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排序方式: 共有626条查询结果,搜索用时 15 毫秒
91.
Here we report that at room temperature in acetonitrile after the reduction of the naphthalimide-site, a synthetic molecular thread undergoes a complete conformational change which makes possible an efficient conversion of chemical energy into mechanical work; such results point out the ability of the thread to act as a molecular device under electrochemical control. 相似文献
92.
93.
Lauceri R Fasciglione GF D'Urso A Marini S Purrello R Coletta M 《Journal of the American Chemical Society》2008,130(32):10476-10477
Kinetics of the porphyrin aggregation leading to a chiral memory system shows a remarkable "catalytic" effect of the noncovalent templates explaining their self-replication ability. 相似文献
94.
95.
Aragoni MC Arca M Bencini A Biagini S Blake AJ Caltagirone C Demartin F De Filippo G Devillanova FA Garau A Gloe K Isaia F Lippolis V Valtancoli B Wenzel M 《Inorganic chemistry》2008,47(18):8391-8404
Two new mixed aza-thia crowns 5-aza-2,8-dithia[9]-(2,9)-1,10-phenanthrolinophane (L(4)) and 2,8-diaza-5-thia[9]-(2,9)-1,10-phenanthrolinophane (L(7)) have been synthesized and characterized. The coordination behavior of L(4) and L(7) toward the metal ions Cu(II), Zn(II), Pb(II), Cd(II), Hg(II), and Ag(I) was studied in aqueous solution by potentiometric methods, in CD3CN/D2O 4:1 (v/v) by (1)H NMR titrations and in the solid state. The data obtained were compared with those available for the coordination behavior toward the same metal ions of structurally analogous mixed donor macrocyclic ligands L(1)-L(3), L(5), L(6): all these contain a phenanthroline subunit but have only S/O/N(aromatic) donor groups in the remaining portion of the ring and are, therefore, less water-soluble than L(4) and L(7). The complexes [Cd(NO3)2(L(5))], [Pb(L(7))](ClO4)2 x 1/2MeCN, [Pb(L(4))](ClO4)2 x MeCN, and [Cu(L(7))](ClO4)2 x 3/2MeNO2 were characterized by X-ray crystallography. The efficacy of L(1)-L(7) in competitive liquid-liquid metal ion extraction of Cu(II), Zn(II), Cd(II), Pb(II), Ag(I), and Hg(II) was assessed. In the absence of Hg(II), a clear extraction selectivity for Ag(I) was observed in all systems investigated. 相似文献
96.
In this paper, we study a capacitated facility location problem with two decision makers. One (say, the leader) decides on which subset of facilities to open and the capacity to be installed in each facility with the goal of minimizing the overall costs; the second decision maker (say, the follower), once the facilities have been designed, aims at maximizing the profit deriving from satisfying the demands of a given set of clients beyond a certain threshold imposed by the leader. The leader can foresee but cannot control the follower’s behavior. The resulting mathematical formulation is a discrete–continuous bilevel optimization problem. We propose a decomposition approach to cope with the bilevel structure of the problem and the integrality of a subset of variables under the control of the leader. Such a proposal has been tested on a set of benchmark instances available in the literature. 相似文献
97.
Single‐Face/All‐cis Arene Hydrogenation by a Supported Single‐Site d0 Organozirconium Catalyst 下载免费PDF全文
Madelyn Marie Stalzer Dr. Christopher P. Nicholas Dr. Alak Bhattacharyya Dr. Alessandro Motta Dr. Massimiliano Delferro Prof. Tobin J. Marks 《Angewandte Chemie (International ed. in English)》2016,55(17):5263-5267
The single‐site supported organozirconium catalyst Cp*ZrBz2/ZrS (Cp*=Me5C5, Bz=benzyl, ZrS=sulfated zirconia) catalyzes the single‐face/all‐cis hydrogenation of a large series of alkylated and fused arene derivatives to the corresponding all‐cis‐cyclohexanes. Kinetic/mechanistic and DFT analysis argue that stereoselection involves rapid, sequential H2 delivery to a single catalyst‐bound arene face, versus any competing intramolecular arene π‐face interchange. 相似文献
98.
Aragoni MC Arca M Devillanova FA Hursthouse MB Huth SL Isaia F Lippolis V Mancini A Soddu S Verani G 《Dalton transactions (Cambridge, England : 2003)》2007,(21):2127-2134
The reaction between the coordinatively unsaturated phosphonodithioato complex [Ni(MeOpdt)2] (1) [MeOpdt = (MeO)(4-MeOC(6)H(4))PS2-] and tptz [2,4,6-tris(2-pyridyl)-1,3,5-triazine] has been investigated. Spectrophotometric and conductometric titrations showed the formation of a neutral and an ionic species, i.e. [Ni(MeOdtp)2(tptz)] (2) and [Ni(tptz)2](MeOdtp)2 (3), in correspondence to 1 : 1 and 2 : 1 tptz : ratios, respectively. XRD studies confirmed the formation of both complexes isolated in the compounds 2.MeOH and 3.4H(2)O. In the neutral complex 2 the central Ni(II) ion features a distorted octahedral coordination, achieved through three N-atoms of tptz and three S-atoms belonging to two MeOpdt anions, one of which unexpectedly acts as a monodentate S-donor. In 3.4H(2)O, the two phosphonodithioato anions are non-coordinating and counterbalance the charge of the [Ni(tptz)2](2+) distorted octahedral complex. From the reaction 2 of with I2 and Br2, crystals of [Ni(tptz)2](I3)2 (5) and [Ni(tptz)Br(micro-Br)]2 (6) have been obtained. The dinuclear complex 6 features a structure showing tubular canals with openings of about 6 x 6 A. 相似文献
99.
100.
Stoliar P Kshirsagar R Massi M Annibale P Albonetti C de Leeuw DM Biscarini F 《Journal of the American Chemical Society》2007,129(20):6477-6484
We investigate the role of self-assembly monolayers in modulating the response of organic field-effect transistors. Alkanethiol monolayers of chain length n are self-assembled on the source and drain electrodes of pentacene field-effect transistors. The charge carrier mobility mu exhibits large fluctuations correlated with odd-even n. For n < 8, mu increases by 1 order of magnitude owing to the decrease of the hole injection barrier and the improved molecular order at the organic-metallic interface. For n > or = 8, mu decays exponentially with an inverse decay length beta = 0.6 A(-1). Our results show that (i) charge injection across the interface occurs by through-bond tunneling of holes mediated by the alkanethiol layer; (ii) in the long-chain regime, the charge injection across the alkanethiol monolayer completely governs the transistor response; (iii) the transistor is a sensitive gauge for probing charge transport across single monolayers. The odd-even effect is ascribed to the anisotropic coupling between the alkanethiol terminal sigma bond and the HOMO level of ordered pentacene molecules. 相似文献