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排序方式: 共有174条查询结果,搜索用时 15 毫秒
31.
David M. Koshy Dr. Shucheng Chen Dr. Dong Un Lee Dr. Michaela Burke Stevens Ahmed M. Abdellah Samuel M. Dull Gan Chen Dr. Dennis Nordlund Dr. Alessandro Gallo Dr. Christopher Hahn Dr. Drew C. Higgins Dr. Zhenan Bao Dr. Thomas F. Jaramillo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(10):4072-4079
Ni,N-doped carbon catalysts have shown promising catalytic performance for CO2 electroreduction (CO2R) to CO; this activity has often been attributed to the presence of nitrogen-coordinated, single Ni atom active sites. However, experimentally confirming Ni−N bonding and correlating CO2 reduction (CO2R) activity to these species has remained a fundamental challenge. We synthesized polyacrylonitrile-derived Ni,N-doped carbon electrocatalysts (Ni-PACN) with a range of pyrolysis temperatures and Ni loadings and correlated their electrochemical activity with extensive physiochemical characterization to rigorously address the origin of activity in these materials. We found that the CO2R to CO partial current density increased with increased Ni content before plateauing at 2 wt % which suggests a dispersed Ni active site. These dispersed active sites were investigated by hard and soft X-ray spectroscopy, which revealed that pyrrolic nitrogen ligands selectively bind Ni atoms in a distorted square-planar geometry that strongly resembles the active sites of molecular metal–porphyrin catalysts. 相似文献
32.
Samir Meskaldji Abdellah Zaiter Lotfi Belkhiri Abdou Boucekkine 《Theoretical chemistry accounts》2012,131(3):1151
Magnetic exchange couplings in bis(ketimide) binuclear UIV/UIV complexes [Cp′2UCl]2(μ-ketimide) diuranium(IV) and [(C5H5)2(Cl)An]2(μ-ketimide) (Cp′ = C5Me4Et; ketimide = N=CMe-(C6H4)-MeC=N) have been investigated computationally using relativistic density functional theory (DFT) combined with the broken
symmetry (BS) approach. Using the B3LYP hybrid functional, the BS ground state of these UIV/UIV 5f
2–5f
2 complexes has been found of lower energy than the high spin (HS) quintet state, indicating an antiferromagnetic character
(estimated coupling constant |J| < 5 cm−1) which has not yet been evidenced unambiguously experimentally. On the contrary, the BP86 GGA functional overestimates greatly
the antiferromagnetic character of the complexes (|J| > 100 cm−1). As recently reported for para-bis(imido) [(C5H5)3U]2(μ-imido) uranium(V) complex, spin polarization is mainly responsible for the antiferromagnetic coupling through the π-network
orbital pathway within the bis(ketimide) bridge. Furthermore, spin polarization is exalted by the combined roles of the 5f metal orbitals and of the π-conjugated ketimide bridging ligand which permit electronic communication between the two uranium
atoms albeit separated by a distance of the order of 10 ?. The MO analysis clarifies which MOs contribute to the antiferromagnetic
coupling in the binuclear complexes under consideration and brings to light the 5f orbitals driving contribution. 相似文献
33.
Abdellah Bahmani Mayouf Sellami Noureddine Bettahar 《Journal of Thermal Analysis and Calorimetry》2012,107(3):955-962
Bismuth mixed oxide powders were prepared by oxalate coprecipitation process. The thermal decomposition behaviour of the coprecipitate
precursors has been followed by thermal analysis (TG-DTA) and FTIR spectroscopy. During the decomposition of the precursor,
several intermediates species were detected and a mechanism of formation of mixed oxide by this method is proposed. After
the thermal treatment, the precursor obtained of suggested formula Ca3[Bi6O6(C2O4)4(OH)3NO3]0.5H2O, has led to the formation of CaBi2O4 at shorter reaction time than the traditional ceramic method. In order to consolidate the results, the coprecipitation in
absence of oxalic precipitant under the same conditions was examined. XRD and scanning electron spectroscopy were used to
study particles sizes and morphology. 相似文献
34.
Maxwell D. Cummings Tse‐I Lin Lili Hu Abdellah Tahri David McGowan Katie Amssoms Stefaan Last Benoit Devogelaere Marie‐Claude Rouan Leen Vijgen Jan Martin Berke Pascale Dehertogh Els Fransen Erna Cleiren Liesbet vanderHelm Gregory Fanning Kristof VanEmelen Origne Nyanguile Kenny Simmen Pierre Raboisson Sandrine Vendeville 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2012,124(19):4715-4718
35.
Abdellah Sebbar 《Proceedings of the American Mathematical Society》2001,129(9):2517-2527
We study and classify all torsion-free genus zero congruence subgroups of the modular group.
36.
Mustapha Aitali Larbi El Firdoussi Abdellah Karim Alejandro F. Barrero Miguel Quirs 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(9):1088-1089
The title compound, [(S)‐2‐(anilinomethyl)pyrrolidine‐N,N′]‐chloro(η6‐para‐cymene)ruthenium(II) chloride, [RuCl‐(C10H14)(C11H16N2)]Cl, has been synthesized by the reaction of [RuCl2(p‐cymene)]2 (p‐cymene is para‐isopropyltoluene) with (S)‐2‐(anilinomethyl)pyrrolidine in triethylamine/2‐propanol. The Ru atom is in a pseudo‐tetrahedral environment coordinated by a chloride ligand, the aromatic hydrocarbon is linked in a η6 manner and the amine is linked via its two N atoms. The chloride anion is involved in hydrogen bonding with the diamine moieties through N—H?Cl interactions, with N?Cl distances of 3.273 (4) and 3.352 (4) Å. 相似文献
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