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排序方式: 共有446条查询结果,搜索用时 62 毫秒
441.
Gourab Kundu Theresa Sperger Prof. Dr. Kari Rissanen Prof. Dr. Franziska Schoenebeck 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(49):22114-22118
We report a new air-stable PdI dimer, [Pd(μ-I)(PCy2tBu)]2, which triggers E-selective olefin migration to enamides and styrene derivatives in the presence of multiple functional groups and with complete tolerance of air. The same dimer also triggers extremely rapid C−C coupling (alkylation and arylation) at room temperature in a modular and triply selective fashion of aromatic C−Br, C−OTf/OFs, and C−Cl bonds in poly(pseudo)halogenated arenes, displaying superior activity over previous PdI dimer generations for substrates that bear substituents ortho to C−OTf. 相似文献
442.
Jason B. Benedict Theresa Bullard Werner Kaminsky Bart Kahr 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(11):m551-m553
The title compound, K+·[(C8H5O4)2H]−·2H2O or K+·C16H11O8−·2H2O, was prepared by slow evaporation of an aqueous solution of potassium hydrogen phthalate. The molecular complex consists of a potassium cation coordinated to a proton‐bound hydrogen phthalate dimer and two water molecules. The potassium cation resides on a twofold axis in a distorted square‐antiprism coordination geometry. The compound is isomorphous with the ammonium analogue, previously misidentified. As potassium hydrogen phthalate is frequently used in the manufacture of buffers, organic carbon standards, acidimetric standards and various other products, the crystallization of a compound with a different stoichiometery from a solution containing the acidimetric standard has important practical implications. 相似文献
443.
Alexander Okorn Arumugam Jayaraman Lukas Englert Merle Arrowsmith Theresa Swoboda Jeanette Weigelt Carina Brunecker Merlin Hess Anna Lamprecht Carsten Lenczyk Maximilian Rang Holger Braunschweig 《Chemical science》2022,13(25):7566
The classical route to the PMe3-stabilised polycyclic aromatic hydrocarbon (PAH)-substituted diborenes B2Ar2(PMe3)2 (Ar = 9-phenanthryl 7-Phen; Ar = 1-pyrenyl 7-Pyr) via the corresponding 1,2-diaryl-1,2-dimethoxydiborane(4) precursors, B2Ar2(OMe)2, is marred by the systematic decomposition of the latter to BAr(OMe)2 during reaction workup. Calculations suggest this results from the absence of a second ortho-substituent on the boron-bound aryl rings, which enables their free rotation and exposes the B–B bond to nucleophilic attack. 7-Phen and 7-Pyr are obtained by the reduction of the corresponding 1,2-diaryl-1,2-dichlorodiborane precursors, B2Ar2Cl2(PMe3)2, obtained from the SMe2 adducts, which are synthesised by direct NMe2–Cl exchange at B2Ar2(NMe2)2 with (Me2S)BCl3. The low-lying π* molecular orbitals (MOs) located on the PAH substituents of 7-Phen and 7-Pyr intercalate between the B–B-based π and π* MOs, leading to a relatively small HOMO–LUMO gap of 3.20 and 2.72 eV, respectively. Under vacuum or at high temperature 7-Phen and 7-Pyr undergo intramolecular hydroarylation of the B B bond to yield 1,2-dihydronaphtho[1,8-cd][1,2]diborole derivatives. Hydrogenation of 7-Phen, 7-Pyr and their 9-anthryl and mesityl analogues III and II, respectively, results in all cases in splitting of the B–B bond and isolation of the monoboranes (Me3P)BArH2. NMR-spectroscopic monitoring of the reactions, solid-state structures of isolated reaction intermediates and computational mechanistic analyses show that the hydrogenation of the three PAH-substituted diborenes proceeds via a different pathway to that of the dimesityldiborene. Rather than occurring exclusively at the B–B bond, hydrogenation of 7-Ar and III proceeds via a hydroarylated intermediate, which undergoes one B–B bond-centered H2 addition, followed by hydrogenation of the endocyclic B–C bond resulting from hydroarylation, making the latter effectively reversible.In contrast to classical B–B bond-centred diborene hydrogenation, polycyclic aromatic hydrocarbon-substituted diborenes first undergo thermal intramolecular hydroarylation, followed by hydrogenation of the remaining B–B and endocyclic B–C bonds. 相似文献
444.
445.
Lukas Scheibelberger Toda Stankovic Kaja Liepert Andreas Kienzle Eva-Maria Patronas Dr. Theresa Balber Prof. Dr. Markus Mitterhauser Prof. Dr. Arvand Haschemi Dr. Katharina Pallitsch 《European journal of organic chemistry》2023,26(31):e202300339
Fluorinated carbohydrates are valuable tools for enzymological studies due to their increased metabolic stability compared to their non-fluorinated analogues. Replacing different hydroxyl groups within the same monosaccharide by fluorine allows to influence a wide range of sugar–receptor interactions and enzymatic transformations. In the past, this principle was frequently used to study the metabolism of highly abundant carbohydrates, while the metabolic fate of rare sugars is still poorly studied. Rare sugars, however, are key intermediates of many metabolic routes, such as the pentose phosphate pathway (PPP). Here we present the design and purely chemical synthesis of a set of three deoxyfluorinated analogues of the rare sugars d -xylulose and d -ribulose: 1-deoxy-1-fluoro-d -ribulose ( 1DFRu ), 3-deoxy-3-fluoro-d -ribulose ( 3DFRu ) and 3-deoxy-3-fluoro-d -xylulose ( 3DFXu ). Together with a designed set of potential late-stage radio-fluorination precursors, they have the potential to become useful tools for studies on the complex equilibria of the non-oxidative PPP. 相似文献
446.
The title compounds are synthesized from the elements (flowing Ar, 1500 K for 2 min, 1300 K for 45 min, and 900 K for 2 h) and characterized by powder XRD. 相似文献