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81.
The graphical unitary group approach has been applied in an efficient implementation of a general multireference configuration interaction (MRCI) method for use with small active molecular orbital spaces in a semiempirical framework. Gradients can be computed analytically for molecular orbitals from a closed-shell or a half-electron open-shell Hartree-Fock calculation. CPU times for single point energy and gradient calculations are reported. The code allows MRCI geometry optimizations of large molecules, as illustrated for the singlet ground state and the four lowest triplet states of fullerene C(76). 相似文献
82.
Andreas Christoforow Julian Wilke Aylin Binici Axel Pahl Claude Ostermann Sonja Sievers Herbert Waldmann 《Angewandte Chemie (International ed. in English)》2019,58(41):14715-14723
Natural products (NPs) inspire the design and synthesis of novel biologically relevant chemical matter, for instance through biology‐oriented synthesis (BIOS). However, BIOS is limited by the partial coverage of NP‐like chemical space by the guiding NPs. The design and synthesis of “pseudo NPs” overcomes these limitations by combining NP‐inspired strategies with fragment‐based compound design through de novo combination of NP‐derived fragments to unprecedented compound classes not accessible through biosynthesis. We describe the development and biological evaluation of pyrano‐furo‐pyridone (PFP) pseudo NPs, which combine pyridone‐ and dihydropyran NP fragments in three isomeric arrangements. Cheminformatic analysis indicates that the PFPs reside in an area of NP‐like chemical space not covered by existing NPs but rather by drugs and related compounds. Phenotypic profiling in a target‐agnostic “cell painting” assay revealed that PFPs induce formation of reactive oxygen species and are structurally novel inhibitors of mitochondrial complex I. 相似文献
83.
Marc F. Tesch Shannon A. Bonke Travis E. Jones Maryam N. Shaker Jie Xiao Katarzyna Skorupska Rik Mom Jens Melder Philipp Kurz Axel Knop‐Gericke Robert Schlgl Rosalie K. Hocking Alexandr N. Simonov 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(11):3464-3470
Manganese oxide (MnOx) electrocatalysts are examined herein by in situ soft X‐ray absorption spectroscopy (XAS) and resonant inelastic X‐ray scattering (RIXS) during the oxidation of water buffered by borate (pH 9.2) at potentials from 0.75 to 2.25 V vs. the reversible hydrogen electrode. Correlation of L‐edge XAS data with previous mechanistic studies indicates MnIV is the highest oxidation state involved in the catalytic mechanism. MnOx is transformed into birnessite at 1.45 V and does not undergo further structural phase changes. At potentials beyond this transformation, RIXS spectra show progressive enhancement of charge transfer transitions from oxygen to manganese. Theoretical analysis of these data indicates increased hybridization of the Mn?O orbitals and withdrawal of electron density from the O ligand shell. In situ XAS experiments at the O K‐edge provide complementary evidence for such a transition. This step is crucial for the formation of O2 from water. 相似文献
84.
Ali M. Abdel‐Mageed Alexander Klyushin Azita Rezvani Axel Knop‐Gericke Robert Schlgl R. Jürgen Behm 《Angewandte Chemie (International ed. in English)》2019,58(30):10325-10329
The electronic and structural properties of Au/ZnO under industrial and idealized methanol synthesis conditions have been investigated. This was achieved by kinetic measurements in combination with time‐resolved operando infrared (DRIFTS) as well as in situ near‐ambient pressure X‐ray photoelectron spectroscopy (NAP‐XPS) and X‐ray absorption near‐edge spectroscopy (XANES) measurements at the O K‐edge together with high‐resolution electron microscopy. The adsorption of CO during the reaction revealed the presence of negatively charged Au nanoparticles/Au sites during the initial phase of the reaction. Near‐ambient‐pressure XPS and XANES demonstrate the build‐up of O vacancies during the reaction, which goes along with a substantial increase in the rate of methanol formation. The results are discussed in comparison with previous findings for Cu/ZnO and Au/ZnO catalysts. 相似文献
85.
Damir A. Safin Maria G. Babashkina Axel Klein Heinrich Nöth Michael Bolte Dmitriy B. Krivolapov 《Polyhedron》2010
Reaction of the potassium salt of N-(diisopropoxyphosphoryl)-p-bromothiobenzamide p-BrC6H4C(S)NHP(O)(OiPr)2 (HL) with Cd(II) cations in freshly dried and distilled EtOH leads exclusively to the complex [Cd(p-BrC6H4C(S)NH2-S)(L-O,S)2] ([Cd(LI)L2]), while the same reaction in H2O leads to the complex [Cd(HL-O)2(L-O,S)2] ([Cd(HL)2L2]). The corresponding reactions with Zn(II) always lead to the complex [Zn(L-O,S)2] ([ZnL2]) regardless of the solvent. The crystal structure of [Cd(HL)2L2].2/3H2O reveals to be a polymorph to the previously reported anhydrous [Cd(HL)2L2]. 相似文献
86.
Banerjee K Dasgupta S Jadhav MR Naik DG Ligon AP Oulkar DP Savant RH Adsule PG 《Journal of AOAC International》2010,93(6):1957-1964
An analytical method is reported for residue analysis of the fungicide meptyldinocap in different fruit matrixes that involves extraction with ethyl acetate, hydrolysis of the residues with ethanolamine, and determination by LC/MS/MS. The method involves extraction of 10 g sample with 10 mL ethyl acetate; evaporation of the ethyl acetate phase to dryness, and subsequent hydrolysis of the residues to 4,6-dinitro-2-(1-methylheptyl) phenol on reaction with 1% ethanolamine. The pH of this hydrolyzed product was neutralized with formic acid and analyzed by LC/MS/MS. The hydrolysis reaction followed pseudo-first-order kinetics, and the reaction product was spectroscopically confirmed as 2-(1-methylheptyl)-4,6-dinitrophenol. The method offered > 80% recoveries at an LOQ of 10 ng/g for grape and mango, 25 ng/g for pomegranate with intralaboratory Horwitz ratio < 0.5, and measurement uncertainties < 10% at LOQ levels. Considering first-order rate kinetics, activation energy, enthalpy of activation, and entropy of activation varied as solvent > mango > grape > pomegranate. Free energy of activation at 298 K was higher than at 280 K and was similar for solvent and three matrixes at both temperatures. 相似文献
87.
Total synthesis of amaryllidaceae alkaloid buflavine 总被引:1,自引:0,他引:1
A concise synthesis of the amaryllidaceae alkaloid buflavine (1) and its regioisomer (2) involving sequential Meyers' biaryl coupling, enecarbamate formation, and hydrogenation followed by ultimate intramolecular reductive amination is presented. 相似文献
88.
Zapf A Jackstell R Rataboul F Riermeier T Monsees A Fuhrmann C Shaikh N Dingerdissen U Beller M 《Chemical communications (Cambridge, England)》2004,(1):38-39
A practical synthesis of a novel class of phosphine ligands, phosphino substituted N-aryl pyrroles (PAP ligands), has been developed. These ligands are applied in the palladium-catalyzed coupling of a variety of aryl and heteroaryl chlorides with phenylboronic acid showing exceedingly high turnover numbers at mild reaction temperatures and even at room temperature. 相似文献
89.
The complex generated from 1/2[Ir(OMe)(cod)]2 and 4,4'-di-tert-butyl-2,2'-bipyridine catalyzes the regioselective borylation of ferrocenes, CpMn(CO)3 and CpMo(CO)3CH3 with a stoichiometric amount of B2pin2. 相似文献
90.
Axel Schunk 《Nachrichten aus der Chemie》2004,52(11):1155-1157