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991.
Dr. Anna F. Staerz Marieke van Leeuwen Dr. Tatiana Priamushko Dr. Torben Saatkamp Dr. Balázs Endrődi Dr. Nina Plankensteiner Dr. Matias Jobbagy Sohrab Pahlavan Dr. Martijn J. W. Blom Dr. Csaba Janáky Dr. Serhiy Cherevko Dr. Philippe M. Vereecken 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(5):e202306503
992.
Maxwell W. Terban Alexander M. Pütz Gökcen Savasci Ute Heinemeyer Bernd Hinrichsen Philippe Desbois Robert E. Dinnebier 《Journal of polymer science. Part A, Polymer chemistry》2020,58(13):1843-1866
Investigations of the atomic structures within polyamides started over 80 years ago and continue today. These weakly ordered materials diffract X-rays poorly and typically require postprocessing to obtain idealized samples for structural studies. An important goal remains to develop techniques to study the local structure in its natural state, with atomic resolution, and with sensitivity to subtle changes due to synthesis conditions or other technologically relevant processing procedures. Here, we compare the structures of as-produced, nonoriented polyamide 6 ([C6H11NO] n) from both hydrolytic and anionic processes. A total scattering pair distribution function approach is used to elucidate information about the atomic bonding, molecular conformation, chain packing, crystallite size, and ratio of ordered to disordered domain content. The results are compared with those from standard analytical methods. 相似文献
993.
994.
Dr. Ian M. Riddlestone Philippe Weis Dr. Arthur Martens Marcel Schorpp Dr. Harald Scherer Prof. Dr. Ingo Krossing 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(45):10546-10551
Upon coordinating P4 to electron poor cyclopentadienyl-iron cations, the average P−P bond distances shrink and the respective P4 breathing mode in the Raman spectra (600 cm−1, P4, free) is blueshifted by >40 cm−1 in [CpFe(CO)(L)(η1-P4)]+ cations (L=CO or PPh3). Analysis suggests that this corresponds to an umpolung of the bonding from more phosphidic in the known, electron-rich systems to more phosphonium-like in the reported electron-poor versions. This may open new functionalization pathways for white phosphorus P4. 相似文献
995.
Dr. Adrien T. Normand Dr. Quentin Bonnin Dr. Stéphane Brandès Dr. Philippe Richard Prof. Paul Fleurat-Lessard Dr. Charles H. Devillers Cédric Balan Prof. Pierre Le Gendre Dr. Gerald Kehr Prof. Gerhard Erker 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(11):2803-2815
Tame d0 phosphidotitanocene cations stabilized with a pendant tertiary phosphane arm are reported. These compounds were obtained by one-electron oxidation of d1 precursors with [Cp2Fe][BPh4]. The electronic structure of these compounds was studied experimentally (EPR, UV/Vis, and NMR spectroscopy, X-ray diffraction analysis) and through DFT calculations. The theoretical analysis of the bonding situation by using the electron localization function (ELF) shows the presence of π-interactions between the phosphido ligand and Ti in the d0 complexes, whereas dπ–pπ repulsion prevents such interactions in the d1 complexes. In addition, CH–π interactions were observed in several complexes, both in solution and in the solid state, between the phosphido ligand and the phosphane arm. The d0 complexes were found to be light sensitive, and decompose through Ti−P bond homolysis to give TiIII species. A naked d0 phosphidotitanocene cation has been trapped by reaction with diphenylacetylene, yielding a Ti/P frustrated Lewis pair (FLP), which was found to be less reactive than a previously reported Zr analog. 相似文献
996.
Dr. Federica Arrigoni Dr. Catherine Elleouet Dr. Andrea Mele Prof. François Y. Pétillon Prof. Dr. Luca De Gioia Prof. Philippe Schollhammer Prof. Giuseppe Zampella 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(72):17536-17545
The electrochemical reduction of complexes [Fe2(CO)4(κ2-phen)(μ-xdt)] (phen=1,10-phenanthroline; xdt=pdt ( 1 ), adtiPr ( 2 )) in MeCN-[Bu4N][PF6] 0.2 m is described as a two-reduction process. DFT calculations show that 1 and its monoreduced form 1− display metal- and phenanthroline-centered frontier orbitals (LUMO and SOMO) indicating the non-innocence of the phenanthroline ligand. Two energetically close geometries were found for the doubly reduced species suggesting an intriguing influence of the phenanthroline ligand leading to the cleavage of a Fe−S bond as proposed generally for this type of complex or retaining the electron density and avoiding Fe−S cleavage. Extension of calculations to other complexes with edt, adtiPr bridge and even virtual species [Fe2(CO)4(κ2-phen)(μ-adtR)] (R=CH(CF3)2, H) or [Fe2(CO)4(κ2-phen)(μ-pdtR)] (R=CH(CF3)2, iPr) showed that the relative stability between both two-electron-reduced isomers depends on the nature of the bridge and the possibility to establish a remote anagostic interaction between the iron center {Fe(CO)3} and the group carried by the bridged-head atom of the dithiolate group. 相似文献
997.
Dr. Daniela Mélanie Delannoy López Dr. Dong Tien Tran Dr. Guillaume Viault Dr. Sofiane Dairi Dr. Philippe Alexandre Peixoto Yoan Capello Laëtitia Minder Prof. Laurent Pouységu Dr. Elisabeth Génot Dr. Carmelo Di Primo Dr. Denis Deffieux Prof. Stéphane Quideau 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(17):5498-5508
A selection of bioactive polyphenols of different structural classes, such as the ellagitannins vescalagin and vescalin, the flavanoids catechin, epicatechin, epigallocatechin gallate (EGCG), and procyanidin B2, and the stilbenoids resveratrol and piceatannol, were chemically modified to bear a biotin unit for enabling their immobilization on streptavidin-coated sensor chips. These sensor chips were used to evaluate in real time by surface plasmon resonance (SPR) the interactions of three different surface-bound polyphenolic ligands per sensor chip with various protein analytes, including human DNA topoisomerase IIα, flavonoid leucoanthocyanidin dioxygenase, B-cell lymphoma 2 apoptosis regulator protein, and bovine serum albumin. The types and levels of SPR responses unveiled major differences in the association, or lack thereof, and dissociation between a given protein analyte and different polyphenolic ligands. Thus, this multi-analysis SPR technique is a valuable methodology to rapidly screen and qualitatively compare various polyphenol–protein interactions. 相似文献
998.
Alexis Gosset Dr. Štěpánka Nováková Lachmanová Dr. Sawsen Cherraben Dr. Gildas Bertho Jérémy Forté Dr. Christian Perruchot Dr. Henri-Pierre Jacquot de Rouville Dr. Lubomír Pospíšil Dr. Magdaléna Hromadová Dr. Éric Brémond Dr. Philippe P. Lainé 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(71):17889-17899
The synergistic functioning of redox-active components that emerges from prototypical 2,2′-di(N-methylpyrid-4-ylium)-1,1′-biphenyl is described. Interestingly, even if a trans conformation of the native assembly is expected, due to electrostatic repulsion between cationic pyridinium units, we demonstrate that cis conformation is equally energy-stabilized on account of a peculiar LUMO (SupLUMO) that develops through space, encompassing the two pyridiniums in a single, made-in-one-piece, electronic entity (superelectrophoric behavior). This SupLUMO emergence, with the cis species as superelectrophore embodiment, originates in a sudden change of electronic structure. This finding is substantiated by insights from solid state (single-crystal X-ray diffraction) and solution (NOE NMR and UV-vis-NIR spectroelectrochemistry) studies, combined with electronic structure computations. Electrochemistry shows that electron transfers are so strongly correlated that two-electron reduction manifests itself as a single-step process with a large potential inversion consistent with inner creation of a carbon-carbon bond (digital simulation). Besides, absence of reductive formation of dimers is a further indication of a preferential intramolecular reactivity determined by the SupLUMO interaction (cis isomer pre-organization). The redox-gated covalent bond, serving as electron reservoir, was studied via atropisomerism of the reduction product (VT NMR study). The overall picture derived from this in-depth study of 2,2′-di(N-methylpyrid-4-ylium)-1,1′-biphenyl proves that trans and cis species are worth considered as intrinsically sharply different, that is, as doubly-electrophoric and singly-superelectrophoric switchable assemblies, beyond conformational isomerism. Most importantly, the through-space-mediated SupLUMO may come in complement of other weak interactions encountered in Supramolecular Chemistry as a tool for the design of electroactive architectures. 相似文献
999.