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551.
Mehmet Nail NasirFrançoise Besson 《Journal of colloid and interface science》2012,387(1):187-193
Bacillomycin D is a natural antimicrobial lipopeptide belonging to the iturin family. It is produced by Bacillus subtilis strains. Bacillomycin D is characterized by its strong antifungal and hemolytic properties, due to its interaction with the plasma membrane of sensitive cells. Until now, only few limited analyses were conducted to understand the biological activities of bacillomycin D at the molecular level. Our purpose was to analyze the conformation of bacillomycin D using IR spectroscopy and to model its interactions with cytoplasmic membranes using Langmuir interfacial monolayers. Our findings indicate that bacillomycin D contains turns and allow to model its three-dimensional structure. Bacillomycin D formed a monolayer film at the air-water interface and kept its turn conformation, as shown by polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS). To identify the membrane lipid target of bacillomycin D, its interactions with pure lipid monolayers were analyzed and an original behavior of the lipopeptide toward cholesterol-containing monolayers was shown. This original behavior was lost when bacillomycin D was interacting with pure cholesteryl acetate monolayers, suggesting the involvement of the alcohol group of cholesterol in the lipopeptide-cholesterol interaction. 相似文献
552.
Shanshan Zhang Tao Sun Zhen Xu Tianduo Li Yang Li Qingfen Niu Haixia Liu 《Tetrahedron letters》2017,58(28):2779-2783
A novel ethynyl-linked A–π–D–π–A structured molecule DPP2Ph2 composed of biphenylene and diketopyrrolopyrrole has been designed and synthesized. A detailed study was carried out on its optical, electrochemical, electronical, and the photoinduced charge-separation properties by using UV–Vis and fluorescence spectroscopy, cyclic voltammetry, DFT calculations and fluorescence quenching experiment. The optical results display that DPP2Ph2 exhibits strong and broad absorption band covering the whole visible region and has a typical fluorescence of aggregation-caused quenching (ACQ) feature. From the data in electrochemistry and fluorescence quenching experiment, the DPP2Ph2 molecule reveals lower HOMO energy level and proper LUMO energy level to obtain efficient charge separation. These results demonstrated that DPP2Ph2 might be a promising donor material for organic solar cells. 相似文献
553.
《Journal of Coordination Chemistry》2012,65(16):2893-2902
Two new coordination polymers, [Pb(bpdc)] n (1) and [Co(bpdc)(phen)] n (2) [H2bpdc?=?benzophenone-2,4′-dicarboxylic acid, phen?=?1,10-phenanthroline], have been synthesized and structurally characterized. Hydrogen bonding and π?···?π stacking extend 1 and 2 into 3-D supramolecular architectures, where 1 exhibits a 3-D framework with 1-D hairpin-like helicates based on Pb–O covalent bonds and 2 displays a 3-D network with 1-D zipper-like chains based on Co–O and Co–N covalent bonds. The FT-IR spectra, PXRD and TG analyses are discussed for 1 and 2. Fluorescence spectra and luminescent lifetime are studied for 1. 相似文献
554.
Dr. Wiktor Zierkiewicz Dr. Rafał Wysokiński Mariusz Michalczyk Prof. Steve Scheiner 《Chemphyschem》2020,21(9):870-877
The ability of the central M atom of the MCl3− anion, with M=Be, Mg, Ca, Sr, Ba, to engage in a noncovalent bond with an approaching nucleophile is gauged by ab initio methods. The N atom of pyridine forms a M⋅⋅⋅N bond with an interaction energy between 12 and 21 kcal mol−1, even though the π-hole above the M atom is not necessarily positive in sign. Despite a strong Coulombic repulsion between two anions, CN− is also able to approach the M atom so as to engage in a metastable complex that is higher in energy than the individual anions. The energy barrier separating this complex from its constituent anion pair is roughly 20 kcal mol−1. Despite the endothermic formation reaction energy of the CN−⋅⋅⋅MCl3− complex, the electron topology signals a strong interaction, more so than in pyridine⋅⋅⋅MCl3− with its exothermic binding energy. The dianionic complex is held together largely on the strength of interorbital interactions, thereby overcoming a repulsive electrostatic component. The latter is partially alleviated by the pyramidalization of the MCl3 unit which makes its π-hole more positive. The complex sinks below the separate monomers in energy when the system is immersed in an aqueous medium, with a binding energy that varies from as much as 20 kcal mol−1 for Be down to 1.2 kcal mol−1 for Ba. 相似文献
555.
ABSTRACTCyclobis(paraquat-p-phenylene) (CBPQT4+) cyclophane represents an ideal π-electron deficient macrocycles, which demonstrates the extraordinary ability of hosting a variety of π-electron-rich guests in its rigid, preorganised cavity. However, this macrocycle undergoes large ring strain and therefore its preparation is often low yielding. In order to increase its yields, high-dilution conditions and template-directed synthesis are employed, which are rather time-consuming, i.e. a few weeks including template removal. Herein, we attempt to solve these problems by either using click reaction, or decreasing the ring strain by using a flexible linker. Three analogues of CBPQT4+ ring were synthesised without the need of guest template, each of which contains two bipyridinium units. Two of these three macrocycles are able to recognise π-electron rich guests within their cavities. However, the one obtained via click reaction demonstrates low guest recognition ability. 相似文献
556.
Dr. Anzhela Galstyan Dr. Yogesh Kumar Maurya Dr. Halina Zhylitskaya Youn Jue Bae Dr. Yi-Lin Wu Prof. Dr. Michael R. Wasielewski Prof. Dr. Tadeusz Lis Prof. Dr. Ulrich Dobrindt Prof. Dr. Marcin Stępień 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(37):8262-8266
Free base, zinc and palladium π-extended porphyrins containing fused naphthalenediamide units were employed as photosensitizers in antimicrobial photodynamic therapy (aPDT). Their efficacy, assessed by photophysical and in vitro photobiological studies on Gram-positive bacteria, was found to depend on metal coordination, showing a dramatic enhancement of photosensitizing activity for the palladium complex. 相似文献
557.
以CCSD(T)/CBS方法的结合能计算结果为标准, 选择CAM-B3LYP-D3BJ/def2-SVPD密度泛函理论方法计算了甲氧基柱[5]芳烃(MeP5)与CnH2n+2(n=1~10, 12, 14, 16) 复合物的结合能, 结果表明, 它们之间存在强烈的相互作用, 且随着烷烃分子碳链的增长而增大; 热力学函数计算结果表明, 在298.15 K, 101325 Pa下, MeP5与CnH2n+2(n=3~10, 12, 14, 16)形成复合物的过程中, ΔG和ΔH均小于零, 是焓驱动的自发过程. 烷烃与MeP5之间C―H…π和C―H…O的协同作用是主客体复合物稳定化的起因, 用二代绝对局域分子轨道能量分解(ALMO-EDA)方法分析此协同作用, 发现其中静电作用和色散作用的贡献相近, 二者加和约占总吸引的94%, 极化能和电荷转移能仅占6%. 相似文献
558.
Dr. Marte Sofie Martinsen Holmsen Dr. Ainara Nova Dr. Sigurd Øien-Ødegaard Dr. Richard H. Heyn Prof. Mats Tilset 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(4):1532-1536
A highly asymmetric AuIII η3-allyl complex has been generated by treating Au(η1-allyl)Br(tpy) (tpy=2-(p-tolyl)pyridine) with AgNTf2. The resulting η3-allyl complex has been characterized by NMR spectroscopy and X-ray crystallography. DFT calculations and variable temperature 1H NMR suggest that the allyl ligand is highly fluxional. 相似文献
559.
Ting Feng Xin Li Dr. Yuan-Yuan An Dr. Sha Bai Dr. Li-Ying Sun Yang Li Prof. Dr. Yao-Yu Wang Prof. Dr. Ying-Feng Han 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(32):13618-13622
The efficient backbone-directed self-assembly of cyclic metalla[3]catenanes by the combination of tetrachloroperylenediimide (TCPDI)-based dinuclear rhodium(III) clips and 4,4′-diazopyridine or 4,4′-dipyridylethylene ligands is realized in a single-step strategy. The topology and coordination geometry of the cyclic metalla[3]catenanes are characterized by NMR spectroscopy, ESI-TOF-MS spectrometry, UV/Vis-NIR spectroscopy, and X-ray diffraction studies. The most remarkable feature of the formed cyclic metalla[3]catenane is that it contains π-aggregates (ca. 2.6 nm) incorporating six TCPDIs. Further studies revealed that cyclic metalla[3]catenanes can be converted reversibly to their corresponding sodium adducts and precursor building blocks, respectively. This strategy opens the possibility of generating unique supramolecular structures from discrete functional π-aggregates with precise arrangements. 相似文献
560.
Development of synthetic methods for silole-containing or –fused polycyclic aromatic compounds has been in great demand. Described in this paper is an easy synthetic method for the high-efficient synthesis of chrysenosilole derivatives from silatricyclic compounds via the Mallory photocyclization reaction. It is noteworthy that those conventional transition-metal and Lewis acid catalyzed or mediated CC bond coupling reactions did not work well for this aryl-aryl coupling reaction. 相似文献