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981.
982.
Mulligan A Lane I Rousseau GB Johnston SM Lennon D Kadodwala M 《The journal of physical chemistry. B》2006,110(2):1083-1090
Naturally occurring metal surfaces possess planes of mirror symmetry on the nanometer-length scale. This mirror symmetry can be lifted and chirality "physically" conveyed onto a surface by adsorbing a chiral molecule. Until now, it has not been known whether the conveying of chirality is limited to just the physical structure or whether it goes deeper and permeates the electronic structure of the underlying surface. By using optically active second harmonic generation (OA-SHG), it is demonstrated that the adsorption of some, but not all, chiral molecules can reversibly, and without significant structural rearrangement, measurably lift the mirror symmetry of the surface electronic structure of a metal. It is proposed that the ability of a chiral molecule to place a significant "chiral perturbation" on the electronic structure of a surface is correlated to its adsorption geometry. The microscopic origins of the observed optical activity are also discussed in terms of classical models of chirality. The results of the study challenge current models of how chiral adsorbates induce enantioselectivity in the chemical/physical behavior of heterogeneous systems, which are based on geometric/stereochemical arguments, by suggesting that chiral electronic perturbations could play a role. 相似文献
983.
984.
Sushko I Novotarskyi S Körner R Pandey AK Cherkasov A Li J Gramatica P Hansen K Schroeter T Müller KR Xi L Liu H Yao X Öberg T Hormozdiari F Dao P Sahinalp C Todeschini R Polishchuk P Artemenko A Kuz'min V Martin TM Young DM Fourches D Muratov E Tropsha A Baskin I Horvath D Marcou G Muller C Varnek A Prokopenko VV Tetko IV 《Journal of chemical information and modeling》2010,50(12):2094-2111
The estimation of accuracy and applicability of QSAR and QSPR models for biological and physicochemical properties represents a critical problem. The developed parameter of "distance to model" (DM) is defined as a metric of similarity between the training and test set compounds that have been subjected to QSAR/QSPR modeling. In our previous work, we demonstrated the utility and optimal performance of DM metrics that have been based on the standard deviation within an ensemble of QSAR models. The current study applies such analysis to 30 QSAR models for the Ames mutagenicity data set that were previously reported within the 2009 QSAR challenge. We demonstrate that the DMs based on an ensemble (consensus) model provide systematically better performance than other DMs. The presented approach identifies 30-60% of compounds having an accuracy of prediction similar to the interlaboratory accuracy of the Ames test, which is estimated to be 90%. Thus, the in silico predictions can be used to halve the cost of experimental measurements by providing a similar prediction accuracy. The developed model has been made publicly available at http://ochem.eu/models/1 . 相似文献
985.
The synthesis of CoII, NiII, CuII and CdII complexes of 2-furfural 4-phenyl semicarbazone (FPSC) with stoichiometric formulae: [M(FPSC)2X2] (M = Co, Ni or Cu; X = Cl or Br), [CuCl2(FPSC)] and [(CdCl2)2(FPSC)] has been obtained for the first time. The complexes were characterized by elemental analysis, molar conductivity, magnetic measurements, i.r., far i.r. and electronic spectra. FPSC is deduced to act as a bidentate ligand in the CoII, NiII and CuII complexes and as a tetradentate one in [(CdCl2)2(FPSC)]. 相似文献
986.
Dr. Denis Frath Dr. Julien Massue Dr. Gilles Ulrich Dr. Raymond Ziessel 《Angewandte Chemie (International ed. in English)》2014,53(9):2290-2310
Multidisciplinary research on novel organic luminescent dyes is propelled by potential applications in plastic electronics and biomedical sciences. The construction of sophisticated fluorescent dyes around a tetrahedral boron(III) center is a particular approach that has fueled the creativity of chemists. Success in this enterprise has been readily achieved with simple synthetic protocols, the products of which display unusual spectroscopic behavior. This account is a critical review of recent advances in the field of boron(III) complexes (excluding BODIPYs and acetylacetonate boron complexes) involving species displaying similar coordination features, and we outline their potential development in several disciplines. 相似文献
987.
Audrey Cassen Yann Gloaguen Laure Vendier Carine Duhayon Amalia Poblador‐Bahamonde Christophe Raynaud Eric Clot Gilles Alcaraz Sylviane Sabo‐Etienne 《Angewandte Chemie (International ed. in English)》2014,53(29):7569-7573
Tuning the nature of the linker in a L~BHR phosphinoborane compound led to the isolation of a ruthenium complex stabilized by two adjacent, δ‐C? H and ε‐Bsp2? H, agostic interactions. Such a unique coordination mode stabilizes a 14‐electron “RuH2P2” fragment through connected σ‐bonds of different polarity, and affords selective B? H, C? H, and B? C bond activation as illustrated by reactivity studies with H2 and boranes. 相似文献
988.
Gilles Olive Dianne D. Ellis Didier Siri Franois Le Moigne Martin Lutz Anthony L. Spek Paul Tordo Jean‐Pierre Reboul 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):720-722
The title compound, C4H11NO6P2, reveals a two‐dimensional network of P—O—H?O=P and N—H?O=P hydrogen‐bond interactions, forming molecular slabs parallel with the (010) plane. One O—H?O interaction is distinct within these sets: whilst forming the shortest intermolecular hydrogen bond, it possesses a short P—O(H) bond of 1.5291 (10) Å. Weak C—H?O contacts link individual stacks to produce a three‐dimensional array. The compound is zwitterionic: one H atom from a P—O—H group has transferred to the pyrrolidine ring N atom. 相似文献
989.
M. Hassan Khodabandeh Hamid Reisi Dr. Mehdi D. Davari Prof. Karim Zare Prof. Mansour Zahedi Prof. Gilles Ohanessian 《Chemphyschem》2013,14(8):1733-1745
Manganese is involved as a cofactor in the activation of numerous enzymes as well as the oxygen‐evolving complex of photosystem II. Full understanding of the role played by the Mn2+ ion requires detailed knowledge of the interaction modes and energies of manganese with its various environments, a knowledge that is far from complete. To bring detailed insight into the local interactions of Mn in metallopeptides and proteins, theoretical studies employing first‐principles quantum mechanical calculations are carried out on [Mn‐amino acid]2+ complexes involving all 20 natural α‐amino acids (AAs). Detailed investigation of [Mn‐serine]2+, [Mn‐cysteine]2+, [Mn‐phenylalanine]2+, [Mn‐tyrosine]2+, and [Mn‐tryptophan]2+ indicates that with an electron‐rich side chain, the most stable species involves interaction of Mn2+ with carbonyl oxygen, amino nitrogen, and an electron‐rich section of the side chain of the AA in its canonical form. This is in sharp contrast with aliphatic side chains for which a salt bridge is formed. For aromatic AAs, complexation to manganese leads to partial oxidation as well as aromaticity reduction. Despite multisite binding, AAs do not generate strong enough ligand fields to switch the metal to a low‐ or even intermediate‐spin ground state. The affinities of Mn2+ for all AAs are reported at the B3LYP and CCSD(T) levels of theory, thereby providing the first complete series of affinities for a divalent metal ion. The trends are compared with those of other cations for which affinities of all AAs have been previously obtained. 相似文献
990.
Gloaguen Y Alcaraz G Petit AS Clot E Coppel Y Vendier L Sabo-Etienne S 《Journal of the American Chemical Society》2011,133(43):17232-17238
The reactivity of the (o-phosphinophenyl)(amino)borane compound HB(N(i)Pr(2))C(6)H(4)(o-PPh(2)) prepared from Li(C(6)H(4))PPh(2) and HBCl(N(i)Pr(2)) toward the bis(dihydrogen) complex RuH(2)(H(2))(2)(PCy(3))(2) (1) was studied by a combination of DFT, X-ray, and multinuclear NMR techniques including solid-state NMR, a technique rarely employed in organometallic chemistry. The study showed that the complex RuH(2){HB(N(i)Pr(2))C(6)H(4)(o-PPh(2))}(PCy(3))(2) (3), isolated in excellent yield as yellow crystals and characterized by X-ray diffraction, led in solution to PCy(3) dissociation and formation of an unsaturated 16-electron complex RuH(2){HB(N(i)Pr(2))C(6)H(4)(o-PPh(2))}(PCy(3)) (4), with a hydride trans to a vacant site. In both cases, the (phosphinoaryl)(amino)borane acts as a bifunctional ligand through the phosphine moiety and a Ru-H-B interaction, thus featuring an agostic interaction. 相似文献