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381.
382.
An overview is presented of classic and more recent applications of liquid chromatography for the analysis of metal species. The different approaches involving ion-exchange, ion-pair, and chelation separation mechanisms are discussed as well as the new philosophy of simply removing interferents before specific detections of metal ions (alkali and alakaline earths, rare earths, heavy and transition metals). New more selective materials enabling difficult separations and studies on multimodal or hyphenated techniques for metal speciation (e.g. arsenic and chromium) are considered. 相似文献
383.
Donatella Desideri Maria Assunta Meli Carla Roselli Corrado Testa 《International journal of environmental analytical chemistry》2013,93(5):331-339
It is well known that ammunition containing depleted uranium (DU) was used by NATO during the Balkan conflict. To evaluate the DU origin (natural uranium enrichment or spent nuclear fuel reprocessing) it is necessary to check the presence of activation products (236U, 239+240Pu, 241Am, 237Np, etc.) in the ammunition. Every transuranium element (TRU) was separated from the uranium matrix by extraction chromatography with microporous polyethylene (Icorene) supporting suitable stationary phases. Plutonium was separated by tri-n-octylamine (TNOA). 241Am was separated by TNOA and di(2ethylhexylphosphoric) acid (HDEHP). Neptunium also was separated by tri-n-octylamine using different conditions. After elution, the TRU elements were electroplated and counted by alpha spectrometry. The TRU decontamination factors from uranium were higher than 106. The final chemical yields ranged from 50 to 70%. The detection limit was 1?Bq?kg?1 for 0.10?g ammunition; 239 + 240Pu and 241Am concentrations in two penetrators were 26 and 70?Bq?kg?1 and <1 and 3.4?Bq?kg?1, respectively; the 237Np concentration in one penetrator was 30.1?Bq?kg?1. The presence of these anthropogenic radionuclides in the penetrators indicates that at least part of the uranium originated from the reprocessing of nuclear fuel, although because of their very low concentrations, the radiotoxicological effect is negligible. 相似文献
384.
Gas‐phase fragmentation of γ‐lactone derivatives by electrospray ionization tandem mass spectrometry
Antonio E. M. Crotti Erika S. Bronze‐Uhle Paulo G. B. D. Nascimento Paulo M. Donate Sérgio E. Galembeck Ricardo Vessecchi Norberto P. Lopes 《Journal of mass spectrometry : JMS》2009,44(12):1733-1741
Fragmentation reactions of β‐hydroxymethyl‐, β‐acetoxymethyl‐ and β‐benzyloxymethyl‐butenolides and the corresponding γ‐butyrolactones were investigated by electrospray ionization tandem mass spectrometry (ESI‐MS/MS) using collision‐induced dissociation (CID). This study revealed that loss of H2O [M + H ?18]+ is the main fragmentation process for β‐hydroxymethylbutenolide (1) and β‐hydroxymethyl‐γ‐butyrolactone (2). Loss of ketene ([M + H ?42]+) is the major fragmentation process for protonated β‐acetoxymethyl‐γ‐butyrolactone (4), but not for β‐acetoxymethylbutenolide (3). The benzyl cation (m/z 91) is the major ion in the ESI‐MS/MS spectra of β‐benzyloxymethylbutenolide (5) and β‐benzyloxymethyl‐γ‐butyrolactone (6). The different side chain at the β‐position and the double bond presence afforded some product ions that can be important for the structural identification of each compound. The energetic aspects involved in the protonation and gas‐phase fragmentation processes were interpreted on the basis of thermochemical data obtained by computational quantum chemistry. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
385.
Joanna Anastassopoulou Evridiki Boukaki Carla Conti Paolo Ferraris Elisabetta Giorgini Corrado Rubini Simona Sabbatini Teo Theophanides Giorgio Tosi 《Vibrational Spectroscopy》2009,51(2):270-275
Microimaging Fourier transform infrared spectroscopy is able to monitor differentiation between normal and malignant tissues. All the specimens, previously submitted to histological analysis, displayed abnormal spectra compared with the corresponding normal tissues with changes in many diagnostic bands like those arising from phosphate, C–O and CH stretching vibrational modes. The comparison between cancer (K) and connective (C) spectra evidenced the following differences: in the vCH region 3000–2800 cm−1 no hypomethylation effect was evident in K; the convolution of the bands of connective indicated an expected higher membrane fluidity; in the neoplastic zone, Amide I and II modes showed convoluted bands with maxima at 1651 and 1547 cm−1, respectively, indicating an α-helix conformation of proteins due to changes in the secondary structure proteins upon carcinogenesis. Other signature bands, such as the deformation O–P–O phosphate band at 965 cm−1, suggested DNA conformational changes in solid cancer, infiltrating cancer and neoplasia in the region 1350–800 cm−1. These characteristic bands have been monitored as a function of the degree of cancer progression. Chemometric methods, such as principal component analysis (PCA) and hierarchical clustering analysis (HCA) have been used in order to distinguish spectra of neoplastic and normal zones. 相似文献
386.
Alessia Bacchi Marcella Balordi Paolo Pelagatti Corrado Pelizzi 《Journal of organometallic chemistry》2009,694(20):3281-3286
The polyfunctional (H)PNX (X = O or N) ligands 1 and 2 react with [Rh(CO)2Cl]2 to give the corresponding chloro carbonyl complexes {Rh[κ2-(H)PN](CO)Cl} (1a and 2a), where the neutral ligands coordinate in a κ2-PN bidentate fashion, the square planar coordination being completed by the CO trans to N and the chloride trans to P. In chloroform solution 1a maintains its original structure, while 2a partially transforms into the cationic species {Rh[κ3-(H)PNO](CO)}Cl. The chloroform solutions of 1a and 2a react with AgPF6 to give the purely cationic species {Rh[κ3-(H)PNO](CO)}PF6 ([1a]+ and [2a]+), while addition of Et3N originates the neutral species {Rh[κ3-PNN′](CO)} (1b and 2b). All the complexes have been characterized by microanalysis, IR, 1H NMR as well as 31P{1H} NMR spectroscopy. The X-ray structures of ligand 1 and complex 1b are also reported. 相似文献
387.
María C. Rodríguez-Argüelles Roberto Cao Ana M. García-Deibe Corrado Pelizzi Jesús Sanmartín-Matalobos Franca Zani 《Polyhedron》2009
Cobalt(II), nickel(II), copper(II) and zinc(II) complexes of 2-thiophenecarbonyl hydrazone of 3-isatin (H2L1) and 2-furoic hydrazones of 3-isatin (H2L2) and 3-(N-methyl)isatin (HL3), with general composition [M(L)2] · nX, where X is ethanol or/and water, were synthesised and characterised. The molecular structure of HL3 showed that it crystallised in the keto form, which is also the more abundant tautomer for the three hydrazone ligands in solution. The three ligands behave as κ2-O,N donors in the cobalt(II) and zinc(II) complexes. The X-ray crystal structure of pseudotetrahedral [Zn(HL1)2] · 1.75MeOH confirmed the O,N coordination mode of the two monodeprotonated ligands in their keto forms. Secondary interactions of zinc ions with the O atoms of each isatin keto residue provoke a substantial distortion towards a square pyramidal form. The interaction of the isatin keto residues is stronger in the three nickel(II) complexes where the three acylhydrazones can be considered as κ3-O,N,O donors. 相似文献
388.
Soldatova AV Kim J Rizzoli C Kenney ME Rodgers MA Rosa A Ricciardi G 《Inorganic chemistry》2011,50(3):1135-1149
The structural, optical, and photophysical properties of 1,4,8,11,15,18,22,25-octabutoxyphthalocyaninato-palladium(II), PdPc(OBu)(8), and the newly synthesized platinum analogue PtPc(OBu)(8) are investigated combining X-ray crystallography, static and transient absorption spectroscopy, and relativistic zeroth-order regular approximation (ZORA) Density Functional Theory (DFT)/Time Dependent DFT (TDDFT) calculations where spin-orbit coupling (SOC) effects are explicitly considered. The results are compared to those previously reported for NiPc(OBu)(8) (J. Phys. Chem. A 2005, 109, 2078) in an effort to highlight the effect of the central metal on the structural and photophysical properties of the group 10 transition metal octabutoxyphthalocyanines. Different from the nickel analogue, PdPc(OBu)(8) and PtPc(OBu)(8) show a modest and irregular saddling distortion of the macrocycle, but share with the first member of the group similar UV-vis spectra, with the deep red and intense Q-band absorption experiencing a blue shift down the group, as observed in virtually all tetrapyrrolic complexes of this triad. The blue shift of the Q-band along the MPc(OBu)(8) (M = Ni, Pd, Pt) series is interpreted on the basis of the metal-induced electronic structure changes. Besides the intense deep red absorption, the title complexes exhibit a distinct near-infrared (NIR) absorption due to a transition to the double-group 1E (π,π*) state, which is dominated by the lowest single-group (3)E (π,π*) state. Unlike NiPc(OBu)(8), which is nonluminescent, PdPc(OBu)(8) and PtPc(OBu)(8) show both deep red fluorescence emission and NIR phosphorescence emission. Transient absorption experiments and relativistic spin-orbit TDDFT calculations consistently indicate that fluorescence and phosphorescence emissions occur from the S(1)(π,π*) and T(1)(π,π*) states, respectively, the latter being directly populated from the former, and the triplet state decays directly to the S(0) surface (the triplet lifetime in deaerated benzene solution was 3.04 μs for Pd and 0.55 μs for Pt). Owing to their triplet properties, PdPc(OBu)(8) and PtPc(OBu)(8) have potential for use in photodynamic therapy (PDT) and are potential candidates for NIR light emitting diodes or NIR emitting probes. 相似文献
389.
D Sadhukhan C Rizzoli E Garribba CJ Gómez-García A Yahia-Ammar LJ Charbonnière S Mitra 《Dalton transactions (Cambridge, England : 2003)》2012,41(38):11565-11568
A mixed valent copper complex [Cu(II)Cu(I)(L)(μ-SCN)(μ(3)-SCN)](n) (LH = N'-((pyridin-2-yl)methylene)acetohydrazide) has been synthesized and characterized. It is a unique example of a 2D mixed valent Cu(II)-Cu(I) interlinked molecular assembly with a very unusual bridging property of the hydrazone ligand. An extraordinary in situ partial Cu(II)→ Cu(I) reduction is observed in this system at room temperature. 相似文献
390.
Corrado Di Natale Marco Santonico Roberto Paolesse Daniel Filippini Arnaldo D’Amico Ingemar Lundström 《Analytical and bioanalytical chemistry》2010,397(2):613-621
Interest in the use of the optical properties of chemical indicators is growing steadily. Among the optical methods that can
be used to capture changes in sensing layers, those producing images of large-area devices are particularly interesting for
chemical sensor array development. Until now, few studies addressed the characterization of image sensors from the point of
view of their chemical sensor application. In this paper, a method to evaluate such performance is proposed. It is based on
the simultaneous measurement of absorption events in a metalloporphyrin layer with an image sensor and a quartz microbalance
(QMB). Exploiting the well-known behaviour of QMB, comparison of signals enables estimation of the minimum amount of absorbed
molecules that the image sensor can detect. Results indicate that at the single pixel level a standard image sensor (for example
a webcam) can easily detect femtomoles of absorbed molecules. It should therefore be possible to design sensor arrays in which
the pixels of images of large-area sensing layers are regarded as individual chemical sensors providing a ready and simple
method for large sensor array development. 相似文献