contain a Pt(bipy)(diacetylide) core with pendant 4-pyridyl (1 and 2) or phenanthroline (3) units which can be coordinated to {Ln(diketonate)(3)} fragments (Ln = a lanthanide) to make covalently-linked Pt(II)/Ln(III) polynuclear assemblies in which the Pt(II) chromophore, absorbing in the visible region, can be used to sensitise near-infrared luminescence from the Ln(III) centres. For 1 and 2 one-dimensional coordination polymers [1Ln(tta)(3)](infinity) and [2Ln(hfac)(3)](infinity) are formed, whereas 3 forms trinuclear adducts [3{Ln(hfac)(3)}(2)] (tta=anion of thenoyl-trifluoroacetone; hfac=anion of hexafluoroacetylacetone). Complexes 1-3 show typical Pt(II)-based (3)MLCT luminescence in solution at approximately 510 nm, but in the coordination polymers [1Ln(tta)(3)](infinity) and [2Ln(hfac)(3)](infinity) the presence of stacked pairs of Pt(II) units with short PtPt distances means that the chromophores have (3)MMLCT character and emit at lower energy ( approximately 630 nm). Photophysical studies in solution and in the solid state show that the (3)MMLCT luminescence in [1Ln(tta)(3)](infinity) and [2Ln(hfac)(3)](infinity) in the solid state, and the (3)MLCT emission of [3{Ln(hfac)(3)}(2)] in solution and the solid state, is quenched by Pt-->Ln energy transfer when the lanthanide has low-energy f-f excited states which can act as energy acceptors (Ln=Yb, Nd, Er, Pr). This results in sensitised near-infrared luminescence from the Ln(III) units. The extent of quenching of the Pt(II)-based emission, and the Pt-->Ln energy-transfer rates, can vary over a wide range according to how effective each Ln(III) ion is at acting as an energy acceptor, with Yb(III) usually providing the least quenching (slowest Pt-->Ln energy transfer) and either Nd(III) or Er(III) providing the most (fastest Pt-->Ln energy transfer) according to which one has the best overlap of its f-f absorption manifold with the Pt(II)-based luminescence. 相似文献
996.
Miller TA Jeffery JC Ward MD Adams H Pope SJ Faulkner S 《Dalton transactions (Cambridge, England : 2003)》2004,(10):1524-1526
Co-crystallisation of the anionic cyanometallate chromophore [Ru(bipy)(CN)4]2- with Yb(III) provides coordination polymers or oligomers containing Ru-CN-Yb bridges; in [K(H2O)4][Yb(H2O)6][Ru(bipy)(CN)4]2.5H2O Ru-->Yb energy-transfer (k > 5 x 10(6) s(-1)) results in partial quenching of the Ru-based luminescence and sensitised near-IR luminescence from the Yb(III) unit. 相似文献
997.
Quigley C Rodríguez-Docampo Z Connon SJ 《Chemical communications (Cambridge, England)》2012,48(10):1443-1445
We report the design and evaluation of a library of chiral bifunctional organocatalysts in which the distance between the catalytically active units can be systematically varied. 相似文献
998.
Martin J. Hollamby Kieran Trickett Azmi Mohamed Stephen Cummings Rico F. Tabor Olesya Myakonkaya Sarah Gold Dr. Sarah Rogers Dr. Richard K. Heenan Dr. Julian Eastoe Prof. 《Angewandte Chemie (International ed. in English)》2009,48(27):4993-4995
Getting their feet wet : Low‐cost hydrocarbon surfactants act as fluid modifiers for supercritical carbon dioxide (scCO2). Increased terminal branching of the surfactant chains aids micelle formation (see middle picture: CO2 green), and more chains allows water to be incorporated (right, blue).
999.
A method for the room temperature copper-mediated trifluoromethylation of aryl and heteroaryl boronic acids has been developed. This protocol is amenable to normal benchtop setup and reactions typically require only 1-4 h. Proceeding under mild conditions, the method tolerates a range of functional groups, allowing access to a variety of trifluoromethylarenes. 相似文献
1000.
Burke AJ Davies SG Garner AC McCarthy TD Roberts PM Smith AD Rodriguez-Solla H Vickers RJ 《Organic & biomolecular chemistry》2004,2(9):1387-1394
Conjugate addition of lithium (S)-N-benzyl-N-alpha-methylbenzylamide to a range of alpha, beta-unsaturated Weinreb amides proceeds with high levels of diastereoselectivity (>95% de). The beta-amino Weinreb amide products may be transformed into beta-amino ketones via reactions with Grignard reagents, while treatment with DIBAL-H furnishes beta-amino aldehydes. Trapping of the aldehyde via Wadsworth-Emmons reaction and subsequent manipulation offers an efficient route to homochiral delta-amino acid derivatives and 2-substituted piperidines. The application of this methodology for the synthesis of (S)-coniine is demonstrated. 相似文献