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111.
Cycloheptyne-dicobalt hexacarbonyl complexes, substituted by propargylic ether functions, undergo 2 + 2 + 2 cycloaddition reactions with alkynes to give tricyclic benzocycloheptanes; an all-intramolecular version of this transformation is also possible. 相似文献
112.
Dr. Bidraha Bagh Saeid Sadeh Prof. Dr. Jennifer C. Green Prof. Dr. Jens Müller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(8):2318-2327
Indium‐bridged [1]ferrocenophanes ([1]FCPs) and [1.1]ferrocenophanes ([1.1]FCPs) were synthesized from dilithioferrocene species and indium dichlorides. The reaction of Li2fc?tmeda (fc=(H4C5)2Fe) and (Mamx)InCl2 (Mamx=6‐(Me2NCH2)‐2,4‐tBu2C6H2) gave a mixture of the [1]FCP (Mamx)Infc ( 41 ), the [1.1]FCP [(Mamx)Infc]2 ( 42 ), and oligomers [(Mamx)Infc]n ( 4 n ). In a similar reaction, employing the enantiomerically pure, planar‐chiral (Sp,Sp)‐1,1′‐dibromo‐2,2′‐diisopropylferrocene ( 1 ) as a precursor for the dilithioferrocene derivative Li2fciPr2, equipped with two iPr groups in the α position, gave the inda[1]ferrocenophane 51 [(Mamx)InfciPr2] selectively. Species 51 underwent ring‐opening polymerization to give the polymer 5 n . The reaction between Li2fciPr2 and Ar′InCl2 (Ar′=2‐(Me2NCH2)C6H4) gave an inseparable mixture of the [1]FCP Ar′InfciPr2 ( 61 ) and the [1.1]FCP [Ar′InfciPr2]2 ( 62 ). Hydrogenolysis reactions (BP86/TZ2P) of the four inda[1]ferrocenophanes revealed that the structurally most distorted species ( 51 ) is also the most strained [1]FCP. 相似文献
113.
Maya Green Gad Marom Jing Li Jang‐Kyo Kim 《Macromolecular rapid communications》2008,29(14):1254-1258
The electrical conductivity of composites of exfoliated graphite nanoplatelets (GNPs), including bromine‐doped GNP, and conjugated polyacrylonitrile has been investigated. The focal point is the dual nature of the graphite nanoparticles, which exhibit both intrinsic electrical conductivity and doping capability of semi‐conductive polymers such as conjugated polyacrylonitrile to form charge‐transfer complexes. The conductivity is particularly enhanced in conjugated polyacrylonitrile composites (e.g., with 6 wt.‐% graphite nanoplatelets) where the value rises from 1 × 10−10 to 2 × 10−3 S · cm−1, which reflects jointly the conductivity of the doped semi‐conductive polymer together with the percolation‐based conductivity of the particles.
114.
Holland JP Barnard PJ Collison D Dilworth JR Edge R Green JC McInnes EJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(19):5890-5907
Detailed chemical, spectroelectrochemical and computational studies have been used to investigate the mechanism of hypoxia selectivity of a range of copper radiopharmaceuticals. A revised mechanism involving a delicate balance between cellular uptake, intracellular reduction, reoxidation, protonation and ligand dissociation is proposed. This mechanism accounts for observed differences in the reported cellular uptake and washout of related copper bis(thiosemicarbazonato) complexes. Three copper and zinc complexes have been characterised by X-ray crystallography and the redox chemistry of a series of copper complexes has been investigated by using electronic absorption and EPR spectroelectrochemistry. Time-dependent density functional theory (TD-DFT) calculations have also been used to probe the electronic structures of intermediate species and assign the electronic absorption spectra. DFT calculations also show that one-electron oxidation is ligand-based, leading to the formation of cationic triplet species. In the absence of protons, metal-centred one-electron reduction gives the reduced anionic copper(I) species, [CuIATSM](-), and for the first time it is shown that molecular oxygen can reoxidise this anion to give the neutral, lipophilic parent complexes, which can wash out of cells. The electrochemistry is pH dependent and in the presence of stronger acids both chemical and electrochemical reduction leads to quantitative and rapid dissociation of copper(I) ions from the mono- or diprotonated complexes, [CuIATSMH] and [Cu(I)ATSMH2]+. In addition, a range of protonated intermediate species have been identified at lower acid concentrations. The one-electron reduction potential, rate of reoxidation of the copper(I) anionic species and ease of protonation are dependent on the structure of the ligand, which also governs their observed behaviour in vivo. 相似文献
115.
Talib J Green C Davis KJ Urathamakul T Beck JL Aldrich-Wright JR Ralph SF 《Dalton transactions (Cambridge, England : 2003)》2008,(8):1018-1026
Electrospray ionisation mass spectrometry (ESI-MS) and circular dichroism (CD) spectroscopy were used to compare the binding of mononuclear nickel, ruthenium and platinum complexes to double stranded DNA (dsDNA) and quadruplex DNA (qDNA). CD studies provided evidence for the binding of intact complexes of all three metal ions to qDNA. ESI mass spectra of solutions containing platinum or ruthenium complexes and qDNA showed evidence for the formation of non-covalent complexes consisting of intact metal molecules bound to DNA. However, the corresponding spectra of solutions containing nickel complexes principally contained ions consisting of fragments of the initial nickel molecule bound to qDNA. In contrast ESI mass spectra of solutions containing nickel, ruthenium or platinum complexes and dsDNA only showed the presence of ions attributable to intact metal molecules bound to DNA. The fragmentation observed in mass spectral studies of solutions containing nickel complexes and qDNA is attributable to the lower thermodynamic stability of the former metal complexes relative to those containing platinum or ruthenium, as well as the slightly harsher instrumental conditions required to obtain spectra of qDNA. This conclusion is supported by the results of tandem mass spectral studies, which showed that ions consisting of intact nickel complexes bound to qDNA readily undergo fragmentation by loss of one of the ligands initially bound to the metal. The ESI-MS results also demonstrate that the binding affinity of each of the platinum and ruthenium complexes towards qDNA is significantly less than that towards dsDNA. 相似文献
116.
Sen Ye Nir Hananya Ori Green Hansen Chen Angela Qian Zhao Jiangang Shen Doron Shabat Dan Yang 《Angewandte Chemie (International ed. in English)》2020,59(34):14326-14330
Selective and sensitive molecular probes for hydrogen peroxide (H2O2), which plays diverse roles in oxidative stress and redox signaling, are urgently needed to investigate the physiological and pathological effects of H2O2. A lack of reliable tools for in vivo imaging has hampered the development of H2O2 mediated therapeutics. By combining a specific tandem Payne/Dakin reaction with a chemiluminescent scaffold, H2O2‐CL‐510 was developed as a highly selective and sensitive probe for detection of H2O2 both in vitro and in vivo. A rapid 430‐fold enhancement of chemiluminescence was triggered directly by H2O2 without any laser excitation. Arsenic trioxide induced oxidative damage in leukemia was successfully detected. In particular, cerebral ischemia‐reperfusion injury‐induced H2O2 fluxes were visualized in rat brains using H2O2‐CL‐510 , providing a new chemical tool for real‐time monitoring of H2O2 dynamics in living animals. 相似文献
117.
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119.
Adam I. Green Dr. Fruzsina Hobor Dr. Christopher P. Tinworth Dr. Stuart Warriner Prof. Andrew J. Wilson Prof. Adam Nelson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(47):10682-10689
Protein–protein interactions (PPIs) provide a rich source of potential targets for drug discovery and biomedical science research. However, the identification of structural-diverse starting points for discovery of PPI inhibitors remains a significant challenge. Activity-directed synthesis (ADS), a function-driven discovery approach, was harnessed in the discovery of the p53/hDM2 PPI. Over two rounds of ADS, 346 microscale reactions were performed, with prioritisation on the basis of the activity of the resulting product mixtures. Four distinct and novel series of PPI inhibitors were discovered that, through biophysical characterisation, were shown to have promising ligand efficiencies. It was thus shown that ADS can facilitate ligand discovery for a target that does not have a defined small-molecule binding site, and can provide distinctive starting points for the discovery of PPI inhibitors. 相似文献
120.
Luke Green Keith Livingstone Dr. Sophie Bertrand Dr. Simon Peace Dr. Craig Jamieson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(65):14866-14870
A range of 1,3,4-oxadiazoles have been synthesized using a UV-B activated flow approach starting from carboxylic acids and 5-substituted tetrazoles. The application of UV light represents an attractive alternative to the traditional thermolytic approach and has demonstrated comparable efficiency and versatility, with a diverse substrate scope, including the incorporation of highly substituted amino acids. 相似文献